Effects of hydrogen-rich saline on inflammatory responses in sciatic nerve and spinal cord of rats with neuropathic pain

Objective To evaluate the effects of hydrogen-rich saline on inflammatory responses in the sciatic nerve and spinal cord of rats with neuropathic pain (NP). Methods Ninety male adult Sprague-Dawley rats, weighing 180-220 g, were randomly divided into three groups (n=30 each) using a random number table: sham operation group (group S); NP group; hydrogen-rich saline group (group H). NP was induced by chronic constrictive injury.The animals were anesthetized with intraperitoneal 10% chloral hydrate 300 mg/kg.The left sciatic nerve was exposed and ligated with 4-0 silk at 1 mm intervals.After ligation of the sciatic nerve, hydrogen-rich saline (0.6 mmol/L) 10 ml/kg was injected intraperitoneally twice a day for 7 consecutive days in group H, and the equal volume of normal saline was given in S and NP groups.At 7, 10 and 14 days after ligation, the mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.The rats were then sacrificed, and the left sciatic nerve and L4-6 segments of the spinal cords were removed for detection of the contents of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and high mobility group box-1 (HMGB1) at 7, 10 and 14 days after ligation. Results Compared with group S, the MWT and TWL were significantly decreased, and the contents of TNF-α, IL-1β and HMGB1 in the left sciatic nerve and spinal cords were increased at each time point in NP and H groups.Compared with group NP, the MWT and TWL were significantly increased, and the contents of TNF-α, IL-1β and HMGB1 in the left sciatic nerve and spinal cords were decreased at each time point in group H. Conclusion Hydrogen-rich saline alleviates NP through inhibiting inflammatory responses in the sciatic nerve and spinal cord of rats. Key words: Hydrogen; Neuralgia; Inflammation; Sciatic nerve; Spinal cord