Mechanisms underlying sex differences in progressive renal disease

Area of Science:

• Nephrology
• Endocrinology
• Cardiovascular Science

Background:

• Men experience a more rapid decline in kidney function than women with nondiabetic renal disease.
• Sex differences in renal disease progression may be independent of hypertension severity.

Purpose of the Study:

• To investigate the mechanisms underlying sex differences in renal disease progression.
• To determine the role of gonadal steroids and nitric oxide (NO) signaling in sex-based disparities in kidney injury.

Main Methods:

• Utilized the renal wrap (RW) model of hypertension in male and female rats.
• Assessed glomerulosclerosis, glomerular volume, proteinuria, and renal nitric oxide synthesis (NOS) and superoxide production.
• Investigated the effects of orchidectomy, ovariectomy, and gonadal steroid replacement (dihydrotestosterone and 17beta-estradiol [E(2)]).

Main Results:

• RW male rats exhibited significantly greater glomerulosclerosis, glomerular volume, and proteinuria than RW females, despite similar blood pressure.
• Orchidectomy attenuated renal injury in males, while ovariectomy exacerbated it in females; steroid replacement reversed these effects.
• Males showed increased endothelial NOS and decreased neuronal NOS, alongside elevated NADPH oxidase activity and p22(phox) subunit abundance, indicative of increased superoxide production.

Conclusions:

• Gonadal steroids significantly influence sex differences in renal injury severity.
• 17beta-estradiol (E(2)) may protect the female kidney by mitigating hypertension-induced superoxide production and associated renal damage.