Impact Of Sex Hormones On Renal Mitochondria Function In Sprague Dawley Rats

Introduction: Until females reach menopause, they are generally protected from renal disease. Mitochondrial function is involved in sexual dimorphisms, however, there is a gap in knowledge regarding the contribution of mitochondrial bioenergetics to renal disease susceptibility. Our studies identified sex differences in renal mitochondrial metabolism, respiration, and ROS production in young healthy rats. We hypothesized here that sex hormones mediate the sex differences in renal mitochondrial bioenergetics. Methods: Male and female Sprague Dawley rats were randomly divided into groups that underwent a gonadectomy or a sham surgery (4 weeks of age). At 6 months of age renal cortex and medulla were used for ex vivo experiments. Mitochondria were isolated and spectrofluorimetry was employed to measure membrane potential (TMRM) and H 2 O 2 production (Amplex Red) along with a Seahorse assay for oxygen consumption rate (OCR). OriginPro was used for analysis (two-way ANOVA with post hoc test). Results: Spectrofluorimetry revealed that oophorectomy reduced membrane potential in mitochondria from the renal medulla compared to shams (p=0.001); this effect was not observed in the medulla of orchiectomized males. Female sham rats had higher H 2 O 2 compared to male sham rats (cortex p<0.001, medulla p<0.001). Removing sex hormones’ influence lowered H 2 O 2 production in both the female cortex and medulla (p<0.001, p<0.001), while in males, the loss of sex hormones led to higher H 2 O 2 production in the medulla (p<0.001). Orchiectomy increased ATP-linked respiration in both the cortex and medulla compared to shams (p=0.02, p=0.04), while an oophorectomy did not alter respiration in either region. ATP-linked respiration was increased in the female shams compared to male shams for both regions (p=0.04, p=0.04). Basal OCR was similar between all groups, with cortical mitochondria exhibiting lower OCR compared to medullary mitochondria for all groups (p<0.001). Conclusions: We report that renal membrane potential, H 2 O 2 , and OCR are uniquely impacted by sex hormones in healthy rats 5 months post-gonadectomy. The observed dissimilarities resulting from sex hormones’ highlight the need to consider sex for the prevention and treatment of renal diseases.