| Objective The present study was performed to establish the sepsis model with insulin resistance in rats and clarify the impact of insulin treatment controlling glucose at two different levels on GLUT4 expression in the skeletal muscle of septic rats.Methods Septic rat model was made by standard cecal ligation and puncture (CLP) and LPS abdominal infusion (O111:B4,1mg/kg). Intubation of cervical artery and vein were made at the same time. Hyperinsulinemic-euglycemic clamp technique was taken 2 or 3 hours after the operation to calculate the insulin resistance index.44 clean Sprague-Dawley rats (260-330g) were randomized into 4 groups:group A (control group, sham operation), group B (sepsis with fluid maintenance), group C (sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L), group D (sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L). The control group (n=8) underwent cervical vessels intubation and laparotomy only. Sepsis group animals (n=36) received operations of cervical vessels intubation, CLP and LPS infusion. After glucose clamp experiment, group A underwent free diet. Group B lived with fluid maintenance. Group C underwent fluid maintenance and insulin treatment controlling blood glucose concentration at 6-8mmol/L. Group D underwent fluid maintenance and insulin treatment controlling blood glucose concentration at 8-10mmol/L. Blood was taken from the tip of the tail and tested by blood glucose meter for glucose concentration. At the 12th hour skeletal muscle was taken from half of the rats in each group. Part of the muscle was collected in sterile tube and stored at -70 ?. The left was stored in neutral formalin. At the 24th hour skeletal muscle was taken from the left rats and stored in the same way. Pathological change was observed by section HE staining. GLUT4 mRNA level was analyzed by RT-PCR. GLUT4 level was determined by western-blot method and immunohistochemical staining.Results (1) Insulin resistance index of sepsis group is lower than sham operation group (17.1±3.6 vs 29.4±2.7,P<0.01); (2) Skeletal muscle section HE staining reveals inflammatory cell infiltration, cell swelling and muscle dissolution. The number of inflammatory cells in sepsis group with insulin treatment is smaller than sepsis with fluid maintenance only. There is no obvious difference between two sepsis groups with insulin treatment. (3) At 12th hour, GLUT4 mRNA expression from the highest group to the lowest is:sham operation group, sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L, sepsis with fluid maintenance and sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L (1.16±0.04 vs 0.87±0.31 vs 0.36±0.17 vs 0.11±0.01,P<0.05); At 24th hour, GLUT4 mRNA expression from the highest group to the lowest is also:sham operation group, sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L, sepsis with fluid maintenance and sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L (0.94±0.20 vs 0.70±0.17 vs 0.55±0.05 vs 0.24±0.06, P?0.05); (4) At 12th hour, GLUT4 level from the highest group to the lowest is:sham operation group, sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L, sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L and sepsis with fluid maintenance (2.07±0.33 vs 1.48±0.46 vs 0.95±0.30 vs 0.45±0.21, P<0.05); At 24th hour, GLUT4 level from the highest group to the lowest is also:sham operation group, sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L, sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L and sepsis with fluid maintenance (1.66±0.35 vs 1.16±0.21 vs 0.89±0.14 vs 0.43±0.09, P<0.05); (5) The expression of GLUT4 on skeletal muscle by immunohistochemical staining, similar to the result of WB, from the highest group to the lowest is:sham operation group, sepsis with insulin treatment controlling blood glucose concentration at 8-10mmol/L, sepsis with insulin treatment controlling blood glucose concentration at 6-8mmol/L and sepsis with fluid maintenance.Conclusion (1) Sepsis can cause hyperglycemia,insulin resistance and decrease GLUT4 mRNA and GLUT4 expression, in skeletal muscle. (2) Insulin treatment can increase GLUT4 mRNA and GLUT4 expression in skeletal muscle of septic rats. (3) The impact of insulin treatment controlling blood glucose concentration at 8-10mmol/L to increase GLUT4 mRNA and GLUT4 expression is stronger than controlling blood glucose concentration at 6-8mmol/Land it is more beneficial to the utilization of glucose in skeletal muscle of septic rats. |
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