Intimal Lesions in Rat Caudal Artery: Ablation, Replacement, and Receptor Studies on the Protective Effects of Estrogen

The incidence of spontaneous lesions of the intima in the rat caudal artery is significantly higher in male than in female Wistar rats at 12 weeks of age. After gonadectomy at 5 weeks, lesions in both sexes at 12 weeks reach a level intermediate between those seen in age-matched intact males and females. After gonadectomy at 5 weeks, lesions in both male and female rats are unaffected by testosterone administration but are reduced to below female control levels by diethylstilbestrol. In contrast, diethylstilbestrol administration does not significantly reduce lesion incidence in intact male rats. Binding studies provided no evidence of estrogen-binding sites in cytosol from caudal arteries, but heart and kidney cytosols from both male and female rats contain a single class of high affinity (10~ M) binding sites with specificity characteristic of estrogen receptors. Longitudinal studies (4-11 weeks of age) provided no evidence for a change in receptor profile as a factor contributing to the increased lesion incidence in mature male rats.