Effect ofhydrogen-rich saline on TLR4/NF-κB signaling pathway in sciatic nerve of rats with diabetic neuropathic pain

Abstract

Objective To evaluate the effect of hydrogen-rich saline on Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling pathway in the sciatic nerve of rats with diabetic neuropathic pain (DNP). Methods Pathogen-free male Sprague-Dawley rats, aged 8 weeks, weighing 180–210 g, were used in the study.DPN model was established by intraperitoneal injection of 1% streptozocin (STZ) 65 mg/kg.Twenty-four diabetic rats were randomly divided into 2 groups (n = 12 each) using a random number table: DPN group and hydrogen-rich saline group (HRS group). Another 12 normal rats were randomly selected and served as control group (group C). At 14 days after STZ injection, hydrogen-rich saline 5 ml/kg was injected intraperitoneally once a day for 14 consecutive days in group HRS, while the equal volume of normal saline was given in C and DNP groups.Mechanical paw withdrawal threshold to von Frey stimuli (MWT) and thermal paw withdrawal latency (TWL) were measured at 2 days before STZ injection (T0), and 7, 14, 21 and 28 days after STZ injection (T1-4). The motor nerve conduction velocity (MNCV) of the right hindlimb was measured after pain threshold was measured at T4.After measurement of neurological function was completed, the expression of TLR4 and NF-κB was detected in the sciatic nerve (by Western blot), the tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) contents in sciatic nerves were measured by enzyme-linked immunosorbent assay, and the neuronal apoptosis was detected by TUNEL.The apoptosis index was calculated. Results Compared with group C, the MWT was significantly decreased at T1-4, TWL was shortened at T2-4, and MNCV was decreased at T4, the expression of TLR4 and NF-κB, contents of TNF-α and IL-6, and apoptosis index were increased in HRS and DNP groups (P<0.05). Compared with group DNP, the MWT was significantly increased, and TWL was prolonged at T3, 4 MNCV was increased T4, and the expression of TLR4 and NF-κB, contents of TNF-α and IL-6, and apoptosis index were decreased in group HRS (P<0.05). Conclusion Hydrogen-rich saline can mitigate DNP through blocking TLR4/NF-κB signaling pathway in the sciatic nerve of rats. Key words: Hydrogen; Diabetes mellitus; Neuralgia; Toll-like receptor 4; NF-kappa B; Sciatica