OBJECTIVETo observe anti-fatigue effect and mechanisms of pre-electroacupuncture (EA) at "Zusanli" (ST 36) in rats undergoing acute treadmill running.

METHODSFifty male SD rats were randomly divided into three groups: a quiet group (group Q, n = 10), a model group (group M, n = 20) and an EA preconditioning group (group EAP, n = 20). After adaptation for undergoing treadmill running, all the rats in group M and group EAP were trained on acute treadmill running. Besides, EA with continuous waves, 2 Hz in frequency and 2 mA in intensity was applied at bilateral "Zusanli" (ST 36) for 30 min, which was applied once daily for continuous 6 days before treadmill running for the rats in Group EAP. Plasma lactate contents were measured immediately and 3 hours after treadmill running, respectively. Changes of dopamine (DA) and serotonin (5-HT) contents obtained immediately and 3 hours after treadmill running, respectively, in hypothalamus and striatum, were detected and compared, and DA/5-HT ratios were calculated.

RESULTSCompared with group Q, the levels of blood lactate and hypothalamic 5-HT tented to increase in rats of group M, and the contents of hypothalamic DA increased significantly (P < 0.01), while the contents of striatal DA and 5-HT in group M decreased significantly (both P < 0.01) at 3 h after treadmill running. Immediately after treadmill running, the contents of DA and 5-HT increased significantly in hypothalamus (both P < 0.01), but decreased significantly in striatum (both P < 0.01) in group EAP, compared with those in group M. Moreover, EA pretreatment markedly decreased the levels of blood lactate (P < 0.05) and hypothalamic 5-HT (P < 0.01), and obviously elevated the ratio of DA/5-HT in the hypothalamus (P < 0.01) at 3 h after treadmill running.

CONCLUSIONPreventive EA at "Zusanli" (ST 36) can accelerate recovery from fatigue, which may be related to its reducing accumulation of blood lactate, elevating DA/ 5-HT ratio in the hypothalamus of the rats undergoing treadmill running.