Changes in blood pressure and vascular adrenergic receptor numbers after isolation stress or dihydrotestosterone (DHT) treatment in the male SHR

The authors have previously reported that treatment with testosterone increased blood pressure and alpha adrenergic receptor numbers in tail artery preparations from male SHRs, while gonadectomy had the opposite effect. In this study, they compared the effects of isolation stress and DHT treatment (800 mg/100 B Wt 3X/wk SC) on blood pressure and alpha and beta receptor numbers in tail artery and abdominal aorta preparations. Blood pressures were significantly higher (P<.05) in the stressed group 238 +/- 3 and the DHT treated group 232 +/- 5 vs. sham group 201 +/- 1. There was no clear change in beta receptor numbers (fmol/mg [3H]DHA) from the tail arteries or abdominal aortas after DHT, 151 +/- 7 and 119 +/- 1 vs. sham values 155 +/- 5 and 120 +/- 8. Beta receptor numbers were lower in the tail arteries and abdominal aortas from the stressed rats, 139 +/- 5 and 107 +/- 1. Alpha1 receptor density (fmol/mg [3H] prazosin) was increased in the DHT treated and stressed animals in both tail arteries 270 +/- 16 and 279 +/- 17 and abdominal aortas 231 +/- 13 and 212 +/- 9 when compared to DHT and non-stressed controls, 255 +/- 6 and 206 +/- 5. These results suggest that the alpha1 receptor changes seen after androgen treatment may be a result of the increased blood pressure rather than a direct effect of the androgens on vascular smooth muscle