Effect of electroacupuncture on P2X4R-p38 MAPK-BDNF signaling pathway in trigeminal ganglion of rats with trigeminal neuralgia / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of electroacupuncture on P2X4R-p38 mitogen-activated protein kinase (p38 MAPK)-brain-derived neurotrophic factor (BDNF) signaling pathway in trigeminal ganglion of rats with trigeminal neuralgia.Methods:Thirty-six clean-grade healthy adult male Sprague-Dawley rats, weighing 190-230 g, aged 2-3 months, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (S group), trigeminal neuralgia group (TN group), and electroacupuncture group (E group). The model was developed by chronic constriction of the infraorbital nerve in anesthetized animals. The infraorbital nerve was only exposed without ligation in group S. Rats received electroacupuncture stimulation at the Baihui and Xiaguan acupoints on the affected side for 20 min after developing the model, with a frequency of 80 Hz, twice a day, for 14 consecutive days in E group. Facial mechanical pain threshold (FMT) was measured at 1 day before developing the model and 3, 7, 14, 21 and 28 days after developing the model. The rats were sacrificed after the last behavioral testing, and the trigeminal ganglia were taken for examination of histopathological changes of trigeminal ganglion (by HE staining) and for determination of the expression of P2X4R, p38 MAPK, phosphorylated p38 MAPK (p-p38 MAPK) and BDNF (by Western blot) and contents of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and IL-6 (by enzyme-linked immunosorbent assay). Results:Compared with group S, the FMT was significantly decreased at each time point after developing the model, the expression of P2X4R, p-p38 MAPK and BDNF in trigeminal ganglion was up-regulated, and the contents of TNF-α, IL-1β and IL-6 were increased ( P<0.05), the pathological changes of the trigeminal ganglion were obvious in group TN. Compared with group TN, the FMT was significantly increased at each time point after developing the model, and the expression of P2X4R, p-p38 MAPK and BDNF in trigeminal ganglion was down-regulated, and the contents of TNF-α, IL-1β and IL-6 were decreased ( P<0.05), and the pathological changes of the trigeminal ganglion were significantly attenuated in group E. Conclusions:The mechanism by which electroacupuncture alleviates trigeminal neuralgia may be related to inhibiting the activity of P2X4R-p38MAPK-BDNF signaling pathway and reducing neuroinflammation in rats.