EFFECT OF ESTROGEN AND ANDROGEN RECEPTOR BLOCKERS ON EXPERIMENTALLY INDUCED MYOCARDIAL INFARCTION IN MALE RATS.
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The incidence of coronary heart disease (CHD) in females is less than males of the same age, suggesting a cardioprotective role for estrogen, while the role of androgens in the development of CHD is controversial. Men have estrogens in their tissues produced by aromatization of androgens in the peripheral circulation but little is known about the possible physiological role of this estrogen in males especially in CHD. This study was designed to evaluate the effect of endogenous male estrogen on experimentally induced myocardial infarction (MI) in male albino rats and its possible relationship to the role of androgens. Fifty-four albino male rats were used in this study. The rats aged 12 weeks and their average weight was 200-250 gm. The animals were divided into 5 groups: Group (1), consisted of 6 rats, served as a control group and was used for the estimation of normal serum level of Creatirt kinase-MB (CK-MB). The other 4 groups (each consisted of 12 rats) were subjected to induction of MI using a single intraperitoneal (Lp.) dose of isoprenaline. after being treated according to one of four protocols of therapy. Group (2) was injected with solvent. Group (3) received i.p. tamoxifen. an antiestrogen, in a dose of mg/ kg/day for 3 days. Group (4) received a single i.p. dose (75 mg / kg) of flutamide. (an anti-androgen). Group (4) was treated using both tamoxifen and flutamide protocols. Induction of MI was carried out 24 hours after the last dose of treatment. Thirty minutes after induction, the rats were sacrificed, blood was collected and hearts were obtained for the estimation of CK-MB and measurement of infarct size, as percentage of left ven- 23 Nasr A. Belacy et al... title, respectively. The obtained results revealed that the enzyme CK-MB was significantly higher in all groups subjected to MI than the control group. Infarction size and CK-MB in group (3) were significantly more than groups (2), (4) and (5) while in group (4) they were significantly less than the other groups. Groups (2) and (5) showed no significant difference. It could be concluded that endogenous estrogen may have a role in cardioprotection in male rats and this role may be related to the role of androgens.