Neuromedin B and gastrin-releasing peptide mRNAs are differentially distributed in the rat nervous system.

The bombesin-like peptides are a family of structurally related amidated peptide ligands that are known to have a variety of potent pharmacological actions on various cells, including neurons in the rat brain. Two mammalian representatives of the bombesin family of peptides have been identified, gastrin-releasing peptide (GRP) and neuromedin B (NMB). Previously, we cloned the rat preproGRP gene and determined the locations of neurons expressing this gene using in situ hybridization. In this study, we describe the structure and sequence of the rat preproNMB gene, and the first detailed cellular localization of preproNMB mRNA in rat brain using in situ hybridization. Nucleotide sequence analysis of cDNA and genomic clones reveals a 117 amino acid precursor whose overall structure is similar to that described for human preproNMB. Sequence similarity between the rat NMB and GRP genes is observed only over a limited 10 amino acid sequence encoding the carboxy termini of the GRP and NMB peptides, the region shown to be necessary and sufficient for high-affinity receptor binding. In situ hybridization studies performed with cRNA probes specific for NMB or GRP mRNA show that the distribution of cells expressing either mRNA in brain is very distinct. NMB mRNA is found most prominently in the olfactory bulb, dentate gyrus, and dorsal root ganglion. In contrast, the highest levels of GRP mRNA are observed in the forebrain (isocortex and hippocampal formation). This heterogeneity of mRNA distribution for these peptides suggests that these 2 structurally related peptides may have very distinct functions as neuropeptides in the rat nervous system.

Neuron-specific expression of high-molecular-weight clathrin light chain.

High-molecular-weight forms of clathrin light chains LCa and LCb contain inserted sequences and are expressed in brain tissue but have not been observed in peripheral tissues. Monoclonal antibodies specific for the high-molecular-weight form of LCb and all forms of LCa were used to analyze their expression in different species and different neuronal cell types. High-molecular-weight light chains were found in bovine, rat, mouse, chicken, and human brain, indicating a conserved pattern of expression. Neuron-specific expression of the high-molecular-weight light chains was suggested by analysis of human brain gray matter and white matter. The former contained a higher proportion of light chains with insertion sequences. Immunohistochemical analysis localized the high-molecular-weight form of LCb to synapses and neuronal perikarya, but not to glial cells. Immunofluorescent labeling of cultured chicken dorsal root ganglia confirmed expression in neurons but not Schwann cells. These results indicate that the high-molecular-weight forms of clathrin light chains are restricted in expression and found in neuronal cells.

1B1075: a brain- and pituitary-specific mRNA that encodes a novel chromogranin/secretogranin-like component of intracellular vesicles.

The rat 1B1075 mRNA encodes a 533-residue novel chromogranin/secretogranin-like acidic protein that contains an apparent secretion signal, several pairs of tandem basic residues, and internally repeated sequence elements. 1B1075 transcripts are detected, by blotting and in situ hybridization, at the highest levels in the neocortex, hippocampus, cerebellar cortex, selected pontine and diencephalic nuclei, and presumptive pituitary corticotrophs, at lower levels in specific nuclei in most other brain regions, but in none of several other tissues. Utilizing antisera to several nonoverlapping synthetic peptide fragments of the predicted protein sequence, we detect a brain- and pituitary-specific 57-kDa protein in cellular processes and fiber tracts, generally consistent with axonal transport from the cell bodies identified by in situ hybridization. Ultrastructural studies demonstrate that this protein is a component of intraneuronal vesicles in axons and vesicle-like structures in dendrites. Based on these data, we suggest the name Secretogranin III for the 1B1075 gene product. In related collaborative studies, a mouse deleted for the 1B1075-homologous gene has been produced that should allow assessment of its physiological role.

Specialized localization of P-glycoprotein recognized by MRK 16 monoclonal antibody in endothelial cells of the brain and the spinal cord.

This communication describes the cellular and ultrastructural localization in the central nervous system of P-glycoprotein (P-GP) recognized by a murine monoclonal antibody, MRK 16. At the ultrastructural level P-GP was strictly confined to the luminal surface of the endothelial cells which comprise the capillary vessels of the brain and the spinal cord. No P-GP was found in the endothelial cells of other organs. Our findings may be useful as a means to define the blood-brain barrier, and they imply that the blood-brain barrier is anatomically characterized by the presence of intercellular tight junctions between continuous nonfenestrated endothelial cells.

An immunohistochemical study of the topography and cellular localization of three neural proteins in the sheep nervous system.

The peroxidase-anti-peroxidase (PAP) method was used to determine the topography and cellular localization of glial fibrillary acidic protein (GFAP), myelin basic protein (MBP) and carbonic anhydrase II (CAII) in the central nervous system (CNS), dorsal root ganglia and dorsal and ventral spinal nerve roots of the sheep. Parallel studies of mouse brain provided comparative data. Several fixatives were compared for their relative merits in preserving marker protein expression: GFAP was well preserved irrespective of the fixative employed; MBP was best preserved in formal sublimate and CAII was best preserved in Carnoy's fluid. In sheep, GFAP expression was seen in protoplasmic and fibrous astrocytes, Bergmann glial cells, a proportion of ependymal cells, amphicytes of spinal ganglia and in a proportion of presumed Schwann cells of dorsal and ventral spinal nerve roots. MBP expression was seen in mature and developing myelin sheaths of the central nervous system and in the cytoplasm of sparse myelinating oligodendroglia of the sub-cortical white matter of the cerebrum. CAII expression was seen in choroid plexus epithelium in all ages of sheep studied and, in a young lamb and an adult sheep, in glia and neuropil of ventral horn grey matter of the spinal cord and in the cytoplasm of white matter glia, presumed fibrous astrocytes, throughout the CNS. Compared with sheep brain, mouse brain showed the following differences in marker protein localization. GFAP was weakly expressed by protoplasmic astrocytes and not expressed in ependyma, oligodendroglia expressing intracytoplasmic MBP were frequent and widespread in neonatal mouse brain, CAII was expressed in myelin and oligodendroglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of neuropeptides in the brain and spinal cord of Wobbler mouse: a model for motoneuron disease.

The Wobbler mouse (wr) exhibits the loss of motoneurons especially in the cervical spinal cord, and thus has been studied as a model for human motoneuron diseases. Wobbler mice selected at various ages and stages during the disease process show increased levels of thyrotropin releasing hormone and substance P in spinal cord and brainstem (medulla). Enkephalins (methionine and leucine) also increase in the spinal cord and brainstem. Somatostatin increases in hypothalamus, perhaps accounting partly for the small size of this mutant mouse via its effect on growth hormone.

Distribution of N-acetylaspartate, N-acetylaspartylglutamate, free glutamate and aspartate following complete mesencephalic transection in rat neuraxis.

The distribution of N-acetylaspartate (NAA), N-acetylaspartylglutamate (NAAG), free glutamate (Glu) and aspartate (Asp) was studied in the neuraxis of rats 48 h after complete transection of brain stem at the intercollicular level. NAA remained unchanged above the transection level but decreased in the neur-axis segments caudal to the lesion. Glu was strongly depressed both in the segments rostral to the transection and in the ones caudal to it. No significant change was found for NAAG and Asp. These findings are consistent with the hypothesis that NAA may be involved in neurotransmission processes and provide further evidence for Glu as transmitter of descending and ascending pathways. In addition, the data obtained do not suggest a direct metabolic or functional relationship between NAA and NAAG nor between these N-acetylderivatives and free Glu and Asp.

Physical and chemical considerations in the in vitro calibration of microdialysis probes for biogenic amine neurotransmitters and metabolites.

The object of the present study was to examine the effects of temperature, oxidation, and pH on in vitro relative recovery of catecholamine and indoleamine neurotransmitters and their metabolites using microdialysis probes. Relative recovery of norepinephrine (NE), dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5HIAA), dopamine (DA), homovanillic acid (HVA), and 5-hydroxytryptamine (5HT) increased with temperature from 0 to 46 degrees C. For each compound, the increase in the amount recovered with increasing temperature was different. The stability of norepinephrine and dopamine was not affected at any temperature using deoxygenated calibration standard solutions containing ascorbic acid but was greatly reduced when exposed to ambient air without antioxidant treatment; catecholamine metabolites and the indole compounds were less affected. No change for in vitro relative recovery was observed by varying the pH of the perfusing solution from 6 to 8. Thus, temperature control in probe calibration as well as analyte stability using antioxidant treatment are important in reducing the error when estimating extracellular concentrations of neurotransmitter and metabolites.

New approach for characterization of lysosulfatide by TLC, fast atom bombardment mass spectrometry and NMR spectroscopy.

Thin layer chromatography of lysosulfatide showed anomalous Rf-values in contrast with such lysosphingolipids as glucopsychosine and galactopsychosine with neutral, acidic, and alkaline developing solvents. This was thought to be due to the presence of oppositely charged sulfate and amino groups in the lysosulfatide. In the negative mode of fast atom bombardment mass spectrometry, the lysosulfatide showed the pseudo molecular ion (M-H)- peak at m/z 540 and sulfate ion peak at m/z 97, whereas in the positive mode, it showed not only the pseudo molecular ion (M+H)+ peak at m/z 542, but also the major peaks of protonated psychosine at m/z 462 and fragment ions of dehydrated sphingosine at m/z 282 and 264, 13C-NMR signals of all carbons of lysosulfatide were determined by using distortionless enhancement by polarization transfer. The difference in chemical shifts of ring carbons of galactose residue between lysosulfatide and galactopsychosine was largest at C-3 (downfield shift), thereby indicating the location of the sulfate group to be at C-3 of galactose. This conclusion is supported by the 1H-NMR spectra of the lysosulfatide and galactopsychosine. Thus, the chemical structure of lysosulfatide was confirmed by fast atom bombardment mass spectrometry and 13C- and 1H-NMR spectroscopy. Furthermore, 13C-NMR signals of C-1 to C-5 of the sphingosine moiety showed significantly different chemical shifts between the lysosulfatide and galactopsychosine. These differences suggested that C-1 to C-5 of sphingosine might be influenced by intramolecular or intermolecular interaction between the sulfate group of the galactose residue and the amino group of sphingosine.(ABSTRACT TRUNCATED AT 250 WORDS)

Olfactory neurons express a unique glycosylated form of the neural cell adhesion molecule (N-CAM).

mAb-based approaches were used to identify cell surface components involved in the development and function of the frog olfactory system. We describe here a 205-kD cell surface glycoprotein on olfactory receptor neurons that was detected with three mAbs: 9-OE, 5-OE, and 13-OE. mAb 9-OE immunoreactivity, unlike mAbs 5-OE and 13-OE, was restricted to only the axons and terminations of the primary sensory olfactory neurons in the frog nervous system. The 9-OE polypeptide(s) were immunoprecipitated and tested for cross-reactivity with known neural cell surface components including HNK-1, the cell adhesion molecule L1, and the neural cell adhesion molecule (N-CAM). These experiments revealed that 9-OE-reactive molecules were not L1 related but were a subset of the 200-kD isoforms of N-CAM. mAb 9-OE recognized epitopes associated with N-linked carbohydrate residues that were distinct from the polysialic acid chains present on the embryonic form of N-CAM. Moreover, 9-OE N-CAM was a heterogeneous population consisting of subsets both with and without the HNK-1 epitope. Thus, combined immunohistochemical and immunoprecipitation experiments have revealed a new glycosylated form of N-CAM unique to the olfactory system. The restricted spatial expression pattern of this N-CAM glycoform suggests a possible role in the unusual regenerative properties of this sensory system.

[Biochemical anatomy of the spinal peptidergic system. Study of normal and pathologic material; plasticity of neuropeptides in adult dorsal root ganglia]. / Anatomie biochimique des systèmes peptidergiques spinaux. Etude de matériel normal et pathologique; plasticité des neuropeptides du ganglion rachidien adulte.

The purpose of this paper is to illustrate the advantages of immunocytochemical studies of spinal neuropeptides in human pathology and in animal experiments. The distribution of neuropeptides in the gray matter of the human spinal cord is summarized. Data obtained on selected pathological cases are able to determine the origin of certain peptidergic afferents to the spinal cord and suggest that the early disappearance of substance P-positive fibers in the motoneuronal columns plays a role in the pathogenesis of amyotrophic lateral sclerosis. In rats, peptide immunocytochemistry is useful for assessing the plasticity of spinal neurons in a model of chronic pain, in chemically induced degeneration of the gray matter and in a model of spinal cord trauma. Finally, a newly developed culture system of adult rat and human dorsal root ganglia demonstrates that the phenotypic expression of neuropeptides can be modulated experimentally, which offers new perspectives for studying the neurobiological role of these mediators and for the tentative repair of spinal lesions by autografts.

Regional brain concentrations of calcitonin gene-related peptide in spontaneously hypertensive and normotensive Wistar-Kyoto rats.

The regional brain and spinal cord concentrations of calcitonin gene-related peptide (CGRP) were measured in age-matched (22-23-week-old) spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. The highest concentration of CGRP in the WKY rats was in the spinal cord (172 +/- 9 pmol/g), followed by the medulla oblongata/pons (88 +/- 5 pmol/g). The relative order of distribution in the remaining regions was: hypothalamus (12.6 +/- 0.8 pmol/g) = striatum greater than thalamus greater than midbrain = hippocampus greater than cortex (2.1 +/- 0.3 pmol/g). The concentration of CGRP in the cerebellum was at the level of the assay's sensitivity (0.5 pmol/g). The relative order of distribution in the SHR strain was essentially the same. However, in comparison with the WKY rats, the SHR had significantly lower levels of CGRP in the hippocampus (-47%), striatum (-49%) and medulla oblongata/pons (-24%), and in the spinal cord (-24%). In younger age-matched (16-17-week-old) rats, the spinal cord and medulla oblongata/pons concentrations of CGRP were also lower in SHR than in WKY rats. CGRP is a putative neurotransmitter which, when administered centrally or peripherally, has potent cardiovascular effects. The reduced levels of this peptide may be an important factor in the cardiovascular and/or behavioural abnormalities of the SHR strain.

[Study of characteristics of monoclonal antibody against substance P].

Cross-reaction of a rat monoclonal antibody (BTP-1) against seventeen substance P analogues was studied. The antibody was of IgG type and related to the carboxyl terminal of substance P, especially methionyl in the terminal, but did not depend on the strength of antagonistic effects of these analogues. It did not show cross-reaction with the following nine peptides: glucagon, endorphin, angiotensin I, II, leucine-enkephalin, methionine-enkephalin, bradykinin, oxytocin and dernorthin, indicating its high specificity to substance P. By means of immuno-enzyme histochemical method, it was shown that stained nerve fibers were located in the gelaliternous substance of Rolando, interpeduncular nucleus, substantia nigra and nerve cell bodies in the vestibular nucleus, lateral tegmental nucleus of mesencephalon and ventral region of third ventricle.

Separation and identification of 2',3'-cyclic nucleotide 3'-phosphodiesterase on isoelectric focusing gels.

A method is presented for the separation and detection of the myelin marker enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase on isoelectric focusing gels and by immunoblotting. The gel staining procedure is a modification of a method used to demonstrate enzyme activity on blots after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional polyacrylamide gel electrophoresis. The results show that immunologically active 2',3'-cyclic nucleotide 3'-phosphodiesterase can be separated under equilibrium conditions on isoelectric focusing gels with an expanded alkaline pH range after solubilization in a mixture of nonionic/zwitterionic detergents and urea. Enzymatically active 2',3'-cyclic nucleotide 3'-phosphodiesterase focused as two closely spaced bands at pIapp 8.1 and 8.8, respectively, while 2',3'-cyclic nucleotide 3'-phosphodiesterase immunoreactivity was detected as four distinct bands at pIapp 4.2, 7.4, 8.8, and 9.3 and a diffuse band at pIapp 7.9-8.2. By two-dimensional separation these five bands showed molecular weights of about 43-47 kDa, i.e., corresponding to reported values for immunologically active 2',3'-cyclic nucleotide 3'-phosphodiesterase. Since enzyme activity is associated with only two of the bands, nonspecific and artifactual banding due to, e.g., detergent micelle formation, is unlikely.

Isolation, purification and characterization of beta-hCGRP from human spinal cord.

Human beta-calcitonin gene-related peptide (beta-hCGRP) was isolated and purified from spinal cord. The complete characterization of this material was based on definitive mass analysis by fast atom bombardment mass spectrometry together with gas phase sequencing. Combining these data we have characterized the structure of beta-hCGRP including the C-terminal sequence, the presence of the S-S bridge and of phenylalanineamide as the C-terminal amino acid, and fully confirmed the amino acid sequence predicted from the nucleotide analysis.

Influence of polar residue deletions on lipid-protein interactions with the myelin proteolipid protein. Spin-label ESR studies with DM-20/lipid recombinants.

The lipid specificities of two related integral membrane proteins of central nervous system myelin, the proteolipid (PLP) and DM-20 proteins, which differ only by the deletion of a polar stretch of 35 contiguous amino acid residues, were studied with spin-labeled lipids after reconstitution into dimyristoyl-phosphatidylcholine. The selectivity in populating lipid association sites at the protein interface and in modulating the lipid exchange between protein and bulk lipid sites was quantitated by the relative association constants and the off-rate constants for exchange, respectively, for both proteins. The sequence deleted in DM-20 (residues 116-150 of PLP) is found to play a major role in determining the lipid selectivity for the parent PLP protein.

Experimental autoimmune encephalomyelitis in the maturing central nervous system. Transfer of myelin basic protein-specific T line lymphocytes to neonatal Lewis rats.

We analyzed the effects of myelin basic protein (MBP)-specific encephalitogenic T line cells in neonatal syngeneic recipients before and after formation of central nervous system myelin. Lewis rat pups (postnatal days 0, 1, 2, 4, 8) were injected intraperitoneally with MBP-specific T cell line in doses which cause clinical and histologic changes of experimental autoimmune encephalomyelitis (EAE) in adult rats. We correlated the susceptibility to transferred EAE with the developmental appearance of MBP as demonstrated by immunohistochemical staining. MBP was barely demonstrable until postnatal day 2 but became definitely apparent on postnatal day 4. All newborn rats that were injected on postnatal day 0, 1, 2 failed to develop any apparent clinical signs, but histologically some recipients displayed slight inflammatory cell infiltration of the meninges and subpial lesions limited to the lower spinal cord. In striking contrast, rats that were injected on postnatal day 4 or 8, developed clinical signs and, in particular, many of the older recipients became moribund. Histologically, these animals displayed marked inflammatory cell infiltrations and white matter destruction within the spinal cord. Clinical and histologic severity clearly increased with the recipient's age. Histologically, there were some differences between adult rat EAE and newborn rat EAE. In contrast to adult rat EAE which displayed grey and white matter involvement with marked perivascular mononuclear cell infiltrations, newborn rat EAE typically showed very severe changes with edema formation selectively in the white matter and the cellular infiltrates were dominated by polymorphonuclear cells and macrophages. Newborn T line-mediated EAE thus strikingly resembles hyperacute EAE induced in immunocompromised (irradiated) recipients.

Computerized quantification of immunofluorescence-labeled axon terminals and analysis of co-localization of neurochemicals in axon terminals with a confocal scanning laser microscope.

The confocal scanning laser microscope (CSLM) offers improved optical resolution and contrast, high photometric precision, and the ability to make optical sections. These benefits were explored for use in quantitative analysis of immunofluorescence-labeled axon terminals. Guidelines were obtained for adjustments of the CSLM parameters. In the present applications, bleaching of the fluorescence did not represent a serious obstacle to analysis with the CSLM. A method was developed to distinguish the background fluorescence from the specific fluorescence labeling. This procedure made way for the development of automated quantification of immunolabeled axon terminals. The automated procedures substantially reduced the man-hour expenditure for analysis and provided highly reproducible quantifications compared with manual methods. The increased resolution and contrast of the CSLM allowed measurements of the fluorescence signal strength of individual axon terminals. The CSLM also allowed detection of co-localized neurochemicals in axon terminals.

Serotonergic innervation of the lateral cervical nucleus: an immunohistochemical study in cats and monkeys (Aotus trivirgatus).

A serotonergic input to the lateral cervical nucleus of cats and monkeys (Aotus trivirgatus) was demonstrated with immunohistochemical methods. In both species, the lateral cervical nucleus was found to contain a network of serotonin-immunoreactive fibers. However, the density of labeled fibers was greater in the monkeys than in the cats. Most labeled fibers were thin and had irregularly spaced varicosities. Electron microscopic examination showed that labeled varicosities were in apposition with dendrites, neuronal somata and unlabeled terminals, but synapses were rare. The results demonstrate that the lateral cervical nucleus receives a serotonergic innervation, as is the case with other somatosensory relay structures such as the spinal dorsal horn and the dorsal column nuclei. The presence of a serotonergic innervation suggests that the transmission of somatosensory information through the lateral cervical nucleus is modulated by a descending pathway. However, its effect on the response properties of neurons in the lateral cervical nucleus is unknown.

Spinal cord edema and changes in tissue content of Na+, K+, and Mg2+ after impact trauma in rats.

Changes in the tissue content of water, Na+, K+, and Mg2+ were measured in spinal cord samples from anesthetized rats subjected to impact trauma (T9 spinal segment) of varying severity: 25 g-cm (low injury), 100 g-cm (high injury). Laminectomized animals served as controls. Rats with high injury were killed at 15 min, 60 min, 4 hr, 24 hr, 3 days, or 7 days after trauma. Those with low injury were killed at 24-hr postinjury. In all groups, spinal cord tissue was rapidly removed (less than 30 sec), frozen in liquid nitrogen, and dissected into the injured segment and adjacent two caudal and rostral segments. Water content was determined as wet weight/dry weight ratios, and cations were measured by atomic absorption spectrophotometry. High injury resulted in statistically significant increases in water content as early as 15 min after trauma. There were concomitant increases in Na+ and decreases in K+ that were apparent at 15 min and were statistically significant by 60-min posttrauma. The increases in water content and Na+ were present to a similar degree in the 4-hr, 24-hr, 3-day, and 7-day groups. In contrast, tissue Mg2+ was reduced and significantly decreased at 4 hr and 24 hr; Mg2+ levels had recovered partially by 3 days and completely by 7 days. Whereas changes in the tissue content of water, Na+, and K+ occurred at 24 hr regardless of the injury severity, changes in total Mg2+ were correlated with the degree of injury. These data are consistent with the conclusion that edema formation (and associated Na+ and K+ changes) after spinal cord trauma may be an epiphenomenon and does not significantly contribute to injury progression. In contrast, reductions in Mg2+ content may represent an important factor in the development of irreversible tissue damage.