The effect of estrogen on serum nitric oxide concentrations in normotensive and DOCA Salt hypertensive ovariectomized rats.
BACKGROUND: Cardiovascular disease (CVD) is less prevalent in premenopausal women and women receiving estrogen replacement therapy (ERT) than in postmenopausal women or men. It proposed that the cardiovascular effects of estrogen are mediated, at least in part, through the ability of estrogen to increase nitric oxide (NO) synthesis. This study investigated the effect of estrogen on serum NO concentrations in normotensive and deoxycorticostrone acetate (DOCA) Salt hypertensive ovariectomized rats. METHODS: Forty-eight female rats were ovariectomized and randomly divided into six groups. Hypertension was induced by DOCA Salt method. DOCA was injected 30 mg/kg of body weight subcutaneously, twice a week with NaCl 1% instead of tap water for drinking throughout the treatment period. Estradiol valerate (Es) was injected i.m. once a week. The groups were as follows: (2) DOCA (4 weeks) and DOCA+Es (6 weeks), (22) DOCA (10 weeks), (222) normal saline (N/S) (4 weeks)+Es (6 weeks), (2V) N/S (10 weeks), (V) DOCA (4 weeks), and (V2) N/S (4 weeks). Serum NO concentrations were measured in groups 1, 3 and 4 before and after treatment. Other groups were used as control. RESULTS: Results showed that in normotensive animals, serum NO concentrations were increased after estrogen treatment significantly (90.20 +/- 18.67 vs. 19.11 +/- 1.78 micromol/l) (p < 0.05). Also, estrogen increased serum NO concentrations in DOCA Salt hypertensive rats (73.54 +/- 22.55 vs. 36.94 +/- 10.73 micromol/l) (p = 0.06). CONCLUSION: Estrogen can increase serum NO concentrations in normotensive and DOCA Salt hypertensive animals and it may be important in cardiovascular effects of estrogen.