Hypothalamic Oxytocin Mediates Social Buffering of the Stress Response

Abstract

Background While stressful life events can enhance the risk of mental disorders, positive social interactions can propagate good mental health and normal behavioral routines. Still, the neural systems that promote these benefits are undetermined. Oxytocin is a hormone involved in social behavior and stress; thus, we focus on the impact that social buffering has on the stress response and the governing effects of oxytocin. Methods Female prairie voles (Microtus ochrogaster) were exposed to 1 hr immobilization stress then recovered alone or with their male partner to characterize the effect of social contact on the behavioral, physiological, and neuroendocrine stress response. In addition, we treated immobilized females recovering alone with oxytocin, or vehicle, and females recovering with their male partner with a selective oxytocin receptor antagonist, or vehicle. Group sizes varied from 6 to 8 voles (n = 98 total). Results We found that 1 hr immobilization increased anxiety-like behaviors and circulating levels of corticosterone, a stress hormone, in females recovering alone, but not the females recovering with their male partner. This social buffering by the male partner on biobehavioral responses to stress was accompanied by increased oxytocin release in the paraventricular nucleus (PVN) of the hypothalamus. Intra-PVN oxytocin injections reduced behavioral and corticosterone responses to immobilization whereas injections of an oxytocin receptor antagonist blocked the effects of the social buffering. Conclusions Together, our data demonstrate that PVN oxytocin mediates the social buffering effects on the stress response, and thus may be a target for treatment of stress-related disorders.

Inhaled oxytocin increases positive social behaviors in newborn macaques

“…It is possible that oxytocin reduced anxiety, resulting in an increased propensity to socially engage with the caregiver. Several studies have shown that oxytocin has stress-buffering effects that are manifested behaviorally in terms of reduced anxiety and increased affiliative motivation (42,64) and physiologically in terms of reduced activity of the hypothalamic-pituitary adrenal (HPA) axis (41,65). The present finding of decreased salivary cortisol following oxytocin administration is consistent with these results, as well as reports that oxytocin locally affects several hypothalamic nuclei, e.g., through dendritic release (66).…”

Moderate Stress-Induced Social Bonding and Oxytocin Signaling are Disrupted by Predator Odor in Male Rats

“…Most previous rodent studies of stress effects on social behavior have used pair-bonded, monogamous rodents to demonstrate a phenomenon called stress buffering, where pair-bonded opposite-sex mates reduce their response to stress via prosocial, affiliative behaviors such as huddling (Smith and Wang, 2014) (reviewed in (Beery and Kaufer, 2015)). Outside of monogamously bonded adult rodents, developmental studies of human and nonhuman primates have provided evidence for both impaired social functioning and enhanced resilience after exposure to early life stress (Dettmer and Suomi, 2014;Gunnar, 2000;Parker et al, 2006).…”

Stress and the social brain: behavioural effects and neurobiological mechanisms

“…Oxytocin release within the paraventricular nucleus of the hypothalamus, triggered by mating, mediated mating-induced anxiolytic behavior in male rats 211 . Oxytocin release that was independent of mating was involved in the buffering of stress-induced increases in anxiety-like behaviors and circulating corticosterone that occur in female prairie voles if the male partner is present 212 . Furthermore, social buffering in rats was also shown to protect from the development of alterations in social interactions that otherwise emerge following stress exposure 213 .…”