ABSTRACT
BACKGROUND: Gender differences have been found in the development of hypertension. The role of estrogen in the association between hyperinsulinemia/insulin resistance and hypertension was investigated in an insulin-induced, insulin-resistant, and hypertensive model. METHODS: Ovariectomized or sham operated female Wistar rats were chronically treated with insulin and/or estrogen via subcutaneous implants (insulin, 2 U/day; 17beta-estradiol 0.5 mg/pellet, 60-day release). Systolic blood pressure was monitored at weeks 0, 3, and 6. At week 7, an oral glucose tolerance test was performed. RESULTS: Ovariectomy resulted in the development of insulin resistance and blood pressure elevation in chronically insulin-treated female rats. Chronic estrogen treatment prevented the elevation in blood pressure and the development of insulin resistance. CONCLUSION: The results indicate that chronic estrogen treatment modifies the insulin-induced hypertension by increasing insulin sensitivity in ovariectomized rats.
Subject(s)
Estrogens/pharmacology , Hypertension/physiopathology , Insulin Resistance , Insulin/pharmacology , Ovariectomy , Analysis of Variance , Animals , Blood Glucose/analysis , Blood Pressure/drug effects , Blood Pressure/physiology , Female , Glucose Tolerance Test , Hypertension/chemically induced , Hypertension/prevention & control , Hypoglycemic Agents/pharmacology , Insulin/blood , Rats , Rats, Wistar , Time FactorsABSTRACT
Hyperinsulinemia and insulin resistance have been linked to hypertension; however, the influence of sex on this relationship has not been well studied. The purpose of this experiment was to compare the effects of chronic insulin treatment on insulin sensitivity and blood pressure in male and female rats. Male and female Wistar rats were treated with insulin (2 U/day) via subcutaneous sustained release implants for 5 wk. Systolic blood pressure was measured via the tail-cuff method before and after treatment, and insulin sensitivity was assessed with an oral glucose tolerance test. The insulin sensitivity of female rats was 4.5-fold greater than male rats. Chronic insulin treatment impaired insulin sensitivity in both sexes; however, this occurred to a greater degree in male rats. Blood pressure increased in male rats treated with insulin only. The results demonstrate that hyperinsulinemia and insulin resistance are associated with hypertension in male rats only. Therefore, the link between these conditions appears to depend on sex.
