Abstract
Effects of betamethasone 17, 21-dipropionate (BMDP) and betamethasone (BM) on hypothalamo-pituitary-adrenal cortex axis following the intravenous or subcutaneous administration were studied in rats. The active site of the main metabolite of BMDP—betamethasone 17-propionate (BMP)—and BM was investigated by the stereotaxical implantation of these glucocorticoids. The ether-induced increase of plasma corticosterone was not suppressed by intravenous administration of BMDP in a dose of 300 μg/kg, but BM suppressed this increase at doses over 10 μg/kg. Subcutaneous administration of a large amount of these steroids (BMDP, 20 mg/kg; BM, 16mg/kg) induced a significant suppression of the ether-induced plasma corticosterone increase. The implantation of the main metabolite of BMDP—BMP—into the anterior or medial hypothalamic area and septum was effective in significantly reducing the ether-induced increase of plasma corticosterone. BMP implants into the posterior hypothalamus or pituitary gland proved to be ineffective. In contrast, BM, when placed into the hypothalamic area (anterior, medial or posterior), septum or pituitary, lowered the plasma corticosterone levels.
