Oxytocin and Social Isolation: Nonapeptide Regulation of Social Homeostasis

Social isolation imposes physiological and behavioural effects that can have a severe impact on health, but the underlying mechanisms remain poorly understood. We reason that mechanisms responsible for the motivation to interact with others and the cognitive assessment of social interactions also mediate the effects of the lack of social interactions. This is because social isolation stress depends on the ability to maintain homeostasis against objective changes from sensory deprivation under physical isolation and subjective changes from perceived unmet social needs. Here, we review evidence for the conserved role played by the oxytocin neurosignalling system via its modulation of social decision-making and stress management. We discuss how oxytocin underlies the influence of both objective and subjective changes in social conditions, by featuring prominently in the control of motivational and cognitive functions in conserved brain regions, and eliciting ultimate health outcomes through interactions with other neuroendocrine systems.