[Effect of beta-endorphin on preoptic region neuronal activity as the center of gonadotropic function regulation].

A study was made of the effect of microiontophoretic application of beta-endorphine on the activity of single preoptic neurons of the diencephalon as the regulating center of gonadotrophic function of the hypophysis. In 44.1% of cases, beta-endorphine exerted an inhibitory effect on the activity of single neurons, the depth of this effect amounted on the average to 54.9 +/- 5.65% on the initial frequency of neurons with a certain type of response to the opiate. The activation effect of beta-endorphine was noted only in 17.7% of the cases, but its intensity reached 225.8 +/- 29.3% on the average. In 38.2% of the cases, application of beta-endorphine did not affect the frequency of spontaneous preoptic neuronal discharges. It is likely that the inhibitory action of beta-endorphine which was seen more frequently among the preoptic neurons underlies the inhibitory effect of opiates on the development of the preovulatory release of luteinizing hormone from the pituitary into the blood.