Effects of 6-hydroxydopamine-induced lesions of the paraventricular nucleus, and of prazosin, on the corticosterone response to restraint in rats.

In rats, with bilateral lesions of the paraventricular nuclei induced by 6-hydroxydopamine, restraint stress failed to elevate levels of corticosterone in plasma, although the resting levels in lesioned animals were similar to those of control rats. Prazosin inhibited the plasma-corticosterone response to restraint in intact rats, at doses which did not by themselves influence resting hormone levels. These results suggest a positive role for noradrenaline, acting through alpha-adrenoceptors, on the stress-induced output of corticotrophin.