Interaction between Renal Sodium‐Glucose Cotransporter 2 and Renin‐Angiotensin System in a PCOS Rat Model

Abstract

Introduction : Polycystic Ovary Syndrome (PCOS) is characterized by androgen excess, oligo/anovulation, and polycystic ovaries. PCOS is co-prevalent with insulin resistance (IR), increased blood pressure (BP), and a dysfunctional renin-angiotensin system (RAS). The RAS has both a vasoconstrictive arm with angiotensin-converting enzyme (ACE) and a vasodilatory arm with ACE2. While PCOS patients require multiple medications to control their comorbidities, it is unknown how these medications interact with each other. ACE inhibitors (ACEi) and sodium-glucose cotransporter 2 inhibitors (SGLT2i) seem to influence each other in male rodents. However, how androgens influence these interactions in females is unknown. We have a well-established rat model that mimics PCOS, including IR, increased BP, and overactive RAS. Using this model, we tested the hypothesis that SGLT2i would attenuate the RAS and that ACEi would decrease renal SGLT2 expression in a rat model of PCOS. Methods : In Experiment 1, four-week old female Sprague Dawley (SD) rats implanted with DHT pellets (7.5mg/90 days) or control were randomized to drinking water with and without the SGLT2i empagliflozin at a dose of 10 mg/kg/day during the last 3 weeks of the study (n=10/group). At 3 months of DHT, fasting plasma was collected for the homeostatic model assessment of IR (HOMA-IR). BP was measured by radiotelemetry. Renal cortex and medulla were collected for quantitative real-time polymerase chain reaction (qRT-PCR) and western blot for ACE and ACE2. In Experiment 2, four-week old female SD rats implanted with DHT pellets (7.5mg/90 days) or control were randomized to drinking water with and without the ACEi enalapril at a dose of 250 mg/mL throughout the study (n=10/group). At 3 months of DHT, kidneys were collected for qRT-PCR for SGLT2. Results : PCOS rats had increased IR, BP, and renal expression of ACE and ACE2 compared to controls. SGLT2i had no impact on IR while causing a small reduction in BP in both groups. SGLT2i decreased cortical ACE mRNA and protein (1.03 ± 0.08 vs 1.37 ± 0.04, P<0.05) in PCOS, and had no impact in controls. SGLT2i also decreased cortical ACE2 protein (1.02 ± 0.05 vs 1.18 ± 0.03, P<0.05) in PCOS, but not in controls. SGLT2i decreased mRNA and protein of medullar ACE and ACE2 in both groups. In Experiment 2, cortical SGLT2 mRNA was increased in PCOS compared to controls. ACEi increased SGLT2 mRNA in controls (30.32 ± 8.03 vs 1.00 ± 0.32, P<0.01) with no effect in PCOS. Conclusions In summary, PCOS rats had increased IR, BP, and intrarenal ACE. Without impacting IR, SGLT2i attenuated both intrarenal ACE and ACE2 expression in PCOS. This suggests ACEi could work synergistically with SGLT2i to reduce BP. PCOS rats have increased SGLT2 mRNA, suggesting a differential response to SGLT2i between PCOS rats and controls, such as shown with cortical ACE. ACEi also increased cortical SGLT2 mRNA in controls, but androgen excess appeared to blunt this effect. Overall, this suggests that there could be a differential response in hyperandrogenemic women taking both SGLT2i and ACEi compared to a woman with normal androgen levels.