Possible Role of Estrogen & Some Natural Products As Cardioprotective Agents in Ovariectomized Rats

Menopause is a normal biological event for most women marked by the end of menstrual periods. During menopause, the ovaries produce progressively smaller amounts of estrogen. The reduction of estrogens also has a detrimental effect on serum antioxidant status in healthy postmenopausal women. Oxidative stress is often the underlying mechanism which causes vascular alterations and cardiac damage. Consequently, postmenopausal women have a much higher risk of heart disease when compared with men of similar age and with other risk Factors.Estrogen replacement therapy (ERT) has been shown to be effective in alleviating the vasomotor symptoms of menopause and reducing cardiovascular mortality risk. The cardioprotective effect of estrogen is thought to occur through a variety of mechanisms, one of them is related to an alteration of lipid and lipoproteins metabolism and the other is linked to its vasodilator effect. Furthermore, the administration of estrogens prevents the increase of lipid peroxidation and depletion of reduced glutathione (GSH) in ovariectomized (OVX) rats.Nicotine addiction in women increases the risk of ischemic stroke. Importantly, women who smoke or exposed to cigarette smoke and use hormone replacement therapy (HRT)/oral contraceptives greatly increase their risk of coronary heart disease and ischemic stroke as compared to nonsmoking women who use occasionally oral contraceptives. Nicotine addiction induces abnormalities in the menstrual cycle and accelerates menopause in women; however, the mechanism by which nicotineabrogates the protective effects of estrogen on cardiovascular disease in females is not clearly understood.This study was carried out to:1- Investigate cardiovascular disorders induced by nicotine exposure (passive smoking) and estrogen depletion (ovariectomy) as a model for postmenopause in women.2- Elucidate the cardioprotective effect of ERT, some natural products such as watermelon juice and omega-3 fatty acids supplementation on ovariectomized rats treated with nicotine.3- Explore histopathological changes in left ventricle and aorta following these experimental interventions.