The MSH/ACTH(4-9) analog Org2766 counteracts isolation-induced enhanced social behavior via the amygdala

MSH/ACTH-like peptides influence social behavior induced by isolation It has been previously demonstrated that changes in locomotor activity as a result of isolation can be counteracted by Org2766 via the amygdala. The present study investigates whether isolation-induced changes in social behavior can also be affected by this peptide via the amygdala. A fully automated observation system was applied for detailed registration and analysis of movements of group-housed and 7-day isolated rats in a social interaction test. Administration of the MSH/ACTH(4-9) analog into the central nucleus of the amygdala elicited decreased locomotion, approach, and avoidance behaviors after isolation as compared to placebo-treated controls. However, general activity and social interest of group-housed rats were not affected by the MSH/ACTH(4-9) fragment. It is hypothesized that the amygdala is a site of action for neuropeptides in modulating social behavior.