血红素加氧酶-1对糖尿病大鼠神经病理性疼痛的影响及可能的机制

摘要

目的:通过抑制和诱导血红素加氧酶-1 (HO-1)的表达,探讨其对糖尿病大鼠神经病理性疼痛的影响及可能的机制.方法:将造模成功的24只糖尿病大鼠随机分为3组(n=8):糖尿病组(A组)；糖尿病+锌原卟啉干预组(B组)；糖尿病+钴原卟啉干预组(C组).另取8只大鼠作为正常对照(D组).于造模前及造模后不同时点测大鼠的机械性缩足反应阈值(paw withdrawal mechanical threshold,PWMT).造模后43 d麻醉大鼠,取坐骨神经制成电镜标本；取L4～L6段脊髓,行HE染色、免疫组化染色及原位末端标记(TUNEL)检测.结果:与造模前相比,A、B、C组造模后7 ～42 d的PWMT显著降低(P＜0.01).造模后14～42 d,与A组比,C组PWMT显著升高(P＜0.05),而B组则显著降低(P＜ 0.05).C组脊髓背角神经元及坐骨神经病变的程度较A组减轻；而B组则较A组加重.与A组比,C组脊髓背角神经元胞浆中HO-1表达增强,凋亡发生率显著降低(P＜0.01)；而B组HO-1表达减弱,凋亡发生率显著升高(P＜0.01).结论:HO-1对糖尿病神经病理性疼痛有治疗作用,这可能与其能够减轻糖尿病外周神经病变及抑制脊髓背角神经元凋亡有关.%Objective: The study was designed to investigate the effect of heme oxygenase-1 (HO-1) on streptozotocin (STZ)-induced neuropathic pain in rats. Methods: Male Sprague Dawley (SD) rats weighing 180 ~ 220 g were used. Diabetes mellitus (DM) was induced via single intraperitoneal injection of STZ at a dose of 65 mg/kg. Twenty four DM rats were randomly divided into 3 groups (n = 8 each): DM group (Group A); DM + HO-1 inhibitor zinc protoporphyrin (ZnPP) group (Group B); DM +HO-1 inducer cobalt protoporphyrin (CoPP) group (Group C). Eight healthy age-matched rats were used as control (Group D). Paw withdrawal mechanical threshold (PWMT) was measured before modeling and on day 7, 14, 21, 28, 35 and 42 after STZ injection. On day 43 after STZ injection, all rats were sacrificed. Sciatic nerves were removed for ultrastructural observation, and lumbar segments (L4 -L6) of spinal cord were removed for pathologic observation (hematoxylin-eosin staining), detection of HO-1 expression (immuno-histohemistry) and apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, TUNEL) in the dorsal horn neurons. Results: After STZ injection, the PWMT of Group A, B and C were significantly decreased on day 7 (P < 0.01), compared with that before injection. From day 14 to day 42 after STZ injection, the PWMT was significantly higher in Group C (P < 0.05) and lower in Group B (P < 0.05), compared with Group A. Administration of CoPP, which induced the expressionrnof HO-1 protein, significantly prevented hyperglycemia-induced mechanical allodynia, attenuated histopathologic changes of sciatic nerves and also significantly decreased the apoptosis of SDH neurons (P < 0.01), compared with untreated diabetic rats. Treatment with ZnPP led to an opposite result. Conclusion: It may be concluded that HO-1 has ameliorative potential in attenuating diabetic neuropathy-associated neuropathic pain.