Comparative adaptive functions of vasopressin and oxytocin
Individual and species differences are commonly observed. These differences are adaptive and context-dependent. Early life experiences can epigenetically tune these systems (see text and Fig. 3).
| Hypothesized Functions | Vasopressin – or AVPR Activation | Oxytocin – or OXTR Activation |
|---|---|---|
| Life history strategies and reproductive investment | More primitive – faster | More modern – slower |
| Lower parental investment and more offspring | Greater parental investment and fewer offspring | |
| Responses to challenges defense strategies | Mobilization (fight-flight) | Immobilization without fear |
| Amplifying stress and fear | Stress coping and resilience | |
| Reduced cooperation | Social cooperation | |
| Mobilization | Activation | Approach |
| Reactive aggression | Positive social behaviors | |
| Immobility with fear | Immobilization without fear | |
| Freezing or subordination? | Parental and sexual behavior | |
| Anxiety | Anxiogenic | Anxiolytic |
| Mild stress | Release of vasopressin | Inhibition of oxytocin? |
| Extreme acute stress | Release of vasopressin | Release of oxytocin |
| Chronic stress | Release of vasopressin? | Inhibition (males?); release of oxytocin (females) |
| Autonomic nervous systema | Sympathoadrenal | Parasympathetic (vagalb) |
| Inflammation | Proinflammatory (primarily) | Anti-inflammatory |
| Pain | Increasing or reducing? | Prevention or reducing |
↵a Interactions between AVP and OXT and the autonomic nervous system support flexibility in behavioral, emotional states and allow different strategies for dealing with challenges with effects that may differ between males and females.
↵b The vagus nerve has more than one branch arising from different source nuclei in the brainstem. The more modern branch arises in the ventral-vagal complex and supports social behaviors and features that are unique to mammals, such as facial expression, social engagement, and language. The more primitive branch arises in DMX (i.e., 10th cranial nerve) and is associated with conservation of energy in response to extreme stressors or trauma (Porges, 2011).