Cellular Targets of Nitric Oxide in the Hippocampus
Cellular Targets of Nitric Oxide in the Hippocampus
复制标题
DOI：
10.1371/journal.pone.0057292
复制
发表时间：
2013-02-25
期刊：
影响因子：
3.7
通讯作者：
Garthwaite, John
中科院分区：
文献类型：
--
作者：
Bartus, Katalin;Pigott, Beatrice;Garthwaite, John
在海马中，如同在许多其他CNS区域中一样，一氧化氮（NO）参与突触可塑性，表现为突触前和/或突触后功能的变化。虽然已知这些变化是由鸟苷酸环化酶偶联的NO受体激活后的cGMP引起的，但试图通过免疫细胞化学在海马切片中定位cGMP以响应NO的尝试未能检测到预期的cGMP升高，即在锥体神经元中。相反，据报道，星形胶质细胞，未鉴定的静脉曲张纤维和GABA能神经末梢是突出的NO靶点，提高了NO通过其他细胞间接作用的可能性。我们已经重新研究了分布的cGMP产生的内源性和外源性NO在海马切片使用免疫组化和新的条件，旨在优化cGMP的积累，因此，其可检测性。这些条件包括使用来自发育中的大鼠海马的组织，磷酸二酯酶-2的有效抑制剂和NO-受体鸟苷酸环化酶的变构增强剂。在这些条件下，cGMP形成响应内源性NO，并被发现在一个人口的锥体细胞胞体在CA 3区和下托，以及在前面描述的结构。外源性NO的额外存在导致海马cGMP达到脑组织记录的最高水平（1700 pmol/mg蛋白质），并在整个锥体细胞层的cGMP免疫标记。轴突和中间神经元的群体也被染色。根据这些结果，免疫组化的共同NO受体β 1-亚基表明广泛的表达。然而，先前在海马和其他地方使用的抗体对α 1亚基的类似染色模式被证明是人为的。结果表明，在海马NO的目标是更多样和广泛的比以前的证据表明，特别是，锥体神经元参与NO依赖的突触可塑性是直接的NO目标。
In the hippocampus, as in many other CNS areas, nitric oxide (NO) participates in synaptic plasticity, manifested as changes in pre- and/or postsynaptic function. While it is known that these changes are brought about by cGMP following activation of guanylyl cyclase-coupled NO receptors attempts to locate cGMP by immunocytochemistry in hippocampal slices in response to NO have failed to detect the cGMP elevation where expected, i.e. in the pyramidal neurones. Instead, astrocytes, unidentified varicose fibres and GABA-ergic nerve terminals are reported to be the prominent NO targets, raising the possibility that NO acts indirectly via other cells. We have re-investigated the distribution of cGMP generated in response to endogenous and exogenous NO in hippocampal slices using immunohistochemistry and new conditions designed to optimise cGMP accumulation and, hence, its detectability. The conditions included use of tissue from the developing rat hippocampus, a potent inhibitor of phosphodiesterase-2, and an allosteric enhancer of the NO-receptive guanylyl cyclase. Under these conditions, cGMP was formed in response to endogenous NO and was found in a population of pyramidal cell somata in area CA3 and subiculum as well as in structures described previously. The additional presence of exogenous NO resulted in hippocampal cGMP reaching the highest level recorded for brain tissue (1700 pmol/mg protein) and in cGMP immunolabelling throughout the pyramidal cell layer. Populations of axons and interneurones were also stained. According with these results, immunohistochemistry for the common NO receptor beta 1-subunit indicated widespread expression. A similar staining pattern for the alpha 1-subunit with an antibody used previously in the hippocampus and elsewhere, however, proved to be artefactual. The results indicate that the targets of NO in the hippocampus are more varied and extensive than previous evidence had suggested and, in particular, that the pyramidal neurones participating in NO-dependent synaptic plasticity are direct NO targets.