Editing Serotonin (section)

====Microanatomy====
Serotonin is released into the synapse, or space between neurons, and diffuses over a relatively wide gap (>20&nbsp;nm) to activate [[5-HT receptor]]s located on the [[dendrite]]s, cell bodies, and [[presynaptic terminal]]s of adjacent neurons.

When humans smell food, dopamine is released to [[incentive salience|increase the appetite]]. But, unlike in worms, serotonin does not increase anticipatory behaviour in humans; instead, the serotonin released while consuming activates [[5-HT2C receptor]]s on dopamine-producing cells. This halts their dopamine release, and thereby serotonin decreases appetite. Drugs that block 5-HT<sub>2C</sub> receptors make the body unable to recognize when it is no longer hungry or otherwise in need of nutrients, and are associated with weight gain,<ref name="pmid19178394">{{cite journal | vauthors = Stahl SM, Mignon L, Meyer JM | title = Which comes first: atypical antipsychotic treatment or cardiometabolic risk? | journal = Acta Psychiatrica Scandinavica | volume = 119 | issue = 3 | pages = 171–179 | date = March 2009 | pmid = 19178394 | doi = 10.1111/j.1600-0447.2008.01334.x | s2cid = 24035040 | doi-access = free }}</ref> especially in people with a low number of receptors.<ref name="pmid15741483">{{cite journal | vauthors = Buckland PR, Hoogendoorn B, Guy CA, Smith SK, Coleman SL, O'Donovan MC | title = Low gene expression conferred by association of an allele of the 5-HT2C receptor gene with antipsychotic-induced weight gain | journal = The American Journal of Psychiatry | volume = 162 | issue = 3 | pages = 613–615 | date = March 2005 | pmid = 15741483 | doi = 10.1176/appi.ajp.162.3.613 }}</ref> The expression of 5-HT<sub>2C</sub> receptors in the [[hippocampus]] follows a [[circadian rhythm|diurnal rhythm]],<ref name="pmid9151722">{{cite journal | vauthors = Holmes MC, French KL, Seckl JR | title = Dysregulation of diurnal rhythms of serotonin 5-HT2C and corticosteroid receptor gene expression in the hippocampus with food restriction and glucocorticoids | journal = The Journal of Neuroscience | volume = 17 | issue = 11 | pages = 4056–4065 | date = June 1997 | pmid = 9151722 | pmc = 6573558 | doi = 10.1523/JNEUROSCI.17-11-04056.1997 }}</ref> just as the serotonin release in the [[ventromedial nucleus]], which is characterised by a peak at morning when the motivation to eat is strongest.<ref name="pmid2197074">{{cite journal | vauthors = Leibowitz SF | title = The role of serotonin in eating disorders | journal = Drugs | volume = 39 | issue = Suppl 3 | pages = 33–48 | year = 1990 | pmid = 2197074 | doi = 10.2165/00003495-199000393-00005 | s2cid = 8612545 }}</ref>

In [[macaque]]s, alpha males have twice the level of serotonin in the brain as subordinate males and females (measured by the concentration of [[5-Hydroxyindoleacetic acid|5-HIAA]] in the [[cerebrospinal fluid]] (CSF)). Dominance status and CSF serotonin levels appear to be positively correlated. When dominant males were removed from such groups, subordinate males begin competing for dominance. Once new dominance hierarchies were established, serotonin levels of the new dominant individuals also increased to double those in subordinate males and females. The reason why serotonin levels are only high in dominant males, but not dominant females has not yet been established.<ref>McGuire, Michael (2013) "Believing, the neuroscience of fantasies, fears, and confictions" (Prometius Books)</ref>

In humans, levels of 5-HT<sub>1A</sub> receptor inhibition in the brain show negative correlation with aggression,<ref>{{cite journal | vauthors = Caspi N, Modai I, Barak P, Waisbourd A, Zbarsky H, Hirschmann S, Ritsner M | title = Pindolol augmentation in aggressive schizophrenic patients: a double-blind crossover randomized study | journal = International Clinical Psychopharmacology | volume = 16 | issue = 2 | pages = 111–115 | date = March 2001 | pmid = 11236069 | doi = 10.1097/00004850-200103000-00006 | s2cid = 24822810 }}</ref> and a mutation in the gene that codes for the [[5-HT2A receptor|5-HT<sub>2A</sub>]] receptor may double the risk of suicide for those with that genotype.<ref name="Basky_2000">{{cite journal | vauthors = Ito Z, Aizawa I, Takeuchi M, Tabe M, Nakamura T | title = [Proceedings: Study of gastrointestinal motility using an extraluminal force transducer. 6. Observation of gastric and duodenal motility using synthetic motilin] | journal = Nihon Heikatsukin Gakkai Zasshi | volume = 11 | issue = 4 | pages = 244–246 | date = December 1975 | pmid = 1232434 }}</ref> Serotonin in the brain is not usually degraded after use, but is collected by serotonergic neurons by [[serotonin transporter]]s on their cell surfaces. Studies have revealed nearly 10% of total variance in anxiety-related personality depends on variations in the [[5-HTTLPR|description of where, when and how many]] serotonin transporters the neurons should deploy.<ref name="pmid8929413">{{cite journal | vauthors = Lesch KP, Bengel D, Heils A, Sabol SZ, Greenberg BD, Petri S, Benjamin J, Müller CR, Hamer DH, Murphy DL | title = Association of anxiety-related traits with a polymorphism in the serotonin transporter gene regulatory region | journal = Science | volume = 274 | issue = 5292 | pages = 1527–1531 | date = November 1996 | pmid = 8929413 | doi = 10.1126/science.274.5292.1527 | s2cid = 35503987 | bibcode = 1996Sci...274.1527L }}</ref>