Doctor Thomas Insel continues his discussion of the two neuropeptides, vasopressin and oxytocin.

People have asked could you measure oxytocin and vasopressin, you know, if I’m engaged I’d love to know if my mate has got a particular vasopressin allele or vasopressin receptor allele. We don’t have any evidence at this point that we’re going to have much of an effect on fidelity in humans. The studies that have been done so far show a statistical difference where you give the peptide, oxytocin in this case, give it to healthy young volunteers, and you ask them to make judgments about someone’s trustworthiness. You can also show with neuroimaging that you can decrease to some extent (it’s not a huge effect) the response in the amygdala to a social threat, again in volunteers. Not so much to a non-social threat, so that’s probably the interesting part from the perspective of the animal work that these peptides seem to really be working on social stimuli, not so much other kinds of stimuli. I’ll tell you though if there is one thing I would take from having worked in this system for 15 years, it’s the recognition that every species is different. You can’t conclude what oxytocin or vasopressin does in the prairie vole and say, 'Oh let’s do it in the montane vole', because you get completely different results. So to jump from prairie vole to primates and particularly human primates is a very big jump indeed. So what you’d want to do before you get too far down this pathway is to map the receptors. What we learned from studies done in many other species was that if you really want to understand the function of these peptides, find out where the receptors are in the brain. That hasn’t been done in a very precise way yet in the human brain. It still needs to be tackled so that we’ll have some idea of whether the results in humans will be more relevant to the voles or to the rats or to the marmosets or to other species that have been studied already.

vasopressin, oxytocin, prairie vole, marmosets, social bonding, attachment, thomas, insel