Objective : To pathological changes and inducible nitric oxide synthase(iNOS), phosphorylated insulin receptor substrate 1 serine 307(p-IRS1ser 307), phosphorylated protein kinase B serine 473(p-AKTser 473), glycogen synthase kinase-3β(GSK-3β), and gluconeogenic synthase(GS) proteins were observed in the liver of rats under the condition of chronic intermittent hypoxia-replicated oxygen in control. And to explore the role of iNOS/IRS1/AKT/GSK-3β signaling pathway in chronic intermittent hypoxia-induced insulin resistance. Methods : Forty SD rats were randomly divided into a control group(NC group) and an experimental group(CIH group), with 20 rats in each group. The NC group was placed in a normoxic environment for 12 weeks, while the CIH group was first subjected to intermittent hypoxia for 8 weeks, and then resumed normoxic rearing until the 12th week. Fasting blood glucose(FBG) and fasting insulin(FINS) were measured at baseline, week 8 and week 12, and liver tissues were taken for pathology and measurement of iNOS, p-IRS1ser 307, p-AKTser 473, GSK3β and GS levels, to compare the differences between groups. Results: t baseline, there was no significant difference in liver pathology between the two groups, and the observed indexes were not statistically significant(P>0.05); at 8 weeks, compared with the NC group, liver pathology in the CIH group showed significant disorganization of hepatic blood sinusoids and hepatocyte cords, obvious hepatocyte edema, smaller nuclei, increased lymphocyte infiltration, and a small number of fat vacuoles, significantly higher levels of FBG, FINS, insulin resistance index(HOMA-IR), iNOS mRNA, p-IRS1ser 307 protein, GSK-3β protein levels, and decreased p-AKTser 473 protein and GS protein levels, all of which were statistically significant(allP<0.05). IRS1ser 307 protein, GSK-3β protein levels were increased, p-AKTser 473 protein and GS protein levels were decreased, and the differences were statistically significant(allP<0.05); at 12 weeks, no lymphocyte infiltration was seen in the CIH group compared with that of the NC group and fat vacuoles significantly increased, and there was no improvement in the other pathological damage that had already occurred, and the levels of p-AKTser 473 protein significantly increased. AKTser 473 protein level significantly increased, p-IRS1ser 307 protein and GS protein levels were significantly reduced, all of which were statistically significant(allP<0.05), and the rest of the observational indexes were not statistically significant. Pearson′s correlation analysis showed that HOMA-IR of CIH group was significantly positively correlated with the levels of iNOS mRNA, p-IRS1ser 307 protein, and GSK-3β protein at 8 weeks(r=0.874, 0.817,0.872;allP<0.05), and significantly negatively correlated with the levels of p-AKTser 473 protein and GS protein(r=-0.886,-0.879;allP<0.05). Conclusion Chronic intermittent hypoxia can lead to hepatic pathological damage that cannot be reversed even by reoxygenation interventions and may mediate the development of insulin resistance by upregulating the IRS1/AKT/GSK-3β signaling pathway through the upregulation of iNOS mRNA expression.

Objective To investigate the effects of chronic intermittent hypoxia(CIH)and reoxygenation on insulin resistance(IR)and expressions of miR-27a-3p/PPARγ/IRS1/PI3K/AKT in rat skeletal muscle.Methods GEO database was used for screening the differentially expressed miRNAs in CIH,and their target genes were subjected to GO and KEGG enrichment analysis followed by construction of the miRNA-mRNA-pathway regulatory network using Cytoscape.In the animal experiment,48 male SD rats were randomly divided into normoxia group and CIH group(8 weeks of CIH followed by 4 weeks of normoxic recovery).Blood and skeletal muscle samples were collected at baseline,8 weeks,and 12 weeks to evaluate the changes in fasting blood glucose(FBG)and fasting insulin(FINS)levels and muscular pathology.RT-qPCR and Western blotting were used to detect the changes in the expressions of miR-27a-3p,PPARγ,GLUT4,IRS1,p-IRS1,PI3K,p-AKT and AKT in the muscular tissues.Results No muscular miRNA datasets for CIH were available in GEO database,from which only a kidney-related dataset(GSE202480)was obtained,based on which a total of 165 differentially expressed miRNAs were identified.GO/KEGG analysis suggested that these miRNAs were involved in muscular regulation and insulin signaling.The miRNA-mRNA-pathway network highlighted miR-27a-3p as a crucial regulator in the PPAR and PI3K/AKT pathway.In the animal experiment,the rats subjected to CIH for 8 weeks showed significantly increased FBG,FINS,HOMA-IR,and PPARγ levels,loose muscle fiber arrangement,decreased cross-sectional area of the muscle fibers,and lowered expressions of miR-27a-3p,p-IRS1/IRS1,PI3K,and p-AKT/AKT in the skeletal muscles.Conclusion CIH increases IR,causes skeletal muscle pathology,downregulates miR-27a-3p expression,upregulates PPARγ expression,and inhibits IRS1/PI3K/AKT insulin signaling in the skeletal muscles of rats,and these changes can be reversed by reoxygenation.MiR-27a-3p may participate in CIH-induced IR by modulating the PPAR γ/IRS1/PI3K/AKT signaling pathway.

Objective To investigate the effects of chronic intermittent hypoxia(CIH)and reoxygenation on insulin resistance(IR)and expressions of miR-27a-3p/PPARγ/IRS1/PI3K/AKT in rat skeletal muscle.Methods GEO database was used for screening the differentially expressed miRNAs in CIH,and their target genes were subjected to GO and KEGG enrichment analysis followed by construction of the miRNA-mRNA-pathway regulatory network using Cytoscape.In the animal experiment,48 male SD rats were randomly divided into normoxia group and CIH group(8 weeks of CIH followed by 4 weeks of normoxic recovery).Blood and skeletal muscle samples were collected at baseline,8 weeks,and 12 weeks to evaluate the changes in fasting blood glucose(FBG)and fasting insulin(FINS)levels and muscular pathology.RT-qPCR and Western blotting were used to detect the changes in the expressions of miR-27a-3p,PPARγ,GLUT4,IRS1,p-IRS1,PI3K,p-AKT and AKT in the muscular tissues.Results No muscular miRNA datasets for CIH were available in GEO database,from which only a kidney-related dataset(GSE202480)was obtained,based on which a total of 165 differentially expressed miRNAs were identified.GO/KEGG analysis suggested that these miRNAs were involved in muscular regulation and insulin signaling.The miRNA-mRNA-pathway network highlighted miR-27a-3p as a crucial regulator in the PPAR and PI3K/AKT pathway.In the animal experiment,the rats subjected to CIH for 8 weeks showed significantly increased FBG,FINS,HOMA-IR,and PPARγ levels,loose muscle fiber arrangement,decreased cross-sectional area of the muscle fibers,and lowered expressions of miR-27a-3p,p-IRS1/IRS1,PI3K,and p-AKT/AKT in the skeletal muscles.Conclusion CIH increases IR,causes skeletal muscle pathology,downregulates miR-27a-3p expression,upregulates PPARγ expression,and inhibits IRS1/PI3K/AKT insulin signaling in the skeletal muscles of rats,and these changes can be reversed by reoxygenation.MiR-27a-3p may participate in CIH-induced IR by modulating the PPAR γ/IRS1/PI3K/AKT signaling pathway.