Distribution of B-50(GAP-43) mRNA and protein in the normal adult human spinal cord

B-50(GAP-43) is a phosphoprotein mainly found in the nervous system which plays a major role in neurite growth during development and regeneration as well as in synaptic remodelling. In the mature intact central nervous system, intense B-50 immunoreactivity (B-50-IR) can still be detected in regions which maintain residual capacity for structural re-organization. B-50 expression has been studied extensively in laboratory animals; however, its distribution and regulation in the human spinal cord is largely unknown. As a first step to analyze lesion-induced structural alterations, we investigated the distribution of B-50 protein and mRNA in the normal adult human spinal cord and dorsal root ganglia. Intense B-50-IR was localized to the superficial laminae of the dorsal horn at all segmental levels, the intermediolateral nucleus at thoracic levels and Onuf’s nucleus at sacral levels. Scattered neurons, particularly in the ventral horn of lumbar and sacral segmental levels (and occasionally also in Clarke’s nucleus) displayed intense B-50-IR in close apposition to the perikaryal and proximal dendritic surfaces. Nonradioactive in situ hybridization indicated that B-50 mRNA could also be detected in neurons of the ventral horn and also in the intermediolateral nucleus. The distribution of B-50 mRNA and protein in the normal human spinal cord shows a marked similarity to that reported in experimental animals, including the selective labelling of Onuf’s nucleus. However, the strong B-50-IR on the surface of some large anterior horn motor neurons has not been observed in other mammals. This finding might reflect a particular state of readiness for synaptic plasticity. Received: 4 August 1997 / Accepted: 27 October 1997     

Distribution of enkephalin and its relation to serotonin in cat and monkey spinal cord and brain stem.

The distribution of enkephalin (ENK)-like immunoreactivity (LI) in spinal cord and medulla oblongata of cat and gray monkey (Macaca fascicularis) was studied by use of immunofluorescence and peroxidase antiperoxidase (PAP) techniques. Possible coexistence between ENK- and 5-hydroxytryptamine (5-HT)-LI was also analyzed with double labeling immunofluorescence. Furthermore, in situ hybridization was used to demonstrate cell bodies in the brain stem expressing mRNA encoding for ENK. ENK-immunoreactive (IR) axonal varicosities and fibers were demonstrated throughout the spinal cord gray matter, with the highest density in the superficial dorsal horn, the area around the central canal, the intermediolateral cell column, the sacral parasympathetic nucleus, and in Onuf's nucleus. In the monkey ventral horn, ENK-IR varicose fibers could in some cases be demonstrated in very close apposition to cell bodies. A low degree of co-localization between ENK- and 5-HT-LI was seen in the spinal cord of both species. Still, fibers containing both compounds could as a rule be demonstrated in every section studied. The highest degree of coexistence was encountered in the motor nucleus of the ventral horn. Six weeks after a low thoracic spinal cord transection a decreased staining for ENK-LI was demonstrated in the ventral horn motor nucleus, whereas other parts of the spinal cord appeared unaffected. In the brain stem of cats after colchicine treatment, ENK-LI was found in a majority of the 5-HT-IR cell bodies in the raphe nuclei (nucleus raphe magnus, pallidus and obscurus) and in the lateral reticular nucleus (rostroventrolateral reticular nucleus). In cat not pretreated with colchicine, a few weakly stained ENK-IR cell bodies could be found in the midline raphe nuclei and in the lateral reticular nucleus with the PAP technique. In the monkey brain stem without colchicine treatment, using the PAP technique, heavily stained ENK-IR cell bodies could be seen in the lateral reticular nucleus whereas, as in the cat, only a few, weakly stained ENK-IR cell bodies could be seen in the midline raphe nuclei. Using in situ hybridization technique, ENK mRNA expressing cells were demonstrated in the lateral reticular nucleus while no convincing mRNA signal could be found over cell bodies in the raphe nuclei. It is concluded that part of the ENKergic innervation of the cord in both species derives from supraspinal or suprasegmental levels.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cellular and Subcellular Distribution of NMDAR1 Splice Variant mRNA in the Rat Lumbar Spinal Cord

The regional distribution of alternatively spliced messenger RNA encoding the N -methyl-D-aspartate (NMDA) receptor R1 subunit (NMDAR1) variants was examined by in situ hybridization in the rat lumbar spinal cord. Splice-specific oligonucleotide probes [recognizing full-length mRNA (NMDAR1-1), deletion exon 21 (NMDAR1-2), deletion exon 22 (NMDAR1-3), combined deletion exons 21 and 22 (NMDAR1-4) and mRNA which lacks (NMDAR1-a) or contains exon 5 (NMDAR1-b)] detected marked differences in abundance and distribution of N- and C-terminal spliced variants. The NMDAR1-a, NMDAR1-2 and NMDAR1-4 mRNAs were evenly distributed throughout all laminae of the dorsal and ventral horns. In the superficial dorsal horn NMDAR1-b mRNA was preferentially detected in laminae II inner and III, while NMDAR1-1 mRNA was restricted to laminae I to III. Large neurons in laminae IV and V contained mainly NMDAR1-a, NMDAR1-2 and NMDAR1-4 mRNAs and occasionally NMDAR1-b. The NMDAR1-3 variant was only detected in very low abundance, being restricted to occasional cells in lamina I and II. In the ventral horn, motor neurons showed strong signals for NMDAR1-a, NMDAR1-b, NMDAR1-2 and NMDAR1-4 mRNAs. Serial sectioning through large motor neurons permitted the detection of multiple splice variants in single neurons. Analysis of the subcellular distribution of the mRNAs revealed that the NMDAR1-1 mRNA was almost exclusively found in the cell nucleus, NMDAR1-a mRNA was largely in the cytoplasm, while all other splice variants showed a homogeneous distribution between nucleus and cytoplasm. Comparison of the in situ hybridization images with functional analyses of heteromeric recombinant receptors will be necessary to ascertain whether splice variants of the NMDAR1 receptor subunit can account for some of the known electrophysiological properties of spinal cord neurons under physiological and pathophysiological conditions.