LESIONS OF HYPOTHALAMIC PVN PARTIALLY ATTENUATE STIMULATORY ACTION OF ALCOHOL ON ACTH-SECRETION IN RATS

We have previously shown that the ability of alcohol to stimulate adrenocorticotropic hormone (ACTH) secretion was significantly blunted by immunoneutralization of endogenous corticotropin-releasing factor (CRF) and that long-term exposure to alcohol increased CRF mRNA levels in the paraventricular nucleus (PVN) of the hypothalamus. In the present study, we further investigated the participating role of the PVN by studying the effect of bilateral lesions of the PVN on alcohol-induced ACTH release. The acute injection of alcohol (1.5 g/kg ip) induced significant increases in plasma ACTH levels in sham-operated animals. Lesions of the PVN attenuated this response but did not abolish it. Indeed, lesioned rats retained significantly elevated ACTH values despite removal of secretagogues of PVN origin. Because removal of hypothalamic CRF can alter ACTH secretion in response to secretagogues, we studied possible changes in pituitary responsiveness to CRF. The results failed to indicate that hyperresponsiveness of the corticotrophs played a major role in accounting for the residual ACTH release of lesioned rats after alcohol treatment. We conclude that brain regions other than the PVN can modulate ACTH release during acute administration of alcohol.