Estrogen replacement restores renal function and water homeostasis in ovariectomized rats: role of AQP2 and oxidative...

Estrogen deficiency is associated with renal dysfunction, oxidative stress, and impaired water homeostasis. This study evaluated the renoprotective effects of estradiol benzoate (EB) on renal function, oxidative stress, and aquaporin-2 (AQP2) gene expression in ovariectomized (OVX) rats.

Fifty adult female Sprague-Dawley rats were allocated to five groups (n = 10/group): sham-operated, OVX control, and OVX groups treated with EB at 25, 50, or 100 µg/kg daily for four weeks. Ovariectomy significantly increased food intake, body weight gain, urine volume, urinary sodium excretion, serum potassium, urea, creatinine, and renal malondialdehyde levels, and decreased glomerular filtration rate (GFR), urinary potassium, urinary creatinine, renal glutathione, and AQP2 expression. Histopathological examination showed glomerular shrinkage, tubular degeneration, congestion, and leukocytic infiltration. EB administration improved electrolyte balance, oxidative stress status, AQP2 expression, and renal histopathological alterations; however, GFR remained significantly reduced in all EB-treated groups, indicating incomplete recovery of glomerular filtration. The 50 µg/kg dose produced the most consistent improvement across functional, biochemical, oxidative, and histological parameters, whereas 100 µg/kg produced the highest AQP2 expression but did not provide additional histological benefit.

EB exerts renoprotective effects in estrogen-deficient rats by improving renal function and electrolyte homeostasis, reducing oxidative stress, and modulating AQP2 expression. These findings support the potential value of estrogen replacement in attenuating renal dysfunction associated with estrogen deficiency.