The Study Of Hyperbaric Oxygen On Blood Glucose And Its Mechanism In STZ-induced Type 1 Diabetic Mice

Hyperbaric oxygen therapy is a treatment that gives the patient high respiratory pressure(above normal pressure),pure oxygen or high oxygen concentration.The primary pathological feature of type 1 diabetes is the destruction of islet ? cells,leading to the absolute deficiency of insulin.Hyperbaric oxygen therapy could promote the proliferation of islet ? cells in non-obese diabetic mice and reduce its diabetic incidence.Ghrelin is an important peptide that regulates glucose metabolism and also can promote the proliferation of islet ? cells in the case of islet ? cells destruction induced by streptozotocin(STZ).Objective: Building STZ induced type 1 diabetic mice(T1DM)models,to observe hyperbaric oxygen(HBO)treatment effects on food intake,body weight and blood glucose in T1 DM mice and effects of HBO on islet and hepatic glycogen storage in T1 DM mice.To further explore the roles of glucose transporter 2(GLUT2),ghrelin and ghrelin related molecules in HBO treatment in improving glucose metabolism of STZ-induced T1 DM.Methods:(1)Male C57BL/6 mice was intraperitoneally injected with STZ(150 mg/kg)to induce T1 DM.Mice were divided into control group,T1 DM group and T1DM+ HBO(1 h / day,100% oxygen concentration,2 atmospheres absolute,lasting for 2 weeks).(2)Food intake,blood glucose and body weight were monitored.(3)Pancreatic islet cells in diabetic mice was observed by immunofluorescence double-staining technique.(4)Hepatic glycogen storage was observed by PAS staining.(5)Western blot was used to detect the GLUT2 expression levels in the pancreas and liver.(6)Immunohistochemical method was used to observe the effect of HBO on GLUT2 expression level of liver membrane and ghrelin-O-acyl transferase(GOAT)expression level in pancreas.(7)Elisa and western blot were used to measure plasma total ghrelin level and GOAT expression level in stomach.(8)Western blot was used to detect the expression levels of GOAT and growth hormone secretagogue receptor(GHSR)in pancreas and liver.Results:(1)2-week HBO significantly reduced T1 DM nocturnal cumulative food intake at 1,2,3,4,5,6 and 12 hours((1.14 ± 0.11)g vs.(3.70 ± 0.24)g,P < 0.05;(1.54 ± 0.19)g vs.(6.26 ± 0.47)g,P < 0.05;(2.25 ± 0.21)g vs.(8.39 ± 0.67)g,P < 0.05;(3.07 ± 0.31)g vs.(9.48 ± 0.97)g,P < 0.05;(3.83 ± 0.39)g vs.(10.53 ± 1.47)g,P < 0.05;(4.44 ± 0.61)g vs.(10.99 ± 1.43)g,P < 0.05;(6.73 ± 0.93)g vs.(14.47 ± 1.98)g,P < 0.05).Body weight of diabetic mice was not significantly improved after 2-week HBO treatment.In addition,HBO significantly decreased diabetic blood glucose compared with T1 DM group((12.30 ± 1.89)mmol /L vs.(20.40 ± 2.23)mmol /L,P < 0.05);(2)After 2-week HBO,the area of pancreatic ? cells in diabetic mice increased significantly(0.23 ± 0.03 vs.0.15 ± 0.02,P < 0.05),accompanied by a decrease in the area of pancreatic ? cells(0.77 ± 0.03 vs.0.85 ± 0.02,P < 0.05)and the expression levels of GLUT2 protein in the pancreas of diabetic mice was increased(1.04 ± 0.05 vs.0.69 ± 0.10,P < 0.05);(3)2-week HBO significantly increased hepatic glycogen storage,and GLUT2 expression in liver membrane decreased(9.52 ± 2.43 vs.19.19 ± 4.04,P < 0.05),while the changes in hepatic total GLUT2 protein expression levels were not statistically significant;(4)The total plasma ghrelin levels in diabetic mice was significantly increased after 2-week HBO((16389.17 ± 906.31)pg/ml vs.(9554.98 ± 1200.69)pg/ml,P < 0.05),accompanied by an increase in gastric GOAT levels(1.02 ± 0.09 vs.0.52 ± 0.05,P < 0.05).In addition,HBO significantly increased pancreatic GOAT expression levels in diabetic mice(1.30 ± 0.05 vs.0.94 ± 0.09,P < 0.05),and the pancreatic GHSR expression levels was not significantly different.HBO decreased the levels of hepatic GHSR(0.67 ± 0.05 vs.0.91 ± 0.02,P < 0.05)in diabetic mice while hepatic GOAT expression was not significantly different.Conclusion: HBO therapy significantly decreased blood glucose in STZ-induced T1 DM mice and improved glucose metabolic disorder.The mechanisms of HBO were related to increasing area of pancreatic islet ? cells and hepatic glycogen storage and regulating GLUT2,ghrelin and ghrelin related molecules expression levels in pancreas and liver.