Rat Model of Menopausal/Andropausal Hypertension with Different Sensitivities to Non-Genomic Antihypertensive Responses of Female and Male Sex Steroids

Abstract

Introduction: Hypertension is prevalent in older women and men, but the impact of sex differences is unclear. Methods: Blood pressure (BP) was evaluated weekly for 15 weeks using tail-cuff plethysmography in intact or gonadectomized female and male rats. Similarly, gonadectomized rats were subcutaneously treated daily for 15 weeks with estradiol in females or testosterone in males. Treatment with estrogen in males and androgen in females for BP was also examined. The non-genomic antihypertensive potency and efficacy of different sex steroids were determined; catheters were implanted in the carotid artery of hypertensive rats for BP recording with bolus injections in the jugular vein at cumulative doses (1x10-7-1x10-4 M kg-1 min-1) of dehydroepiandrosterone (DHEA), estradiol, testosterone, or 5β-dihydrotestosterone (5β-DHT). Results: data showed a time-dependent increase in BP after gonadectomy in female and male rats until hypertension values were reached. Males are more sensitive to the development of hypertension than females. The increases in BP in females and males were completely prevented by estradiol or testosterone, respectively. Testosterone completely prevented hypertension in females, whereas estradiol only partially in males. Antihypertensive potencies in conscious hypertensive rats were DHEA=5β-DHT=testosterone>>estradiol, in females and DHEA=5β-DHT>>testosterone>>estradiol in males. The efficacy was DHEA=5β-DHT=testosterone>>estradiol in females and 5β-DHT=DHEA>>testosterone>>estradiol in males. Conclusion: Gonadectomized males developed hypertension faster than females, suggesting that androgen deficiency plays an important role in BP reduction. Antihypertensive responses of steroids are structure-dependent, estradiol demonstrated the lowest potency, whereas 5β-DHT was a potent antihypertensive without estrogenic and androgenic actions, suggesting it as a therapeutic candidate for controlling hypertension in both sexes.