Study On Renal Protective Effect Of Estrogen Through GPER In RIRI Rats

Objective:To investigate the role of G protein-coupled estrogen receptor?GPER?in estrogen inhibiting oxidative stress response and reducing renal ischemia reperfusion injury?RIRI?in rats and its possible mechanism.Methods:?1?Forty female SD rats were selected,and all of them underwent OVX treatment.After 2 weeks of recovery,they were randomly allocate into five groups?8 rats of each group?:Ovariectomized group without treatment after ovary removal?OVX group?,The group with renal ischemia reperfusion injury after ovary removal?OVX+I/R group?,Estrogen intervention before I/R injury model?OVX+I/R+E₂ group?,GPER-specific agonist G1 intervention before I/R injury model?OVX+I/R+G1 group?,GPER specific blocker G15 intervention and E₂ intervention before I/R injury model?OVX+I/R+E₂+G15 group?.OVX group:no treatment,conventional feeding after ovary removal operation.OVX+I/R group:Removed the right kidney of the rats,and clamped the left renal pedicle for 45 minutes with a non-invasive arterial clip to prepare the I/R model.OVX+I/R+E₂ group:hypodermic injection of E₂?100 ug/kg?was given 1 hour before I/R injury,the remaining steps refer to the OVX+I/R group.OVX+I/R+G1 group:G1?100 ug/kg?was intraperitoneally injected 1 hour before I/R injury,the remaining steps refer to the OVX+I/R group.OVX+I/R+E₂+G15 group:G15?300 ug/kg?was given intraperitoneally 1.5 hours before I/R injury,and E₂?100ug/kg?was given subcutaneously 30 minutes before I/R injury,the remaining steps refer to the OVX+I/R group.Rats in each group were fed normally for 24 hours after the above operation,and the left kidney was removed after blood collection from the abdominal aorta.?2?Serum creatinine?Cr?and blood urea nitrogen?BUN?levels were measured by a fully automated biochemical analyzer.?3?Kidney damage in each group was observed by hematoxylin-eosin?HE?and Paller score was obtained..?4?SOD activity and MDA content in kidney tissue were detected by SOD kit and MDA kit.?5?The expression of p-PI3K/PI3K and p-Akt/Akt in renal tissues of each group was detected by Western blot.Results:?1?Compared with the OVX group,the levels of BUN and Cr in the OVX+I/R group were significantly increased.Compared with the OVX+I/R group,the levels of Cr and BUN in the E₂ intervention group and G1 intervention group decreased significantly,while the levels of Cr and BUN in the E₂+G15intervention group increased significantly compared with the E₂ intervention group.?2?Histopathological changes of kidney under microscope after HE staining:In the OVX group,the glomerular and tubular structures were normal,the interstitium was not hyperemic,edema was not observed,and there was no inflammatory cell infiltration;In the OVX+I/R group,the renal tubules were significantly expanded,the cells were swollen to varying degrees,and even necrotic and exfoliating,the renal interstitium was edema,and inflammatory cell infiltration was obvious;The renal tubules of the E₂ group and G1 group were slightly dilated,the epithelial cells were slightly swollen,there was less necrosis,and the infiltration degree of inflammatory cells was significantly reduced;The E₂+G15 group had unclear tubular structure,and some epithelial cells showed necrosis and exfoliation.Paller results show that,compared with OVX,the renal tissue of OVX+I/R group was seriously damaged.Compared with the OVX+I/R group,the renal injury was reduced after E₂ and G1 intervention.Compared with the E₂ group,the E₂+G15 group had severe kidney damage,and the G15 intervention reversed the protective effect of E₂.?3?Index of oxidative stress in renal tissue:Compared with OVX group,SOD activity in IR group was significantly decreased and MDA content was significantly increased;Compared with the IR group,the SOD activity and MDA content in the renal tissue of rats in the E₂ and G1 intervention groups were significantly increased and decreased;SOD activity in the kidney tissue of the E₂+G15 group was lower than that of the E₂ group,and MDA content was significantly higher than that of the E₂ group.?4?WesternBlot:Compared with the OVX group,the expression of p-PI3K and p-Akt in the kidney tissues of the I/R group was significantly decreased;Compared with the I/R group,the expression of p-PI3K and p-Akt was significantly increased in the E₂ and G1 intervention groups;There was no significant difference between the E₂ intervention group and the G1 intervention group.The expression of p-PI3K and p-Akt was significantly decreased in the E₂+G15 intervention group compared with the E₂ intervention group.Conclusion:Estrogen plays a protective role on renal ischemia-reperfusion injury by reducing the oxidative stress response of the kidney,and the mechanism may involve the activation of the PI3K/Akt signaling pathway;GPER is involved in the protection of estrogen against renal ischemia-reperfusion injury,and GPER plays an important role in the protection of kidney.