溴氰菊酯染毒大鼠的脑组织中GCS亚单位和Nrf2表达的时间进程

Time course of gene expression of gamma-glutamylcysteine synthetase subunit and Nrf2 in brain tissues of rats exposed by deltamethrin

目的研究溴氰菊酯(DM)对大鼠大脑皮层和海马组织γ-谷氨酰半胱氨酸合成酶(GCS)轻亚单位(GCSl)和重亚单位(GCSh)mRNA表达,以及GCSh和转录因子NF-E2相关因子2(Nrf2)基因蛋白表达时间进程的影响。方法DM染毒组(DM12·50mg/kg bw)和溶剂对照组大鼠染毒1次,分别于大鼠染毒后不同时间点处死大鼠,分离皮层和海马。用逆转录聚合酶链式反应(RT-PCR)方法测定mRNA表达的相对量。联合用免疫组织化学方法和图像分析系统检测海马和大脑皮层中GCS重亚单位蛋白(GCS-HS)和Nrf2蛋白的水平。结果(1)DM染毒后第5h和第48h大鼠大脑皮层中GCSh mRNA相对水平分别降低至对照组的83·9%、86·0%(P<0·05),第5h、24h和48h Nrf2mRNA分别增高至0h对照组的146·4%、145·2%和147·9%(P<0·05)。(2)DM染毒后第5h和24h海马中GCSh mRNA相对水平分别增高至0h对照组的118·4%、118·4%(P<0·05),第5h海马中GCSl mRNA比0h对照组、24h和48h组均高,增高至对照组的121·4%(P<0·05)。DM染毒后各时间点海马Nrf2mRNA水平未见明显的变化(P>0·05)。(3)DM染毒后海马不同分区(CA1、CA2、CA3和齿状回)和大脑皮层中的GCS催化亚单位(GCS-HS)和转录因子Nrf2蛋白水平均未见明显改变。结论本实验条件下DM染毒后,大鼠海马GCSh和GCSl mRNA基因表达出现上调,而脑皮层GCSh基因表达出现下调,Nrf2mRNA水平表达出现上调,但海马和皮层组织中的GCS-HS和Nrf2蛋白水平未见显著变化。

Objective To investigate the time course of mRNA expression of gamma- glutamylcysteine synthetase light （GCSI） and heavy subunit （GCSh）, as well as protein expression of both GCSh and NF-E2 related factor 2 （Nrf2） in cerebral cortex and hippocampus in rats exposed at single dose of deltamethrin （DM）. Methods Wistar male rats were exposed at single dose of DM （12.50mg/kg bw） with i.p. At various time points of post-exposure, the rats were sacrificed at indicated time, then their cerebral cortex and hippocampus were isolated. The relative amount of mRNA expression of these genes was measured by the method of reverse transcription polymerase chain reaction （RT-PCR）. The protein level was detected by the method of immunohistochemistry and image analysis system. Results （1） At 5 and 48h after DM exposure, GCSh mRNA relative levels in cerebral cortex in rats were significantly decreased to 83.9 % and 86.0 % of mRNA level of corresponding tissue of control group at Oh, respectively （P 〈 0.05）. At 5,24 and 48h after DM exposure, transcriptional factors Nrf2 mRNA relative levels were more higher than those of both control and 72h group and increased to 146.4%, 145.2% and 147.9% of those of control group at Oh, respectively（ P 〈 0.05）. （2） At 5 and 48h after DM exposure,GCSh mRNA relative levels in hippocampus were significantly increased to118.4% and 118.4% of those of control group at Oh, respectively（ P 〈 0.05 ）. At 5h after DM exposure, GCSI mRNA relative levels in hippocampus were more higher than those of control,24h and 48h group and increased to 121.4% of those of control group at Oh（ P 〈 0.05）. Conclusion After single dose of DM exposure, there are up-regulation of mRNA expression of both GCSh and GCSI gene in rats hippocampus, down-regulation of mRNA expression of GCSh gene and up-regulation of mRNA expression of Nrf2 gene in rats cerebral cortex under the experimental condition.