Investigating the Contribution of Agouti-Related Peptide (AGRP) on Ghrelin’s Ability to Promote Social Interaction in Mice

Ghrelin is a stomach-derived peptide that acts as an endogenous ligand for growth hormone secretagogue receptor (GHSR). GHSR is abundantly expressed in the brain with high expression found in AGRP/NPY neurons within the hypothalamic arcuate nucleus. Emerging evidence suggests that ghrelin promotes social interaction whereas ghrelin receptor antagonists increase social vigilance. In this present thesis, we investigated the contribution of AGRP on ghrelin's ability to promote social interaction. 63 male and female C57BL/6J mice were assigned to groups receiving IP injections of saline or ghrelin, followed by saline or the MC3/4R agonist melanotan-II, then tested on a social interaction test to investigate how these drug treatments affected social behaviors. Results showed that IP ghrelin promotes social approach and motivation, whereas IP MTII enhances social vigilance. No interaction effects between the two drugs were found, suggesting that ghrelin promotes the motivation for social interaction, and these effects are independent from AGRP.