氯化甲基汞对发育阶段大鼠小脑转录因子CREB DNA结合活性的影响

The effect of methylmercury chloride on DNA binding activities of transcription factor, cAMP responsible element binding protein, of nuclearprotein extracts from cerebella of developing rats

目的 :探讨氯化甲基汞 ( MMC)对发育大鼠小脑组织转录因子 CREB DNA结合活性的影响。方法 :将妊娠大鼠于妊娠 7～ 1 0 d连续 4d每日灌胃给予氯化甲基汞 4mg· kg-1,取生后 1、3、7、1 4d大鼠小脑组织提取核蛋白。采用凝胶移位法观察 MMC对发育阶段大鼠小脑转录因子CREB DNA结合活性的影响。结果 :对照组和实验组各发育阶段小脑组织 CREB在凝胶移位电泳中均呈现两条迟滞带 ;对照组和实验组 P1 - 7大鼠幼仔小脑 CREB DNA结合活性随生后发育时间延长呈下降趋势 ;实验组大鼠幼仔小脑 CREB DNA结合活性均高于相应对照组。结论 :CREB参与大鼠脑发育的调节 ;甲基汞所致发育脑组织损伤可能与其引起 CREB DNA结合活性升高有关。

Objective: To study on the effects of methylmercury chloride (MMC) on DNA binding activities of transcription factor,cAMP responsible element binding (CREB) protein, in cerebella of developing rat. Methods: Sinse 7 th day 50 pregnant rats were daily received 4 mg·kg -1 . bw of MMC through intragastric infusion until 10 th days in tested groups and salt solution were given in control groups. Then killed the mice at 1 st ,3 rd ,7 th and 14 th postnatal day,respectively,isolated cerebella and extracted cerebella nuclear protein. The CREB DNA binding activity of cerebella nuclear protein extracts were done with electrophoretic mobility shift assays(EMSAs).Results: The binding activity of CREB in nuclei of rat cerebella to CREB probe showed two bands on gel shifts in both control and experiment groups. A decreasing tendency appeared in amount of CREB from rat cerebella of normal control group as postnatal time went on from P1(postnatal day) to P7. CREB DNA binding activity of tested animals at different developing time was higher than that in control groups. Conclusion: CREB from rat brain tissue involved in brain development process.Elevation of CREB binding activity from rat cerebellar exposed to MMC might be the key molecular mechanism of MMC damage of the developing brains.