Aliaga Esteban Enrique, Mendoza I, Tapia-Arancibia L
Departamento de Fisiología, Universidad de Valparaíso, Playa Ancha, Valparaiso, Chile.
J Neural Transm (Vienna). 2009 Jan;116(1):23-32. doi: 10.1007/s00702-008-0159-8. Epub 2008 Dec 11.
We investigated subcellular localization of total brain-derived neurotrophic factor (BDNF) mRNA (panBDNF) and its different 5' exon-specific transcripts in cultured hypothalamic neurons. Non-isotopic in situ hybridization (DIG-labeled exon-specific riboprobes) associated with immunocytochemical MAP2 or GFAP labeling was used for detection. We found that under basal conditions panBDNF mRNA was localized in neuronal soma and in primary dendritic processes. Transcripts I and II were weakly expressed in neuronal soma while transcripts IV and VI mRNA were strongly expressed. panBDNF mRNA and transcript VI mRNA were detected in proximal dendritic processes and in astrocytes. N-methyl-D: -aspartate (NMDA) treatment decreased the dendritic label of panBDNF and transcript VI mRNA. In contrast, MK-801 (NMDA antagonist) treatment extended the labeling of all the transcripts in dendrites while K(+) depolarization only extended the dendritic labeling of panBDNF and transcript VI mRNAs. These results suggest a NMDA-receptor dependent inhibitory mechanism for dendritic destination of BDNF transcripts in hypothalamic neurons.
我们研究了全脑源性神经营养因子（BDNF）mRNA（泛BDNF）及其不同5'外显子特异性转录本在培养的下丘脑神经元中的亚细胞定位。采用与免疫细胞化学MAP2或GFAP标记相关的非同位素原位杂交（地高辛标记的外显子特异性核糖探针）进行检测。我们发现，在基础条件下，泛BDNF mRNA定位于神经元胞体和初级树突状突起中。转录本I和II在神经元胞体中弱表达，而转录本IV和VI mRNA则强表达。在近端树突状突起和星形胶质细胞中检测到泛BDNF mRNA和转录本VI mRNA。N-甲基-D-天冬氨酸（NMDA）处理降低了泛BDNF和转录本VI mRNA的树突标记。相反，MK-801（NMDA拮抗剂）处理延长了所有转录本在树突中的标记，而K(+)去极化仅延长了泛BDNF和转录本VI mRNA的树突标记。这些结果表明，下丘脑神经元中BDNF转录本的树突定位存在一种NMDA受体依赖性抑制机制。
