摘要:
为了明确内质网应激(endoplasmic reticulum stress,ERS)介导的凋亡在2,2’,4,4’-四溴联苯醚(2,2’,4,4’-tetrabromodiphenylether,PBDE-47)致大鼠神经毒性中的作用，在脑发育的突增期(出生第10天)，分别用0 mg·kg-1、1 mg·kg-1、5 mg·kg-1和10 mg·kg-1 PBDE-47进行单次灌胃染毒，并从出生第8天开始每天给予150 mg·kg-1 ERS抑制剂4-苯基丁酸(phenylbutyric acid,PBA)，持续3周。仔鼠出生第8周末，从对照组、10 mg·kg-1 PBDE-47处理组、150 mg·kg-1 PBA处理组和150 mg·kg-1 PBA+10 mg·kg-1 PBDE处理组中随机选取8只大鼠进行水迷宫实验。然后将所有动物断头处死，分离大鼠海马组织，观察其海马组织形态学改变、测定ERS标志分子(GRP78、IRE1和CHOP)和凋亡相关蛋白Cyt c的表达水平。结果显示，10 mg·kg-1 PBDE-47处理可导致雌性大鼠海马CA4区细胞排列紊乱、锥形神经细胞数量减少甚至消失，尼氏小体数量减少，大鼠逃避潜伏期延长(P<0.05)。5和10 mg·kg-1 PBDE-47处理可显著上调ERS相关蛋白IRE1和CHOP的表达水平(P<0.05)，并明显增强海马组织凋亡相关蛋白Cyt c的表达。PBA干预可明显降低PBDE-47诱导的IRE1和CHOP以及Cyt c蛋白的表达水平，提示PBDE-47可通过ERS介导凋亡，导致大鼠海马组织损伤，从而影响大鼠学习记忆功能。
Abstract:
To investigate the roles of endoplasmic reticulum stress mediated apoptosis in neurotoxicity of SD rats induced by 2,2',4,4'-tetrabromodiphenylether (PBDE-47), 60 neonatal female Sprague-Dawley rats were randomly divided into 6 groups, and 2 groups of them were injected by intraperitoneal two times a day to give 4-phenylbutyric acid (PBA), an inhibitor of endoplasmic reticulum stress, for a total dose of 150 mg·kg-1 continued for 3 weeks from the eighth day after birth. At the tenth day, they were administered with 0 and 10 mg·kg-1 PBDE-47 in single gavage respectively. Similarly, animals in the other 4 groups received 0 mg·kg-1, 1 mg·kg-1, 5 mg·kg-1 and 10 mg·kg-1 PBDE-47 respectively. At the eighth weekend, 8 rats in Control, 10 mg·kg-1 PBDE-47 group, 150 mg·kg-1 PBA group, and 150 mg·kg-1 PBA+ 10 mg·kg-1 PBDE-47 group were administrated Morris water maze experiment to test their spatial learning and memory ability. Then all animals were sacrificed and hippocampus were isolated. HE staining was observed in hippocampus, the apoptosis levels and ERS markers (GRP78, IRE1 and CHOP) expression levels in hippocampus were observed with Western blooting. The results of Morris water maze experiment showed that 10 mg·kg-1 PBDE-47 damaged the learning and memory ability, and the PBDE-47 exposed group needed more time and longer distance to find the platform (P<0.05). Histology detection found that PBDE-47 caused the disordered arrangement of the cells in hippocampal CA3 region, the decrease and even disappearing of deeply stained conical neurons and the reduction of Nissl body. The protein expression levels of Cyt c, IRE1 and CHOP were significantly increased in the 5 and 10 mg·kg-1 PBDE-47 groups as compared to control. Moreover, PBA ameliorated the increase expression of ERS relative proteins, and the level of cell apoptosis were decreased evidently. Collectively, these results approve that PBDE-47 could damage the hippocampal neuron and disturb the learning and memory ability through the endoplasmic reticulum mediated apoptosis.
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