EFFECTS OF CORTICOSTERONE ON SPONTANEOUS DISCHARGES OF RAT HYPOTHALAMIC PARAVENTRICULAR NEURONS IN VITRO

Experiments were performed to investigate the effects of corticosterone on ele-trical activities of paraventricular neurons in rat hypothalamic slices.In unstimu-lated conditions,most of the neurons had either a slow irregular(48.1%)or fastcontinuous pattern(42.5%)of discharge.Only a small portion(9.4%)of the cellsshows phasic activity.During perfusion of the slices with corticosterone(10~(-7),10~(-6)mol/L),25 out of 104 paraventricular neurons were profoundly inhibited with ashort latency,8 neurons were excited and the remaining cells showed no response.The response,the magnitude of the cells which depended upon the concentration ofcorticosterone,could be reversed by concomitant application of RU38486(10~(-7),10~(-6)mol/L),a competitive antagonist of glucocorticoid's cytosolic receptor.These results provide further evidence that corticosterone has rapid effects onrat hypothalamic paraventricular neurons,and suggests the existence of membranereceptors for glucocorticoid in paraventricular neurons.