The Effect And Mechanisms Of Long-acting GLP-1 Receptor Agonist Semaglutide On Phenotypic Transition Of Microglia And Neuroinflammation After Cerebral Ischemia/Reperfusion In Rats

Objective:To explore the effect and potential mechanisms of long-acting glucagon-like peptide-1(GLP-1)receptor agonist Semaglutide on phenotypic transition and neuroinflammation of microglia after cerebral ischemia / reperfusion(I/R)in rats.Methods:A total of 126 healthy adult male Sprague-Dawley(SD)rats weighing 280~300g were randomly divided into a sham operation group(Sham group,n=18),a cerebral ischemia-reperfusion model group(I/R group,n=54),and a Semaglutide-treated group(Sema+I/R group,n=54).I/R group and Sema+I/R group respectively were divided into 3subgroups(n=18 per subgroup)according to different time points of detection indicators after successful modeling(1d,3d,7d post-I/R).The modified Zea-Longa method was used to induce the cerebral ischemia-reperfusion model.Then,the Sema+I/R group was injected intraperitoneally with Semaglutide(10nmol/kg)before the animals’ meals every other day,while Sham group and I/R group were respectively received equal volume of normal saline instead of Semaglutide.Detected the fasting glucose levels of tail vein,as well maked neurologic deficit score at 1d,3d,7d after I/R,and then sacrificed to take out the brain tissue.Expression of CD68(the biomarker of M1-like microglia),CD206(the biomarker of M1-like microg-lia),TNF-α(pro-inflammatory cytokines),TGF-β(anti-inflammatory cytokines)and P65(NF-κB signaling pathway related cytokines)in penumbra were detected by immunohistochemistry and western blot analysis.Results:1.Physiologic parameter and neurologic evaluation:There is no statistical significance in the fasting glucose levels of tail vein between subgroups of Sham group,I/R group and Sema+I/R group(P>0.05).Furthermore,Sema+I/R group showed better functional recovery than I/R group(P<0.05).2.Assessment of cerebral infarct area: Compared with the I/R group,Sema+I/R group showed that the cerebral infarct area was significantly decreased(P<0.05).3.Immunohistochemistry and Western blot analyses:1)M1-like microglia related indicators:Compared with the Sham group,each subgroup of I/R group were observed that the expression of CD68,TNF-α and p65 were up-regulated.Among them,the expression of P65 did not change significantly between 1d and 3d,while there was a downward trend at 7d.The expression of TNF-α peaked at 3d,while a downward trend occurred at 7d.The expression of CD68 had no significant difference between 1d and 3d,while the peak appeared at 7d.Compared with the subgroups of I/R group(1d,3d,7d),the expression of P65,TNF-α,and CD68 were reduced in Sema + I / R group.2)M2-like microglia related indicators:Compared with the Sham group,the expression of CD206 and TGF-β were showed significantly increased.The change trend of CD206 and TGF-β were roughly synchronousd,with a peak at 3d and a downward trend at7 d.Compared with the subgroups of I/R group(1d,3d,7d),the expression of CD206 and TGF-β were increased at 1d,but there was no significant difference at 3d and 7d in Sema+I/R group.Conclusion:The long-acting glucagon-like peptide-1(GLP-1)receptor agonist Semaglutide can promote microglia to M2-like phenotypes and curb microglia toM1-like phenotypes,resulting in inhibiting neuroinflammatory response,promoting nerve repair,to exert neuroprotective effects after I/R in rats.