Oxytocinplaysanimportantroleintheneuroanatomyofintimacy,specificallyinsexualreproductionofbothsexes,inparticularduringandafterchildbirth.Itisreleasedinlargeamountsafterdistensionofthecervixanduterusduringlabor,facilitatingbirth,maternalbonding,and,afterstimulationofthenipples,lactation.Studieshavebeguntoinvestigateoxytocin’sroleinvariousbehaviors,includingorgasm,socialrecognition,pairbonding,anxiety,andmaternalbehaviors.Itissometimesreferredtoasthe“bondinghormone”.Thereissomeevidencethatoxytocinpromotesethnocentricbehavior,incorporatingthetrustandempathyofin-groupswiththeirsUSPicionandrejectionofoutsiders.FurThermore,geneticdifferencesintheoxytocinreceptorgenehavebeenassociatedwithmaladaptivesocialtraitssuchasaggressivebehavior.

Innon-mammalianspeciesthesebehaviorsarecontrolledbyoxytocin-likepeptides,whichdifferatpositions4and/or8. Theseoxytocin-ilkepeptidesincludemesotocin(withanisoleucine-8)andisotocin(glutamine-4changedtoserineandarginine-8changedtoisoleucine).Oxytocinoccursinplacentalmammals;mesotocinoccursinamphibians,reptiles,andbirds,andisotocinoccursinfishes.

OurIsotocinsolutionisaperfectcomplementforourOxytocinEIAandCLIAkitsforthoseresearchersstudyingfish. TherelativebindingofIsotocininourOxytocinassaysisshownbelow.