Estradiol Treatment at Midlife Fails to Modify Renal Outcomes in Obese Ovariectomized Mice

The growing population of adults aged 65 years or older has led to more postmenopausal women affected by renal disease, often associated with an increased risk of developing metabolic disorders such as diabetes. High-fat diet (HFD) further worsens health risks by causing systemic metabolic disturbances such as obesity, insulin resistance, and hyperglycemia. Additionally, HFD-driven changes in renal metabolic pathways are strongly linked to impaired kidney function. In our previous study, we demonstrated that treatment with 17β-estradiol (E2) improved metabolic outcomes in ovariectomized (OVX) C57BL/6J mice fed with HFD by reducing adiposity and enhancing glucose homeostasis. In this study, we investigated the hypothesis that HFD-associated metabolic dysfunction in middle-aged OVX mice will lead to altered renal morphology with the onset of renal injury, which is attenuated by E2 treatment. Kidney tissues and urine collected from our previous study were utilized for this work. In brief, female mice, approximately 9 months (M) old, were maintained on either a phytoestrogen-free high-fat diet (HFD; BioServ #F3282) or on a control low-fat diet (LFD; BioServ #F4031) for 12 weeks (12-13M old) prior to ovariectomy. Following OVX, mice were implanted with a silastic tube containing either E2 or vehicle (VEH; cholesterol) and continued their respective diets for an additional 8 to 10 weeks (14-15M old). Renal protein levels of injury markers were measured by Western blot analysis in the four groups (LFD-OVX-VEH, LFD-OVX+E2, HFD-OVX-VEH, HFD-OVX+E2). In HFD-VEH mice, significantly increased body weight (BW; HFD-OVX-VEH: 42.7 ± 0.7 g vs. LFD-OVX-VEH: 31.2 ± 1.2 g, p< 0.01; n =11) and kidney weight (KW; HFD-OVX-VEH: 0.21 ± 0.005 g vs. LFD-OVX-VEH: 0.18 ± 0.007 g, p< 0.01; n =10 and 11) were observed. Estradiol significantly decreased BW in HFD-OVX mice compared with HFD-OVX-VEH mice group (p< 0.01); however, no change was observed in KW in HFD-OVX+E2 vs. HFD-OVX-VEH mice. We assessed renal injury markers in kidney tissues from these mice. No significant change was observed in the renal tubular injury marker, neutrophil gelatinase-associated lipocalin (NGAL), between HFD-fed and LFD-fed mice. However, E2 treatment in HFD-OVX mice exhibited a trend toward reduced NGAL protein levels. Although HFD did not change the tubular injury marker, kidney injury molecule-1 (KIM-1) levels, interestingly, E2 treatment significantly increased KIM-1 and glycosylated KIM-1 levels in both LFD and HFD-fed mice compared with diet-matched vehicle-treated groups. Urinary protein/creatine ratio was comparable in all 4 mice groups. Initial screening of renal morphology (hematoxylin and eosin stain) revealed glomerulomegaly (an adaptive response to fewer nephrons or increased demand on the kidneys, such as from obesity) and increased tubular injury in HFD-fed mice, which was not attenuated by E2 treatment. In summary, our preliminary findings indicate that HFD-fed middle-aged ovariectomized mice with pre-existing metabolic conditions develop renal morphological changes; however, protein levels of injury markers remain unchanged, and E2 treatment does not exert a significant effect. These results suggest that midlife E2 therapy does not improve renal outcomes in obese ovariectomized mice. Funding source: NIH grant R03AG075396 (awarded to PK), COBRE in aging and regenerative medicine (P30GM145498), P01 AG071746 for Project 4 (awarded to AZ), and PPG Cores. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.