Magnusson K R, Clements J R, Wu J Y, Beitz A J
Department of Veterinary Biology, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
Synapse. 1989;4(1):55-69. doi: 10.1002/syn.890040107.
It is proposed that taurine is an inhibitory neurotransmitter/neuromodulator in the CNS. The present study localized taurine-containing neurons within the rat hippocampus with the use of a monoclonal antibody against conjugated taurine (Tau2) in conjunction with an antiserum against cysteine sulfinic acid decarboxylase (CSADC), a synthesizing enzyme for taurine. Taurine-like immunoreactivity Tau-LI) and CSADC-LI were colocalized in neurons of the dentate gyrus, CA1(/CA2), CA3, and CA4. Of all the cells examined, pyramidal basket cells within the granule cell layer of the dentate gyrus were most intensely stained with both Tau2 and CSADC. Granule cells were also double-labeled with Tau-LI and CSADC-LI. Cell nuclei and dendrites in the CA1 region stained more intensely with Tau2 than somata. CSADC-LI was colocalized with Tau-LI within these neurons. Light staining with both Tau2 and the CSADC antiserum was inconsistently present in CA3 and CA4 neurons and was found to be highly dependent on the type of fixation and delay to fixation. Tau-LI was more consistently present in increased numbers of neurons in CA3 when glutaraldehyde was added to the paraformaldehyde fixative solution. Hippocampi which were immersion-fixed in paraformaldehyde following a 0-, 6-, or 24-hour postmortem delay exhibited a lack of Tau2 staining in the CA3 region in the majority of animals studied, similar to some paraformaldehyde perfusion-fixed rats. These studies suggest that taurine was present in the majority of neurons within the major cell layers of the rat hippocampus, but Tau-LI was more easily lost from neurons in the CA3 region following delay to fixation. The localization of Tau-LI in excitatory neurons such as granule cells and pyramidal cells is not consistent with its proposed inhibitory transmitter role. However, the prominent Tau2 staining in dendrites of the CA1 region provides anatomical support for the hypothesis that taurine may be released from dendrites in the CA1 region and may function as a neuromodulator of calcium flux in these pyramidal neurons.
有人提出，牛磺酸是中枢神经系统中的一种抑制性神经递质/神经调质。本研究使用抗共轭牛磺酸的单克隆抗体（Tau2）结合抗半胱氨酸亚磺酸脱羧酶（CSADC，牛磺酸的合成酶）的抗血清，对大鼠海马体内含牛磺酸的神经元进行定位。牛磺酸样免疫反应性（Tau-LI）和CSADC免疫反应性（CSADC-LI）共定位于齿状回、CA1（/CA2）、CA3和CA4的神经元中。在所有检查的细胞中，齿状回颗粒细胞层内的锥体细胞篮状细胞用Tau2和CSADC染色最深。颗粒细胞也用Tau-LI和CSADC-LI进行了双重标记。CA1区的细胞核和树突用Tau2染色比胞体更强烈。CSADC-LI与Tau-LI在这些神经元中共定位。在CA3和CA4神经元中，Tau2和CSADC抗血清的淡染色不一致，并且发现高度依赖于固定类型和固定延迟。当在多聚甲醛固定液中加入戊二醛时，CA3中数量增加的神经元中Tau-LI更一致地出现。在死后延迟0、6或24小时后用多聚甲醛浸泡固定的海马体，在大多数研究动物的CA3区缺乏Tau2染色，类似于一些多聚甲醛灌注固定的大鼠。这些研究表明，牛磺酸存在于大鼠海马体主要细胞层的大多数神经元中，但在固定延迟后，CA3区的神经元中Tau-LI更容易丢失。Tau-LI在颗粒细胞和锥体细胞等兴奋性神经元中的定位与其提出的抑制性递质作用不一致。然而，CA1区树突中显著的Tau2染色为牛磺酸可能从CA1区的树突中释放并可能作为这些锥体细胞中钙通量的神经调质这一假设提供了解剖学支持。
