NITRIC-OXIDE SYNTHASE IN THE VISUAL-CORTEX OF MONOCULAR MONKEYS AS REVEALED BY LIGHT AND ELECTRON-MICROSCOPIC IMMUNOCYTOCHEMISTRY
NITRIC-OXIDE SYNTHASE IN THE VISUAL-CORTEX OF MONOCULAR MONKEYS AS REVEALED BY LIGHT AND ELECTRON-MICROSCOPIC IMMUNOCYTOCHEMISTRY
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DOI：
10.1016/0006-8993(93)90275-r
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发表时间：
1993-08-20
期刊：
影响因子：
2.9
通讯作者：
GO, CG
中科院分区：
文献类型：
--
作者：
AOKI, C;FENSTEMAKER, S;GO, CG
最近的研究表明，一氧化氮(NO)可以通过改变激活的突触强度和调节局部脑血流而在神经元兴奋性中发挥重要作用。我们试图确定一氧化氮合酶(NOS)的水平是否反过来也可以受到神经活动的调节。结果显示，在单眼猕猴皮质V1区，剥夺眼优势柱的4C神经纤维层中的NOS免疫反应较紧邻的非剥夺柱减弱。对4C板层的进一步观察表明，柱间NOS免疫反应的差异并不反映NOS标记的核周膜的分布差异，因为在单眼或正常双眼猕猴的4C板层中，NOS免疫反应的神经元相对较少。电子显微镜显示，4C板层内大多数(80%)的NOS免疫反应是轴突终末。也有一氧化氮合酶免疫反应阳性的棘突和树突，但在浅层更常见。为了确定4C神经纤维层的柱间差异是否对应于浅层一氧化氮合酶细胞密度的变化，我们进行了一系列的定量分析。在浅层中，一氧化氮合酶细胞分为两类：少数较大且呈强烈的一氧化氮合酶免疫反应，较多的(约24倍)较小但呈轻度免疫反应。对横跨2-3层的40微米厚的切面上的559个小的和105个大的一氧化氮合酶免疫反应细胞的分布分析表明，对于被剥夺的(较浅的)和未被剥夺的(较深的)斑块，与每个斑点相关的细胞(大的和小的)的数量大约是14个。这些单元格从柱的中心到外围均匀分布。对颗粒下层一氧化氮合酶细胞分布的分析也没有发现任何柱状差异。这些观察结果表明，局部神经活动可能通过改变神经元远端轴突内的NOS蛋白水平而与NO的释放相耦合。这一机制可能与一氧化氮合酶更瞬时的催化激活一起起作用。超微结构分析进一步表明，NO除了可能作为树突起的逆行信使外，还可能作为终末的顺行和逆行信使。
Recent results indicate that nitric oxide (NO) can play an important role in neuronal excitability by modifying the strength of activated synapses and regulating local cerebral blood flow. We sought to determine whether the level of NO synthase (NOS) could, in turn, also be regulated by neural activity. Results using a polyclonal anti-NOS antibody showed that, in cortical area V1 of monocular monkeys, NOS-immunoreactivity is diminished in lamina 4C neuropil of the deprived ocular dominance columns relative to the immediately adjacent non-deprived columns. Closer examination of lamina 4C indicated that the intercolumnar difference in NOS-immunoreactivity does not reflect differences in the distribution of NOS-labeled perikarya, since relatively few neurons were immunoreactive for NOS in lamina 4C of either monocular or normal binocular monkeys. Electron microscopy revealed that the majority ( > 80%) of NOS-immunoreactive profiles in lamina 4C are axon terminals. NOS-immunoreactive spines and dendritic shafts also are present but these are more prevalent in the superficial laminae. In order to determine whether the intercolumnar differences in lamina 4C neuropil correspond to altered densities of NOS cells in the superficial laminae, we performed a series of quantitative analyses. In the superficial laminae, NOS-cells occur as two distinguishable classes: a few that are large and intensely NOS-immunoreactive and many more (ca. 24-fold) that are small and lightly immunoreactive. Analysis of the distribution of 559 small and 105 large NOS-immunoreactive cells within 40-mum-thick tangential sections spanning laminae 2-3 showed that the number of cells (large and small together) associated with each blob is approximately 14 for both deprived (lighter) and non-deprived (darker) blobs. These cells are distributed evenly from the center to periphery of columns. Analysis of the distribution of NOS-cells in the infragranular laminae also did not reveal any columnar differences. These observations suggest that local neural activity may be coupled to NO release via alteration of NOS protein levels specifically within distal axonal processes of neurons. This mechanism could operate in conjunction with the more instantaneous catalytic activation of NOS. Ultrastructural analyses further suggest that NO may act as an anterograde and retrograde messenger arising from terminals in addition to its proposed role as a retrograde messenger arising from dendrites.