[Effects of corticosterone on spontaneous discharges of rat hypothalamic paraventricular neurons in vitro]

Experiments were performed to investigate the effects of corticosterone on electrical activities of paraventricular neurons in rat hypothalamic slices. In unstimulated conditions, most of the neurons had either a slow irregular (48.1%) or fast continuous pattern (42.5%) of discharge. Only a small portion (9.4%) of the cells shows 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 a short latency, 8 neurons were excited and the remaining cells showed no response. The response, the magnitude of the cells which depended upon the concentration of corticosterone, 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 on rat hypothalamic paraventricular neurons, and suggests the existence of membrane receptors for glucocorticoid in paraventricular neurons.