Localization of the ras-like rab3A protein in the adult rat brain.

Rab3A is a small GTP-binding synaptic vesicle protein, shown to dissociate from synaptic vesicle membranes upon depolarization-induced exocytosis. Using an antiserum raised against rab3A, we found that the antigen was localized to the neuropil of specific brain regions, but was not present in major fiber tracts or most cell bodies. For example, the neuropil of several thalamic nuclei (i.e, dorsal lateral geniculate nucleus, lateral posterior nucleus, ventroposterior nucleus), cerebral cortex, upper layers of the superior colliculus and matrix zones of the neostriatum, were strongly immunoreactive, while the anterior commissure, corpus callosum, optic tract and internal capsule were devoid of staining. The hippocampus, dark staining was observed in the stratum oriens, stratum radiatum and molecular layer of the dentate gyrus, while the pyramidal, stratum lacunosum moleculare and dentale granule layers were not stained. In cerebellum the molecular layer and to a lesser extent, the underlying granule cell layer showed enhanced immunoreactivity. Seven days after excitotoxic lesions of the cerebral cortex, rab3A immunoreactivity was diminished in the mirror locus in the contralateral coritcal hemisphere and in certain thalamic nuclei ipsilateral to the injection site. These results show that rab3A is localized to a number of specific regions. Its absence from other areas suggests that this synaptic vesicle protein is not universal to all neuronal terminals and pathways. In addition, our lesion studies indicate that for some brain regions, much of the antigen originates in cortical neurons and is distributed within specific axonal projections.     

A case–control association study between the CYP3A4 and CYP3A5 genes and schizophrenia in the Chinese Han population

In this study, variants of two genes coding for cytochrome P450 enzyme (CYP3A4 and CYP3A5) were analysed in a case–control sample using 398 schizophrenic patients and 391 healthy controls. All subjects were unrelated Han Chinese from Shanghai. No difference was observed on the allelic or genotypic distribution of CYP3A4 and CYP3A5 gene polymorphisms between the groups. However, the two-marker haplotypes covering components CYP3A41G and CYP3A53 were observed to be significantly associated with schizophrenia (corrected global p = 0.0009). In addition, we identified one common risk haplotype, G/G (present in 59.5% of the general population). The results suggest that CYP3A4 and CYP3A5 might play a role in genetic susceptibility to schizophrenia. However, confirmatory studies in independent samples are needed.     

Constitutive expression of c-myb mRNA in the adult rat brain

In this study, we demonstrated the c-myb mRNA expression in the adult rat brain using an in situ hybridization technique. We found c-myb mRNA signals in the various regions of the forebrain and midbrain including the cerebral cortex, thalamus, hippocampus, hypothalamus, superior and inferior colliculi and central gray. In the cerebellum, a diffuse signal was found in the granular layer while some positive cells were detected in the molecular layer as well. In addition, a number of cells showed intense signals in many nuclei of the medulla oblongata. The constitutive expression of c-myb mRNA in the different kinds of neural cells suggests that this gene might be involved in the normal function of these neurons.     

Transplants of immature astrocytes promote axonal regeneration in the adult rat brain

To study beneficial effects of immature astrocytes on axonal regeneration in the injured adult mammalian brain, we have stereotactically implanted cultured astrocytes from embryonic (E 14–16) rat cerebral cortex into the lesion site following transection of the postcommissural fornix. The spatio-temporal pattern of axonal degeneration and regrowth in the proximal fornix stump was investigated using wheat germ agglutinin-horseradish peroxidase tracing techniques and quantitative analysis of myelinated axon profiles. Transection of the postcommissural fornix tract caused disintegration of the axons in the distal stump as well as rapid and pronounced retrograde axonal degeneration up to 800–1,200 μm proximal to the lesion site. While a small bundle of subicular fibers spontaneously extended to the lesion site within 4 weeks after injury, axonal regeneration was markedly stimulated in those animals that had received an astroglial implant. Following the former pathway, regenerating axons sprouted towards the implant but did not penetrate the graft. Instead, the axons elongated over the surface of the transplant, avoiding growth into the surrounding neuropil or into the distal fornix segment. In grafted animals we further observed a substantial increase in the number of myelinated axons of approximately 31.5% (at the level of 800 μm) and approximately 40% (at the 400 μm level) compared with the injured tract lacking a transplant. Our results indicate the capacity of juvenile astrocytes to stimulate axonal regeneration after injury of the post-commissural fornix tract in the adult rat brain. We further demonstrate myelination of the regenerated axons. © 1994 Wiley-Liss, Inc.     

1,25-Dihydroxyvitamin D3 receptors in the central nervous system of the rat embryo

We have mapped areas within the central nervous system (CNS) of the developing fetal rat which immunostain for the 1,25-dihydroxyvitamin D₃ receptor (VDR). The VDR was detected from days 12 to 21 of gestation throughout the CNS; immunostaining was particularly intense in the neuroepithelium and within the differentiating fields of various areas of the brain. Cells within the spinal cord, dorsal root, and other ganglia exhibited positive staining for the VDR. The intensity of staining for the VDR diminished or disappeared in the neuroepithelium throughout the CNS during the later days of development, while in the differentiating fields single VDR immunoreactive cells were observed. The presence of the VDR in the CNS was confirmed by in situ hybridization and RNA-based polymerase chain reaction methods with di-deoxy sequencing of the resultant DNA product. These results support the hypothesis that 1,25-dihydroxyvitamin D₃, through interactions with the VDR, may play a role in the development of the CNS.     

Cognitive dysfunction, urinary retention, and a lesion in the thalamus--beware of possible toxocariasis of the central nervous system

Toxocariasis of the central nervous system is usually characterized by an eosinophilic meningitis, encephalitis or myelitis. We here report a patient with an at least 7 years history of unexplained neurologic signs and symptoms. MRI showed a cystic lesion in the left thalamus, compatible with a parasitic infection. Blood and CSF analyses were positive for Toxocara canis IgG Western-blot, but were otherwise unremarkable. The case report raises the question whether there are chronic or late variants of this disease.     

大鼠神经系统内谷氨酸受体2／3亚型的定位分布

用特异性抗体的免疫细胞化学染色技术观察谷氨酸受体 2 / 3亚型 (GluR2 / 3)在大鼠神经系统的定位分布。结果显示GluR2 / 3样阳性神经元主要分布于大脑皮质、尾壳核、苍白球、隔核、海马CA1～CA4区、齿状回、乳头体、小脑Purkinje细胞层、动眼神经核、滑车神经核、臂旁核、三叉神经运动核、上橄榄复合体、三叉神经脊束核、面神经核、疑核、迷走神经背运动核、舌下神经核、楔束核、薄束核、延髓和脊髓背角I～Ⅱ层、背根节、三叉神经节等。本研究结果表明GluR2 / 3样阳性结构广泛分布于大鼠神经系统 ,为Glu发挥兴奋效应提供了作用位点。     

srGAP3在正常成年大鼠脑内的表达

目的 探讨slit—robo GTP激活蛋白3(slit-robo GTP activated protein 3，srGAP3)在正常成年大鼠中枢神经系统中的分布。方法 应用免疫组织化学ABC法研究了srGAP3蛋白在正常成年大鼠脑内的分布和定位。结果 srGAP3蛋白在正常成年大鼠脑中分布非常广泛，在脑内各主要结构如大脑皮质、海马、杏仁核、丘脑和下丘脑的部分核团、中脑、脑桥、小脑及延髓等均有表达。srGAP3免疫反应阳性物质位于神经元的细胞核周围。结论 srGAP3蛋白在正常成年大鼠脑中有很广泛的表达，提示srGAP3蛋白在成年大鼠中枢神经系统的功能活动中可能也起重要作用。     

Lipopolysaccharide evokes the modulation of brain cytochrome P4501A in the rat

The cytochrome P450 enzyme system is a multigene family of enzymes that is modulated in the liver during systemic inflammatory responses or during infection Several forms of the enzyme are expressed in discrete areas of the brain and likely play a critical role in the metabolism of drugs and endogenous chemicals in the central nervous system (CNS). Even though the brain responds to inflammation in a manner different from most tissues, we examined the possible modification of a major cytochrome P450 form (CYP1A) in the brain during inflammation confined to that organ. Total brain CYP1A activity, as measured by ethoxyresorufin dealkylase (EROD), was downregulated 24 and 48 h following the administration of a single dose of lipopolysaccharide (LPS). Regionally, a similar effect was determined in the cortex, hippocampus and the mid-brain but the activity in the cerebellum was unaffected. The examination of coronal brain sections using an antibody directed against CYP1A indicated that the enzyme was distributed in discrete cells of the hippocampus, thalamus and cortex and in the tanycytes surrounding the third ventricle. In each of these areas, the immunoreactivity was diminished in animals receiving LPS as compared to saline-treated animals. LPS also evoked the expression of the small molecular weight heat shock protein hsp27 throughout the brain indicating the development of an inflammatory response. These studies indicate that inflammation localized to the CNS causes an alteration in the levels and activity of a major cytochrome P450 form in the brain. This could have implications to the metabolism or activation of drugs and endogenous chemicals in the CNS during a disease state that features an inflammatory component.     

Developmental expression offlt3 mRNA in the mouse brain

The expression and localization offlt3 mRNA were investigated using Northern blotting andin situ hybridization during the developmental process of the mouse brain. By Northern blotting, the expression of theflt3 gene was not detected in embryonic, neonatal, or early postnatal brains, but was markedly increased with age. In adult mice,flt3 was abundantly expressed in the cerebellum, moderately in the pons, and faintly in the thalamus and the cerebral cortex. Byin situ hybridization, some neurons that expressedflt3 formed synaptic connections with each other. The present findings suggest that theflt3 gene expression is related to the cell type and the developmental process.     

Localization of organ-specific antigens in the nervous system of the rat

Summary Localization of organ-specific brain antigens in the central nervous system of the rat has been studied by means of indirect immunofluorescence. Rabbit antiserum against homogenate of rat brain, previously absorbed with normal serum and homogenates of rat organs (kidney, liver, spleen), reacted with the water-soluble antigens of rat brain prepared by extraction with phosphate buffer (pH 7.3) and ultracentrifugation at 50000×g to give one band in the immunodiffusion test and 2–3 precipitation arcs in immunoelectrophoresis. There was also a positive reaction with peripheral nerve. The antigen was detectable in all regions of the CNS. Cells with distinct cytoplasmic immunofluorescence were most frequently observed in cerebellar white matter, pons, cerebellar pedunculi, longitudinal tracts of the brain stem. Positive immunofluorescence reaction has appeared in the outer plexiform layer and granular layer of the retina, satellite cells of the spinal root ganglia and Schwann cells. A similar reaction was observed in human, mouse and guinea pig brain slices. Both the morphological and immunochemical reactions are indicative of glial localization of this antigen.     

Differential expression of the small chondroitin/dermatan sulfate proteoglycans decorin and biglycan after injury of the adult rat brain

Chondroitin sulfate proteoglycans are widespread extracellular matrix proteins and are specifically upregulated after CNS injury at the lesion site. Many proteoglycan core proteins have been described in the rat brain, but detailed analysis of individual proteoglycans expressed after injury are missing. The present study represents an initial attempt to assess the diversity and timing of lesion-induced expression of proteoglycans in order to elucidate their functional role in CNS injury and repair. Using immunocytochemical methods we analysed the expression of decorin and biglycan in the transected postcommissural fornix of the adult rat. Transection of the fornix induced the upregulation of both decorin and biglycan. However, their expression differed with respect to time course, regional extent and cellular localization. The rapid upregulation of decorin within a wide area around the lesion was followed by a massive appearance of biglycan that remained restricted to the transection site. Three months after lesion, differences of the area size of decorin- and biglycan-immunoreactivities were no longer detectable. Both proteoglycans were restricted to the lesion site and the fornix stumps. While decorin was primarily expressed by astrocytes, biglycan was deposited extracellularly in sheet-like structures. The upregulation of both proteoglycans persisted for at least up to 6 months after lesion. These strong but divergent lesion-induced expression patterns indicate important but different roles of decorin and biglycan in CNS injury.     

DNA polymerases δ and e in developing and aging rat brain

Our study reveals the presence of DNA polymerases δ and e, participating in DNA replication and repair, along with already known polymerases α and β, in the developing and aging rat brain. This was achieved through a protocol that takes advantage of the reported differential sensitivities of different DNA polymerases towards certain inhibitors such as butylphenyl and butylanilino nucleotide analogs, 2′, 3′-dideoxythymidine triphosphate, the monoclonal antibody of human polymerase α and the use of preferred template primers and proliferating cell nuclear antigen. The results indicate that while polymerase β seems to be the predominant one, significant levels of polymerases α, δ and e are also present at all the postnatal ages studied and that the relative proportion of polymerase e increases with age. The data suggest that the rat brain is equipped with a sustained DNA repair capacity throughout the life span.     

Hypoxia/reoxygenation induces apoptosis through biphasic induction of protein synthesis in cultured rat brain neurons

To investigate biochemical events accounting for the outcome of central neurons following hypoxia/reoxygenation, cultured neurons from fetal rat forebrain were exposed to hypoxia (95% N₂/5% CO₂) for 6 h, and then reoxygenated for up to 96 h. Time-dependent changes in macromolecular biosynthesis were analysed by incorporation of [³H]uridine and [³H]leucine and were coupled to cell viability and lactate dehydrogenase leakage. Morphological features of necrosis and apoptosis were scored following nuclear incorporation of the fluorescent dye 4,6-diamidino-2-phenylindole. Hypoxia led to a 36% reduction of cell viability at the end of the reoxygenation period, while 23% of the neurons exhibited apoptosis. A biphasic increase in the rates of protein synthesis was measured 1 h after the onset of hypoxia (77% above controls) and by 48-h postreoxygenation (72%). The presence of cycloheximide during hypoxia inhibited both peaks of synthesis and prevented the development of apoptosis. Protein electrophoresis outlined specific alterations in constitutive proteins, and immunohistochemistry revealed an overexpression of the pro-apoptotic gene products Bax and ICE. Therefore, hypoxia followed by reoxygenation would trigger sequential changes in synthesis of specific proteins, leading to delayed and mainly apoptotic neuronal death.     

A study of FHL1, BAG3, MATR3, PTRF and TCAP in Australian muscular dystrophy patients

FHL1, BAG3, MATR3 and PTRF are recently identified myopathy genes associated with phenotypes that overlap muscular dystrophy. TCAP is a rare reported cause of muscular dystrophy not routinely screened in most centres. We hypothesised that these genes may account for patients with undiagnosed forms of muscular dystrophy in Australia. We screened a large cohort of muscular dystrophy patients for abnormalities in FHL1 (n = 102) and TCAP (n = 100) and selected patients whose clinical features overlapped the phenotypes previously described for BAG3 (n = 9), MATR3 (n = 15) and PTRF (n = 7). We found one FHL1 mutation (c.311G>A, p.C104Y) in a boy with rapidly progressive muscle weakness and reducing body myopathy who was initially diagnosed with muscular dystrophy. We identified no pathogenic mutations in BAG3, MATR3, PTRF or TCAP. In conclusion, we have excluded these five genes as common causes of muscular dystrophy in Australia. Patients with reducing body myopathy may be initially diagnosed as muscular dystrophy.     

In vitro myelin basic protein synthesis in the PNS and CNS of myelin deficient (mld) mutant mice

The CNS of the mutant mld has a severe myelin deficit. In contrast, myelination is normal in the PNS. Previous studies showed that myelin basic proteins (MBP) are practically missing in mld CNS and PNS tissues. Using an in vitro system and immunoprecipitation, we present evidence that MBP synthesis is repressed in the PNS and in the CNS of mld mutants.     

Rolipram induces c-fos protein-like immunoreactivity in ependymal and glial-like cells in adult rat brain

We tested the effects of the cyclic AMP-dependent phosphodiesterase inhibitor 4- (3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (rolipram) on c-fos protein-like immunoreactivity (FOS-IR) in adult rat brain. Rolipram (25–100 mg/kg, i.p.) did not detectibly alter basal FOS-IR in neurons but induced FOS-IR in glial-like cells scattered in white matter regions and in ependymal cells lining the lateral and third ventricles. This induction was observed at 1 and 4 h after injection but was not detectable 10 min or 24 h after rolipram injection