Expression of inhibin α in the human adrenal gland and adrenocortical tumors

We studied the expression of inhibin alpha-subunit in normal and hyperplastic adrenal glands, as well as in various adrenocortical tumors. The protein expression of inhibin alpha was performed by immunohistochemistry. Virilizing adenomas showed strong immunoreactivity against monoclonal inhibin alpha-subunit antibody, whereas other adenomas were only weakly positive or completely negative. In the adrenal cortex no inhibin alpha immunoreactivity was detected in the zona glomerulosa. Zona fasciculata showed weak staining for inhibin alpha, however, strong immunostaining was detected in zona reticularis both in normal and hyperplastic adrenal glands. Adrenal medulla was negative for inhibin alpha. In conclusion, we show high expression of inhibin alpha subunit in zona reticularis of normal and hyperplastic adrenal glands as well as strong expression in virilizing adenomas.