Wynne B, Harvey A R, Robertson D, Sirinathsinghji D J
Department of Physiology, University of Western Australia, Nedlands, Perth, Australia.
J Chem Neuroanat. 1995 Dec;9(4):289-300. doi: 10.1016/0891-0618(95)00095-x.
This study was concerned with the distribution of a variety of putative neuromodulator and neurotransmitter systems in auditory regions of the rat brainstem using in situ hybridization histochemistry. Serial brain sections were screened for the presence of mRNAs for (i) precursors of the neuroactive substances cholecystokinin, somatostatin, proenkephalin and substance P (preprotachykinin), (ii) glutamic acid decarboxylase, the key synthesizing enzyme for GABA, or (iii) subunits alpha 1, alpha 2 and alpha 3 of the GABAA receptor. Detectable message for all of these probes was found in at least one auditory brainstem area. There were clear differences in the distribution of the various mRNAs in subregions of the inferior colliculus, superior olivary complex, lateral lemniscus and cochlear nucleus. Cells expressing mRNA for glutamic acid decarboxylase were most prominent in the inferior colliculus, but were also present in all lower auditory brainstem nuclei, except the medial superior olivary nucleus and medial nucleus of trapezoid body. The mRNA for GABAA alpha 1 receptor subunits was detectable in all auditory regions investigated, although at different levels of expression. GABAA alpha 2 and alpha 3 mRNA signals were seen in inferior colliculus, lateral lemniscus and in almost all superior olivary complex regions, but in fewer cells and at lower levels than the GABAA alpha 1 subtype. Moderate to high levels of preprocholecystokinin mRNA expression were seen in all subregions of the inferior colliculus. In other auditory brainstem areas, preprocholecystokinin mRNA levels were either low or absent. With regard to mRNAs for the neuroactive peptides somatostatin, preprotachykinin and preproenkephalin, all were expressed in the inferior colliculus but there were differences in their cellular distribution. For example, there were almost no preprotachykinin mRNA expressing cells in the central nucleus of inferior colliculus and levels of somatostatin mRNA were especially high in the dorsal cortex and in layer 3 of the external cortex of inferior colliculus. There were also differences in the pattern of expression of these mRNAs in the various brainstem auditory nuclei; there was no preprotachykinin mRNA in any part of the superior olivary complex, only somatostatin mRNA was found in the ventral cochlear nucleus, and expression of preproenkephalin mRNA was pronounced in the ventral nucleus of the trapezoid body and the rostral periolivary zone. The data are considered in light of the connectivity and functional organization of the auditory brainstem.
本研究利用原位杂交组织化学方法，关注大鼠脑干听觉区域中多种假定的神经调质和神经递质系统的分布。对系列脑切片进行筛查，以检测以下物质的mRNA的存在情况：(i) 神经活性物质胆囊收缩素、生长抑素、前脑啡肽和P物质（前速激肽原）的前体；(ii) 谷氨酸脱羧酶，即GABA的关键合成酶；或(iii) GABAA受体的α1、α2和α3亚基。在至少一个听觉脑干区域发现了所有这些探针的可检测信号。在下丘、上橄榄复合体、外侧丘系和耳蜗核的亚区域中，各种mRNA的分布存在明显差异。表达谷氨酸脱羧酶mRNA的细胞在下丘最为突出，但在所有较低级的听觉脑干核中也有存在，除了内侧上橄榄核和梯形体内侧核。在所有研究的听觉区域均能检测到GABAAα1受体亚基的mRNA，尽管表达水平不同。GABAAα2和α3 mRNA信号见于下丘、外侧丘系以及几乎所有上橄榄复合体区域，但与GABAAα1亚型相比，表达的细胞较少且水平较低。在下丘的所有亚区域均可见到中等至高水平的前胆囊收缩素原mRNA表达。在其他听觉脑干区域，前胆囊收缩素原mRNA水平要么较低，要么不存在。关于神经活性肽生长抑素、前速激肽原和前脑啡肽原的mRNA，它们均在下丘表达，但细胞分布存在差异。例如，下丘中央核中几乎没有表达前速激肽原mRNA的细胞，而生长抑素mRNA水平在背侧皮质和下丘外侧皮质第3层特别高。这些mRNA在各个脑干听觉核中的表达模式也存在差异；上橄榄复合体的任何部分均无前速激肽原mRNA，仅在腹侧耳蜗核中发现生长抑素mRNA，而前脑啡肽原mRNA在梯形体腹侧核和吻侧橄榄周区表达明显。根据听觉脑干的连接性和功能组织对这些数据进行了分析。
