持续惊厥后不同年龄大鼠海马凋亡调控基因表达的变化

Differences of apoptotic-regulating gene expression in the hippocampus in rats with different ages after status convulsion

摘要:

目的：比较惊厥持续状态（SC）后不同年龄大鼠海马凋亡调控基因 bcl-2 和 c-Jun 表达的变化，探索未成熟脑耐受惊厥性脑损伤的分子基础。方法：制作幼年和成年 Wistar大鼠 SC 模型，同时设置正常对照组和实验对照组，每组 8 只。于 SC 后3 h，6 h，12 h，1 d，3 d和7 d分别处死动物，免疫组化、原位杂交和 RT-PCR 测定海马 bcl-2 和 c-Jun 蛋白及mRNA的表达。结果：SC 后幼年组和成年组海马 c-Jun 蛋白表达均升高，SC 后 6 h 达高峰，显著高于正常对照组（P<0.01），12 h 后开始回落。幼年 SC 组 c-Jun 蛋白表达于 SC 后 1 d 已降至幼年正常对照组水平，而成年 SC 组直至 SC 后 7 d 仍显著高于成年正常对照组（P<0.05）。SC 后 6 h，12 h，1 d，3 d和 7 d 成年 SC 组 c-Jun 蛋白表达均显著高于幼年 SC 组（P<0.05）。SC 后幼年组和成年组海马 c-Jun mRNA 的表达与其蛋白表达规律类似。SC 后幼年组和成年组海马 bcl-2 蛋白及mRNA表达升高不明显。结论：SC诱导海马凋亡促进基因 c-Jun 表达增高，幼年鼠较成年鼠表达明显为弱，且持续时间短，这可能是未成熟脑抵抗惊厥性脑损伤的机制之一。SC 未能明显诱发凋亡抑制基因 bcl-2 的强表达，其表达受年龄影响小。

Abstract:

OBJECTIVE: To explore the molecular mechanism of brain protection against convulsive brain damage in premature brains by observing the changes of apoptotic-regulating genes of bcl-2 and c-Jun expression in the hippocampus in Wistar rats with different ages after status convulsion (SC). METHODS: SC was induced in infant Wistar rats (IRs) and adult Wistar rats (ARs) by intraperitoneal injection of lithium-pilocarpine. The rats were sacrificed at 3 hrs, 6 hrs, 12 hrs, 1 day, 3 days and 7 days after SC (n=8). Bcl-2 and c-Jun protein and mRNA levels were measured using immunocytochemistry, RT-PCR and in situ hybridization. RESULTS: c-Jun protein levels increased significantly at 3 hrs and reached the peak at 6 hrs after SC in both IRs and ARs compared to those in the normal control group (P<0.01). c-Jun protein levels started to decrease 12 hrs after SC in both IRs and ARs. The expression of c-Jun protein in IRs returned to the basal level 1 day after SC, while remained higher in ARs than in the normal control group by 7 days after SC. The expression of c-Jun protein in ARs was much higher than that in IRs from 6 hrs to 7 days after SC (P<0.05). c-Jun mRNA level was in parallel with the protein level as mentioned in IRs and ARs after SC. There were no changes observed in both bcl-2 protein and bcl-2 mRNA levels after SC in IRs and ARs. CONCLUSIONS: SC may induce an up-regulation of proapoptotic gene c-Jun in the hippocampus after SC, with a less strong extent and shorter duration in IRs compared to that in ARs. This might be one mechanism of brain protection against convulsive brain damage in IRs. The expression of bcl-2 remains unchanged after SC and is not affected by age in both IRs and ARs.