The role of prostaglandins in neuroendocrine junctions: studies in the pineal gland and the hypothalamus.

This article discusses current experimental evidence indicating a role for prostaglandins (PGs) in pineal and median eminence neuroendocrine junctions. Both tissues release PGs, particularly of the E series, upon exposure to norepinephrine (NE) and through alpha-adrenoceptors. Exposure of pineal and median eminence explants to nanomolar concentrations of PGE2 augments melatonin and GnRH release, respectively. In the pineal gland, this effect appears to be linked to the stimulation of adenylate cyclase. Both in vivo and in vitro PG synthesis inhibitors impair the hormone release elicited by NE. In the pineal gland, PGE2 also constitutes a trans-synaptic negative signal for NE release. PGs receptors are present in pineal and hypothalamic membranes.