Effect of gastrogin on AMPK/TRPA1 signaling pathway in rats with neuropathic pain / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of gastrogin on AMP-activated protein kinase (AMPK)/transient receptor potential anchor protein 1 (TRPA1) signaling pathway in rats with neuropathic pain.Methods:Thirty-six SPF-grade healthy male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-230 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation+ normal saline group (SHAM group), neuropathic pain+ normal saline group (NP group), and neuropathic pain+ gastrogin group (GAS group). Neuropathic pain was induced by chronic constrictive injury to sciatic nerve under 2% isoflurane anaesthesia. The sciatic nerve was only exposed but not ligated in SHAM group. Gastrogin 100 mg/kg was intraperitoneally injected for 14 consecutive days after developing the model in GAS group, while the equal volume of normal saline was given instead in SHAM and NP groups. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 1 day before developing the model (T 0) and 1, 3, 5, 7, 10 and 14 days after developing the model (T 1-6). The rats were anesthetized and sacrificed following the measurement of pain thresholds at T 4 and T 6. The lumbar segment (L 4-6) of the spinal cord was removed for determination of TRPA1 mRNA expression (by quantitative real-time polymerase chain reaction), expression of TRPA1, AMPK and p-AMPK (by Western blot), expression of TRPA1 (by immunofluorescence staining) and expression of tumor necrosis-alpha(TNF-α), interleukin-1beta(IL-1β) and c-fos (by immunohistochemistry). Results:Compared with SHAM group, MWT and TWL were significantly decreased at T 1-6, the expression of TRPA1 mRNA, TRPA1, TNF-α, IL-1β and c-fos was up-regulated, the expression of p-AMPK was down-regulated ( P<0.05), and no significant change was found in AMPK expression in NP group ( P>0.05). Compared with NP group, MWT at T 3-6 and TWL at T 2-6 were significantly increased, the expression of TRPA1 mRNA, TRPA1, TNF-α, IL-1β and c-fos was down-regulated, and p-AMPK expression was up-regulated ( P<0.05), and no significant change was found in AMPK expression in GAS group ( P>0.05). Conclusions:The mechanism by which gastrogin reduces neuropathic pain may be related to modulating the expression of the AMPK/TRPA1 signaling pathway in rats.