Physiological and endocrine effects of social contact.

Nonnoxious sensory stimulation associated with friendly social interaction induces a psychophysiological response pattern involving sedation, relaxation, decreased sympathoadrenal activity, and increased vagal nerve tone and thereby an endocrine and metabolic pattern favoring the storage of nutrients and growth. It is suggested that oxytocin released from parvocellular neurons in the paraventricular nucleus (PVN) in response to nonnoxious stimulation integrates this response pattern at the hypothalamic level. The response pattern just described characterized by calm, relaxation, and anabolic metabolism could be regarded as an antithesis to the well known fight-flight response in which mental activation, locomotor activity, and catabolic metabolism are expressed. Furthermore, the health-promoting aspect of friendly and supportive relationships might be a consequence of repetitive exposure to nonnoxious sensory stimulation causing the physiological endocrine and behavioral changes just described.