Neuroendocrinological study of prolactin releasing peptide

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Prolactin-releasing peptide(PrRP) was found as an endogenous ligand of an orphan G-protein coupled receptor(hGR3 for human and GPR10 for rat) in 1998. The PrRP is known to stimulate prolactin secretion and release in vitro and in vivo which suggest PrRP is a candidate of a prolactin-releasing hypophysiotropic factor. However, our morphological studies showed that PrRP-producing cell bodies were manily localized in the nucleus tractus solitary of medulla oblongata. Our previous study showed that PrRP is not classical hypophysiotropic factor but it stimulates ACTH secretion through CRH secretion and act as stress mediator in the central nermous system. In this study we demonstrated that PrRP produced in the adrenaline cells in the adrenal gland. In addition PrRP producing cells appeared in the area postrema of adrenalectomized rats. On the other hand, regulation of PrRP producing cells have not been well studied, we therefore examined the function of PrRP positive cells in the SON after nicotine treatment and found nicotine stimulates PrRP cells and non-PrRP cells in the SON. In addition we examined stress response of PrRP cells with or without estrogen treatment. In this study we found estrogen suppress stress response of PrRP cells.