Toll-like receptors (TLRs) play an important role in the recognition of a specific pattern of microbial components and lead to activation of innate immunity. The purpose of this study was to examine the effect of exercise training on mRNA expression of TLR2 and TLR4 in rat tissues. Female F344 rats were divided into a sedentary(S) group and a training (T) group. At the first week, training rats ran at 15-21 m/min, 15-30 min/day, for 5 days/week. From the second to the fourth week, training rats ran at 21 m/min, 30 min/day, for 5 days/week. We assessed TLR2 and TLR4 mRNA expression in the lung, the liver, the spleen and the soleus muscle using realtime RT-PCR. Although thymic atrophy and the extension of exhaustion time were detectable, the basal levels of stress hormone (catecholamine and corticosterone) were unchanged by exercise training. TLR2 mRNA expression in the lung tended to be lower in the T group than in the S group, but there were no statistically significant differences. Similarly, TLR4 mRNA expression was not significantly different between the S and T groups. These findings suggest that mild exercise training might not affect TLR2 and TLR4 mRNA expression in the lung, the liver, the spleen and the musle tissue.

DESCENTE SPORTS SCIENCE Vol.33/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE