Polgár E, Furuta T, Kaneko T, Todd A
Spinal Cord Group, Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, Glasgow G12 8QQ, UK.
Neuroscience. 2006 May 12;139(2):687-97. doi: 10.1016/j.neuroscience.2005.12.021. Epub 2006 Jan 30.
Although it is established that neurokinin B is expressed by some neurons in laminae I-III of the rat spinal dorsal horn, little is known about the proportions of cells in these laminae that express neurokinin B, or whether these are excitatory or inhibitory neurons. Neurokinin B is derived from preprotachykinin B, and we have used an antibody against preprotachykinin B to address these issues. We found that preprotachykinin B-immunoreactive neurons were present throughout laminae I-III, constituting 10-11% of the neuronal population in laminae I-II, and 4% of that in lamina III. They formed a prominent band in the ventral half of lamina II (where they made up 16% of the population) and the dorsalmost part of lamina III. The great majority (99%) of preprotachykinin B-immunoreactive axonal boutons contained the vesicular glutamate transporter 2, while none contained glutamic acid decarboxylase. Since most of these boutons are likely to be derived from local preprotachykinin B-expressing cells, these observations suggest that most of the latter are excitatory interneurons. Although 9% of preprotachykinin B-labeled axonal varicosities were substance P-immunoreactive, none contained calcitonin gene-related peptide, which is consistent with reports that neurokinin B is not expressed by primary afferent axons. Many of the preprotachykinin B-immunoreactive cells contained compounds that are present in putative excitatory neurons in laminae I-III: calbindin (84%), protein kinase Cgamma (76%) or somatostatin (31%). However, there was little or no overlap between preprotachykinin B and three other markers associated with excitatory neurons in these laminae: the mu opioid receptor MOR-1, the neurokinin 1 receptor and neurotensin. These results suggest that neurokinin B is expressed by specific populations of excitatory neurons in the superficial dorsal horn. By examining expression of Fos protein in response to intraplantar injection of formaldehyde we provide evidence that many of the preprotachykinin B cells in lamina I and the outer part of lamina II respond to noxious stimulation.
虽然已确定神经激肽B在大鼠脊髓背角I - III层的一些神经元中表达，但对于这些层中表达神经激肽B的细胞比例，以及它们是兴奋性神经元还是抑制性神经元，人们了解甚少。神经激肽B源自前速激肽原B，我们使用了一种抗前速激肽原B的抗体来解决这些问题。我们发现，前速激肽原B免疫反应性神经元存在于整个I - III层，在I - II层中占神经元总数的10 - 11%，在III层中占4%。它们在II层腹侧半部（占该层细胞总数的16%）和III层最背侧部分形成一条明显的带。绝大多数（99%）前速激肽原B免疫反应性轴突终扣含有囊泡型谷氨酸转运体2，而无一含有谷氨酸脱羧酶。由于这些终扣大多可能源自局部表达前速激肽原B的细胞，这些观察结果表明，后者中的大多数是兴奋性中间神经元。虽然9%的前速激肽原B标记的轴突膨体是P物质免疫反应性的，但无一含有降钙素基因相关肽，这与神经激肽B不由初级传入轴突表达的报道一致。许多前速激肽原B免疫反应性细胞含有I - III层中假定的兴奋性神经元中存在的化合物：钙结合蛋白（84%）、蛋白激酶Cγ（76%）或生长抑素（31%）。然而，前速激肽原B与这些层中与兴奋性神经元相关的其他三种标记物之间几乎没有重叠：μ阿片受体MOR - 1、神经激肽1受体和神经降压素。这些结果表明，神经激肽B由浅背角中特定群体的兴奋性神经元表达。通过检查对足底注射甲醛的反应中Fos蛋白的表达，我们提供了证据表明I层和II层外侧部分的许多前速激肽原B细胞对有害刺激有反应。
