Gardenoside suppresses the pain in rats model of chronic constriction injury by regulating the P2X3 and P2X7 receptors

Objectives: Here, using rat model, we investigated the roles of gardenoside in the chronic constriction injury (CCI) of the ischiadic nerve.

Methods: Bennett and Xie's unilateral sciatic nerve CCI model was used in this study. A total of 60 rats were divided into control group (CN), sham group (Sham), CCI group, and gardenoside administrated CCI group. An aliquot of 5 mL gardenoside solution was administrated through gavage once per day for 14 d. Mechanical withdrawal threshold (MWT) and the thermal withdrawal latency (TWL) were detected. The levels of inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in spinal fluid were detected by ELISA. By using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot, we analyzed the expression of P2X purinoceptor 3 and 7 (P2X3 and P2X7 receptors) in different groups. The expression of p-ERK/ERK and p-p38/p38 were also detected by western blot.

Results: We found out that gardenoside could significantly improve the sciatica by partially restore the decrease of MWT and TWL in CCI rats. The levels of iNOS, IL-1β, and TNF-α were higher in CCI group (p < .05). The expressions of P2X3 and P2X7 were significantly increased in the CCI rats compared to control rats (p < .05). The levels of p-ERK/ERK and p-p38/p38 were also obviously increased in CCI group (p < .05). After treated with the gardenoside, these increases were decreased.

Conclusions: These results indicated that gardenoside may be able to relief CCI-induced neuropathic pain by regulating the P2X3 and the P2X7 expression on the ischiadic nerve.