Effects of iontophoretically applied cortisol on tuberoinfundibular neurons in hypothalamic paraventricular nucleus of anesthetized rats.

Effects of cortisol on 22 tuberoinfundibular (TI) neurons in the paraventricular nucleus (PVN) of the hypothalamus were examined in urethane-anesthetized rats. Iontophoretically applied cortisol excited 10 (45%) of 22 TI-neurons tested, whereas the cortisol inhibited 4 (31%) of 13 neurons in the periventricular hypothalamic nucleus. Intravenously applied cortisol (0.5 mg in 0.5 ml saline) excited 4 (36%) of 11 TI neurons tested and inhibited 1 (9%). These results suggest that cortisol may have an excitatory effect on TI neurons in the PVN.