Editing Pheromone (section)

==Pheromone receptors==
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===In the olfactory epithelium===
{{Further|Trace amine-associated receptor}}
The human [[trace amine-associated receptor]]s are a group of six [[G protein-coupled receptor]]s (i.e., [[TAAR1]], [[TAAR2]], [[TAAR5]], [[TAAR6]], [[TAAR8]], and [[TAAR9]]) that&nbsp;– with exception for TAAR1&nbsp;– are expressed in the human [[olfactory epithelium]].<ref name="IUPHAR TAAR" /> In humans and other animals, TAARs in the [[olfactory epithelium]] function as [[olfactory receptor]]s that detect [[Volatility (chemistry)|volatile]] [[amine]] [[odorant]]s, including certain pheromones;<ref name="IUPHAR TAAR">{{cite web|title=Trace amine receptor: Introduction|url=http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=64|publisher=International Union of Basic and Clinical Pharmacology|access-date=15 February 2014|quote=Importantly, three ligands identified activating mouse Taars are natural components of mouse urine, a major source of social cues in rodents. Mouse Taar4 recognizes β-phenylethylamine, a compound whose elevation in urine is correlated with increases in stress and stress responses in both rodents and humans. Both mouse Taar3 and Taar5 detect compounds (isoamylamine and trimethylamine, respectively) that are enriched in male versus female mouse urine. Isoamylamine in male urine is reported to act as a pheromone, accelerating puberty onset in female mice [34]. The authors suggest the Taar family has a chemosensory function that is distinct from odorant receptors with a role associated with the detection of social cues.&nbsp;... The evolutionary pattern of the TAAR gene family is characterized by lineage-specific phylogenetic clustering [26,30,35]. These characteristics are very similar to those observed in the olfactory GPCRs and vomeronasal (V1R, V2R) GPCR gene families.|archive-date=23 February 2014|archive-url=https://web.archive.org/web/20140223102849/http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=64|url-status=dead}}</ref><ref name="TAAR 2015 review - olfactory TAARs" /> these TAARs putatively function as a class of pheromone receptors involved in the olfactive detection of social cues.<ref name="IUPHAR TAAR" /><ref name="TAAR 2015 review - olfactory TAARs" />

A review of studies involving non-human animals indicated that TAARs in the olfactory epithelium can mediate [[reward system|attractive]] or [[aversives|aversive]] behavioral responses to a [[receptor agonist]].<ref name="TAAR 2015 review - olfactory TAARs" /> This review also noted that the behavioral response evoked by a TAAR can vary across species (e.g., TAAR5 mediates attraction to [[trimethylamine]] in mice and aversion to trimethylamine in rats).<ref name="TAAR 2015 review - olfactory TAARs">{{cite journal | vauthors = Liberles SD | title = Trace amine-associated receptors: ligands, neural circuits, and behaviors | journal = Current Opinion in Neurobiology | volume = 34 | pages = 1–7 | date = October 2015 | pmid = 25616211 | pmc = 4508243 | doi = 10.1016/j.conb.2015.01.001 | quote = Furthermore, while some TAARs detect aversive odors, TAAR-mediated behaviors can vary across species.&nbsp;... The ability of particular TAARs to mediate aversion and attraction behavior provides an exciting opportunity for mechanistic unraveling of odor valence encoding. }}<br />[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508243/figure/F2/ Figure 2: Table of ligands, expression patterns, and species-specific behavioral responses for each TAAR]</ref> In humans, hTAAR5 presumably mediates aversion to trimethylamine, which is known to act as an hTAAR5 agonist and to possess a foul, fishy odor that is aversive to humans;<ref name="TAAR 2015 review - olfactory TAARs" /><ref name="hTAAR5 and trimethylamine aversion">{{cite journal | vauthors = Wallrabenstein I, Singer M, Panten J, Hatt H, Gisselmann G | title = Timberol® Inhibits TAAR5-Mediated Responses to Trimethylamine and Influences the Olfactory Threshold in Humans | journal = PLOS ONE | volume = 10 | issue = 12 | pages = e0144704 | date = 2015 | pmid = 26684881 | pmc = 4684214 | doi = 10.1371/journal.pone.0144704 | quote = While mice produce gender-specific amounts of urinary TMA levels and were attracted by TMA, this odor is repellent to rats and aversive to humans [19], indicating that there must be species-specific functions.&nbsp;... Furthermore, a homozygous knockout of murine TAAR5 abolished the attraction behavior to TMA [19]. Thus, it is concluded that TAAR5 itself is sufficient to mediate a behavioral response at least in mice.&nbsp;... Whether the TAAR5 activation by TMA elicits specific behavioral output like avoidance behavior in humans still needs to be examined. | doi-access = free | bibcode = 2015PLoSO..1044704W }}</ref> however, hTAAR5 is not the only olfactory receptor that is responsible for trimethylamine olfaction in humans.<ref name="TAAR 2015 review - olfactory TAARs" /><ref name="hTAAR5 and trimethylamine aversion" /> {{As of|December 2015|post=,}} hTAAR5-mediated trimethylamine aversion has not been examined in published research.<ref name="hTAAR5 and trimethylamine aversion" />

===In the vomeronasal organ===
{{Further|Vomeronasal receptor}}
In [[reptile]]s, [[amphibia]] and non-primate mammals pheromones are detected by regular [[olfactory]] membranes, and also by the [[vomeronasal organ]] (VNO), or Jacobson's organ, which lies at the base of the [[nasal septum]] between the nose and mouth and is the first stage of the [[accessory olfactory system]].<ref name="PUB00007338">{{cite journal | vauthors = Pantages E, Dulac C | title = A novel family of candidate pheromone receptors in mammals | journal = Neuron | volume = 28 | issue = 3 | pages = 835–845 | date = December 2000 | pmid = 11163270 | doi = 10.1016/S0896-6273(00)00157-4 | doi-access = free }}</ref> While the VNO is present in most amphibia, reptiles, and non-primate mammals,<ref>{{cite book| vauthors = Carlson NR |title=Physiology of behavior|date=2013|publisher=Pearson|location=Boston|isbn=978-0-205-23939-9 |page=335|edition=11th}}</ref> it is absent in [[bird]]s, adult [[catarrhine]] monkeys (downward facing nostrils, as opposed to sideways), and [[ape]]s.<ref name="PUB00007339">{{cite journal | vauthors = Keverne EB | title = The vomeronasal organ | journal = Science | volume = 286 | issue = 5440 | pages = 716–720 | date = October 1999 | pmid = 10531049 | doi = 10.1126/science.286.5440.716 }}</ref> An active role for the human VNO in the detection of pheromones is disputed; while it is clearly present in the [[fetus]] it appears to be [[atrophy|atrophied]], shrunk or completely absent in adults. Three distinct families of [[vomeronasal receptor]]s, putatively pheromone sensing, have been identified in the vomeronasal organ named V1Rs, V2Rs, and V3Rs. All are [[G protein-coupled receptors]] but are only distantly related to the receptors of the main olfactory system, highlighting their different role.<ref name="PUB00007338" />