Exploring the Analgesic Initiation Mechanism of Tuina in the Dorsal Root Ganglion of Minor CCI Rats via the TRPV1/TRPA1-cGMP Pathway

Tuina is a treatment method in traditional Chinese medicine which has analgesic effects and effectively alleviates the symptoms of neuropathic pain (NP). Transient receptor potential vanilloid type 1 (TRPV1) and transient receptor potential ankyrin type 1 (TRPA1) play major roles in transmitting nociceptive sensory signals in the nociceptive primary sensory dorsal root ganglion (DRG) nerve. The nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate(cGMP) pathway exerts both nociceptive and antinociceptive effects in various chronic pain models. TRPV1 and TRPA1 mediate the influx of calcium, which stimulates the generation of NO. Subsequently, NO activates the NO/cGMP/protein kinase G (PKG) signaling pathway, thereby improving hyperalgesia. In the present study, oa rat model of NP with minor chronic constriction injury (CCI) of the right sciatic nerve of NP was established. The results of behavioral testing showed that, after a one-time tuina intervention, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were prolonged to varying degrees in the tuina group compared with the model group. Similarly, the expression of TRPV1, TRPA1, NO, soluble Guanylate Cyclase β (sGCβ), cGMP, and PKG1 was significantly decreased in the DRG of the tuina and tuina + TRPV1/TRPA1 antagonist group was significantly decreased. These findings suggest that the tuina intervention can effectively improve the symptoms of thermal and mechanical allodynia caused by peripheral nerve injuries. Tuina exerts immediate analgesic effects through the TRPV1/TRPA1-NO-cGMP-PKG signaling pathway.