GABA- and glutamate-immunoreactive synapses on sympathetic preganglionic neurons projecting to the superior cervical ganglion
GABA- and glutamate-immunoreactive synapses on sympathetic preganglionic neurons projecting to the superior cervical ganglion
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DOI：
10.1016/s0165-1838(98)00069-1
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发表时间：
1998-07-15
期刊：
影响因子：
--
通讯作者：
Minson, JB
中科院分区：
文献类型：
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作者：
Llewellyn-Smith, IJ;Arnolda, LF;Minson, JB
我们以前的工作表明，投射到大鼠肾上腺髓质的交感节前神经元上的几乎所有突触都对抑制性氨基酸γ-氨基丁酸和兴奋性氨基酸L-谷氨酸呈免疫反应。为了研究其他组的交感节前神经元是否也是如此，并确定不同组的交感节前神经元包含每种类型的氨基酸神经递质的比例是否相同，我们对投射到颈上神经节的交感节前神经元进行了逆行标记，并在超薄切片上用免疫金包埋后对GABA和谷氨酸免疫反应进行了定位。大鼠和兔交感节前神经元投射到颈上神经节的胞体和树突与GABA免疫阳性神经纤维和谷氨酸免疫阳性神经纤维均有突触和直接接触。在大鼠，投射到颈上神经节的交感节前神经元的GABA阳性神经元占48.9%，谷氨酸阳性神经元占51.7%。在同一切片上对谷氨酸和GABA的双重免疫金标记法，以及对这两种抗原的连续连续切片的标记，表明GABA和谷氨酸存在于不同的神经纤维群中，这些神经纤维为投射到颈上神经节的交感节前神经元提供输入。我们现在已经证明，GABA或谷氨酸存在于投射到颈上神经节的交感节前神经元的几乎所有输入，以及几乎所有供应肾上腺髓质的交感节前神经元的输入。这些发现与中枢自主神经通路中所有快速突触传递可能由兴奋性或抑制性氨基酸介导的假说一致。此外，我们还发现投射到颈上神经节的交感节前神经元和交感肾上腺神经元之间谷氨酸免疫反应阳性神经元的比例有统计学差异(数据来自Llewell yn-Smith等人的数据)。[Llewell yn-Smith，I.J.，PhEND，K.D.，Minson，J.B.，Pilowsky，P.M.，Chalmers，J.P.，1992.大鼠胸段脊髓逆行标记交感神经元上的谷氨酸免疫反应突触。脑研究581，67-80])，节前电子学供应肾上腺髓质比供应颈上神经节的神经节前电子接收更多的兴奋性输入。这种对交感肾上腺神经元的兴奋性输入的增加可能解释了压力感受器卸载后这些神经元的主要激活。(C)1998 Elsevier Science B.V.保留所有权利。
Our previous work suggests that virtually all of the synapses on sympathetic preganglionic neurons projecting to the rat adrenal medulla are immunoreactive for either the inhibitory amino acid, gamma-aminobutyric acid (GABA) or the excitatory amino acid, L-glutamate. To investigate whether or not this is true for other groups of sympathetic preganglionic neurons, and to determine whether or not the proportion of inputs containing each type of amino acid neurotransmitter is the same for different groups of sympathetic preganglionic neurons, we retrogradely labelled rat and rabbit sympathetic preganglionic neurons projecting to the superior cervical ganglion and used post-embedding immunogold on ultrathin sections to localise GABA- and glutamate-immunoreactivity. The cell bodies and dendrites of both rat and rabbit sympathetic preganglionic neurons projecting to the superior cervical ganglion received synapses and direct contacts from nerve fibres immunoreactive for GABA and from nerve fibres immunoreactive for glutamate. In the rat, GABA was present in 48.9% of the inputs to sympathetic preganglionic neurons projecting to the superior cervical ganglion, and glutamate was present in 51.7% of inputs. Double immunogold labelling for glutamate and GABA on the same section, as well as labelling of consecutive serial sections for the two antigens, indicated that GABA and glutamate occur in separate populations of nerve fibres that provide input to rat sympathetic preganglionic neurons projecting to the superior cervical ganglion. We now have shown that GABA or glutamate is present in virtually all of the inputs to sympathetic preganglionic neurons projecting to the superior cervical ganglion and in essentially all of the inputs to sympathetic preganglionic neurons supplying the adrenal medulla. These findings are consistent with the hypothesis that all fast synaptic transmission in central autonomic pathways may be mediated by either excitatory or inhibitory amino acids. Furthermore, we showed a statistically significant difference in the proportion of glutamate-immunoreactive inputs between sympathetic preganglionic neurons projecting to the superior cervical ganglion and sympathoadrenal neurons (data from Llewellyn-Smith et al. [Llewellyn-Smith, I.J., Phend, K.D., Minson, J.B., Pilowsky, P.M., Chalmers, J.P., 1992. Glutamate immunoreactive synapses on retrogradely labelled sympathetic neurons in rat thoracic spinal cord. Brain Res. 581, 67-80]), with preganglionics supplying the adrenal medulla receiving more excitatory inputs than those supplying the superior cervical ganglion. This increased excitatory input to sympathoadrenal neurons may explain the predominant activation of these neurons following baroreceptor unloading. (C) 1998 Elsevier Science B.V. All rights reserved.