PHARMACOLOGICAL EFFECTS ON SOCIAL INTERACTION 1 Effects of Pharmacological Manipulations on Natural Social Interaction in Rhesus Macaques: A Pilot Investigation

The neuropeptide oxytocin has been shown to have prosocial effects in both monkeys and humans, leading to its proposed use as a treatment for social disorders in humans such as Autism Spectrum Disorder (ASD). The opioid system interacts with the oxytocinergic system in an antagonistic manner, so that inactivation of the opioid system causes an increase in oxytocin levels. In this experiment, we administered either oxytocin alone, the opioid antagonist naloxone alone, the combination of the two, or a saline control to two non-human primate subjects (one female, one male) to examine the effects on natural social behaviors of rhesus macaques. We recorded the behavior of the subject monkey in the cage for 90 minutes and used a computer scoring software to mark specific behavior types. We found that oxytocin increased huddling and prosocial behavior in the male subject and increased the mean duration of grooming given in the female subject. Naloxone was found to increase prosocial behavior in the male subject and decrease antisocial behavior in the female subject. The combination of oxytocin and naloxone slightly increased prosocial behavior in the female subject but showed no clear effect in the male subject. Further studies with a larger sample size are needed to provide helpful insight into how to more effectively translate lab-based results from controlled studies into natural behavioral settings. PHARMACOLOGICAL EFFECTS ON SOCIAL INTERACTION 3