Oxytocin effects on emotional processes: separation distress, social bonding, and relationships to psychiatric disorders.

Abstract

Centrally administered oxytocin exerts powerful effects on a large variety of behavioral and physiological processes.'t2 As documented in many chapters of this volume, a substantial role for oxytocin has been established in the control of sexual and maternal behaviors in all mammalian species that have been studied. Homologous patterns of behavior have been observed following central administration of the evolutionary precursor, vasotocin, into avian and reptilian species, suggesting a remarkable conservation of sociosexual functions for this family of posterior pituitary nonapeptides.) The behavioral effects of oxytocin offer a prime example of a general principle which seems to be emerging from neuropeptide research-that there is a functional harmony between the peripheral and central effects of neuropeptides. One working premise of our research is that this principle holds not only for the physiological and behavioral effects of these hormones, but that it also extends to the emotional/psychological effects of these peptides within the brain. Indeed, neuropeptides may serve as key neuromodulators within the genetically provided emotional operating systems of the brain that coordinate behavioral, physiological, and psychological responses to major life-challenging circum~tances.~J In other words, many peptide systems may serve command functions in the brain that help synchronize a variety of bodily and brain systems to unconditionally promote coherent organismic response to primal survival needs. Other examples of this general principle are the ability of angiotensin to conserve water in the periphery and instigate thirst centrally,6 the ability of insulin to conserve fuel peripherally and to facilitate satiety centrally,' the ability of MSH to promote pigmentary camouflage peripherally and hiding behaviors centrally,8 the ability of CRF to promote stress responses peripherally and anxiety ~entrally,~ and the ability of LH-RH to promote gonadal readiness peripherally and sexual urgency centrally.'O One of the most striking examples of this principle is the ability of oxytocin to mediate maternal intent, sexual readiness, and perhaps neuropsychic emotional patterns that go along with these behavioral tendencies. Although neurodynamic emotional processes are difficult to measure empirically, some indication of the status of such putative brain systems can be obtained through the analysis of the unconditional emotive behavior patterns in animal^.^.^ A straightforward emotional prediction is that brain oxytocin may evoke warm positive feelings of social strength and comfort when aroused by peripheral stimuli. For instance, as mother and infant share in the nursing experience, brain oxytocin