Esclapez M, Houser C R
Brain Research Institute, University of California at Los Angeles, USA.
Neuroscience. 1995 Jan;64(2):339-55. doi: 10.1016/0306-4522(94)00406-u.
The distribution and extent of glutamate decarboxylase 65 (GAD65) mRNA-labeled neurons that coexpress pre-prosomatostatin mRNA were studied in the rat dentate gyrus of the dorsal and ventral hippocampal formation. The distribution of each group of neurons was determined initially by nonradioactive in situ hybridization experiments with digoxigenin-labeled riboprobes for GAD65 mRNA and pre-prosomatostatin mRNA. Double labeling experiments were then conducted with digoxigenin-labeled riboprobes for GAD65 mRNA and 35S-labeled riboprobes for pre-prosomatostatin mRNA. In the dorsal and ventral dentate gyrus, GAD65 mRNA-containing neurons were highly concentrated in the hilus and in the innermost part of the granule cell layer whereas only a few labeled neurons were scattered in the molecular layer. Pre-prosomatostatin mRNA-containing neurons were primarily located in the hilus and were virtually absent from the molecular and granule cell layers. The simultaneous detection of GAD65 and pre-prosomatostatin mRNAs in the same sections showed that the vast majority of pre-prosomatostatin mRNA-containing neurons in the hilus of the dentate gyrus were also labeled for GAD65 mRNA. In contrast many GAD65 mRNA-labeled neurons did not contain pre-prosomatostatin mRNA. These included all neurons in the molecular layer, neurons within the inner granule cell layer and neurons interspersed amongst double labeled neurons in the hilus. Quantitative analyses indicated that a very high percentage of hilar pre-prosomatostatin mRNA-containing neurons coexpressed GAD65 mRNA in the dorsal (96%) and ventral (92%) dentate gyrus. In contrast only a part of the total population of hilar GAD65 mRNA-containing neurons were also labeled for pre-prosomatostatin mRNA in the dorsal (43%) and ventral (53%) dentate gyrus. In the CA3c region, the percentages of neurons containing both mRNAs were similar to those observed in the hilus. The findings demonstrate that the vast majority of hilar somatostatin neurons, which have previously been shown to be extremely vulnerable to ischemia and seizure-induced damage, are GABA neurons. However, the total population of GAD65 mRNA-containing neurons in the hilus is substantially larger than the somatostatin-containing subgroup, and these findings reinforce the suggestion that GABA neurons are a major component of the diverse group of neurons in the hilus of the dentate gyrus.
在大鼠背侧和腹侧海马结构的齿状回中，研究了共表达前促生长抑素原mRNA的谷氨酸脱羧酶65（GAD65）mRNA标记神经元的分布和范围。首先通过用洋地黄毒苷标记的GAD65 mRNA和前促生长抑素原mRNA的核糖探针进行非放射性原位杂交实验，确定每组神经元的分布。然后用洋地黄毒苷标记的GAD65 mRNA核糖探针和35S标记的前促生长抑素原mRNA核糖探针进行双重标记实验。在背侧和腹侧齿状回中，含GAD65 mRNA的神经元高度集中在齿状回门和颗粒细胞层的最内层，而只有少数标记神经元散在于分子层。含前促生长抑素原mRNA的神经元主要位于齿状回门，分子层和颗粒细胞层几乎没有。在同一切片中同时检测GAD65和前促生长抑素原mRNA表明，齿状回门中绝大多数含前促生长抑素原mRNA的神经元也被标记为GAD65 mRNA。相反，许多GAD65 mRNA标记的神经元不含前促生长抑素原mRNA。这些包括分子层中的所有神经元、内颗粒细胞层内的神经元以及齿状回门中双重标记神经元之间散布的神经元。定量分析表明，在背侧（96%）和腹侧（92%）齿状回中，齿状回门中含前促生长抑素原mRNA的神经元中有非常高比例共表达GAD65 mRNA。相反，在背侧（43%）和腹侧（53%）齿状回中，齿状回门中含GAD65 mRNA的神经元总数中只有一部分也被标记为前促生长抑素原mRNA。在CA3c区域，含两种mRNA的神经元百分比与在齿状回门中观察到的相似。这些发现表明，绝大多数先前已证明极易受到缺血和癫痫诱导损伤的齿状回门生长抑素神经元是GABA能神经元。然而，齿状回门中含GAD65 mRNA的神经元总数明显大于含生长抑素的亚组，这些发现进一步支持了GABA能神经元是齿状回门中多种神经元主要组成部分的观点。
