Prolactin-releasing peptide

Prolactin-releasing peptide (PrRP), an RFamide peptide, had been originally identified as a stimulator of prolactin release from the anterior pituitary. However, further studies revealed that the prolactin-releasing effect of PrRP is inconsistent and different from ordinary hypophysiotropic hormones. However, PrRP is demonstrated to have some physiological roles, such as inhibition of feeding, obesity, and stress response, and control of the release of hypothalamic hormones in mammals. On the other hand, PrRP2 (C-RFa) has been identified as a neuropeptide that originates from a common ancestral gene of PrRP. PrRP2 is found in vertebrates except for mammals. PrRP2 is a potent stimulator of prolactin in teleosts, but has a lesser effect in amphibians and chickens. As in PrRP, PrRP2 is related to energy homeostasis in teleosts and chickens. The physiological functions of PrRP and PrRP2 may have changed through evolution.