Editing Amphetamine (section)

===Pharmacodynamics===
{{For|a simpler and less technical explanation of amphetamine's mechanism of action|Adderall#Mechanism of action}}
{{Amphetamine pharmacodynamics}}
Amphetamine exerts its behavioral effects by altering the use of [[monoamines]] as neuronal signals in the brain, primarily in [[catecholamine]] neurons in the reward and executive function pathways of the brain.<ref name="Miller" /><ref name="cognition enhancers" /> The concentrations of the main neurotransmitters involved in reward circuitry and executive functioning, dopamine and norepinephrine, increase dramatically in a dose-dependent manner by amphetamine because of its effects on [[monoamine transporter]]s.<ref name="Miller" /><ref name="cognition enhancers" /><ref name="E Weihe" /> The [[reinforcement|reinforcing]] and [[motivational salience]]-promoting effects of amphetamine are due mostly to enhanced dopaminergic activity in the [[mesolimbic pathway]].<ref name="Malenka_2009" /> The [[euphoric]] and locomotor-stimulating effects of amphetamine are dependent upon the magnitude and speed by which it increases synaptic dopamine and norepinephrine concentrations in the [[striatum]].<ref name="Amph Uses" />

Amphetamine potentiates monoaminergic neurotransmission by entering the presynaptic neuron both as a substrate for monoamine transporters ([[Dopamine transporter|DAT]], [[Norepinephrine|NET]], and, [[Serotonin transporter|SERT]]) and by passive diffusion across the [[neuronal membrane]].<ref name="Stahl2021">{{Cite book |title=Stahl's essential psychopharmacology: neuroscientific basis and practical applications |vauthors=Stahl SM |publisher=Cambridge University Press |year=2021 |isbn=9781108975292 |edition=5th |location=Cambridge |pages=471–73 |quote=Unlike methylphenidate and reuptake blocking drugs used for depression, amphetamine is a competitive inhibitor and pseudosubstrate for NETs and DATs (Figure 11-32, top left), binding at the same site that the monoamines bind to the transporters, thus inhibiting NE and DA reuptake. At the doses of amphetamine used for the treatment of ADHD, the clinical differences between the actions of amphetamine versus methylphenidate can be relatively small. However, at the high doses of amphetamine used by stimulant addicts, additional pharmacological actions of amphetamine are triggered.&nbsp;...<br /> Once there in sufficient quantities, such as occurs at doses taken for abuse, amphetamine is also a competitive inhibitor of the vesicular transporter (VMAT2) for both DA and NE. Once amphetamine hitch-hikes another ride into synaptic vesicles, it displaces DA there, causing a flood of DA release. As DA accumulates in the cytoplasm of the presynaptic neuron, it causes the DATs to reverse directions, spilling intracellular DA into the synapse, and also opening presynaptic channels to further release DA in a flood into the synapse. These pharmacological actions of high-dose amphetamine are not linked to therapeutic action in ADHD but to reinforcement, reward, and euphoria in amphetamine abuse. &nbsp;...<br /> The D-isomer of amphetamine is more potent than the L-isomer for DAT binding, but D- and L- amphetamine isomers are more equally potent in their actions on NET binding. Thus, D-amphetamine preparations will have relatively more action on DATs at lower therapeutic doses utilized for the treatment of ADHD.}}</ref><ref name="handbook2022_DAT">{{Cite book |title=Handbook of Substance Misuse and Addictions |vauthors=Tendilla-Beltran H, Arroyo-García LE, Flores G |publisher=Springer International Publishing |year=2022 |isbn=978-3-030-92391-4 |veditors=Patel VB, Preedy VR |location=Cham |pages=2176–2177 |chapter=Chapter 102: Amphetamine and the Biology of Neuronal Morphology |doi=10.1007/978-3-030-92392-1 |quote=At low concentrations, amphetamines (extracellular) and dopamine (intracellular) are interchanged as described by the exchange diffusion model&nbsp;... Amphetamines can also increase dopaminergic transmission by channel-like transport which involves second-messenger signaling. Amphetamines increase PKC activity, which increase DAT N-terminus domain phosphorylation, and consequently DAT activity, which, because of the amphetamines, will release dopamine from the presynaptic terminal.&nbsp; PKC and CaMKIIα-mediated reverse transport have also been demonstrated in NET&nbsp;...<br /> Also, amphetamines can indirectly enhance monoaminergic neurotransmission through the stimulation of trace amine-associated receptor 1 (TAAR1) (Underhill et al. 2021). TAAR1 is an intracellular G protein-coupled receptor (GPCR), which has activity that promotes the endocytosis of both DAT and the excitatory amino acid transporter 3 (EAAT3). DAT endocytosis, together with the aforementioned mechanisms, contributes to the enhancement of the dopaminergic neurotransmission.&nbsp;... <br /> It is important to note that amphetamines also stimulate protein kinase A (PKA) activity, which in turn inhibits RhoA activity and consequently reduces DAT internalization.}}</ref> Transporter-mediated uptake competes with reabsorption of [[endogenous]] neurotransmitters from the synaptic cleft and produces competitive [[Reuptake inhibitor|reuptake inhibition]] as a consequence.<ref name="Stahl2021" /> Once inside the neuronal [[cytosol]], amphetamine initiates intracellular [[Biochemical cascade|signaling cascades]] that activate [[protein kinase C]] (PKC), leading to [[phosphorylation]] of DAT, NET, and SERT.<ref name="handbook2022_DAT" /> PKC-dependent phosphorylation of monoamine transporters can either reverse their direction to induce efflux of cytosolic neurotransmitters into the synaptic cleft, or trigger the withdrawal of transporters into the presynaptic neuron ([[Endocytosis|internalization]]), thereby ceasing their reuptake function in a non-competitive manner.<ref name="handbook2022_DAT" /><ref name="Kinase-dependent transporter regulation review" /> Amphetamine also causes a rise in [[Calcium in biology|intracellular calcium]], an effect associated with transporter phosphorylation through a [[Ca2+/calmodulin-dependent protein kinase II alpha|Ca²⁺/calmodulin-dependent protein kinase II alpha]] (CaMKIIα) signaling cascade.<ref name="handbook2022_DAT" /> Unlike PKC, CaMKIIα-mediated transporter phosphorylation appears to reverse the direction of DAT and NET without triggering internalization.<ref name="handbook2022_DAT" /><ref name="2020_Reith">{{cite journal |vauthors=Reith ME, Gnegy ME |date=2020 |title=Molecular Mechanisms of Amphetamines |journal=Handbook of Experimental Pharmacology |volume=258 |pages=265–297 |doi=10.1007/164_2019_251 |pmid=31286212 |isbn=978-3-030-33678-3 |quote=At lower doses, amphetamine preferentially releases a newly synthesized pool of DA. Administration of the tyrosine hydroxylase inhibitor α-methyl-para-tyrosine (AMPT) simultaneously with amphetamine blocks the DA-releasing effect of amphetamine (Smith 1963; Weissman et al. 1966; Chiueh and Moore 1975; Butcher et al. 1988).&nbsp;...<br /> Undoubtedly vesicles contribute strongly to the maximal DA released by amphetamine, although VMAT2 is not absolutely required for amphetamine to release DA from nerve terminals (Pifl et al. 1995; Fon et al. 1997; Wang et al. 1997; Patel et al. 2003).&nbsp;...<br /> However, the study in rat PC12 cells and hDAT-HEK293 cells demonstrated some involvement of extracellular Ca2+ (effect of nisoxetine or removal of extracellular Ca2+) and as well as of Ca2+ stores in the endoplasmic reticulum (blockade by thapsigargin) (Gnegy et al. 2004).&nbsp;...<br /> The increase in intracellular Ca2+ stimulated by amphetamine activates two major modulators of amphetamine action: protein kinase C (PKC) and Ca2+ and calmodulin-stimulated protein kinase II (CaMKII).}}</ref>

Amphetamine has been identified as a [[full agonist]] of [[TAAR1|trace amine-associated receptor 1]] (TAAR1), a {{nowrap|[[Gs alpha subunit|G<sub>s</sub>-coupled]]}} and {{nowrap|[[Gq alpha subunit|G<sub>q</sub>-coupled]]}} [[G protein-coupled receptor]] (GPCR) discovered in 2001, which is important for regulation of brain monoamines.<ref name="Miller" /> Several reviews have linked amphetamine’s agonism at TAAR1 to modulation of monoamine transporter function and subsequent neurotransmitter efflux and reuptake inhibition at monoaminergic synapses.{{#tag:ref|<ref name="Miller" /><ref name="handbook2022_DAT" /><ref name="2022 T1 LDX">{{Cite journal |vauthors=Quintero J, Gutiérrez-Casares JR, Álamo C |date=11 August 2022 |title=Molecular Characterisation of the Mechanism of Action of Stimulant Drugs Lisdexamfetamine and Methylphenidate on ADHD Neurobiology: A Review |journal=Neurology and Therapy |volume=11 |issue=4 |pages=1489–1517 |doi=10.1007/s40120-022-00392-2 |issn= |pmc=9588136 |pmid=35951288 |quote=The active form of the drug has a central nervous system stimulating activity by the primary inhibition of DAT, NET, trace amine-associated receptor 1 (TAAR1) and vesicular monoamine transporter 2 (SLC18A2), among other targets, therefore regulating the reuptake and release of catecholamines (primarily NE and DA) on the synaptic cleft.&nbsp;...<br /> LDX can also promote the increase of DA in the synaptic cleft by activating protein TAAR1, which produces the efflux of monoamine NTs, mainly DA, from storage sites on presynaptic neurons. TAAR1 activation leads to intracellular cAMP signalling that results in PKA and PKC phosphorylation and activation. This PKC activation decreases DAT1, NET1 and SERT cell surface expression, intensifying the direct blockage of monoamine transporters by LDX and improving the neurotransmission imbalance in ADHD. |doi-access=free}}</ref><ref>{{Cite journal |vauthors=Garey JD, Lusskin SI, Scialli AR |year=2020 |title=Teratogen update: Amphetamines |url=https://pubmed.ncbi.nlm.nih.gov/32755038 |journal=Birth Defects Research |volume=112 |issue=15 |pages=1171–1182 |doi=10.1002/bdr2.1774 |pmid=32755038 |quote=According to a systematic review of the literature on CNS actions of amphetamine by Faraone (2018), the primary pharmacologic effect of amphetamine is to increase central dopamine and norepinephrine activity. The trace amine-associated receptor 1 (TAAR1) is a G-coupled receptor expressed in the monoaminergic regions of the brain (Lam et al., 2018). When activated by appropriate ligands including methamphetamine, dopaminergic function is modulated (Miner, Elmore, Baumann, Phillips, & Janowsky, 2017).&nbsp;...<br /> It has long been assumed that amphetamines are indirectly acting sympathomimetic amines, with responses being due to the release of norepinephrine from sympathetic neurons (Broadley, 2010). With the discovery of TAAR in blood vessels and evidence that amphetamine binds to these receptors, it has been suggested that the vasoconstrictor effect may be due in part to this additional mechanism (Broadley, Fehler, Ford, & Kidd, 2013).}}</ref>|group="sources"|name="TAAR1 phosphorylation"}} Activation of {{abbr|TAAR1|trace amine-associated receptor 1}} increases {{abbrlink|cAMP|cyclic adenosine monophosphate}} production via [[adenylyl cyclase]] activation, which triggers [[protein kinase A]] (PKA)- and PKC-mediated transporter phosphorylation.<ref name="Miller" /><ref name="2022 T1 LDX" /><ref name="pmid114599292">{{cite journal |vauthors=Borowsky B, Adham N, Jones KA, Raddatz R, Artymyshyn R, Ogozalek KL, Durkin MM, Lakhlani PP, Bonini JA, Pathirana S, Boyle N, Pu X, Kouranova E, Lichtblau H, Ochoa FY, Branchek TA, Gerald C |date=July 2001 |title=Trace amines: identification of a family of mammalian G protein-coupled receptors |journal=Proceedings of the National Academy of Sciences |volume=98 |issue=16 |pages=8966–8971 |bibcode=2001PNAS...98.8966B |doi=10.1073/pnas.151105198 |pmc=55357 |pmid=11459929 |doi-access=free |title-link=doi}}</ref> Monoamine [[autoreceptors]] (e.g., [[D2sh|D<sub>2</sub> short]], [[Alpha-2 adrenergic receptor|presynaptic α<sub>2</sub>]], and [[5-HT1A#Autoreceptors|presynaptic 5-HT<sub>1A</sub>]]) have the opposite effect of TAAR1, and together these receptors provide a regulatory system for monoamines.<ref name="Miller" /><ref name="Miller+Grandy 2016" /><ref name="handbook2022_TAAR1">{{Cite book |title=Handbook of Substance Misuse and Addictions |vauthors=Liu J |publisher=Springer International Publishing |year=2022 |isbn=978-3-030-92391-4 |veditors=Patel VB, Preedy VR |location=Cham |pages=560–565 |chapter=Chapter 28: Trace Amine-Associated Receptor 1 and Its Links to Addictions |doi=10.1007/978-3-030-92392-1 |quote=The study further showed that amphetamine (AMPH) activated TAAR1 by interacting with G13 and GS α-subunits to increase RhoA and PKA activity, respectively (Underhill et al. 2021).&nbsp;...<br />  Using microdialysis showed that TAAR1 knockout mice showed higher AMPH-triggered dopamine, norepinephrine, and serotonin levels in the striatum (Lindemann et al. 2008; Wolinsky et al. 2007). As mentioned above, the psychostimulants amphetamines are TAAR1 agonists. These studies may suggest that amphetamines activate TAAR1 in WT animals to attenuate the behavioral responses to amphetamines.}}</ref> Notably, amphetamine and [[Trace amine|trace amines]] possess high binding affinities for TAAR1, but not for monoamine autoreceptors.<ref name="Miller" /><ref name="Miller+Grandy 2016" /> Although TAAR1 is implicated in amphetamine-induced transporter phosphorylation, the [[Magnitude (mathematics)|magnitude]] of TAAR1-mediated monoamine release in humans remains unclear.<ref name="TAAR1 phosphorylation" group="sources" /><ref name="handbook2022_TAAR1" /> Findings from studies using TAAR1 [[gene knockout]] models suggest that, despite facilitating monoamine release through [[reverse transport]], TAAR1 activation may paradoxically attenuate amphetamine’s psychostimulant effects in part by opening [[G protein-coupled inwardly rectifying potassium channels]], an action that reduces [[neuronal firing]].<ref name="Miller" /><ref name="handbook2022_TAAR1" />

Amphetamine is also a substrate for the vesicular monoamine transporters [[VMAT1]] and [[Vesicular monoamine transporter 2|VMAT2]].<ref name="Amphetamine VMAT2 pH gradient">{{cite journal | vauthors = Sulzer D, Cragg SJ, Rice ME | title = Striatal dopamine neurotransmission: regulation of release and uptake | journal =Basal Ganglia| volume = 6 | issue = 3 | pages = 123–148 | date = August 2016 | pmid = 27141430 | pmc = 4850498 | doi = 10.1016/j.baga.2016.02.001 | quote = Despite the challenges in determining synaptic vesicle pH, the proton gradient across the vesicle membrane is of fundamental importance for its function. Exposure of isolated catecholamine vesicles to protonophores collapses the pH gradient and rapidly redistributes transmitter from inside to outside the vesicle.&nbsp;... Amphetamine and its derivatives like methamphetamine are weak base compounds that are the only widely used class of drugs known to elicit transmitter release by a non-exocytic mechanism. As substrates for both DAT and VMAT, amphetamines can be taken up to the cytosol and then sequestered in vesicles, where they act to collapse the vesicular pH gradient.}}</ref><ref name="VMAT2ADHD">{{Cite journal |vauthors=Warlick Iv H, Tocci D, Prashar S, Boldt E, Khalil A, Arora S, Matthews T, Wahid T, Fernandez R, Ram D, Leon L, Arain A, Rey J, Davis K |year=2024 |title=Role of vesicular monoamine transporter-2 for treating attention deficit hyperactivity disorder: a review |url=https://pubmed.ncbi.nlm.nih.gov/39302436/ |journal=Psychopharmacology |volume=241 |issue=11 |pages=2191–2203 |doi=10.1007/s00213-024-06686-7 |pmid=39302436 |quote=Current psychopharmacology research shows that at high doses (non-therapeutic ranges), VMAT-2 can be “inhibited” by amphetamines, causing VMAT-2 vesicles to release the classical monoamines DA and NE into the axoplasm; however, this model is no longer broadly accepted. For instance, Stahl (2014) reported that VMAT-2 is not affected by amphetamines at therapeutic doses but is affected at higher doses.}}</ref> Under normal conditions, VMAT2 transports cytosolic monoamines into synaptic vesicles for storage and later [[Exocytosis|exocytotic]] release. When amphetamine accumulates in the presynaptic terminal, it collapses the vesicular pH gradient and releases vesicular monoamines into the neuronal cytosol.<ref name="Amphetamine VMAT2 pH gradient" /><ref name="VMAT2ADHD" /> These displaced monoamines expand the cytosolic pool available for reverse transport, thereby increasing the capacity for monoamine efflux beyond that achieved by amphetamine-mediated transporter phosphorylation alone.<ref name="2020_Reith" /><ref name="VMAT2ADHD" /> Although VMAT2 is recognized as a major target in amphetamine-induced monoamine release at higher doses, some reviews have challenged its relevance at therapeutic doses.<ref name="Stahl2021" /><ref name="2020_Reith" /><ref name="VMAT2ADHD" />

In addition to [[Membrane transport protein|membrane]] and [[Vesicular monoamine transporter|vesicular monoamine transporters]], amphetamine also inhibits [[SLC1A1]], [[SLC22A3]], and [[SLC22A5]].{{#tag:ref|<ref name="E Weihe" /><ref name="EAAT3">{{cite journal |vauthors=Underhill SM, Wheeler DS, Li M, Watts SD, Ingram SL, Amara SG | title = Amphetamine modulates excitatory neurotransmission through endocytosis of the glutamate transporter EAAT3 in dopamine neurons | journal =Neuron| volume = 83 | issue = 2 | pages = 404–416 | date = July 2014 | pmid = 25033183 | pmc = 4159050 | doi = 10.1016/j.neuron.2014.05.043 | quote = AMPH also increases intracellular calcium (Gnegy et al., 2004) that is associated with calmodulin/CamKII activation (Wei et al., 2007) and modulation and trafficking of the DAT (Fog et al., 2006; Sakrikar et al., 2012).&nbsp;... For example, AMPH increases extracellular glutamate in various brain regions including the striatum, VTA and NAc (Del Arco et al., 1999; Kim et al., 1981; Mora and Porras, 1993; Xue et al., 1996), but it has not been established whether this change can be explained by increased synaptic release or by reduced clearance of glutamate.&nbsp;... DHK-sensitive, EAAT2 uptake was not altered by AMPH (Figure 1A). The remaining glutamate transport in these midbrain cultures is likely mediated by EAAT3 and this component was significantly decreased by AMPH}}</ref><ref name="IUPHAR VMATs">{{cite web|title=SLC18 family of vesicular amine transporters|url=http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=193|website=IUPHAR database|publisher=International Union of Basic and Clinical Pharmacology|access-date=13 November 2015}}</ref><ref name="SLC1A1">{{cite web | title=SLC1A1 solute carrier family 1 (neuronal/epithelial high affinity glutamate transporter, system Xag), member 1 [ Homo sapiens (human) ] | url=https://www.ncbi.nlm.nih.gov/gene/6505 | website=NCBI Gene | publisher=United States National Library of Medicine&nbsp;– National Center for Biotechnology Information | access-date=11 November 2014 | quote = Amphetamine modulates excitatory neurotransmission through endocytosis of the glutamate transporter EAAT3 in dopamine neurons.&nbsp;... internalization of EAAT3 triggered by amphetamine increases glutamatergic signaling and thus contributes to the effects of amphetamine on neurotransmission.}}</ref><ref name="SLC22A3">{{cite journal |vauthors=Zhu HJ, Appel DI, Gründemann D, Markowitz JS | title = Interaction of organic cation transporter 3 (SLC22A3) and amphetamine | journal =Journal of Neurochemistry| volume = 114 | issue = 1 | pages = 142–149 |date=July 2010 | pmid = 20402963 | pmc = 3775896 | doi = 10.1111/j.1471-4159.2010.06738.x}}</ref><ref name="SLC22A5">{{cite journal |vauthors=Rytting E, Audus KL | s2cid = 31465243 | title = Novel organic cation transporter 2-mediated carnitine uptake in placental choriocarcinoma (BeWo) cells | journal =Journal of Pharmacology and Experimental Therapeutics| volume = 312 | issue = 1 | pages = 192–198 |date=January 2005 | pmid = 15316089 | doi = 10.1124/jpet.104.072363}}</ref><ref name="pmid13677912">{{cite journal |vauthors=Inazu M, Takeda H, Matsumiya T | title = [The role of glial monoamine transporters in the central nervous system] | language = ja | journal =Nihon Shinkei Seishin Yakurigaku Zasshi | volume = 23 | issue = 4 | pages = 171–178 |date=August 2003 | pmid = 13677912}}</ref>|group="sources"|name="Reuptake inhibition"}} SLC1A1 is [[excitatory amino acid transporter 3]] (EAAT3), a glutamate transporter located in neurons, SLC22A3 is an extraneuronal monoamine transporter that is present in [[astrocyte]]s, and SLC22A5 is a high-affinity [[carnitine]] transporter.<ref name="Reuptake inhibition" group="sources" /> Amphetamine is known to strongly induce [[cocaine- and amphetamine-regulated transcript]] (CART) [[gene expression]],<ref name="Drugbank-amph" /><ref name="CART NAcc">{{cite journal |vauthors=Vicentic A, Jones DC | title = The CART (cocaine- and amphetamine-regulated transcript) system in appetite and drug addiction | journal =Journal of Pharmacology and Experimental Therapeutics| volume = 320 | issue = 2 | pages = 499–506 |date=February 2007 | pmid = 16840648 | doi = 10.1124/jpet.105.091512 | s2cid = 14212763 | quote = The physiological importance of CART was further substantiated in numerous human studies demonstrating a role of CART in both feeding and psychostimulant addiction.&nbsp;... Colocalization studies also support a role for CART in the actions of psychostimulants.&nbsp;... CART and DA receptor transcripts colocalize (Beaudry et al., 2004). Second, dopaminergic nerve terminals in the NAc synapse on CART-containing neurons (Koylu et al., 1999), hence providing the proximity required for neurotransmitter signaling. These studies suggest that DA plays a role in regulating CART gene expression possibly via the activation of CREB.}}</ref> a [[neuropeptide]] involved in feeding behavior, stress, and reward, which induces observable increases in neuronal development and survival ''[[in vitro]]''.<ref name="Drugbank-amph" /><ref name="CART functions">{{cite journal |vauthors=Zhang M, Han L, Xu Y | title = Roles of cocaine- and amphetamine-regulated transcript in the central nervous system | journal =Clinical and Experimental Pharmacology and Physiology| volume = 39 | issue = 6 | pages = 586–592 |date=June 2012 | pmid = 22077697 | doi = 10.1111/j.1440-1681.2011.05642.x | s2cid = 25134612 | quote = Recently, it was demonstrated that CART, as a neurotrophic peptide, had a cerebroprotective against focal ischaemic stroke and inhibited the neurotoxicity of β-amyloid protein, which focused attention on the role of CART in the central nervous system (CNS) and neurological diseases.&nbsp;... The literature indicates that there are many factors, such as regulation of the immunological system and protection against energy failure, that may be involved in the cerebroprotection afforded by CART}}</ref><ref name="CART">{{cite journal |vauthors=Rogge G, Jones D, Hubert GW, Lin Y, Kuhar MJ |title=CART peptides: regulators of body weight, reward and other functions |journal=Nature Reviews Neuroscience |volume=9 |issue=10 |pages=747–758 |date=October 2008 |pmid=18802445 |pmc=4418456 |doi=10.1038/nrn2493 |quote=Several studies on CART (cocaine- and amphetamine-regulated transcript)-peptide-induced cell signalling have demonstrated that CART peptides activate at least three signalling mechanisms. First, CART 55–102 inhibited voltage-gated L-type Ca2+ channels&nbsp;...}}</ref> The CART receptor has yet to be identified, but there is significant evidence that CART binds to a unique {{nowrap|[[Gi alpha subunit|G<sub>i</sub>/G<sub>o</sub>-coupled]]}} {{abbr|GPCR|G protein-coupled receptor}}.<ref name="CART" /><ref name="pmid21855138">{{cite journal |vauthors=Lin Y, Hall RA, Kuhar MJ |title=CART peptide stimulation of G protein-mediated signaling in differentiated PC12 cells: identification of PACAP 6–38 as a CART receptor antagonist |journal=Neuropeptides |volume=45 |issue=5 |pages=351–358 |date=October 2011 |pmid=21855138 |pmc=3170513 |doi=10.1016/j.npep.2011.07.006}}</ref> Amphetamine also inhibits [[monoamine oxidase]]s at very high doses, resulting in less monoamine and trace amine metabolism and consequently higher concentrations of synaptic monoamines.<ref name="PubChem Header">{{cite encyclopedia |title=Amphetamine |section-url=https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3007 |publisher=United States National Library of Medicine&nbsp;– National Center for Biotechnology Information. PubChem Compound Database |access-date=17 April 2015 |date=11 April 2015 |section=Compound Summary}}</ref><ref name="BRENDA MAO Homo sapiens">{{cite encyclopedia |title=Monoamine oxidase (Homo sapiens)|url=http://www.brenda-enzymes.info/enzyme.php?ecno=1.4.3.4&Suchword=&organism%5B%5D=Homo+sapiens&show_tm=0 |publisher=Technische Universität Braunschweig. BRENDA |access-date=4 May 2014 |date=1 January 2014}}</ref> In humans, the only post-synaptic receptor at which amphetamine is known to bind is the [[5-HT1A receptor|{{nowrap|5-HT1A}} receptor]], where it acts as an agonist with low [[micromolar]] affinity.<ref name="5HT1A secondary">{{cite encyclopedia |title=Amphetamine |publisher=University of Alberta: T3DB |url=http://www.t3db.ca/toxins/T3D2706 |access-date=24 February 2015 |section=Targets}}</ref><ref name="5HT1A Primary">{{cite journal |vauthors=Toll L, Berzetei-Gurske IP, Polgar WE, Brandt SR, Adapa ID, Rodriguez L, Schwartz RW, Haggart D, O'Brien A, White A, Kennedy JM, Craymer K, Farrington L, Auh JS |date=March 1998 |title=Standard binding and functional assays related to medications development division testing for potential cocaine and opiate narcotic treatment medications |journal=NIDA Research Monograph |volume=178 |pages=440–466 |pmid=9686407}}</ref>

The full profile of amphetamine's short-term drug effects in humans is mostly derived through increased cellular communication or [[neurotransmission]] of [[dopamine]],<ref name="Miller">{{cite journal | vauthors = Miller GM |title=The emerging role of trace amine-associated receptor 1 in the functional regulation of monoamine transporters and dopaminergic activity | journal =Journal of Neurochemistry |volume=116 |issue=2 |pages=164–176 |date=January 2011 |pmid=21073468 |pmc=3005101 |doi=10.1111/j.1471-4159.2010.07109.x}}</ref> [[serotonin]],<ref name="Miller" /> [[norepinephrine]],<ref name="Miller" /> [[epinephrine]],<ref name="E Weihe">{{cite journal |vauthors=Eiden LE, Weihe E |title=VMAT2: a dynamic regulator of brain monoaminergic neuronal function interacting with drugs of abuse | journal =Annals of the New York Academy of Sciences| volume = 1216 |issue = 1 | pages = 86–98 | date=January 2011 | pmid = 21272013 | pmc=4183197 | doi = 10.1111/j.1749-6632.2010.05906.x | quote = VMAT2 is the CNS vesicular transporter for not only the biogenic amines DA, NE, EPI, 5-HT, and HIS, but likely also for the trace amines TYR, PEA, and thyronamine (THYR)&nbsp;... [Trace aminergic] neurons in mammalian CNS would be identifiable as neurons expressing VMAT2 for storage, and the biosynthetic enzyme aromatic amino acid decarboxylase (AADC).&nbsp;... AMPH release of DA from synapses requires both an action at VMAT2 to release DA to the cytoplasm and a concerted release of DA from the cytoplasm via "reverse transport" through DAT.| bibcode = <!-- No --> }}</ref> [[histamine]],<ref name="E Weihe" /> [[cocaine and amphetamine regulated transcript|CART peptides]],<ref name="Drugbank-amph" /><ref name="CART NAcc" /> [[endogenous opioid]]s,<ref name="Amphetamine-induced endogenous opioid release review">{{cite journal | vauthors = Finnema SJ, Scheinin M, Shahid M, Lehto J, Borroni E, Bang-Andersen B, Sallinen J, Wong E, Farde L, Halldin C, Grimwood S | title = Application of cross-species PET imaging to assess neurotransmitter release in brain | journal =Psychopharmacology| volume = 232 | issue = 21–22 | pages = 4129–4157 | date = November 2015 | pmid = 25921033 | pmc = 4600473 | doi = 10.1007/s00213-015-3938-6 | quote = More recently, Colasanti and colleagues reported that a pharmacologically induced elevation in endogenous opioid release reduced [<sup>11</sup>C]carfentanil binding in several regions of the human brain, including the basal ganglia, frontal cortex, and thalamus (Colasanti et al. 2012). Oral administration of d-amphetamine, 0.5&nbsp;mg/kg, 3&nbsp;h before [<sup>11</sup>C]carfentanil injection, reduced BPND values by 2–10%. The results were confirmed in another group of subjects (Mick et al. 2014). However, Guterstam and colleagues observed no change in [<sup>11</sup>C]carfentanil binding when d-amphetamine, 0.3&nbsp;mg/kg, was administered intravenously directly before injection of [<sup>11</sup>C]carfentanil (Guterstam et al. 2013). It has been hypothesized that this discrepancy may be related to delayed increases in extracellular opioid peptide concentrations following amphetamine-evoked monoamine release (Colasanti et al. 2012; Mick et al. 2014).}}</ref><ref name="Opioids">{{cite journal | vauthors = Loseth GE, Ellingsen DM, Leknes S | title = State-dependent μ-opioid modulation of social motivation | journal =Frontiers in Behavioral Neuroscience| volume = 8 | pages = 430 | date = December 2014 | pmid = 25565999 | pmc = 4264475 | doi = 10.3389/fnbeh.2014.00430 | quote = Similar MOR activation patterns were reported during positive mood induced by an amusing video clip (Koepp et al., 2009) and following amphetamine administration in humans (Colasanti et al., 2012). | doi-access = free | title-link = doi }}</ref><ref name="Opioids cited primary source">{{cite journal | vauthors = Colasanti A, Searle GE, Long CJ, Hill SP, Reiley RR, Quelch D, Erritzoe D, Tziortzi AC, Reed LJ, Lingford-Hughes AR, Waldman AD, Schruers KR, Matthews PM, Gunn RN, Nutt DJ, Rabiner EA | title = Endogenous opioid release in the human brain reward system induced by acute amphetamine administration | journal =Biological Psychiatry| volume = 72 | issue = 5 | pages = 371–377 | date = September 2012 | pmid = 22386378 | doi = 10.1016/j.biopsych.2012.01.027| s2cid = 18555036 }}</ref> [[adrenocorticotropic hormone]],<ref name="Human amph effects" /><ref name="Primary: Human HPA axis" /> [[corticosteroid]]s,<ref name="Human amph effects" /><ref name="Primary: Human HPA axis" /> and [[glutamate]],<ref name="EAAT3" /><ref name="SLC1A1" /> which it affects through interactions with {{abbr|CART|cocaine- and amphetamine-regulated transcript}}, {{nowrap|{{abbr|5-HT1A|serotonin receptor 1A}}}}, {{abbr|EAAT3|excitatory amino acid transporter 3}}, {{abbr|TAAR1|trace amine-associated receptor 1}}, {{abbr|VMAT1|vesicular monoamine transporter 1}}, {{abbr|VMAT2|vesicular monoamine transporter 2}}, and possibly other [[biological target]]s.{{#tag:ref|<ref name="Miller" /><ref name="E Weihe" /><ref name="IUPHAR VMATs" /><ref name="SLC1A1" /><ref name="CART NAcc" /><ref name="5HT1A secondary" />|group="sources"}} Amphetamine also activates seven human [[carbonic anhydrase]] enzymes, several of which are expressed in the human brain.<ref name="Amphetamine-induced activation of 7 hCA isoforms" />

Dextroamphetamine displays higher binding affinity for DAT than levoamphetamine, whereas both [[Enantiomer|enantiomers]] share comparable affinity at NET;<ref name="Stahl2021" /> Consequently, dextroamphetamine produces greater {{abbr|CNS|central nervous system}} stimulation than levoamphetamine, roughly three to four times more, but levoamphetamine has slightly stronger cardiovascular and peripheral effects.<ref name="Stahl2021" /><ref name="Westfall" /> Dextroamphetamine is also a more potent agonist of {{abbr|TAAR1|trace amine-associated receptor 1}} than levoamphetamine.<ref name="TAAR1 stereoselective">{{cite journal |vauthors=Lewin AH, Miller GM, Gilmour B |date=December 2011 |title=Trace amine-associated receptor 1 is a stereoselective binding site for compounds in the amphetamine class |journal=Bioorganic & Medicinal Chemistry |volume=19 |issue=23 |pages=7044–7048 |doi=10.1016/j.bmc.2011.10.007 |pmc=3236098 |pmid=22037049}}</ref>

====Dopamine====
In certain brain regions, amphetamine increases the concentration of dopamine in the [[synaptic cleft]] by modulating {{abbr|DAT|dopamine transporter}} through several overlapping processes.<ref name="2020_Reith" /><ref name="handbook2022_DAT">{{Cite book |title=Handbook of Substance Misuse and Addictions |vauthors=Tendilla-Beltran H, Arroyo-García LE, Flores G |publisher=Springer International Publishing |year=2022 |isbn=978-3-030-92391-4 |veditors=Patel VB, Preedy VR |location=Cham |pages=2176–2177 |chapter=Chapter 102: Amphetamine and the Biology of Neuronal Morphology |doi=10.1007/978-3-030-92392-1 |quote=At low concentrations, amphetamines (extracellular) and dopamine (intracellular) are interchanged as described by the exchange diffusion model&nbsp;... Amphetamines can also increase dopaminergic transmission by channel-like transport which involves second-messenger signaling. Amphetamines increase PKC activity, which increase DAT N-terminus domain phosphorylation, and consequently DAT activity, which, because of the amphetamines, will release dopamine from the presynaptic terminal.&nbsp; PKC and CaMKIIα-mediated reverse transport have also been demonstrated in NET&nbsp;...<br /> Also, amphetamines can indirectly enhance monoaminergic neurotransmission through the stimulation of trace amine-associated receptor 1 (TAAR1) (Underhill et al. 2021). TAAR1 is an intracellular G protein-coupled receptor (GPCR), which has activity that promotes the endocytosis of both DAT and the excitatory amino acid transporter 3 (EAAT3). DAT endocytosis, together with the aforementioned mechanisms, contributes to the enhancement of the dopaminergic neurotransmission.&nbsp;... <br /> It is important to note that amphetamines also stimulate protein kinase A (PKA) activity, which in turn inhibits RhoA activity and consequently reduces DAT internalization.}}</ref><ref name="2022 T1 LDX" /> Amphetamine can enter the [[presynaptic neuron]] either through {{abbr|DAT|dopamine transporter}} or by diffusing across the neuronal membrane directly.<ref name="Miller" /><ref name="handbook2022_DAT" /> As a consequence of DAT uptake, amphetamine produces competitive reuptake inhibition at the transporter.<ref name="Miller" /><ref name="Amph Uses" /> Upon entering the presynaptic neuron, amphetamine provokes the release of [[Ca²⁺]] from [[endoplasmic reticulum]] stores, an effect that raises intracellular calcium to levels sufficient for downstream kinase-dependent signalling.<ref name="Kinase-dependent transporter regulation review" /><ref name="2020_Reith" /> Subsequently, amphetamine initiates kinase-dependent signaling cascades that activate both [[protein kinase A]] (PKA) and [[protein kinase C]] (PKC).<ref name="handbook2022_DAT" /><ref name="2022 T1 LDX" /> Phosphorylation of DAT by either kinase induces transporter [[Endocytosis|internalization]] ({{nowrap|non-competitive}} reuptake inhibition), but {{nowrap|PKC-mediated}} phosphorylation alone induces the [[Reverse transport|reversal of dopamine transport]] through DAT (i.e., dopamine [[wiktionary:efflux|efflux]]).<ref name="handbook2022_DAT" /><ref name="Kinase-dependent transporter regulation review" />

{{abbr|TAAR1|trace amine associated receptor 1}} is a [[biomolecular target]] of amphetamine that can trigger the activation of PKA- and PKC-dependent pathways.<ref name="Miller" /><ref name="handbook2022_DAT" /><ref name="2022 T1 LDX" /> TAAR1 agonism also activates [[Transforming protein RhoA|Ras homolog A]] (RhoA) and its downstream effector, [[Rho-associated coiled-coil kinase]] (ROCK), which results in transient internalization of DAT and [[Excitatory amino acid transporter 3|EAAT3]];{{#tag:ref|Mesolimbic dopamine neurons co-express the glutamate transporter EAAT3 alongside DAT, permitting amphetamine-induced EAAT3 internalization to influence glutamatergic signaling in the [[mesolimbic pathway]].<ref name="EAAT3" /><ref name="handbook2022_DAT" />|name="mesolimbic EAAT3"|group="note"}}<ref name="Amphetamine signaling through ROCKs" /><ref name="handbook2022_DAT" /> as intracellular {{abbrlink|cAMP|cyclic adenosine monophosphate}} accumulates, PKA is activated and inhibits RhoA activity, thereby terminating ROCK-mediated transporter internalization.<ref name="Amphetamine signaling through ROCKs" /><ref name="handbook2022_DAT" /> Importantly, TAAR1 has been demonstrated to also produce inhibitory effects on dopamine release that may attenuate amphetamine's psychostimulant effects.<ref name="handbook2022_TAAR1" /> Through direct activation of [[G protein-coupled inwardly-rectifying potassium channel|G protein-coupled inwardly-rectifying potassium channels]], {{abbr|TAAR1|trace amine associated receptor 1}} reduces the [[Action potential|firing rate]] of dopamine neurons, preventing a hyper-dopaminergic state.<ref name="GIRK">{{cite journal |vauthors=Ledonne A, Berretta N, Davoli A, Rizzo GR, Bernardi G, Mercuri NB | title = Electrophysiological effects of trace amines on mesencephalic dopaminergic neurons | journal =Frontiers in Systems Neuroscience| volume = 5 | pages = 56 | date = July 2011 | pmid = 21772817 | pmc = 3131148 | doi = 10.3389/fnsys.2011.00056 | quote = Three important new aspects of TAs action have recently emerged: (a) inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization. | doi-access = free | title-link = doi }}</ref><ref name="Genatlas TAAR1">{{cite web | url = http://genatlas.medecine.univ-paris5.fr/fiche.php?symbol=TAAR1 | title = TAAR1 | date = 28 January 2012 | website = GenAtlas | publisher = University of Paris | access-date = 29 May 2014 | quote={{•}} tonically activates inwardly rectifying K(+) channels, which reduces the basal firing frequency of dopamine (DA) neurons of the ventral tegmental area (VTA) }}</ref>

Amphetamine's effect on intracellular calcium is associated with DAT phosphorylation through [[Ca2+/calmodulin-dependent protein kinase II alpha|Ca²⁺/calmodulin-dependent protein kinase II alpha]] (CAMKIIα), in turn producing dopamine efflux.<ref name="handbook2022_DAT" /><ref name="Kinase-dependent transporter regulation review" /><ref name="DAT regulation review">{{cite journal |vauthors=Vaughan RA, Foster JD | title = Mechanisms of dopamine transporter regulation in normal and disease states | journal =Trends in Pharmacological Sciences| volume = 34 | issue = 9 | pages = 489–496 | date = September 2013 | pmid = 23968642 | pmc = 3831354 | doi = 10.1016/j.tips.2013.07.005 | quote = AMPH and METH also stimulate DA efflux, which is thought to be a crucial element in their addictive properties [80], although the mechanisms do not appear to be identical for each drug [81]. These processes are PKCβ– and CaMK–dependent [72, 82], and PKCβ knock-out mice display decreased AMPH-induced efflux that correlates with reduced AMPH-induced locomotion [72].}}</ref> Notably, because conventional PKC [[isoforms]] can be activated by calcium ions, the rise in intracellular calcium can also promote PKC activation and subsequent DAT phosphorylation independent of TAAR1.<ref name="2020_Reith" />
{| class="wikitable" style="text-align: center;"
|+ Effects of amphetamine on [[membrane transport protein]]s in dopamine neurons
! Trigger mechanism
! [[Signal transduction|Secondary effector]]<br />[[protein kinase]]
! Phosphorylated<br />transporter
! Effect on transporter function
! Effect on neurotransmission
! <small>Sources</small>
|-
| {{abbrlink|ER|Endoplasmic reticulum}} Ca²⁺ release<sup>†</sup>
| {{abbrlink|CAMKIIα|Calcium/calmodulin-dependent protein kinase II alpha}}
| {{abbrlink|DAT|Dopamine transporter}}
| [[Reverse transport]] of [[dopamine]]
| Dopamine efflux into synaptic cleft
| <ref name="2020_Reith" /><ref name="Kinase-dependent transporter regulation review">{{cite journal |vauthors=Bermingham DP, Blakely RD |date=October 2016 |title=Kinase-dependent Regulation of Monoamine Neurotransmitter Transporters |journal=Pharmacol. Rev. |volume=68 |issue=4 |pages=888–953 |doi=10.1124/pr.115.012260 |pmc=5050440 |pmid=27591044 |quote=<!--RhoA signaling--> The Amara laboratory recently provided evidence that AMPH triggered DAT endocytosis is clathrin-independent and requires the small GTPase Rho (Wheeler et al., 2015)...<!--CAMKII signaling--> Whereas little support for CaMKII regulation of DA uptake exists, substantial evidence supports a role for the kinase in DAT-dependent DA efflux triggered by AMPH... Importantly, AMPH treatment of DAT transfected cells produced a rise in intracellular Ca2+ that could be blocked by thapsigargin or cocaine, supporting a model whereby AMPH is first transported into cells where it can then produce release of endoplasmic reticulum Ca2+ stores. Subsequently, AMPH was shown to activate CaMKII in DAT transfected cells (Wei et al., 2007).&nbsp;... At present, information is lacking as to the site(s) that support CaMKII phosphorylation of DAT in vivo ... The current model... DAT by phosphorylating one or more Ser residues in the transporter N terminus. This phosphorylation is then thought to facilitate conformational changes that place the transporter in a “DA efflux-willing” conformation.}}</ref>
|-
| {{abbrlink|TAAR1|Trace amine-associated receptor 1}} activation
| [[Rho-associated protein kinase|ROCK]]<sup>‡</sup>
| DAT
| Transporter [[Endocytosis|internalization]]
| Dopamine [[Reuptake inhibitor|reuptake inhibition]]
| <ref name="handbook2022_DAT" /><ref name="Amph RhoA+ROCK signaling to DAT - primary">{{cite journal | vauthors = Wheeler DS, Underhill SM, Stolz DB, Murdoch GH, Thiels E, Romero G, Amara SG | title = Amphetamine activates Rho GTPase signaling to mediate dopamine transporter internalization and acute behavioral effects of amphetamine | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 112 | issue = 51 | pages = E7138–E7147 | date = December 2015 | pmid = 26553986 | pmc = 4697400 | doi = 10.1073/pnas.1511670112 | doi-access = free | bibcode = 2015PNAS..112E7138W | quote = These observations support the existence of an unanticipated intracellular target that mediates the effects of AMPH on RhoA and cAMP signaling and suggest new pathways to target to disrupt AMPH action.&nbsp;... Using a ROCK inhibitor, Y27632, blocked the effects of AMPH pretreatment on dopamine uptake... The activation of intracellular signaling pathways by AMPH and the Rho-mediated internalization of DAT are also observed in nonneural cell lines... Cytoplasmic cAMP appears to integrate both intracellular signals through GTPase activation and extracellular signals from GPCR-coupled pathways... Thus, modulation of the Rho activation/inactivation sequence provides a mechanism by which drugs and endogenous neurotransmitters can influence the response of dopamine neurons to AMPH.}}</ref><ref name="Amphetamine signaling through ROCKs">{{cite journal | vauthors = Saunders C, Galli A | title = Insights in how amphetamine ROCKs (Rho-associated containing kinase) membrane protein trafficking | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 112 | issue = 51 | pages = 15538–15539 | date = December 2015 | pmid = 26607447 | pmc = 4697384 | doi = 10.1073/pnas.1520960112 | doi-access = free | bibcode = 2015PNAS..11215538S | quote = In this elegant and thorough study (7), Amara and her collaborators identify multiple novel targets for intracellular AMPH. They demonstrate that cytoplasmic AMPH stimulates a secondary pathway of cAMP production, which leads to Rho inactivation by PKA-dependent phosphorylation.&nbsp;... ROCK inhibition blocks the effects of AMPH pretreatment on DA uptake, supporting previous studies suggesting a role for ROCK in AMPH’s behavioral effects... These results further support the idea that direct activation of cytoplasmic signaling cascades by AMPH might contribute to the behavioral effects of acute AMPH exposure.}}</ref>
|-
| TAAR1 activation
| [[Rho-associated protein kinase|ROCK]]<sup>‡</sup>
| {{abbrlink|EAAT3|Excitatory amino acid transporter 3}}
| Transporter internalization
| [[Glutamate]] reuptake inhibition
| <ref name="handbook2022_DAT" /><ref name="handbook2022_TAAR1" /><ref name="Amphetamine signaling through ROCKs" />
|-
| TAAR1 activation
| {{abbrlink|PKA|Protein kinase A}}
| DAT
| Transporter internalization
| Dopamine reuptake inhibition
| <ref name="Miller" /><ref name="handbook2022_DAT" /><ref name="2022 T1 LDX" />
|-
| TAAR1 activation
| {{abbrlink|PKC|Protein kinase C}}
| DAT
| Reverse transport of dopamine<br />Transporter internalization
| Dopamine efflux into synaptic cleft<br />Dopamine reuptake inhibition
| <ref name="Miller" /><ref name="handbook2022_DAT" /><ref name="2022 T1 LDX" />
|-
|{{abbr|ER|Endoplasmic reticulum}} Ca²⁺ release<sup>†</sup>
|{{abbrlink|PKC|Protein kinase C}}
|DAT
|Reverse transport of dopamine<br />Transporter internalization
|Dopamine efflux into synaptic cleft<br />Dopamine reuptake inhibition
|<ref name="2020_Reith" /><ref name="Kinase-dependent transporter regulation review" />
|-
| colspan="5" | † Amphetamine interacts with an unidentified intracellular target to trigger release of [[endoplasmic reticulum]] Ca²⁺ stores, thereby supplying the cytosolic Ca²⁺ required for protein kinase activation.
‡ ROCK-mediated transporter internalization is transient due to the inactivation of [[RhoA]] (which activates ROCK) by PKA.
| <ref name="handbook2022_DAT" /><ref name="Kinase-dependent transporter regulation review" /><ref name="Amphetamine signaling through ROCKs" />
|}
Amphetamine is also a substrate for the presynaptic [[vesicular monoamine transporter]], {{abbr|VMAT2|vesicular monoamine transporter 2}}.<ref name="Amphetamine VMAT2 pH gradient" /> Following amphetamine uptake at VMAT2, amphetamine induces the collapse of the vesicular pH gradient, which results in a dose-dependent release of dopamine molecules from [[Synaptic vesicle|synaptic vesicles]] into the cytosol via dopamine efflux through VMAT2.<ref name="Amphetamine VMAT2 pH gradient" /><ref name="VMAT2ADHD2">{{Cite journal |vauthors=Warlick Iv H, Tocci D, Prashar S, Boldt E, Khalil A, Arora S, Matthews T, Wahid T, Fernandez R, Ram D, Leon L, Arain A, Rey J, Davis K |year=2024 |title=Role of vesicular monoamine transporter-2 for treating attention deficit hyperactivity disorder: a review |url=https://pubmed.ncbi.nlm.nih.gov/39302436/ |journal=Psychopharmacology |volume=241 |issue=11 |pages=2191–2203 |doi=10.1007/s00213-024-06686-7 |pmid=39302436 |quote=Current psychopharmacology research shows that at high doses (non-therapeutic ranges), VMAT-2 can be “inhibited” by amphetamines, causing VMAT-2 vesicles to release the classical monoamines DA and NE into the axoplasm; however, this model is no longer broadly accepted. For instance, Stahl (2014) reported that VMAT-2 is not affected by amphetamines at therapeutic doses but is affected at higher doses.}}</ref> Subsequently, the cytosolic dopamine molecules are released from the presynaptic neuron into the synaptic cleft via reverse transport at {{abbr|DAT|dopamine transporter}}.<ref name="Amphetamine VMAT2 pH gradient" /><ref name="VMAT2ADHD2" />

====Norepinephrine====
Similar to dopamine, amphetamine dose-dependently increases the level of synaptic norepinephrine, the direct precursor of [[epinephrine]]. Amphetamine is believed to affect norepinephrine analogously to dopamine.<ref name="handbook2022_DAT" /><ref name="2020_Reith" /><ref name="2022 T1 LDX" /> In other words, amphetamine induces competitive {{abbr|NET|norepinephrine transporter}} reuptake inhibition, non-competitive reuptake inhibition and efflux at phosphorylated NET via PKC activation, CAMKIIα-mediated NET efflux without internalization, and norepinephrine release from {{abbr|VMAT2|vesicular monoamine transporter 2}}.<ref name="handbook2022_DAT" /><ref name="2020_Reith" /><ref name="2022 T1 LDX" />

====Serotonin====
Amphetamine exerts analogous, yet less pronounced, effects on serotonin as on dopamine and norepinephrine.<ref name="Miller" /> Amphetamine affects serotonin via {{abbr|VMAT2|vesicular monoamine transporter 2}} and is thought to phosphorylate {{abbr|SERT|serotonin transporter}} via a PKC-dependent signaling cascade.<ref name="2022 T1 LDX" /> Like dopamine, amphetamine has low, micromolar affinity at the human [[5-HT1A receptor]].<ref name="5HT1A secondary2">{{cite encyclopedia |title=Amphetamine |publisher=University of Alberta: T3DB |url=http://www.t3db.ca/toxins/T3D2706 |access-date=24 February 2015 |section=Targets}}</ref><ref name="5HT1A Primary" />

====Other neurotransmitters, peptides, hormones, and enzymes====
{| class="wikitable sortable" style="margin-left: 8px; float:right; text-align:center"
|+ Human [[carbonic anhydrase]]<br />activation potency
! [[Enzyme]]
! K<sub>A</sub> ({{abbrlink|nM|nanomolar}})
! class="unsortable" | <small>Sources</small>
|-
| [[Carbonic anhydrase 4|hCA4]] || 94 ||<ref name="Amphetamine-induced activation of 7 hCA isoforms" />
|-
| [[Carbonic anhydrase 5A, mitochondrial|hCA5A]] || 810 ||<ref name="Amphetamine-induced activation of 7 hCA isoforms">{{cite journal | vauthors = Angeli A, Vaiano F, Mari F, Bertol E, Supuran CT | title = Psychoactive substances belonging to the amphetamine class potently activate brain carbonic anhydrase isoforms VA, VB, VII, and XII | journal = Journal of Enzyme Inhibition and Medicinal Chemistry | volume = 32 | issue = 1 | pages = 1253–1259 | date = December 2017 | pmid = 28936885 | pmc = 6009978 | doi = 10.1080/14756366.2017.1375485 | quote = Here, we report the first such study, showing that amphetamine, methamphetamine, phentermine, mephentermine, and chlorphenteramine, potently activate several CA isoforms, some of which are highly abundant in the brain, where they play important functions connected to cognition and memory, among others26,27.&nbsp;... We investigated psychotropic amines based on the phenethylamine scaffold, such as amphetamine 5, methamphetamine 6, phentermine 7, mephentermine 8, and the structurally diverse chlorphenteramine 9, for their activating effects on 11 CA isoforms of human origin&nbsp;... The widespread hCA I and II, the secreted hCA VI, as well as the cytosolic hCA XIII and membrane-bound hCA IX and XIV were poorly activated by these amines, whereas the extracellular hCA IV, the mitochondrial enzymes hCA VA/VB, the cytosolic hCA VII, and the transmembrane isoform hCA XII were potently activated. Some of these enzymes (hCA VII, VA, VB, XII) are abundant in the brain, raising the possibility that some of the cognitive effects of such psychoactive substances might be related to the activation of these enzymes.&nbsp;... CAAs started to be considered only recently for possible pharmacologic applications in memory/cognition therapy27. This work may bring new lights on the intricate relationship between CA activation by this type of compounds and the multitude of pharmacologic actions that they can elicit.<br /> —Table 1: CA activation of isoforms hCA I, II, IV, VII, and XIII [5: amphetamine]<br /> —Table 2: CA activation of isoforms hCA VA, VB, VI, IX, XII, and XIV [5: amphetamine]}}</ref><ref name="IUPHAR Amphetamine">{{cite web | title=Amphetamine: Biological activity | url=https://www.guidetopharmacology.org/GRAC/LigandDisplayForward?tab=biology&ligandId=4804 | website=IUPHAR/BPS Guide to Pharmacology | publisher=International Union of Basic and Clinical Pharmacology | access-date=31 December 2019}}</ref>
|-
| [[Carbonic anhydrase 5B, mitochondrial|hCA5B]] || 2560 || <ref name="Amphetamine-induced activation of 7 hCA isoforms" />
|-
| [[Carbonic anhydrase 7|hCA7]] || 910 || <ref name="Amphetamine-induced activation of 7 hCA isoforms" /><ref name="IUPHAR Amphetamine" />
|-
| [[Carbonic anhydrase 12|hCA12]] || 640 || <ref name="Amphetamine-induced activation of 7 hCA isoforms" />
|-
| [[Carbonic anhydrase 13|hCA13]] || 24100 || <ref name="Amphetamine-induced activation of 7 hCA isoforms" />
|-
| [[Carbonic anhydrase 14|hCA14]] || 9150 || <ref name="Amphetamine-induced activation of 7 hCA isoforms" />
|-
|}
Acute amphetamine administration in humans increases [[endogenous opioid]] release in several brain structures in the [[reward system]].<ref name="Amphetamine-induced endogenous opioid release review" /><ref name="Opioids" /><ref name="Opioids cited primary source" /> Extracellular levels of [[Glutamate (neurotransmitter)|glutamate]], the primary [[Neurotransmitter#Excitatory and inhibitory|excitatory neurotransmitter]] in the brain, have been shown to increase in the striatum following exposure to amphetamine.<ref name="EAAT3" /> This increase in extracellular glutamate presumably occurs via the amphetamine-induced internalization of [[EAAT3]], a glutamate reuptake transporter, in dopamine neurons.<ref name="EAAT3" /><ref name="SLC1A1" /> This internalization is mediated by [[RhoA]] activation and its downstream effector [[Rho-associated coiled-coil kinase|ROCK]].<ref name="handbook2022_DAT" /><ref name="EAAT3 review">{{cite journal | vauthors = Bjørn-Yoshimoto WE, Underhill SM | title = The importance of the excitatory amino acid transporter 3 (EAAT3) | journal = Neurochem. Int. | volume = 98 | issue = | pages = 4–18 | date = September 2016 | pmid = 27233497 | pmc = 4969196 | doi = 10.1016/j.neuint.2016.05.007 | quote = Recently, it was reported that amphetamine decreases the surface expression of EAAT3 (Underhill et al., 2014).&nbsp;...<br />RhoA is a downstream target of intracellular amphetamine. Both mechanisms of RhoA activation lead to a rapid decrease the surface expression of EAAT3. }}</ref> Amphetamine also induces the selective release of [[histamine]] from [[mast cell]]s and efflux from [[Tuberomammillary nucleus|histaminergic neurons]] through {{abbr|VMAT2|vesicular monoamine transporter 2}}.<ref name="E Weihe" /> Acute amphetamine administration can also increase [[adrenocorticotropic hormone]] and [[corticosteroid]] levels in [[blood plasma]] by stimulating the [[hypothalamic–pituitary–adrenal axis]].<ref name="Evekeo" /><ref name="Human amph effects">{{cite book | vauthors = Gunne LM | title=Drug Addiction II: Amphetamine, Psychotogen, and Marihuana Dependence | date=2013 | publisher=Springer | location=Berlin, Germany; Heidelberg, Germany | isbn=9783642667091 | pages=247–260 | access-date=4 December 2015 | chapter=Effects of Amphetamines in Humans | chapter-url=https://books.google.com/books?id=gb_uCAAAQBAJ&pg=PA247}}</ref><ref name="Primary: Human HPA axis">{{cite journal | vauthors = Oswald LM, Wong DF, McCaul M, Zhou Y, Kuwabara H, Choi L, Brasic J, Wand GS | title = Relationships among ventral striatal dopamine release, cortisol secretion, and subjective responses to amphetamine | journal =Neuropsychopharmacology| volume = 30 | issue = 4 | pages = 821–832 | date = April 2005 | pmid = 15702139 | doi = 10.1038/sj.npp.1300667 | s2cid = 12302237 | quote = Findings from several prior investigations have shown that plasma levels of glucocorticoids and ACTH are increased by acute administration of AMPH in both rodents and humans| doi-access = free | title-link = doi }}</ref><!--
Amphetamine has no direct effect on [[acetylcholine]] neurotransmission, but several studies have noted that acetylcholine release increases after its use.<ref name="Acetylcholine">{{cite journal |vauthors=Hutson PH, Tarazi FI, Madhoo M, Slawecki C, Patkar AA | title = Preclinical pharmacology of amphetamine: implications for the treatment of neuropsychiatric disorders | journal =Pharmacol Ther| volume = 143 | issue = 3 | pages = 253–264 | date = September 2014 | pmid = 24657455 | doi = 10.1016/j.pharmthera.2014.03.005}}</ref> In lab animals, amphetamine increases acetylcholine levels in certain brain regions as a downstream effect.<ref name="Acetylcholine" /> -->

In December 2017, the first study assessing the interaction between amphetamine and human [[carbonic anhydrase]] enzymes was published;<ref name="Amphetamine-induced activation of 7 hCA isoforms" /> of the eleven carbonic anhydrase enzymes it examined, it found that amphetamine potently activates seven, four of which are highly expressed in the [[human brain]], with low nanomolar through low micromolar activating effects.<ref name="Amphetamine-induced activation of 7 hCA isoforms" /> Based upon preclinical research, cerebral carbonic anhydrase activation has cognition-enhancing effects;<ref name="Carbonic anhydrase modulators 2019 Review" /> but, based upon the clinical use of [[carbonic anhydrase inhibitor]]s, carbonic anhydrase activation in other tissues may be associated with adverse effects, such as [[ocular]] activation exacerbating [[glaucoma]].<ref name="Carbonic anhydrase modulators 2019 Review">{{cite journal | vauthors = Bozdag M, Altamimi AA, Vullo D, Supuran CT, Carta F | title = State of the Art on Carbonic Anhydrase Modulators for Biomedical Purposes | journal = Current Medicinal Chemistry | volume = 26 | issue = 15 | pages = 2558–2573 | date = 2019 | pmid = 29932025 | doi = 10.2174/0929867325666180622120625 | s2cid = 49345601 | quote = CARBONIC ANHYDRASE INHIBITORS (CAIs). The design and development of CAIs represent the most prolific area within the CA research field. Since the introduction of CAIs in the clinical use in the 40', they still are the first choice for the treatment of edema [9], altitude sickness [9], glaucoma [7] and epilepsy [31].&nbsp;... CARBONIC ANHYDRASE ACTIVATORS (CAAs)&nbsp;... The emerging class of CAAs has recently gained attraction as the enhancement of the kinetic properties in hCAs expressed in the CNS were proved in animal models to be beneficial for the treatment of both cognitive and memory impairments. Thus, CAAs have enormous potentiality in medicinal chemistry to be developed for the treatment of symptoms associated to aging, trauma or deterioration of the CNS tissues.}}</ref>