Effects Of Ah R And ARNT2 On BDNF Transcriptional Changes In Brain Induced By Prenatal Benzo [a] Pyrene Exposure In Rat

Objective:To study the effect of B[a]P exposure during pregnancy on the interaction between transcription factor AHR and Arnt2 and the role of heterodimer AHR-Arnt2 in BDNF gene transcription.Methods:120 3-month-old SD rats were purchased,which including male and female(1:1).Next,pregnant rats were randomly divided into five groups: blank groups,olive oil,10,20 and 40mg/kg group.Each group contained 12 rats.They were intraperitoneally injected with corresponding dose B[a]P 17~19 days after conception.Westernbloting was used to detect the expression of AhR protein in the cerebral cortex of children of all ages.Protein co-immunoprecipitation method was used to determine the interaction between AhR and ARNT2 in cortical mice of different ages.Chromatin immunoprecipitation combined with PCR was used to determine the binding of AhRARNT2 to BDNF promoter in cortical mice of different ages.RT-PCR was used to determine the expression of BDNF m RNA in the cortex of children of different ages.Result:1.In PND1 and PND14,the AhR expression of 40mg/kg was higher contrast to blank group by westernblot.In PND7,the 20mg/kg,40mg/kg group AhR expression growth contract to blank group(P(27)0.05).These results indicate that B[a]P exposure during pregnancy can increase the expression of AhR in the cerebral cortex of early birth rats.2.The results of protein immunoprecipitation assay showed that the interaction between AhR and ARNT2 in the cortex of PND1 and PND7 mice was enhanced in the 20mg/kg and 40mg/kg groups(P(27)0.05).In PND14,the AhR-ARNT2 interaction was enhanced in the 20mg/kg group but was not statistically significant.These results indicated that B[a]P exposure during the early development of the cortex of rats resulted in enhanced levels of AhR-ARNT2 interaction.3.Chromatin immunoprecipitation-PCR results showed that binding of BDNF transcriptome 1 promoter to AhR-ARNT2 was increased in PND1,20mg/kg and40mg/kg groups(P(27)0.05).In PND7,BDNF transcript promoter 1 binding to AhRARNT2 increased in 20mg/kg group(P(27)0.05).4.RT-PCR results showed that BDNF m RNA expression was decreased in PND140mg/kg groups(P(27)0.05).In PND7,the 20mg/kg and 40mg/kg groups BDNF m RNA expression were lower(P(27)0.05).It is suggested that the binding of AhRARNT2 dimer to BDNF promoter may lead to the decrease of BDNF m RNA expression.Conclusion:1.Exposure to B[a]P during pregnancy increased the expression of AhR in the cortex of offspring rats.2.B[a]P exposure during pregnancy enhanced AhR-Arnt2 interaction.3.Heterodimer AhR-ARNT2 binds to the BDNF promoter,resulting in a decrease in the transcription function of BDNF gene.