Distribution, subcellular localization and ontogeny of ASIC1 in the mammalian central nervous system

The acid-sensitive ion channel ASIC1 is a proton-gated ion channel from the mammalian nervous system. Its expression in sensory neurons and activation by low extracellular pH suggest that ASIC is involved in transmitting nociceptive impulses produced by the acidification caused by injury or inflammation. However, ASIC1 expression is not restricted to sensory neurons. To understand the functional role of ASIC1 in the CNS we investigated its expression and subcellular distribution therein. In particular, we examined the presence of ASIC1 in domains where the local pH may drop sufficiently to activate ASIC1 under physiological conditions. Immunostaining with specific antibodies revealed broad expression of ASIC1 in many areas of the adult rat brain including the cerebral cortex, hippocampus and cerebellum. Within cells, ASIC1 was found predominantly throughout the soma and along the branches of axons and dendrites. ASIC1 was not enriched in the microdomains where pH may reach low values, such as in synaptic vesicles or synaptic membranes. Pre- or postsynaptic ASIC1 was not gated by synaptic activity in cultured hippocampal neurons. Blockage or desensitization of ASIC1 with amiloride or pH 6.7, respectively, did not modify postsynaptic currents. Finally, the ontogeny of ASIC1 in mouse brain revealed constant levels of expression of ASIC1 protein from embryonic day 12 to the postnatal period, indicating an early and almost constant level of expression of ASIC1 during brain development.     

Nerve growth factor in the primate central nervous system: regional distribution and ontogeny

An enzyme immunoassay for nerve growth factor was developed to determine the regional distribution and ontogenic change in the macaque (Macaca fascicularis) CNS. The standard curve of mouse nerve growth factor paralleled the dilution curves of extracts from the primate CNS at the adult and pre-natal stages. Furthermore, the nerve growth factor immunoreactive material comigrated with mouse nerve growth factor by means of carboxy methyl cellulose chromatography. These findings suggest that the immunoreactive material extracted from the primate CNS is mouse nerve growth factor-like molecules. At the adult stage, the highest level of nerve growth factor was in the hippocampus, with relatively high levels also in the hypothalamus, the cerebral cortex, the amygdala, the basal nucleus of Meynert, the septal nucleus, the cerebellum and the caudate nucleus. No detectable amounts were observed in the spinal cord, the substantia nigra or the dentate nucleus. In addition to the CNS, the pituitary gland contained about four times the level found in the hippocampus. At embryonic day 120, a high level of nerve growth factor already existed in the occipital cortex (80% of the level at the adult stage) and in the hippocampus (70% of the level at the adult stage). Between embryonic day 120 and the newborn stage in the occipital cortex and between embryonic day 120 and postnatal day 60 in the hippocampus, nerve growth factor levels increased about 1.7-fold, and after that, they gradually decreased until the adult stage was reached. In contrast, in the cerebellum, the level was quite high during the pre-natal period and declined to one-third at postnatal day 60. The developmental changes in nerve growth factor and choline acetyltransferase activity in the hippocampus were well correlated (r = 0.963) between embryonic day 120 and postnatal day 60. Our studies reveal that nerve growth factor is present in the primate CNS. The high level of nerve growth factor during embryonic stages and the good correlation with choline acetyltransferase activity suggest a physiological role for nerve growth factor in the development of the primate CNS.     

Aquaporin-4 in the central nervous system: cellular and subcellular distribution and coexpression with KIR4.1

Aquaporin-4 (AQP4) is the predominant water channel in the neuropil of the central nervous system. It is expressed primarily in astrocytes, but also occurs in ependymocytes and endothelial cells. A striking feature of AQP4 expression is its polarized distribution in brain astrocytes and retinal Muller cells. Thus, immunogold analyses have revealed an enrichment of AQP4 in endfeet membranes in contact with brain microvessels or subarachnoidal space and a low but significant concentration in non-endfeet membranes, including those astrocyte membranes that ensheath glutamate synapses. The subcellular compartmentation of AQP4 mimics that of the potassium channel Kir4.1, which is implicated in spatial buffering of K(+). We propose that AQP4 works in concert with Kir4.1 and the electrogenic bicarbonate transporter NBC and that water flux through AQP4 contributes to the activity dependent volume changes of the extracellular space. Such volume changes are important as they affect the extracellular solute concentrations and electrical fields, and hence neuronal excitability. We conclude that AQP4-mediated water flux represents an integral element of brain volume and ion homeostasis.     

Cellular and subcellular localization of 5-hydroxytryptamine1B receptors in the rat central nervous system: immunocytochemical, autoradiographic and lesion studies.

The localization of 5-hydroxytryptamine1B receptors in the rat central nervous system was investigated using anti-peptide antibodies that recognize a selective portion of the third intracytoplasmic loop of the receptor protein. At the light microscope level the densest 5-hydroxytryptamine1B receptor-like immunoreactivity was observed in ventral pallidum, globus pallidus, substantia nigra and dorsal subiculum. In addition, moderate immunoreactivity was found in the entopeduncular nucleus, the superficial gray layer of the superior colliculus, the caudate-putamen and the deep nuclei of the cerebellum. This distribution matched perfectly that previously described from radioligand binding studies. At the ultrastructural level, 5-hydroxytryptamine1B receptor-like immunoreactivity was associated with axons and axon terminals in the three areas examined: substantia nigra, globus pallidus and superficial gray layer of the superior colliculus. In all cases, immunostaining was located on the plasma membrane of unmyelinated axon terminals and in the cytoplasm close to the plasmalemma. Synaptic differentiations were never labelled but, in some cases, 5-hydroxytryptamine1B receptor-like immunoreactivity was found in their close vicinity. Injection of kainic acid into the neostriatum resulted in a marked decrease in receptor-like immunoreactivity in the globus pallidus and the substantia nigra, consistent with the location of 5-hydroxytryptamine1B receptors on terminals of striatopallidal and striatonigral fibres, respectively. A reduction in 5-hydroxytryptamine1B receptor-like immunoreactivity was also noted in the superficial gray layer of the superior colliculus after contralateral enucleation, as expected of the location of 5-hydroxytryptamine1B receptors on the terminals of retinocollicular fibres. In both lesion experiments, immunolabelled degenerating terminals were observed in the projection areas. Anterograde labelling experiments coupled with immunocytochemical detection further showed that 5-hydroxytryptamine1B receptors in the substantia nigra are located on axons of striatal neurons. These data provide anatomical support for the idea that 5-hydroxytryptamine1B receptors act as terminal receptors involved in presynaptic regulation of the release of various neurotransmitters, including 5-hydroxytryptamine itself.     

Zebrafish developmental genetics and central nervous system development

The central nervous system (CNS) is the most complex tissue of vertebrates. Recently, the zebrafish has emerged as a powerful genetic system for studying early development, and large-scale mutagenic screens for embryonic patterning defects have been accomplished. Mutants isolated in these screens are proving helpful in unravelling the molecular hierarchies involved in the development of the CNS. We review here recent studies in zebrafish which shed light on the genetic pathways involved in induction and regionalization of the CNS.     

Immunohistochemical localization of ryanodine receptors in mouse central nervous system.

The distribution of ryanodine receptor-like immunoreactivity in the mouse central nervous system was studied using two antibodies raised against synthetic peptides. These peptides represented a region conserved between the cardiac and skeletal muscle forms and a region specific to the cardiac form. Western blotting analysis and [3H]ryanodine binding analysis showed ryanodine receptors are expressed in all the brain regions. The activity was prominent in hippocampus and cerebral cortex. Immunohistochemical study demonstrated that the ryanodine receptors were localized unevenly in somata. Some apical and proximal dendrites in some cells were also labeled. In hippocampus pyramidal neurons in CA2-3 region were more labeled than CA1 region. Immunohistochemical distribution revealed by two antibodies was essentially the same but the fibers were more immunoreactive with the antibody raised against the cardiac muscle ryanodine form. The localization of ryanodine receptors was quite different from that of inositol 1,4,5-trisphosphate receptors.     

Wide distribution and subcellular localization of histamine in sympathetic nervous systems of different species

Previous studies have demonstrated that histamine (HA) acts as a neurotransmitter in the cardiac sympathetic nervous system of the guinea pig. The aim of the current study was to examine whether HA widely exists in the sympathetic nervous systems of other species and the subcellular localization of HA in sympathetic terminals. An immunofluorescence histochemical multiple-staining technique and anterograde tracing method were employed to visualize the colocalization of HA and norepinephrine (NE) in sympathetic ganglion and nerve fibers in different species. Pre-embedding immunoelectron microscopy was used to observe the subcellular distribution of HA in sympathetic nerve terminals. Under the confocal microscope, coexistence of NE and HA was displayed in the superior cervical ganglion and celiac ganglion neurons of the mouse and dog as well as in the vas deferens, mesenteric artery axon, and varicosities of the mouse and guinea pig. Furthermore, colocalization of NE and HA in cardiac sympathetic axons and varicosities was labeled by biotinylated dextranamine injected into the superior cervical ganglion of the guinea pig. By electron microscopy, HA-like high-density immunoreactive products were seen in the small vesicles of the guinea pig vas deferens. These results provide direct cellular and subcellular morphological evidence for the colocalization of HA and NE in sympathetic ganglion and nerve fibers, and support that HA is classified as a neurotransmitter in sympathetic neurons.     

Autoradiographic distribution of receptors to FLFQPQRFamide, a morphine-modulating peptide, in rat central nervous system.

The neuropeptide FLFQPQRFamide is a structure related to FMRFamide which is able to inhibit the effects of both endogenous and exogenous opiates. This morphine-modulating activity is mediated via the stimulation of specific FLFQPQRFamide receptors, different from opiate receptors. In vitro quantitative receptor autoradiography was performed on frozen sections of rat central nervous system to characterize binding properties and visualize FLFQPQRFamide receptors using the specific ligand [125I]YLFQPQRFamide, a radio-iodinated analogue of FLFQPQRFamide. [125I]YLFQPQRFamide appeared to interact reversibly with a single class of binding sites (KD = 0.2 nM). The specific binding represented 80% of the total binding at 0.05 nM, the FLFQPQRFamide concentration used in this mapping study. Sites labelled with [125I]YLFQPQRFamide were distributed heterogeneously within the brain and spinal cord. A high density of FLFQPQRFamide binding sites was detected in the most external layers of the dorsal horn of spinal cord and various nuclei of pons and medulla including trigeminal, dorsal tegmental and reticular nuclei. Nucleus of solitary tract, parabrachial, ambiguous and facial nuclei are also intensively labelled. Some structures of mesencephalon and diencephalon exhibited a high density of FLFQPQRFamide binding sites: central gray, raphe nuclei and thalamic nuclei such as parafascicular, laterodorsal, central median, paratenial and paraventricular nuclei. Suprachiasmatic and mammillary nuclei, lateral, posterior and anterior areas of hypothalamus and medial preoptic area exhibited high labelling. FLFQPQRFamide binding sites were also seen in some structures of the dopaminergic meso-cortico-limbic system including ventral tegmental area, cingulate cortex, lateral septum and the head of the caudate-putamen. Dense labelling appeared in the presubiculum of hippocampus. The dissimilar mapping of FLFQPQRFamide and opiate brain receptors confirms our previous pharmacological findings in FLFQPQRFamide binding studies on rat spinal cord membranes, showing that FLFQPQRFamide receptors are different from opiate receptors. There was a good correspondence between localization of binding sites and that of the putative endogenous peptide. Both occur in brain areas previously associated with analgesic action of opiates. However, the mapping of FLFQPQRFamide receptors in the central nervous system suggests that the FLFQPQRFamide system could be implicated in other physiological functions.     

The regional distribution of the nerve-stimulating phosphopeptide (nerveside, substance B) in the central nervous system

1. The nerve-stimulating phosphopeptide, nerveside, is present mainly in the cerebrum and brain stem, while the cerebellum contains only a trace amount of it.2. Nerveside is uniformly distributed over all parts of the cerebral cortex.3. The cerebral cortex contains the greatest concentration of nerveside. If the nerveside activity of 1 g cerebral cortex is expressed as 100 then the relative activities of the other parts of the C.N.S. are hippocampus 41, caudate nucleus 21, diencephalon (without hypothalamus) 24, midbrain 19, pons 7, medulla 12 and cerebellum 6.4. The nerveside activity of the hypothalamus is the same as that of the cerebral cortex.5. The pattern of distribution of nerveside in the C.N.S. suggests that it may be part of a corticipetal or corticifugal system.     

The identification of four prostaglandins in dog brain and their regional distribution in the central nervous system

1. Experiments were carried out to determine whether the prostaglandins, which have been identified as natural constituents of the brain, are widely distributed or concentrated in special regions of the central nervous system.2. Prostaglandins E(1), E(2), F(1alpha) and F(2alpha) have been identified in dog brain using solvent partition, column and thin layer chromatographic and bio-assay techniques.3. Each of these prostaglandins is distributed throughout all regions of the central nervous system investigated (cortex, hippocampus, caudate nucleus, hypothalamus, cerebellum, medulla and pons, cortical white matter and spinal cord).4. This distribution suggests that the role of prostaglandins in the central nervous system is not confined to any specific region.     

Vim及其在中枢神经系统的分布与作用

简要描述了中间丝Vim分子的外显子、内含子以及Vim的基因调控 ,总结了Vim蛋白及其亚单位的结构、装配、磷酸化调节和Vim与其它中间丝的相互作用。在发育时期的CNS ,Vim广泛表达于胶质细胞、神经元 ,成年期则特异地表达在少数胶质细胞和神经元内 ,并表达于整个星形胶质细胞的培养时期。Vim参与了神经元的芽生和某些特殊胶质细胞的构筑、形态和功能 ,并与部分CNS恶性肿瘤的行为学有关     

Immunocytochemical localization of acyl-CoA oxidase in the rat central nervous system

Peroxisomal -oxidation, consisting of four steps catalysed by an acyl-CoA oxidase, a multifunctional protein and a thiolase, is responsible for the shortening of a variety of lipid compounds. The first reaction of this pathway is catalysed by a FAD-containing acyl-CoA oxidase, three isotypes of which have been so far recognised. Among these, straight-chain acyl-CoA oxidase (ACOX) acts on long and very long chain fatty acids, prostaglandins and some xenobiotics. We investigated ACOX localisation by means of a sensitive, tyramide based, immunocytochemical technique, thus obtaining a complete distribution atlas of the enzyme in adult rat CNS. Granular immunoreaction product was found in the cytoplasm of neuronal and glial cells, both in the perikarya and in the cell processes. ACOX immunoreactive neurons were present to variable extent, in either forebrain or hindbrain areas. Specifically, the strongest signal was detected in the pallidum, septum, red nucleus, reticular formation, nuclei of the cranial nerves, and motoneurons of the spinal cord. We then compared the ACOX immunoreactivity pattern with our previous distribution maps of other peroxisomal enzymes in the adult rat brain. While ACOX appeared to colocalise with catalase in the majority of cerebral regions, some differences with respect to d-amino acid oxidase were noted. These observations support the hypothesis of heterogeneous peroxisomal populations in the nervous tissue. The wide distribution of the enzyme in the brain is consistent with the severe and generalised neurological alterations characterising the peroxisomal disorder caused by ACOX deficiency (pseudo-neonatal adrenoleukodystrophy).     

Ethnic distribution of primary central nervous system tumors in Washington, DC, 1971 to 1985.

An ethnic analysis was made of 8947 cases of primary central nervous system (CNS) tumors seen at the Armed Forces Institute of Pathology (AFIP), Washington, DC, from 1971 to 1985. Results showed a slightly higher frequency of primary CNS tumors in whites than in blacks with a white:black case ratio of 9:1 against the white:black population ratio in the United States of 7.4:1. Gliomas appeared to be twofold more frequent in whites than in blacks with a white:black case ratio of 12.1:1. However, meningiomas and pituitary adenomas were more common in blacks with a white:black case ratio of 6.7:1 and 4.2:1, respectively. When these results were compared with the results of a previous identical study using similar materials collected at AFIP from 1958 to 1970, the relative paucity of gliomas and higher frequency of meningiomas and pituitary adenomas in American blacks is again confirmed, thus re-emphasizing the importance of genetic factors in the genesis of primary CNS tumors. The remarkable decreasing white:black case ratio of primary CNS tumors as a whole (9:1 compared with 13.7:1) since 1970 probably reflects the socioeconomic improvement of American blacks during the same period.     

The distribution of enkephalin immunoreactive fibers and terminals in the monkey central nervous system: An immunohistochemical study

Using immunohistochemical techniques, the distribution of met-enkephalin fibers and terminals was studied in the central nervous system of adult old-world monkeys. Areas which showed the greatest density of immunoreactivity included substantia gelatinosa, nucleus tractus solitarius, nucleus parabrachialis, substantia nigra, median eminence, globus pallidus (external segment), patches within the striatum and the region of nucleus accumbens and the olfactory area. Striking and discrete zones of enkephalin immunoreactive fibers and terminals which did not conform to known nuclear boundaries were observed in the latter areas.The distribution of enkephalin in the monkey is compared to what has been described in the rat central nervous system. In general, the two species are similar, however, differences were observed in some areas including the hypoglossal nucleus, substantia nigra and in the region of the nucleus accumbens and olfactory area. The results are discussed with regard to the possible functional significance of enkephalin localization in regions related to regulation of pain, mood, and autonomie function.     

The expression and localization of Prune2 mRNA in the central nervous system

A family of Bcl-2/adenovirus E1B 19 kDa-interacting proteins (BNIPs) plays critical roles in several cellular processes such as cellular transformation, apoptosis, neuronal differentiation, and synaptic function, which are mediated by the BNIP2 and Cdc42GAP homology (BCH) domain. Prune homolog 2 (Drosophila) (PRUNE2) and its isoforms - C9orf65, BCH motif-containing molecule at the carboxyl terminal region 1 (BMCC1), and BNIP2 Extra Long (BNIPXL) - have been shown to be a susceptibility gene for Alzheimer's disease, a biomarker for leiomyosarcomas, a proapoptotic protein in neuronal cells, and an antagonist of cellular transformation, respectively. However, precise localization of PRUNE2 in the brain remains unclear. Here, we identified the distribution of Prune2 mRNA in the adult mouse brain. Prune2 mRNA is predominantly expressed in the neurons of the cranial nerve motor nuclei and the motor neurons of the spinal cord. The expression in the dorsal root ganglia (DRG) is consistent with the previously described reports. In addition, we observed the expression in another sensory neuron in the mesencephalic trigeminal nucleus. These results suggest that Prune2 may be functional in these restricted brain regions.     

Immunodeficiency, growth hormone deficiency and central nervous system involvement in a girl.

We describe a mentally retarded 12-year-old girl with ataxia in whom diagnostic evaluation for short stature revealed isolated growth hormone (GH) deficiency and multiple central nervous system (CNS) lesions. Assessment of immunologic status, performed because of the persistence of recurrent respiratory tract infections, showed associated deficiencies of IgG2-IgG4 and specific antibody response; in addition, in vitro lymphocyte response to mitogens was low, in vitro production of interleukin-2 and of IgM was absent, and natural killer activity was decreased. The possibility that association of the CNS lesions, GH deficiency and immune defects could be due to alterations of the neuro-immuno-endocrine network secondary to a disturbance of neurotransmitters induced by precocious CNS damage of a viral or ischemic nature is discussed.