Background/aims: No studies have clearly demonstrated how sex hormones are involved in the observed gender difference in growth and plasma cholesterol levels in animals fed hypercholesterolemic diets. This study was conducted to determine the effects of gender, gonadectomy (GNX), and sex hormones on growth, plasma cholesterol and cortisol levels in Sprague-Dawley rats.
Methods: In the first of two experiments, equal numbers of male and female 4-week-old rats were divided into three groups: sham-operated control, GNX, or GNX + 17alpha-methyltestosterone (MT). The rats were fed a hypercholesterolemic diet for 4 weeks. In a second experiment, 24 GNX females were equally divided into three groups: control, 17beta-estradiol (E(2)), or MT. These rats were fed a normocholesterolemic diet for 3 weeks.
Results: The average total plasma cholesterol level in female rats was twice that in male rats. MT administration to GNX male and GNX female rats decreased plasma cholesterol levels by 23 and 45%, respectively. Weekly intramuscular injection of E(2) markedly suppressed growth while increasing plasma cortisol levels in GNX female rats.
Conclusion: Testosterone decreases plasma cholesterol levels in rats fed a hypercholesterolemic diet and E(2) suppresses growth of rats, inducing the secretion of hormones that increase with stress.
Copyright 2008 S. Karger AG, Basel.