不同剂量神经生长因子对神经源性疼痛大鼠脊髓Fos蛋白的影响

Effect of different dose nerve growth factor on Fos protein expression in the spinal cord of rats with neuropathic pain

背景:神经生长因子对神经元的存活、生长发育、分化、再生和功能维持起到调控作用。目的:进一步验证不同剂量神经生长因子对神经源性痛大鼠的治疗作用以及对脊髓中Fos蛋白的影响。设计、地点:随机对照动物实验,在上海第九人民医院完成。材料:健康成年雄性Wistar大鼠72只,体质量180～200g,随机分为4组,模型组及腹腔注射神经生长因子4,8,16μg组,每组18只。方法:72只大鼠结扎左侧坐骨神经制备坐骨神经慢性缩窄性损伤模型;腹腔注射神经生长因子4,8,16μg组,造模后分别腹腔注射神经生长因子4,8,16μg/(kg?d)。主要观察指标:①于术前和术后第1,2,3,5,7,10,14天进行行为学观察和机械性痛阈测定。②于术后第2,7,14天各组分别处死大鼠各6只,取脊髓,应用免疫组织化学方法和图像分析系统检测脊髓中Fos蛋白的表达。结果:模型组大鼠术后出现自发抬足、舔足等自发痛表现,术后第3天起开始出现痛阈下降,第14天达最低值,而注射神经生长因子组大鼠没有自发痛表现,没有出现机械性痛阈的低常期,第10,14天模型组大鼠痛阈与其余各组比较差异有显著性意义(P<0.05)。4组大鼠术后第1天机械性痛阈普遍升高;注射神经生长因子16μg组大鼠术后第1天机械性痛阈比其他各组低(P<0.01),第2天机械性痛阈恢复至术前水平,低于注射神经生长因子4μg组(P<0.05)。术后模型组大鼠脊髓Fos蛋白表达进行性升高,而其他各组大鼠脊髓中仅有少量Fos阳性神经元,模型组与其余各组比较差异显著(P<0.01)。术后第2天注射神经生长因子16μg组大鼠脊髓Fos蛋白表达最低,与模型组和注射神经生长因子4μg组比较,差异有显著性意义(P<0.01)。结论:神经生长因子对大鼠神经源性痛有治疗作用,且大剂量较小剂量作用更为明显,其机制可能与抑制脊髓中Fos蛋白表达有关。

BACKGROUND： Nerve growth factor （NGF） plays a regulatory effect on survival, growth, differentiation, and regeneration of neurons. OBJECTIVE： To verify the therapy effects and the expression of Fos protein with different dose of NGF on the spinal cord of rats with neuropathic pain. DESIGN, TIME AND SETTING： The randomized controlled animal experiment was performed at the Shanghai Ninth People＇s Hospital. MATERIALS： A total of 72 male, health, adult; Wistar rats, weighing 180-200 g, were randomly divided into 4 groups, namely, model group and NGF with 4, 8, 16μg groups, with 18 animals in each group. METHODS： All rats were prepared sciatic nerve chronic constriction injury models. Rats were intraperitoneal injected NGF with 4, 8, 16μg/（kgod） in the experimental groups. MAIN OUTCOME MEASURES：①Behavioral observation and mechanical pain threshold testing was performed prior to and at days 1, 2, 3, 5, 7, 10, 14 after operation.②Six of rats in each group were sacrificed at days 2, 7, and 14 after operation, and the expression of Fos protein in the spinal cord were assayed with the immunohistochemical methods and image analysis. RESULTS： In the model group, rats raised and licked feet spontaneously after operation, and the mechanical pain threshold was decreased from the 3rd day, and reached the lowest at day 14. However, in the NGF groups, rat exhibited no spontaneous pain, without subnormal period of mechanical pain threshold. The mechanical pain threshold in rats of the model group was significant different to the other groups at days 10 and 14 after operation （P 〈 0.05）. The mechanical pain threshold in rats of all groups increased, but which of 16μg NGF group was lower than the other groups on the first day after operation （P〈0.01） and lower than that of the 4μg NGF group at 2 days after operation （P 〈 0.05）. The expression of Fos protein in the spinal cord of the model group was increased than that of the other groups after operation （P 〈 0.01 ）. The expression of Fos protein in the spinal cord of the 16μg NGF group was less than that of model and 4μg NGF groups at day 2 after operation （P 〈 0.01 ）. CONCLUSION： NGF has therapeutical effect on neuropathic pain of rats, especially with large dosage. The mechanisms may be inhibiting the expression of Fos protein in the spinal cord of rats.