Adrenal rather than central dysfunction limits HPA axis recovery after chronic glucocorticoid treatment in male mice

Even after adjusting for macrophage content, CORT secretion was disproportionately low relative to the remaining adrenocortical cell mass despite supraphysiologic ACTH stimulation. The adrenal is thus the principal site of post-withdrawal GIAI, involving adrenocortical cell loss and a superimposed defect in steroidogenesis. We next tested whether preserving adrenal trophic signaling during glucocorticoid exposure could prevent GIAI.

Adrenal function recovered more slowly in mice treated with DEX and daily cosyntropin (a synthetic ACTH analog) compared to those treated with DEX alone. In contrast, mice with non-suppressible endogenous ACTH due to targeted hypothalamic deletion of the glucocorticoid receptor maintained normal adrenal architecture and steroidogenic capacity despite prolonged DEX treatment. Pharmacologic treatments that mimic sustained trophic signaling to the adrenal during chronic glucocorticoid treatment may thus prevent GIAI.