2022, Vol. 26 ›› Issue (26): 4199-4204

Analgesic effect and mechanism of pivot meridian hyperthermia in a rat model of neuropathological pain

Qin Qin, Xia Tian, Li Yuefa, Zhang Lingling, Qin Haixia   

Abstract: BACKGROUND: Pivot meridian hyperthermia is an external treatment method guided by the central meridian theory of traditional Chinese medicine (TCM). Studies have shown that it may have a better effect on neuropathic pain, but the specific efficacy evidence and mechanism of action are still unclear.
OBJECTIVE: To investigate the analgesic effect of pivot meridian hyperthermia in a rat model of neuropathological pain and its mechanism based on behavior indicators and molecular biological indicators.
METHODS: Eighty male healthy Sprague-Dawley rats were randomly divided into a blank control group, a model control group, a hyperthermia group, and a TCM hyperthermia group, with 20 rats in each group. In the last three groups, the L5 spinal nerve was ligated to prepare the rat model of neuropathic pain. In the hyperthermia group, cotton pads soaked in 45°C saline were used to heat the gall bladder meridian circulation parts of the rats’ bilateral feet. In the TCM hyperthermia group, cotton pads soaked in 45°C Chinese medicinal solution were applied to heat the gall bladder meridian circulation parts of the rats’ bilateral feet. Treatment in each group was performed once a day. Behavior testing was started after 15 minutes of each hot compress, to measure paw withdrawal mechanical threshold and paw withdrawal thermal latency. The expression levels of vesicular glutamate transporter 2 and Toll-like receptor 4 protein in rat spinal cord tissue were detected after 14 days of continuous treatment.
RESULTS AND CONCLUSION: Compared with the model control group, paw withdrawal mechanical threshold was significantly higher and paw withdrawal thermal latency was significantly lower in the hyperthermia and TCM hyperthermia groups at 7 and 14 days of treatment (P < 0.05). Moreover, the TCM hyperthermia group showed better efficacy than the hyperthermia group (P < 0.05). Compared with the model control group, the expression levels of vesicular glutamate transporter 2 and Toll-like receptor 4 protein were significantly lower in the hyperthermia and TCM hyperthermia groups (P < 0.05). However, there was no significant difference between the hyperthermia and TCM hyperthermia groups (P > 0.05). To conclude, pivot meridian hyperthermia has a significant analgesic effect in neuropathological pain rats, and its mechanism may be related to inhibiting vesicular glutamate transporter 2/Toll-like receptor 4 signaling pathways.
Key words: neuropathological pain, pivot meridian hyperthermia, analgesia, vesicular glutamate transporter 2, Toll-like receptor 4 protein, traditional Chinese medicine, rat