胃促生长素对脓毒症大鼠脑功能障碍的影响及相关机制

Effects of ghrelin on brain dysfunction in septic rats and the related mechanisms

目的探讨炎性因子在脓毒症大鼠脑功能障碍发病机制中的作用及胃促生长素(ghrelin)对脓毒症大鼠脑功能和脑部炎性反应的影响。方法将64只雄性Sprague-Dawley(SD)大鼠随机分为假手术组(Sham组)、假手术+ghrelin组(Sham+ghrelin组)、盲肠结扎穿孔(CLP)组及CLP+ghrelin组,每组16只。采用CLP法制作大鼠脓毒症脑病模型。Sham+ghrelin组和CLP+ghrelin组于造模后即刻及12h后腹腔注射ghrelin80μg/kg,Sham组及CLP组于相应时间点腹腔注射等量的0.9%氯化钠溶液。将每组再分为3个亚组:第1亚组6只,于术后6h采用动物神经功能评分表对大鼠进行评分,而后麻醉断头取左侧海马组织,采用酶联免疫吸附试验检测肿瘤坏死因子(TNF)-α及白细胞介素(IL)-6的表达情况;第2亚组6只,于术后24h进行上述处理;第3亚组4只,于术后24h灌注取脑组织行尼氏染色后进行病理学检查。结果造模后24h,CLP组及CLP+ghrelin组大鼠的神经功能评分均显著低于Sham组及Sham+ghrelin组(P值均<0.05),CLP+ghrelin组显著高于CLP组(P<0.05),Sham+ghrelin组与Sham组间的差异无统计学意义(P>0.05)。造模后6、24h,Sham组与Sham+ghrelin组间海马组织中TNF-α及IL-6表达的差异均无统计学意义(P值均>0.05),CLP组及CLP+ghrelin组海马组织中TNF-α及IL-6的表达水平均显著高于Sham组及Sham+ghrelin组(P值均<0.05),CLP+ghrelin组显著低于CLP组(P值均<0.05)。CLP组大鼠海马神经元明显变性、坏死、丢失,排列疏松,部分神经元核固缩,细胞质内尼氏小体减少;CLP+ghrelin组与CLP组相比,上述病理改变明显减轻,但未完全消失。结论 ghrelin对脓毒症大鼠的脑功能起到一定的保护作用,其机制可能与下调炎性因子TNF-α及IL-6的表达而减轻海马神经元的损伤有关。

Objective To investigate the effects of ghrelin on brain function and brain inflammatory reaction in septic rats, and to study the role of inflammatory cytokines in the pathogenesis of brain dysfunction. Methods Sixty-four male Sprague-Dawtey （SD） rats were randomly divided into 4 groups （sham operation group, sham＋ghrelin group, cecal ligation and puncture [-CLP] group, and CLP＋ ghrelin group, n = 16）. The septic encephalopathic rat model was established by CLP. Ghrelin （80 αg/kg） was administered by intraperitoneal injection immediately and 12 h after operation in sham＋ ghrelin group and CLP-I-ghrelin group. Meanwhile, the same volume of normal saline was given in sham operation group and CLP group. Each group was then divided into 3 subgroups. The 6 rats in the first subgroup performed neurological assessment 6 h after CLP or sham operation and then were killed under anesthesia to examine the inflammatory cytokines （tumor necrosis factor [TNF]-α and interleukin [IL]-6） in the left hippocampus. The 6 rats in the second subgroup conducted the same procedure 24 h after CLP or sham operation. The brain tissue of the 4 rats in the third subgroup was taken out for pathological examination by Nissl＇s staining. Results Compared with sham operation group and sham ＋ ghrelin group, neurological scores were significantly decreased 24 h after operation, TNF-α and IL-6 levels in the hippocampus were significantly increased in CLP group and CLP ＋ ghrelin group 6 h and 24 h after operation （all P〈0.05）. Compared with CLP group, neurological scores were significantly increased, TNF-α and IL-6 levels were significantly decreased in CLP ＋ ghrelin group （both P〈0. 05）. There were no significant differences in theneurological scores and the levels of TNF-α and IL-6 between sham operation group and sham ＋ ghrelin group （all P〈0. 05）. In CLP group, the obvious denaturation, necrosis, loss and loosen arrangement of neuron in hippocampus appeared, nuclear pyknosis happened in some neurons, and the amount of Nissl＇s body was significantly decreased. These changes became weak in CLP ＋ ghrelin group. Conclusion Ghrelin has a protective effect on brain function of septic encephalopathic rats. It may be associated with the down-regulation of inflammatory cytokines and the reduction of neuron loss in hippocampus. （Shanghai Med J, 2012, 35-298-301）