Glucocorticoid-induced hypertension and cardiac injury: effects of mineralocorticoid and glucocorticoid receptor antagonism.

Glucocorticoids are widely administered for the treatment of various disorders, although their long-term use results in adverse effects associated with glucocorticoid excess. We investigated the pathophysiological roles of glucocorticoid receptors (GRs) and mineralocorticoid receptors (MRs) in the cardiac changes induced by exogenous corticosterone in rats. Corticosterone or vehicle was injected twice daily in rats from 8 to 12 weeks of age. The effects of the GR antagonist RU486, the MR antagonist spironolactone, or both agents on corticosterone action were also determined. Corticosterone induced hypertension, left ventricular (LV) fibrosis, and LV diastolic dysfunction. Neither RU486 nor spironolactone affected corticosterone-induced hypertension, whereas spironolactone, but not RU486, attenuated the effects of corticosterone on LV fibrosis and diastolic function. Corticosterone also increased cardiac oxidative stress and inflammation in a manner sensitive to spironolactone but not to RU486. The corticosterone-induced LV atrophy was not affected by either RU486 or spironolactone. Our results implicate MRs in the cardiac fibrosis and diastolic dysfunction, but not MRs or GRs in the cardiac atrophy, induced by corticosterone. Neither MRs nor GRs appear to contribute to corticosterone-induced hypertension.