Toll-like receptor 4 activation in skeletal muscle of diet-induced obese rats

Toll-like receptor 4 (TLR4) is found in the membrane of skeletal muscle cells. A variety of factors can activate TLR4. It has been shown that TLR4 expression reduce after aerobic training, but more studies considering the influences of different types of training on TLR4 expression are necessary. The purpose of this study was to evaluate the influence of 8 weeks of aerobic training on muscle TLR4 Expression in rats. Twenty Male Wistar rats (200±20 g) divided into four groups: control, training, high fat diet (HFD) and HFD+exerise. High fat diet was made by adding 10% animal oil, 2% cholesterol and 0.5% colic acid to standard rodent chow. Training group performed a swimming training protocol (1 h/day, and 5 days/week for 8 weeks). Forty eight hours after the final session of training, the rats were sacrificed and their gastrocnemius muscle was removed for determination of TLR4 expression. Training significantly decreased TLR4 messenger RNA and protein expression (p 0.05). Levels of TLR4 expression in the HFD group was significantly (p 0.05) higher tahn control ones. Our result displayed that training in rats induceed a critical suppression in the TLR4 signaling in muscle. These data give noticeable progress in our knowledge of the events that link physical training to an improvement in inflammation.