Exhaustive exercise increases inflammatory response via Toll like receptor-4 and NF-κBp65 pathway in rat adipose...

Cytokines (IL-6, IL-10, and TNF-α) are increased after exhaustive exercise in the retroperitoneal adipose tissue (RPAT) and mesenteric adipose tissue (MEAT). An exhaustive acute exercise protocol induces inflammation in adipose tissue that lasts 6 h after the exercise has ended. It is well-established that this protocol increases circulating plasma levels of non-esterified fatty acids (NEFAs) and lipopolysaccharides (LPS), compounds that are important in stimulating signaling via toll like receptor-4 (TLR-4) in different type cells. In the present study, we investigated the regulation of TLR-4 and DNA-binding of nuclear factor-κBp65 (NF-κBp65) in different depots of adipose tissue in rats after exhaustive exercise. Rats were killed by decapitation immediately (E0 group, n=6), 2 (E2 group, n=6), and 6 h (E6 group, n=6) after the exhaustive exercise, which consisted of running on a treadmill (approximately 70% V(O2max) ) for 50 min and then running at an elevated rate that increased at 1 m/min, until exhaustion. The control group (C group, n=6) was not subjected to exercise. In RPAT, TLR-4, MYD-88, and IkBα increased in the E2 group after exercise. MYD-88 and TRAF6 remained increased in the E6 group in comparison with the control group. DNA-binding of NF-κBp65 was not altered. In MEAT, TLR-4, MYD-88, TRAF6, and DNA-binding of NF-κBp65 were increased only in the E6 group. In conclusion, we have shown that increases in pro-inflammatory cytokines in adipose tissue pads after exhaustive exercise may be mediated via TLR-4 signaling, leading to increases in NF-κBp65 binding to DNA in MEAT.