Serum level of vascular endothelial growth factor is increased by estrogen replacement therapy in normotensive and DOCA–Salt hypertensive ovariectomized rats

BackgroundCardiovascular disease (CVD) is the leading cause of death in developed countries. Previous studies have shown that hormone replacement therapy reduces the risk of CVD in postmenopausal women, however, the mechanism remains unclear. This study was designed to evaluate the effect of estrogen on serum vascular endothelial growth factor (VEGF) concentration in normotensive and hypertensive ovariectomized rats.MethodsForty-eight female rats were ovariectomized and randomly divided into 6 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 experiment. Estradiol valerate (Es) was injected 2 mg/week i.m. The groups were as follows: (i) DOCA (4 weeks) and DOCA + Es (6 weeks); (ii) DOCA (10 weeks); (iii) Normal saline (N/S) (4 weeks) and Es (6 weeks); (iv) N/S 10 weeks; (v) DOCA (4 weeks), and (vi) N/S (4 weeks). Serum VEGF concentration was measured in groups 1 to 4.ResultsResults showed that in normotensive animals that received estrogen treatment, serum VEGF concentration was significantly higher than those not receiving estrogen (269 ± 41 vs. 106 ± 36 pg/ml) (P < 0.05). In hypertensive group, serum VEGF level was also increased after estrogen therapy compare to those not receiving estrogen (326 ± 55 vs. 121 ± 28 pg/ml (P < 0.05).ConclusionIt is possible that the increase in serum VEGF concentration after estrogen therapy may contribute to the cardiovascular effects of estrogen in normotensive and hypertensive conditions.