Analgesic effects of Chinese Tuina massage in a rat model of pain.

Previous clinical trials have suggested that the Chinese Tuina massage may exert transient analgesic effects. However, further investigation regarding the underlying mechanism has been hindered by the lack of a suitable animal model of pain. The present study established a rat model of hind leg pain by injecting 5.8% hypertonic saline solution (HSS) into the left gastrocnemius muscle. The effects of various Tuina massages on the pain thresholds of the rats were then measured. In addition, the effects of ipsilateral and contralateral Tuina massages on C-fiber-evoked field potentials following electrical stimulation of the left sciatic nerve were determined. Alterations in the gastrocnemius muscle tissues following various Tuina applications were investigated using hematoxylin and eosin, and desmin staining, as well as malondialdehyde and superoxide dismutase assays. Heavy hand pressure transiently reduced the pain sensitivity of both posterior limbs, despite HSS only being injected into the left hind leg. Tuina massage treatments that lasted for 15 min were associated with the best results and an absence of local tissue changes. The results of electrical sciatic nerve stimulation demonstrated that ipsilateral and contralateral Tuina massage may decrease the level of peripheral nociceptive C-fiber activity. In the present study, the Chinese Tuina massage exerted analgesic effects in a rat model of pain, which did not involve tissue damage, following a 15 min massage. Therefore, the rat model of pain used in the present study may provide a novel approach for investigating the molecular and physiological mechanisms underlying the therapeutic effects of Tuina massage.