Herman J P, Watson S J
Department of Anatomy and Neurobiology, University of Kentucky Medical Center, Lexington 40536-0084, USA.
Brain Res. 1995 Apr 24;677(2):243-9. doi: 10.1016/0006-8993(95)00152-g.
Localization and regulation of mineralocorticoid receptor (MR) heteronuclear RNA (hnRNA) was assessed in rat hippocampus using an intron-directed in situ hybridization approach. The presence of hnRNA in the cell nucleus reflects recent gene transcriptional events and can be used as an index of neuronal transcriptional activation or inhibition. In the present study, sections incubated with an MR intron probe labeled cells in all regions known to contain MR mRNA. Signal generated by the intron probe was localized specifically to the nuclear compartment, consistent with recognition of hnRNA. Analysis of distribution across hippocampus indicated that MR hnRNA was particularly abundant in dentate gyrus (DG). In contrast, MR mRNA shows similar levels of expression across all hippocampal subfields. Exposure of animals to acute restraint markedly reduced MR hnRNA levels in CA1 and DG 60 min and 120 min following stress exposure, consistent with reduced gene transcription. These data support the hypothesis that stress-induced glucocorticoid secretion can rapidly affect transcription of steroid receptor genes. MR mRNA levels did not decrease over comparable time periods, suggesting either a significant lag-time between transcriptional changes and changes in cytoplasmic mRNA pools or stimulus-driven alterations in post-transcriptional RNA processing.
采用内含子导向的原位杂交方法，在大鼠海马体中评估盐皮质激素受体（MR）异核核糖核酸（hnRNA）的定位与调控。细胞核中hnRNA的存在反映了近期的基因转录事件，可作为神经元转录激活或抑制的指标。在本研究中，用MR内含子探针孵育的切片标记了所有已知含有MR mRNA的区域中的细胞。内含子探针产生的信号特异性定位于核区室，这与hnRNA的识别一致。对海马体分布的分析表明，MR hnRNA在齿状回（DG）中特别丰富。相比之下，MR mRNA在所有海马亚区的表达水平相似。动物在急性束缚应激下，应激暴露60分钟和120分钟后，CA1和DG中的MR hnRNA水平显著降低，这与基因转录减少一致。这些数据支持以下假设：应激诱导的糖皮质激素分泌可迅速影响类固醇受体基因的转录。在相当的时间段内，MR mRNA水平并未下降，这表明转录变化与细胞质mRNA池变化之间存在显著的滞后时间，或者是转录后RNA加工过程中受刺激驱动的改变。
