OPIOID CONTROL OF GONADOTROPIN-SECRETION IN HUMANS

Hypothalamus-pituitary-axis (HPA) is constantly under the modulatory e ffect of many substances, such as neurotransmitters, neuromodulators a nd steroid hormones. Recently, the involvement of endogenous opioid pe ptides (EOP) in the control of the neuroendocrine mechanism modulating gonadotrophin secretion has been supported by several authors. It has been demonstrated that acute morphine administration decreases lutein izing hormone (LH) plasma levels and this is due to an inhibitory modu lation on gonadotrophin releasing hormone discharge from the hypothala mic neurons. EOP are usually increased by stressant situations. In str ess-induced amenorrhoea, the presence of low LH plasma levels and an a bnormal LH pulsatile secretion has been related to an increased opioid activity, thus supporting the integrative role of opioids between hor monal and neuronal afferences of brain