Effect of gonadectomy on isoproterenol-induced myocardial infarction.

Adult male and female Sprague-Dawley rats were subjected to an isoproterenol-induced myocardial infarction. Six weeks before the induction of myocardial infarction, some of the animals had been orchiectomized or ovariectomized. The animals were autopsied at regularly timed intervals on days 1, 2, 3, 8, and 15 after myocardial infarction. The gonadectomized animals manifested less severe untoward changes, survived in greater numbers, and experienced superior repair of their damaged hearts. Circulating levels of enzymes (e.g., CPK, GOT, GPT, and LDH), lipids, glucose, and BUN rose and fell during the acute necrosis and repair phases with distinct differences between the intact and castrated animals. Reciprocal changes in the weight of the adrenal and thymus glands, coupled with dynamic changes in circulating corticosterone levels, reflected marked temporal changes in the spectrum of adrenal steroids being secreted, as well as gonadal hormone mediated changes affecting adrenocortical function. The implications of these findings are that adrenocortical, androgenic, and estrogenic hormones condition the nature of the pathophysiologic response to acute myocardial infarction in rats.