[Interaction of endogenous opioid peptides with the function of the hypothalamo-hypophyseal-testicular axis]

Since the discovery of endogenous opioid peptides and opioid receptors in the brain, their has been considerable interest in their possible role in a variety of physiological and pharmacological processes. The endogenous opioids and opiate active substances have been clearly implicated in the regulation of male reproductive function. It has been demonstrated that opioid peptides inhibit gonadotropin and TSH secretion and enhance PRL, GH and ACTH. It is believed that opioids elicit their action at the hypothalamic level, most likely by modulating the liberation of hypothalamic releasing or inhibiting factors. In healthy male adults the endogenous opioid peptides (EOP) produce a decrease in serum levels of gonadotropins. Administration of specific opiate antagonists decreases luteinizing hormone (LH) release and increases the frequency and amplitude of the LH pulses. The effects of EOP and specific opiate antagonists are altered in some hypothalamic-hypophysis-testis axis pathologies.