ANTIMINERALOCORTICOID CANRENOATE ENHANCES SECRETORY ACTIVITY OF THE HYPOTHALAMUS-PITUITARY-ADRENOCORTICAL (HPA) AXIS IN HUMANS

In rats, both hippocampal glucocorticoid and mineralocorticoid receptors (MR) have been shown to participate in the regulation of basal hypothalamus-pituitary-adrenocortical (HPA) secretory activity. Inhibition of hippocampal MRs enhanced the activity of the HPA axis in these animals. We tested the influence of potassium cancrenoate, a selective MR antagonist, on basal cortisol secretion in 10 healthy young men during sleep. Cortisol, ACTH, vasopressin and growth hormone (GH) were determined at 22.00, 23.00, 01.00, 04.00 and 07.00 h. Sleep was monitored by somnopolygraphy. Potassium canrenoate (200 mg) was administered intravenously at 08.00 and 17.00 h the preceding day. Compared with a placebo condition, potassium canrenoate elevated cortisol levels throughout the night, with significant (p < 0.05) increases at 22.00, 23.00, 01.00 and 07.00 h. Effects of canrenoate on ACTH levels were not significant, and there was also no effect on plasma vasopressin levels. GH concentrations at 04.00 and 07.00 h were higher after canrenoate than placebo (p < 0.05). Changes induced by canrenoate paralleling those in animals after intracerebroventricular administration of MR antagonists suggest that central nervous MRs are involved in the regulation of HPA secretory activity also in humans.