Repeated central administration of α-MSH does not alter the antipyretic effect of α-MSH in young and aged rabbits

Abstract α-Melanocyte-stimulating hormone is a potent antipyretic when administered centrally or peripherally; however, there are no previous data on development of tolerance to the antipyretic action of this neuropeptide. In previous research, aged rabbits were more sensitive to low doses of α-MSH than young rabbits. We tested the antipyretic action of α-MSH in young and old rabbits after twice daily injections of the peptide for 10 days. Neither aged nor younger rabbits showed altered responses to α-MSH. This lack of tolerance underscores the importance of α-MSH to physiological control and survival of the host.