|（1.Department of Physical Education，Nanchang University，Nanchang 330031，China；2.Chengdu Sport University，Chengdu 610041，China；3.School of Health and Human Sciences，Southern Cross University，Lismore，NSW 2480，Australia；4.Division of Physical Education，Jiangxi University of Traditional Chinese Medicine，Nanchang 330004，China)
Abstract: By means of swimming training, the authors induced rat’s Th1/Th2 imbalance, observed and analyzed the patterns of changing of JAK2/STAT4 pathways and their upstream cytokines in the process of development of such an imbalance, so as to probe into the molecular mechanism of intensive training inducing the Th1/Th2 imbalance. The authors randomly divided 16-week old male SD rats graded clean into a calm control group (group C) and a swimming training group (group T), then randomly divided each of these groups into a 24h group and a 7d group according to different sampling times, carried out the training by using the 4-week load progressively increased swimming training method, measured the protein expressions of pJAK2, pSTAT4, JAK2 and STAT4 in cardiac blood lymphocytes by using the western blotting method, measured the contents of IFN-γ, IL-4 and IL-12 in cardiac blood plasma by using the ELISA method, and revealed the following findings: 1) the levels of IFN-γ, IFN-γ/IL-4 and IL-12 in blood plasma of the rats in group T were all significantly lowered that those of the rats in group C (P<0.01, P<0.05, P<0.01); the contents of IL-12 and IFN-γ in blood plasma of the rats in groups C and T were sig-nificantly correlative (P<0.01); 2) the protein expressions of pJAK2 and pSTAT4 in blood lymphocytes of the rats in group T were all significantly lowered that those of the rats in group C (P<0.05, P<0.01). The said findings indicate that the 4-week load progressively increased training may induce the Th1/Th2 imbalance by reducing the secretion of IL-12, suppressing the process of phosphorylation of key cytokines JAK2 and STAT4 in JAK2/STAT4 signaling pathways, and reducing the synthesis of type Th1 cytokine IFN-γ.
Key words: sports physiology；Th1/Th2 balance；JAK2；STAT4；IL-12；IFN-γ；IL-4