Stereologic studies on the long-term effect of prazosin on rat adrenal cortex

Adult female rats were treated with prazosin, a selective alpha 1-adrenoceptor inhibitor, for 60 days in doses of 0.5 mg/kg/day or 0.5 mg/kg/8 h. Prolonged prazosin administration lowered the gain of body weight and significantly decreased systolic blood pressure and heart weight. Prazosin administered every 8 h also lowered serum triglycerides but did not change the total cholesterol level. Selective alpha 1-inhibitor treatment increased the adrenal gland weight and decreased the number of adrenocortical cells; in every 8 h treated group this effect being connected with a marked cell hypertrophy (in all adrenocortical zones). Our results suggest that prazosin induced changes in the structure of the rat adrenal cortex depend on activation of the hypothalamo-pituitary-adrenocortical axis and possibly on the small inhibition of the proliferative activity of rat adrenocortical cells.