Dexamethasone-induced adrenal cortex atrophy and recovery of the gland from partial, steroid-induced atrophy.

This study aims to examine the effects of low dexamethasone (DX) doses on cellular and functional changes in the rat adrenal cortex and to observe the recovery of the gland from DX-induced partial atrophy. Within seven days doses of 15, 30 and 60 micrograms DX/100 g/day resulted in a dose dependent decrease in body and adrenal gland weight. Within two weeks the lowest DX dose tested caused further decrease in adrenal weight. DX markedly lowered plasma ACTH and corticosterone (B) level, B content in the gland and B output by adrenal slices. Adrenocortical atrophy induced by 15 micrograms DX was dependent upon the linear decrease in the volume of fasciculata and reticularis zones, in the average volume of the fasciculata cell and in the number of adrenocortical cells in the entire cortex. This dose of DX resulted in a prompt and potent inhibition of proliferative activity of adrenocortical cells as assessed by the counting of metaphases per adrenal section. Partial adrenal atrophy evoked by 7 day DX-treatment was reversible within seven days of the discontinuation of the steroid treatment. Recovery of the gland depended mainly on the increases in the volume of all adrenocortical zones, in the average volume of fasciculata cell and in the number of parenchymal cells in the gland. Seven days after discontinuation of DX administration plasma ACTH was significantly higher than in controls. Plasma B and B secretion by adrenal slices were similar to the control group while B content in the gland was still depressed.(ABSTRACT TRUNCATED AT 250 WORDS)