Effect of hydrogen-rich saline on autophagy in spinal neurons of rats with neuropathic pain

Abstract

Objective To evaluate the effect of hydrogen-rich saline on autophagy in the spinal neurons of rats with neuropathic pain. Methods Sixty pathogen-free male Sprague-Dawley rats, aged 8-10 weeks, weighing 220-250 g, were randomly assigned into 3 groups (n=20 each)using a random number table: sham operation group (S group), neuropathic pain group (NP group), and hydrogen-rich saline group (H group). Neuropathic pain was produced by chronic constriction injury of the sciatic nerve in the rats anesthetized with chloral hydrate.Hydrogen-rich saline 5 ml/kg was injected intraperitoneally once a day for 7 consecutive days in group H, while the equal volume of normal saline was given instead in S and NP groups.The mechanical paw withdrawal threshold (MWT)and thermal paw withdrawal latency (TWL)were measured at 1 day before operation (T0)and 1, 3, 5 and 7 days after operation (T1-4). The animals were sacrificed after measurement of pain threshold at day 7 after operation.L4-6 segments of the spinal cord were harvested to detect the expression of autophagy-related proteins microtubule-associated protein 1 light chain 3 Ⅱ (LC3 Ⅱ), Beclin-1 and p62 by Western blot. Results Compared with group S, the MWT was significantly decreased, and the TWL was significantly shortened at T2-4, and the expression of LC3Ⅱ, Beclin-1 and p62 was significantly up-regulated at T4 in NP and H groups (P<0.05). Compared with group NP, the MWT was significantly increased, and the TWL was significantly prolonged at T2-4, and the expression of LC3Ⅱ and Beclin-1 was significantly up-regulated, and the expression of p62 was significantly down-regulated at T4 in group H (P <0.05). Conclusion The mechanism by which hydrogen-rich saline reduces neuropathic pain is related to induction of autophagy in the spinal neurons of rats. Key words: Hydrogen; Neuralgia; Autophagy; Spinal cord