NUTRITIONAL INFERTILITY - THE ROLE OF THE INTERCONNECTED HYPOTHALAMICNEUROPEPTIDE Y-GALANIN-OPIOID NETWORK

Neuropeptide Y (NPY) has been implicated in the hypothalamic regulatio n of reproduction and energy homeostasis. The perikarya located primar ily in the arcuate nucleus (ARC) of the hypothalamus constitute a comm on source of NPY. Projections from these neurons along two distinct pa thways, namely the reproductive axis of the ARC-median eminence-medial preoptic area and the orexigenic axis of the ARC-paraventricular nucl eus and neighboring regions, participate in regulation of these two ne uroendocrine functions. Additionally the NPY neuronal system within th e basal hypothalamus is morphologically and functionally linked with g alanin and the opioid networks which also play roles in the control of reproduction and ingestive behavior. Recent experimental evidence ind icates that genetic, hormonal, and environmental factors that cause nu tritional imbalance and metabolic disturbances, along with depressed p ituitary gonadal function, produce alterations in the synthesis, stora ge, and release of NPY and in other connected peptidergic systems in t he hypothalamus. The current findings summarized in this review suppor t our concept that NPY may be one of the essential messenger molecules that serve as a communication bridge between the neural processes tha t regulate reproduction and those that maintain energy homeostasis. Mo dification in information flow within this peptidergic network due to nutritional imbalance may adversely impact hypothalamo-pituitary-gonad al function. (C) 1996 Academic Press, Inc.