脑源性神经营养因子在大鼠炎性痛中的作用

目的 评价脑源性神经营养因子(BDNF)在大鼠炎性痛中的作用.方法 鞘内置管成功的雌性未交配SD大鼠60只,体重150～180 g,随机分为5组(n=12):假手术组(Ⅰ组)、假手术+BDNF中和抗体组(Ⅱ组)、炎性痛组(Ⅲ组)、炎性痛+IgG对照抗体组(Ⅳ组)和炎性痛+BDNF中和抗体组(Ⅴ组).Ⅲ组、Ⅳ组和Ⅴ组于左后肢外踝关节腔内注射完全弗式佐剂50μl,制备炎性痛模型;Ⅰ组和Ⅱ组于左后肢外踝关节腔内注射生理盐水50μl.造模后第1天时Ⅱ组、Ⅳ组和Ⅴ组分别鞘内注射BDNF中和抗体、IgG对照抗体和BDNF中和抗体15 .μg/10μl,1次/d,连续3 d.分别于造模前及造模后第3、5、7、10、14天时,测定大鼠热缩足反射潜伏期(PWTL).于造模后第3天PWTL测定结束后处死大鼠,取L4～6脊髓背角,采用荧光免疫组化法和Western blot法测定BDNF和p-ERK1/2的蛋白表达水平.结果 与Ⅰ组比较,Ⅱ组PWTL、脊髓背角BDNF和p-ERK1/2的蛋白表达差异无统计学意义(P＞0.05),Ⅲ组和Ⅳ组PWTL缩短,脊髓背角BDNF和p-ERK1/2的蛋白表达上调,Ⅴ组PWTL缩短(P＜0.01),脊髓背角BDNF和p-ERK1/2的蛋白表达差异无统计学意义(P＞0.05);与Ⅲ组比较,Ⅳ组PWTL、脊髓背角BDNF和p-ERK1/2的蛋白表达差异无统计学意义(P＞0.05),Ⅴ组PWTL延长,脊髓背角BDNF和p-ERK1/2的蛋白表达下调(P＜0.01).结论 脊髓背角BDNF可通过其下游的p-ERK1/2信号转导通路参与大鼠炎性痛的形成.

Role of brain-derived neurotrophic factor in inflammatory pain in rats

Objective To evaluate the role of brain-derived neurotrophic factor (BDNF) in inflammatory pain in rats. Methods Sixty female SD rats weighing 150-180 g in which intrathecal (IT) catheters were successfully placed without complication were randomly divided into 5 groups (n= 12 each): group Ⅰ sham operation; group Ⅱ sham operation + IT anti-BDNF antibody; group Ⅲ inflammatory pain; group Ⅳinflammatory pain + IT control IgG and group Ⅴ inflammatory pain + IT anti-BDNF antibody. Inflammatory pain was induced by injecting complete Freund's adjuvant (CFA) into ankle joint cavity of left hindpaw, while in sham operation group equal volume of normal saline was injected instead of CFA. Anti-BDNF antibody or control IgG 15 μg/10 μl was injected IT once a day for 3 days after inflammatory pain was induced. Paw withdrawal latency to thermal stimuli (PWTL) was measured one day before and at 3, 5, 7, 10 and 14 d after inflammatory pain was induced. The rat was sacrificed on 3 rd day of IT anti-BDNF antibody or control IgG injection. The lumbar segment L4-6 of the spinal cord was removed for detection of the expression of BDNF and p-ERK1/2 by immunohistochemistory and Western blot. Results Intra-articular CFA injection significantly increased the expression of BDNF and p-ERK1/2 in the spinal cord in group Ⅲ as compared with sham-operated animals in group Ⅰ . IT antiBDNF antibody injection significantly suppressed the expression of BDNF and p-ERK1/2. PWTL was significantly shortened after intra-articular CFA injection in group Ⅲ as compared with group Ⅰ . IT anti-BDNF antibody reversed the inflammation-induced thermal hyperalgesia in group Ⅴ but IT control IgG did not. Conclusion BDNF in the spinal cord may be involved in inflammatory pain through p-ERK1/2 signal transduction pathway.