The RFamide-Related Peptides

This chapter focuses on the RFamide-related peptides (RFRP). RFRP represents a family of regulatory peptides that possess the signature Arg-Phe-NH₂ at their C-terminus. The first member of this family, the tetrapeptide Phe-Met-Arg-Phe-NH₂, was originally isolated from the ganglia of the venus clam on the basis of its cardiovascular activity. The main populations of RFRP-containing neurons are present in the periventricular region of the hypothalamus, in the nucleus of the solitary tract and the reticular nucleus of the brain stem, and in the dorsal horn of the spinal cord. Consistent with this distribution, RFRPs exert various effects in the central nervous system (CNS) such as modulation of nociceptive transmission, control of feeding behavior, and regulation of pituitary hormone secretion. Finally, the presence of both prolactin-releasing peptide (PrRP) and GPR10 in brain areas involved in pain modulation suggests that PrRP may affect the transmission of nociceptive stimuli. RFRPs exert a large array of biological effects including cardioexcitatory activities, modulation of muscle contraction, control of locomotor activity, regulation of hydric balance, and neuromodulatory activities.