Gabbott P L, Bacon S J
University Department of Pharmacology, Oxford, U.K.
Neuroscience. 1994 May;60(2):417-40. doi: 10.1016/0306-4522(94)90254-2.
This study investigated the morphology and quantitative distribution of neurons containing NADPH diaphorase activity in the ventral lateral geniculate nucleus of the rat. The pattern of diaphorase staining revealed a strongly reactive lateral subdivision and a weakly staining medial subdivision. A characteristic feature of the diaphorase staining in the lateral part was its "stripe-like" appearance. These "diaphorase stripes" resulted from regions of strong somatic and neuropil diaphorase activity lying between unstained fibre bundles coursing dorsoventrally through the nucleus. Two distinct populations of diaphorase reactive cell types were present--class A and class B neurons. The ratio of class A to class B diaphorase neurons was approximately 14:1 (A:B). Diaphorase reactive neurons made up 73% of the total neuron population in the lateral subdivision, and 31% in the medial subdivision. A third population of cells was found exclusively in the optic tract--class C neurons. Quantitative analyses in the coronal and sagittal planes indicated that the principal processes of both class A and class B neurons were oriented preferentially--either parallel with, or perpendicular to the outlying optic tract. Diaphorase enzyme histochemistry in combination with GABA immunocytochemistry demonstrated the co-localization of GABA immunoreactivity in the majority of class B neurons, whereas class A and class C neurons were GABA immunonegative. Furthermore a large population of GABA-immunoreactive neurons was present that were not stained for diaphorase activity. From this and previous studies, it can be concluded that a high proportion of the diaphorase reaction class A neurons are geniculotectal projection cells, while diaphorase reaction class B neurons represent a numerically small subpopulation of "local-circuit" inhibitory neurons. Since diaphorase activity co-localizes with nitric oxide synthase, the results indicate the likely involvement of nitric oxide in the neuronal operations of both subpopulations of geniculotectal projection neurons and "local-circuit" GABAergic neurons in the rat's ventral lateral geniculate nucleus.
本研究调查了大鼠腹外侧膝状核中含有NADPH黄递酶活性的神经元的形态和定量分布。黄递酶染色模式显示外侧亚区反应强烈，内侧亚区染色较弱。外侧部分黄递酶染色的一个特征是其“条纹状”外观。这些“黄递酶条纹”是由强烈的胞体和神经毡黄递酶活性区域形成的，这些区域位于贯穿细胞核背腹走行的未染色纤维束之间。存在两种不同的黄递酶反应性细胞类型——A类和B类神经元。A类与B类黄递酶神经元的比例约为14:1（A:B）。黄递酶反应性神经元在外侧亚区占神经元总数的73%，在内侧亚区占31%。发现第三类细胞仅存在于视束中——C类神经元。冠状面和矢状面的定量分析表明，A类和B类神经元的主要突起优先定向——要么与外侧视束平行，要么垂直于外侧视束。黄递酶酶组织化学与GABA免疫细胞化学相结合表明，大多数B类神经元中存在GABA免疫反应性共定位，而A类和C类神经元为GABA免疫阴性。此外，存在大量未被黄递酶活性染色的GABA免疫反应性神经元。从本研究及以往研究可以得出结论，黄递酶反应性A类神经元中很大一部分是膝状-顶盖投射细胞，而黄递酶反应性B类神经元代表数量较少的“局部回路”抑制性神经元亚群。由于黄递酶活性与一氧化氮合酶共定位，结果表明一氧化氮可能参与大鼠腹外侧膝状核中膝状-顶盖投射神经元和“局部回路”GABA能神经元这两个亚群的神经元活动。
