Effect of bilateral adrenalectomy and corticosteroid therapy on the secretion of corticotrophin-releasing factor activity from the hypothalamus of the rat in vitro.

The rat hypothalamus in vitro preparation was used to investigate the effect of bilateral adrenalectomy, with and without replacement therapy, on the release of corticotrophin-releasing factor(CRF). Corticotrophin-releasing factor was estimated using 48 h basal hypothalamic lesioned assay rats and corticosterone production of excised adrenals was used as the end point. Bilateral adrenalectomy resulted in depletion of hypothalamic CRF content within the first 2 h after the operation but this effect was prevented by replacement therapy with corticosterone. Thereafter, the hypothalamic CRF content returned to values not significantly different from the intact control level. Bilateral adrenalectomy caused an increase in both basal and acetylcholine-induced release of CRF and it is suggested that corticosteroids exert a negative feedback effect on the hypothalamus.