Effects of the hypolipidemic drug nafenopin on the zona glomerulosa of the rat adrenal cortex: morphological counterparts of functional alterations.

The effects of nafenopin, a hypolipidemic drug, on the zona glomerulosa of the rat adrenal cortex were investigated. Chronic nafenopin treatment significantly lowered serum cholesterol level, but did not alter blood aldosterone concentration, though the biosynthesis of adrenal cortico-steroid hormones seems to be largely dependent upon a continuous uptake of cholesterol from plasma lipoproteins. Stereology showed that the treatment provoked a notable lipid droplet depletion, coupled with a significant proliferation of smooth endoplasmic reticulum (SER) profiles. Since SER is known to be involved in the endogenous synthesis of cholesterol, the hypothesis is advanced that SER hypertrophy is a compensatory response enabling zona glomerulosa cells to maintain an adequate level of aldosterone output even in the absence of a normal supply of exogenous cholesterol.