EFFECTS OF NITRIC-OXIDE ON NEUROENDOCRINE FUNCTION AND BEHAVIOR

Nitric oxide (NO) is an unusual chemical messenger. NO mediates blood vessel relaxation when produced by endothelial cells. When produced by macrophages, NO contributes to the cytotoxic function of these immune cells. NO also functions as a neurotransmitter and neuromodulator in the central and peripheral nervous systems. The effects on blood vesse l tone and neuronal function form the basis for an important role of N O on neuroendocrine function and behavior. NO mediates hypothalamic po rtal blood flow and, thus, affects oxytocin and vasopression secretion ; furthermore, NO mediates neuroendocrine function in the hypothalamic -pituitary-gonadal and hypothalamic-pituitary-adrenal axes. NO influen ces several motivated behaviors including sexual, aggressive, and inge stive behaviors. Learning and memory are also influenced by NO. Taken together, NO is emerging as an important chemical mediator neuroendocr ine function and behavior. (C) 1997 Academic Press.