4-苯基丁酸钠盐通过抑制内质网应激反应改善大鼠创伤性脑损伤

Sodium 4-phenylbutyrate ameliorates traumatic brain injury in rats by reducing endoplasmic reticulum stress

目的观察内质网应激相关蛋白葡萄糖调控蛋白78(GRP78)、磷酸化胰腺内质网激酶(p-PERK)和C/EBP同源蛋白(CHOP)在大鼠弥漫性脑创伤后的表达变化,探讨4-苯基丁酸钠盐(4-PBA)通过抑制内质网应激,减轻创伤后脑损伤(TBI)程度的机制。方法将90只雄性SD大鼠随机分为假手术(sham)组、TBI组和4-PBA组。Marmarou法建立SD大鼠中度弥漫性脑创伤模型;于伤后即刻腹腔注射4-PBA(120 mg/kg)每天1次,共3d。分别于伤后3、6、12、24、48和72 h处死大鼠,观察伤后24、48和72 h大鼠的神经行为表现;HE染色观察病理学改变;免疫组织化学法及Western blotting检测伤后不同时间点皮质区GRP78、p-PERK和CHOP蛋白的表达。结果4-PBA组大鼠脑创伤后的神经功能缺损明显改善,与TBI组相比差异具有统计学意义(P<0.05)。与Sham组相比,TBI组GRP78、p-PERK和CHOP蛋白表达明显升高(P<0.05),GRP78于伤后3 h增加,12 h达高峰,之后逐渐减少,72 h回落至基线水平;p-PERK于12 h达高峰(P<0.05);CHOP于24 h达高峰,48～72h回落,仍高于基线水平(P<0.05);4-PBA组GRP78、p-PERK与CHOP的表达均低于TBI组(P<0.05)。结论脑创伤后启动内质网应激反应,4-PBA对脑创伤大鼠具有脑保护作用,其机制之一是通过阻断内质网应激启动的PERK/CHOP途径而实现的。

Objective To investigate the expression of the endoplasmic reticulum stress-associated proteins glucose regulated protein 78 （GRP78） , phosphorylation pancreatic ER kinase （p-PERK） and C/EBP homologous protein （CHOP） in rats after traumatic brain injury （TBI）, and the mechanism of sodium 4-phenylbutyrate （4-PBA） on neuronal injury by reducing endoplasmic reticulum stress after TBI. Methods A total of 114 male Sprague-Dawley rats were randomly divided into 3 groups： the sham, TBI, TBI plus 4-PBA groups. A rat model of diffuse brain injury was established according to Marmarou＇ s falling model. The rats in 4-PBA group were treated with 4-PBA （ 120 mg/kg） i.p. immediately after TBI, once a day for 3 days. At 3, 6, 12, 24, 48 and 72 hours after injury, the brain tissue samples were prepared for examination of brain pathological changes, and determination of the expression of GRP78, p-PERK and CHOP, by means of immunohistochemistry and Western blotting. Behavioral tests were performed at 24, 48 and 72 hours after injury. Results Compared with the sham group, GRP78, p-PERK and CHOP were significantly increased in the TBIgroup. GRP78 began to increase at 3 hours after injury, peaked at the 12 hours, and then gradually returned to the basic level, p-PERK peaked at 12 hours, whereas, CHOP peaked at 24 hours, and then redueed at 48-72 hours, but still was higher than the basie level. At the corresponding times, compared with the TBI group, the expression of GRP78, p-PERK and CHOP decreased remarkably in the 4-PBA group（P 〈0.05）. The scores of behavioral test were significantly increased in 4-PBA group,compared with TBI group（ P 〈 0.05 ）. Conclusion Endoplasmic retieulum stress is started after traumatic brain injury in rats. 4-PBA has a proteetive effect on TBI, which may be related to inhibition of endoplasmic reticulum stress induced PERK/CHOP pathway.