Cardioprotective effects of aqueous Schizandra chinensis fruit extract on ovariectomized and balloon-induced carotid artery injury rat models: effects on serum lipid profiles and blood pressure.

ABSTRACT

AIM OF THE STUDY The fruit from Schizandra chinensis, a member of the Magnoliaceae family, has been used to treat menopause-related symptoms. We have previously reported that an aqueous extract of Schizandra chinensis fruit (ScEx) caused vascular relaxation via the production of endothelial nitric oxide. Estrogen-like molecules are known to play a protective role in cardiovascular diseases through several mechanisms, but the cardioprotective effects of ScEx have not been clearly demonstrated. Therefore, we investigated the vasculoprotective effects of ScEx on ovariectomized (OVX) and balloon-induced carotid artery injury rat models. MATERIALS AND METHODS: An aqueous extract of Schizandra chinensis (ScEx) was examined for its cardioprotective effects. To test the arterial response to injury, we applied the balloon-induced carotid artery model to OVX Sprague-Dawley (SD) rats. Rats were subcutaneously administered vehicle, 17ß-estradiol (E2; 0.02 or 0.2mg/kg/day), or ScEx (0.2 or 2.0mg/kg/day) over the course of the study. Vessel morphology was assessed two weeks after injury. To identify the cardioprotective effects after ScEx treatment, we measured serum lipid profiles and blood pressure levels in the OVX- and sham-operated normotensive and spontaneously hypertensive rats (SHR). Serum lipid profiles were measured in OVX rats after five weeks of treatment with vehicle, E2 (0.5mg/kg/day), or ScEx (0.5 or 5.0mg/kg/day). Tail systolic blood pressure in OVX SHR was measured weekly. RESULTS: In the balloon-induced carotid artery injury model, treatment with E2 (0.2mg/kg/day) or ScEx (2.0mg/kg/day) reduced the intimal area and the intima-to-media ratio compared to control animals. Injection of ScEx or E2 reduced body weight gain but did not inhibit the decrease in uterine weight. Treatment with ScEx (5.0mg/kg/day) or E2 (0.5mg/kg/day) in OVX SD rats reduced total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), TC/high-density lipoprotein cholesterol (HDL-C), and TC-(HDL-C)/HDL-C compared to control animals. In OVX rats, treatment with ScEx or E2 also significantly reduced LDL-C compared with the OVX control rats, and systolic blood pressure was significantly attenuated compared to OVX control and the sham control rats. CONCLUSIONS: ScEx treatment restored endothelial function in rats that underwent balloon-induced carotid artery injury, and it reduced serum cholesterol levels in OVX rats. Similar to E2, ScEx exhibited hypotensive effects in OVX SHR. Therefore, ScEx and E2 exhibited similar cardioprotective effects, thereby suggesting that ScEx is a potential candidate to replace estradiol in the prevention and treatment of cardiovascular diseases.