Marmigère Frédéric, Rage Florence, Tapia-Arancibia Lucia
Laboratoire de Plasticité Cérébrale, UMR 5102 CNRS, Université Montpellier 2, CC 090, Place Eugène Bataillon, France.
Neurochem Int. 2003 Mar;42(4):353-8. doi: 10.1016/s0197-0186(02)00100-6.
Brain derived-neurotrophic factor (BDNF) belongs to the neurotrophin family and regulates the survival, differentiation and maintenance of function in different neuronal populations. We previously reported that glutamate increases the expression of BDNF mRNA, its four transcripts and the BDNF peptide in fetal hypothalamic neurons, essentially through NMDA receptor activation. In the present study, we investigated whether GABA interacts with glutamate in the regulation of BDNF gene expression. BDNF and Trk B (BDNF receptor) mRNAs were determined by RNAse protection assay. BDNF transcripts expression levels were evaluated by semi-quantitative RT-PCR. BDNF peptide content was analyzed by enzyme immunoassay (ELISA).We found that picrotoxin (a GABA(A) receptor antagonist) stimulated BDNF mRNA expression and that GABA decreased the glutamate-induced augmentation with no effect on the expression of mRNA encoding the BDNF receptor, Trk B. Measurements of BDNF transcripts levels showed that transcripts containing exons I and III were increased by picrotoxin, whereas those containing exons II and IV were unchanged. GABA solely diminished the glutamate-stimulated expression of transcripts containing exon III. In addition, GABA also inhibited the stimulatory effect of glutamate on BDNF peptide content. Our findings show an interaction between glutamate and GABA on BDNF expression (mRNA, transcripts and peptide) in fetal hypothalamic neurons.
脑源性神经营养因子（BDNF）属于神经营养因子家族，可调节不同神经元群体的存活、分化和功能维持。我们之前报道过，谷氨酸主要通过NMDA受体激活来增加胎儿下丘脑神经元中BDNF mRNA、其四种转录本以及BDNF肽的表达。在本研究中，我们调查了γ-氨基丁酸（GABA）在BDNF基因表达调控中是否与谷氨酸相互作用。通过核糖核酸酶保护试验测定BDNF和Trk B（BDNF受体）mRNA。通过半定量逆转录聚合酶链反应（RT-PCR）评估BDNF转录本的表达水平。通过酶免疫测定法（ELISA）分析BDNF肽含量。我们发现印防己毒素（一种GABA(A)受体拮抗剂）刺激BDNF mRNA表达，而GABA可降低谷氨酸诱导的增加，且对编码BDNF受体Trk B的mRNA表达无影响。BDNF转录本水平的测量结果显示，含有外显子I和III的转录本因印防己毒素而增加，而含有外显子II和IV的转录本则未改变。GABA单独减弱了含有外显子III的转录本的谷氨酸刺激表达。此外，GABA还抑制了谷氨酸对BDNF肽含量的刺激作用。我们的研究结果表明，谷氨酸和GABA在胎儿下丘脑神经元的BDNF表达（mRNA、转录本和肽）上存在相互作用。
