Exercise intensity and the expression of toll-like receptor 4 and nuclear transcription factor-κB in the diabetic liver

Abstract

Objective To investigate the changes in toll-like receptor 4 (TLR4) and nuclear transcription factor-κB (NF-κB) expression in the livers of diabetic rats after exercise at different intensities. Methods Fifty Sprague-Dawley rats were randomly divided into a control group (NC), a diabetic group (DM), a low intensity exercise group (LIE), a medium intensity exercise group (MIE) and a high intensity exercise group (HIE), each of 10. The control group was given a normal diet. Type 2 diabetes was induced in the others through feeding a high-fat and high-sugar diet, as well as injecting a small dose of streptozotocin intraperitoneally. The three exercising groups swam to 40%, 70% and 100% of their exhaustion times once a day, 6 d/w for 6 weeks. Due to infection, drowning and other reasons, only 8 rats in each of the DM, LIE and MIE groups, as well as 7 in the HIE group survived. After the intervention, body weight, liver weight and fasting blood glucose (FBG) were tested. The expression of TLR4 and NF-κB mRNA in the livers was tested using RT-PCR technology, and the expression of TLR4 and NF-κB protein in the liver was tested using immunohistochemistry. Results Compared with the NC group, the average body weight and liver weight of the other four groups decreased significantly, while the FBG and the expression of TLR4 and NF-κB mRNA and protein increased significantly. There were significant differences among the exercise groups with the lowest values in the MIE group. Conclusion Six weeks of aerobic exercise can reduce FBG and the level of expression of TLR4 and NF-κB mRNA and protein in the liver, at least in rats. The effect of exercise at medium intensity is best. Key words: Exercise; Diabetes mellitus; Liver; Toll-like receptor 4; Nuclear transcription factor-κB