Expression of the adrenocorticotropin receptor in cortisol-secreting adrenocortical tumors and healthy adrenals in dogs

Abstract

Introduction : Hyperadrenocorticism is a common disease in dogs by which adrenocortical cortisol secretion is increased. One of the causes of hypercortisolism is a functional adrenocortical tumor. Adrenocorticotropic hormone (ACTH) is a major regulator in steroid synthesis. Human research has revealed a high ACTH-receptor mRNA expression in functional adenomas and low expression in carcinomas compared to controls. This research compared the expression of the ACTH-receptor in the adrenal cortex of 39 dogs with adrenal-dependent hypercortisolism, of which 27 are carcinomas and 12 are adenomas, with 15 normal adrenals. Materials and methods: Adrenal tissue was derived from 39 dogs with hypercortisolism (27 carcinomas and 12 adenomas) and 15 normal adrenals served as controls. ACTH-receptor mRNA levels are measured with quantitative PCR, while ACTH-receptor protein levels are examined by western blot. Results: ACTH-receptor mRNA expression is downregulated in carcinomas compared to normal adrenals. Expression in adenomas is not significantly different from controls. Western blot results show a downregulation of ACTH-receptor expression and therefore support the qPCR results.