CNS regulation of reproduction: peptidergic mechanisms.

The coordinated activities of several networks of peptidergic neurons contribute to the overall neural regulation of reproduction and associated behaviours. Key elements are rostral hypothalamic cells that synthesize and release LHRH from their median eminence nerve terminals, subject to modulation by a variety of endogenous transmitters and neuropeptides including VIP, CCK, opioids and somatostatin. In the CNS, LHRH may also participate in intercellular communication to facilitate the expression of estrogen-sensitive sexual behavior. Vasopressin and oxytocin also appear to modulate maternal and reproductive behavior. In addition, 'oxytocinergic' neurons recorded during lactation and milk ejection display unique bursting activity patterns deemed important for efficient release of hormone. However, endogenous opioid peptides appear able to dissociate this stimulus-secretion coupling mechanism, possibly through interference with a calcium sensitive component in nerve terminals.