Roles of prolactin-releasing peptide and RFamide related peptides in the control of stress and food intake.

Subsequent to the isolation of the first recognized RFamide neuropeptide, FMRFamide, from the clam, a large number of these peptides have been identified. There are now five groups of RFamide peptides identified in mammals. RFamide peptides show diversity with respect to their N-terminal sequence and biological activity. RFamide peptides have been implicated in a variety of roles, including energy metabolism, stress and pain modulation, as well as effects in the neuroendocrine and cardiovascular systems. In the present minireview, we focus on prolactin-releasing peptide (PrRP) and RFamide related peptide (RFRP) with respect to their roles in the control of energy metabolism and stress responses. Both food intake and stressful stimuli activate PrRP neurons. The administration of PrRP affects energy metabolism and neuroendocrine systems. PrRP-deficient or PrRP receptor-deficient mice show abnormal energy metabolism and/or stress responses. On the other hand, RFRP neurons are activated by stressful stimuli and the administration of RFRP induces neuroendocrine and behavioral stress responses. Taken together, these data suggests that PrRP and RFRP neurons play a role in the control of energy metabolism and/or stress responses.