Iontophoresis of cortisol inhibits responses of identified paraventricular nucleus neurones to sciatic nerve stimulation.

Responses of paraventricular nucleus (PVN) neurones were examined following stimulation of the sciatic nerve, and concomitant with iontophoretic application of cortisol. Sciatic nerve stimulation excited the majority of cells (22/24, 92%) and iontophoretic application of cortisol reduced the spontaneous activity of 16 of the cells tested (67%). Cortisol prevented neuronal responses to sciatic nerve stimulation in 11 cases (50%) but some of the cells inhibited by the steroid still responded to the stimulation, whilst some cells unaffected by cortisol alone were found not to respond during exposure to the stimulus. These results indicate an inhibitory role for glucocorticoids in the regulation of PVN neuronal activity and responses to afferent neural stimuli.