Biomedical subjects

C Aoki

Publications and source records attributed to C Aoki.

At least 55 records · Page 3Linked to original sources

PubMed1996

Second case of zoonotic Onchocerca infection in a resident of Oita in Japan.

A non-gravid female Onchocerca was found in histopathological sections of a biopsy specimen taken from a painful nodule in the wrist of a 57-year old woman in Oita, in southern Japan. Six species of Onchocerca have been found in animals in Japan: two in wild bovids, one in equids, and three in domestic bovids of which one, Onchocerca sp., is only known by the microfilaria and infective stage. Distinctive morphological features of the worm, including a three-layered thick cuticle with prominent annular ridges at wide intervals, high somatic muscles and narrow lateral chords, resembled those of O. gutturosa, one of the three bovine Onchocerca species transmitted in the Oita region. However Onchocerca sp., which is also transmitted in this region, cannot be excluded. An ELISA test of the patient serum suggests that infections by Onchocerca spp. might be distinguished from those by Dirofilaria immitis, of which the number of human cases is increasing in Japan.

Animals↗

PubMed1995

Differential localization of NMDA and AMPA receptor subunits in the lateral and basal nuclei of the amygdala: a light and electron microscopic study.

Anatomical and physiological studies indicate that the amino acid L-glutamate is the excitatory transmitter in sensory afferent pathways to the amygdala and in intraamygdala circuits involving the lateral and basal nuclei. The regional, cellular, and subcellular immunocytochemical localizations of N-methyl-D-aspartate (NMDA) and L-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), two major classes of glutamate receptors, were examined in these areas of the amygdala. A monoclonal antibody and a polyclonal antiserum directed against the R1 subunit of the NMDA receptor were used. Each immunoreagent produced distinct distributions of perikaryal and neuropilar staining. Dendritic immunoreactivity was localized primarily to asymmetric (excitatory) synaptic junctions, mostly on spines, consistent with the conventional view of the organization and function of NMDA receptors. Whereas the anti-NMDAR1 antiserum produced sparse presynaptic axon terminal labeling and extensive glial labeling, the anti-NMDAR1 antibody labeled considerably fewer glia and many more presynaptic axon terminals. Labeled presynaptic terminals formed asymmetric and symmetric synapses, suggesting presynaptic regulation of both excitatory and inhibitory transmission. Immunoreactivity for different subunits of the AMPA receptor (GluR1, GluR2/3, and GluR4) was uniquely distributed across neuronal populations, and some receptor subunits were specific to certain cell types. Immunoreactivity for GluR1 and Glu2/3 was predominantely localized to dendritic shafts and was more extensive than that of GluR4 due to heavy labeling of proximal portions of dendrites. The distribution of GluR4 immunoreactivity was similar to NMDAR1: GluR4 was seen in presynaptic terminals, glia, and dendrites and was primarily localized to spines. The presynaptic localization of GluR4 in the absence of GluR2 suggests glutamate-mediated modulation of presynaptic Ca++ concentrations. These data add to our understanding of the morphological basis of pre- and postsynaptic transmission mechanisms and synaptic plasticity in the amygdala.

Amygdala↗

PubMed1995

The earliest events in vesicular stomatitis virus infection of the murine olfactory neuroepithelium and entry of the central nervous system.

After intranasal instillation of mice with vesicular stomatitis virus (VSV), olfactory receptor neurons are infected. By 12 to 24 hr postinfection, VSV antigens are observed in adjoining supporting and basal cells and in other structures of the olfactory epithelium and lamina propria. Peripheral deafferentation of the olfactory epithelium with Triton X-100 or bilateral surgical bulbectomy does not prevent spread of VSV to the central nervous system (CNS); the route of spread differs considerably from the route taken when the olfactory nerve is intact. In contrast to rabies virus and HSV-1, VSV does not use the trigeminal nerve for entry into the brain, as the trigeminal ganglion remains virus-free following intranasal infection. These results indicate that VSV has a strong tropism for olfactory receptor cells, using them for entry into the CNS. Both retrograde and anterograde transneuronal and nonneuronal (ependymal cells and cerebrospinal fluid) pathways are utilized by VSV within the CNS.

Animals↗

PubMed1995

Demonstration of endothelin (ET) receptors on cultured rabbit chondrocytes and stimulation of DNA synthesis and calcium influx by ET-1 via its receptors.

Endothelin (ET) receptors on chondrocytes were demonstrated using cultured rabbit costal chondrocytes. After crosslinking the receptors on the cells with 125I-ET-1, two major bands of 43 kDa and 46 kDa were separated by SDS-PAGE. Scatchard analysis demonstrated two classes of ET receptors with Kd values of 1 x 10(-10) M and 5 x 10(-9) M. The numbers of high- and low-affinity receptors were 1 x 10(4) and 2 x 10(5) per cell, respectively. The binding of ET-1 to chondrocytes was increased by treatment with PTH, DBcAMP, TGF-beta 1, IL-1 beta, RA and EGF. ET-1 stimulated DNA synthesis in cultured rabbit chondrocytes. ET-1 also stimulated calcium incorporation through the cell membrane of chondrocytes. These findings indicate that ET-1 has a physiological effect on chondrocytes via its receptors on the cells.

Animals↗

PubMed1995

Pathogenesis of murine encephalitis limited by defective interfering particles. An immunohistochemical study.

To determine whether defective interfering (DI) particles alter viral encephalitis BALB/c mice were inoculated intranasally with standard vesicular stomatitis virus (VSV) and its DI particles. Addition of 10(7) PFU equivalents of DI particles to 10(5) PFU of VSV reduced morbidity but did not delay disease onset. Less mortality was also observed. When 10(3) PFU equivalents of DI particles or UV-irradiated DI particles were substituted, these effects were absent. Attempts to correlate mortality with virus recovered from the brain could not be made due to considerable variations in the few surviving mice. Immunohistochemical analysis obtained from 121 mice showed that inoculation of DI particles limited the specific pathways of VSV antigen dissemination within the central nervous system, and new pathways were not substituted. In the group of mice with reduced mortality due to DI particles, at day 4 post inoculation VSV antigen was limited to the outer layers of the glomeruli of the olfactory bulb and to the accessory olfactory bulb, whereas there was deeper invasion of the olfactory bulb and olfactory ventricular system with mice infected with standard VSV alone. Correlation between mortality and extent of invasion became more difficult to make from 8 days on, when VSV antigens were found in discrete areas of the brain. By 12 days, few surviving mice contained any detectable VSV antigen in their brains. These results demonstrate that DI particles have potential as therapeutic agents. Also, mortality resulting from VSV-induced encephalitis, although poorly understood, may be determined very early, possibly while the virus is replicating at the site of inoculation.

Animals↗

PubMed1995

[Enzyme immunoassay for cytokines].

Cytokines produced by different types of cells function by cell to cell interaction both in vitro and in vivo. Over thirty different molecules react in almost all physiological phenomena, such as in the fields of immunology, hematology, endocrinology, neurology, cardiology and nephrology. Previous observations indicate that the abnormal production of cytokines plays a part of pathogenesis of diseases. Therefore, it is necessary to know the amount of cytokines in the biological specimens for recognizing the pathogenic significance of cytokines. In this paper, we show the EIA-Kits of cytokines which are purchased. And we demonstrate the methods, advantages and disadvantages in the different enzyme immunoassays (EIA, DELFIA and Chemiluminescen-EIA) of interleukin 6 which we extensively investigated from basic to clinical experiments may be routinely used in the clinical examination in the near future.

Biomarkers↗

PubMed1995

Investigation of Culicoides (Diptera: Ceratopogonidae) in relation to the transmission of bovine Onchocerca and other filariae in central Kyushu, Japan.

In Kyushu, Japan, where a human case of zoonotic onchocerciasis was found, a survey was conducted to know if the bovine Onchocerca species of this region, O. gutturosa, O. lienalis and O. sp., which develop in local Simulium spp., were also transmitted by Culicoides. A total of 17,006 out of 42,582 females of eight Culicoides species captured by light-traps from May to November in 1989 and 1990 at two cattle sheds, one in Oita and one in Kumamoto, were dissected and examine for Onchocerca infection. Overall results showed that none of the species had filarial infections except 4 of 946 C. arakawae, an ornithophilic species, collected in Oita which harboured filarial larvae with a short tail, belonging to Lemdaninae. Unsheathed microfilariae indistinguishable from O. lienalis or O. gutturosa were found in the midgut of only one blood-fed C. matsuzawai collected in Oita. It is concluded that Culicoides species would not be vectors of these three bovine Onchocerca species. Additional collections of Culicoides in a residential area of Oita showed that several filarial species, Lemdaninae and Splendidofilarinae, probably from birds, are transmitted by C. arakawae.

Animals↗

PubMed1994

Expression of trkC in a mouse osteoblastic cell line and its response to neurotrophin-3.

In a cultured osteoblastic cell line, MC3T3-E1 derived from newborn mouse calvaria, the mRNA encoding TRKC, which is the receptor molecule of neurotrophin-3 (NT-3), was detected by the polymerase chain reaction (PCR) method. The mRNAs of the normal type and one alternative form (C14) were highly expressed in the exponential growth phase of MC3T3-E1 cells and decreased as the cells reached the differentiation stage. NT-3, but not nerve growth factor (NGF), stimulated the proliferation of MC3T3-E1 cells in a dose-dependent manner. NT-3 also stimulated calcium incorporation through the surface of MC3T3-E1 cells, indicating the association of NT-3 and its receptor on the cell surface.

Animals↗

PubMed1994

Perikaryal and synaptic localization of alpha 2A-adrenergic receptor-like immunoreactivity.

Through molecular cloning, the existence of three distinct subtypes of alpha 2-adrenergic receptors (alpha 2AR)--A, B and C--has been established and are referred to as alpha 2A AR, alpha 2B AR and alpha 2CAR. Due to limitations in pharmacological tools, it has been difficult to ascribe the role of each subtype to the central functions of alpha 2AR. In situ hybridization studies have provided valuable information regarding their distribution within brain. However, little is known about their subcellular distribution, and in particular, their pre- versus postsynaptic localization or their relation to noradrenergic neurons in the CNS. We used an antiserum that selectively recognizes the A-subtype of alpha 2AR to determine: (1) the regional distribution of the receptor within brains of rat and monkey; (2) the subcellular distribution of the receptor in locus coeruleus (LC) of rats and prefrontal cortex of monkeys; and (3) the ultrastructural relation of the receptor to noradrenergic processes in LC. Light microscopic immunocytochemistry revealed prominent immunoreactivity in LC, the brainstem regions modulating the baroreflex, the granule cell layer of the cerebellar cortex, the paraventricular and supraoptic nuclei of the hypothalamus (PVN, SON), the basal ganglia, all thalamic nuclei, the hippocampal formation and throughout cerebral cortical areas. Comparison of results obtained from rat and monkey brains revealed no apparent interspecies-differences in the regional distribution of immunoreactivity. Immunoreactivity occurred as small puncta, less than 1 micron in diameter, that cluster over neuronal perikarya. Besides these puncta, cell bodies, proximal dendrites and fine varicose processes--most likely to be axonal--of the PVN and SON and the hippocampal granule cells also exhibited homogeneously intense distribution of immunoreactivity. Subcellularly, alpha 2AAR-ir in LC and prefrontal cortex were associated with synaptic and non-synaptic plasma membrane of dendrites and perikarya as well as perikaryal membranous organelles. In addition, cortical tissue, but not LC, exhibited prominent immunoreactivity within spine heads. Rat brainstem tissue immunolabeled dually for alpha 2AAR and dopamine beta-hydroxylase (D beta H, the noradrenaline-synthesizing enzyme) revealed that alpha 2AAR-li occurs in catecholaminergic terminals but is also prevalent within non-catecholaminergic terminals. Terminals exhibiting alpha 2AAR-li formed symmetric and asymmetric types of synapses onto dendrites with and without D beta H-immunoreactivity. These results indicate that: (1) the A-subtype of alpha 2AR is distributed widely within brain; (2) alpha 2AAR-li reflects the presence of newly synthesized alph 2AAR in perikarya as well as those receptors along the plasma membrane of perikarya, dendritic trunks and spines; and (3) alpha 2AAR in LC may operate as heteroreceptors on non-catecholaminergic terminals as well as autoreceptors on noradrenergic terminals.

Animals↗

PubMed1994

Expression of nerve growth factor family neurotrophins in a mouse osteoblastic cell line.

With cultured osteoblastic cells, clone MC3T3-E1 derived from newborn mouse calvaria, the mRNAs encoding three representative neurotrophins, namely, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), were proved in estimation by the polymerase chain reaction (PCR) method. The increase and then subsequent decrease of all three mRNAs within the proliferation phase were followed by their gradual increase in the differentiation phase, with a tendency of enhancement by exogenous TGF-beta as was particularly evident in the case of NGF. These findings were further substantiated by identification of NGF-like neutrophils in the conditioned medium of the osteoblastic cells by an immunoblotting and neurite extension assay.

Animals↗

PubMed1994

Distribution of vesicular stomatitis virus proteins in the brains of BALB/c mice following intranasal inoculation: an immunohistochemical analysis.

Earlier studies have shown that intranasal instillation of vesicular stomatitis virus (VSV), a negative-sense RNA virus, in mice and rats can result in infection of the brain, hind-limb paralysis and death. Using an antiserum directed against VSV proteins, we sought to determine the potential neuronal and non-neuronal pathways VSV utilize, for central nervous system dissemination in BALB/c mice. Within 12 h following intranasal inoculation of VSV, VSV antigen could be detected in the olfactory nerve layer of the ipsilateral olfactory bulb. Within 3-4 days post-inoculation (p.i.), VSV had disseminated into the glomeruli of the olfactory bulb as well as the anterior olfactory nuclei that were ipsilateral to the VSV instillation. Within the glomeruli, VSV antigen was more prevalent in the granule cells than in the mitral cells. Correspondingly, the lateral olfactory tract, where axons of mitral cells course, remained VSV negative throughout 7 days p.i. By 7 days p.i., viral proteins were detected in several additional regions extending to the brainstem. These included regions involved in theta-rhythm generation during exploration and REM sleep, i.e. the septal nuclei, the supramammillary body, and the hippocampal formation, as well as the amygdaloid complex and brainstem neuromodulatory centers, such as the dorsal raphé and locus coeruleus. Structures abutting the ventricular surfaces, such as the dorsal cochlear nucleus, were also labeled. Tracts immunoreactive to VSV included the dorsal tegmental tract, fascia retroflexus, Probst tract, and mesencephalic tract of the trigeminal motor nerve. Besides the lateral olfactory tract, tracts that remained VSV negative included the anterior commissure, the corpus callosum and the mammillary peduncle. The pattern of VSV immunoreactivity supports the idea that following infection of the olfactory bulb glomeruli, VSV spreads via both ventricular surfaces and retrograde transport within axons of neuromodulatory transmitter systems innervating the olfactory bulb. Conversely, regions exhibiting low levels of VSV antigen are not likely to be involved in VSV dissemination. In particular, the paucity of VSV antigen in some of the terminal fields of neuromodulatory systems indicate that anterograde transport is more selective than retrograde transport. Surprisingly, the principal neurons of the olfactory glomeruli, thalamus, cerebral cortex and the hippocampus, all of which use L-glutamate as the excitatory neurotransmitter, are much less involved in viral dissemination.

Administration, Intranasal↗

PubMed1994

Assessment of bone density in the distal radius with computer assisted X-ray densitometry (CXD).

A modified and improved radiographic absorptiometry of the distal radius which enables on-site analysis, called computer assisted X-ray densitometry (CXD), was evaluated from the viewpoint of quality assessment. Its precision and the correlation with dual energy X-ray absorptiometry (DXA) was evaluated in 12 volunteers (mean age 44.7 years). The profile of CXD-measured radial bone mineral density (RBMD) from 142 subjects (75 premenopausal and 67 postmenopausal women, mean ages 44.9 and 50.6 years, respectively) were compared with previous data by other methodologies of bone mineral analysis. The intra-assay coefficient of variation (CV) was 0.617%, the inter-assay CV was 2.064%, and the inter-observer CV was 0.673%. The correlation between CXD-measured RBMD and DXA-measured RBMD was of statistical significance (r2 = 0.733, P < 0.01). The correlation of CXD-measured RBMD with age, height or weight corresponded well with previous reports. CXD-measured RBMD and DXA-measured vertebral bone mineral density (VBMD) also had a significant positive correlation, but their correlation was not so close (r2 = 0.149, P < 0.01). The discriminative ability of osteoporosis by CXD was of acceptable level (odd's ratio = 5.72, P < 0.05), when assessed by comparison with bone dystrophy score (BDS) on the plain vertebral radiogram. Although some problems remain in technical standardization, CXD could be an easy, inexpensive, and widely applicable alternative of non-weight bearing cancellous bone densitometry.

Absorptiometry, Photon↗

PubMed1994

Ultrastructural localization of D2 receptor-like immunoreactivity in midbrain dopamine neurons and their striatal targets.

Potential cellular substrates for functions ascribed to the dopamine D2 receptor were examined in rat brain using immunoperoxidase for localization of a D2 receptor peptide and immunogold staining for the catecholamine biosynthetic enzyme tyrosine hydroxylase (TH). Specificity of the rat polyclonal antiserum, raised against a 15 amino acid fragment from the third intracellular loop of the D2 receptor, was shown by immunoblot analysis and by selective labeling of cultured Chinese hamster ovary cells permanently transfected with the cDNA for the D2 receptor. Although the light microscopic distribution of immunolabeling for the D2 peptide was diffuse, it was selectively localized to regions containing dopamine cells (substantia nigra and ventral tegmental area) or their forebrain projections (dorsal and ventral striatum, nucleus accumbens, and olfactory tubercles). Electron microscopic examination of the medial substantia nigra and ventral tegmental area revealed readily detectable peroxidase immunoreactivity for the D2 peptide, primarily associated with the smooth endoplasmic reticulum and plasmalemmal surfaces of dendrites. Many D2 peptide-immunoreactive dendrites also contained immunogold labeling for TH, although some dendrites were singly labeled for either marker. In the medial and dorsolateral striatum, immunoperoxidase product for the D2 peptide was localized most extensively in dendrites, with the greatest intensity of immunolabeling seen in spines. A number of striatal dendrites exhibiting D2 peptide labeling were contacted by axon terminals immunoreactive for TH. Additionally, D2 peptide immunoreactivity was distributed to some synaptic vesicles and portions of the plasmalemmal surface in unmyelinated axons and in axon terminals. Most D2 peptide-immunoreactive terminals either lacked detectable membrane specializations, or formed thin, symmetric synapses in single sections. A few D2 peptide-labeled terminals formed asymmetric junctions on dendritic spines. In dually labeled sections, most D2 peptide-immunoreactive terminals lacked detectable immunolabeling for TH. However, in fortunate planes of section, peroxidase product for D2 peptide immunoreactivity was occasionally seen in pre-terminal portions of axons whose terminal varicosities contained immunogold labeling for TH. These ultrastructural results are consistent with the localization of a dopamine D2 receptor-like protein that is strategically positioned to subserve (1) autoreceptor functions at the level of dendrites in the midbrain and presynaptic axon terminals in the striatum, as well as (2) postsynaptic actions on striatal spiny dendrites and other nondopamine terminals.

Animals↗

PubMed1994

Differential expression of homeobox-containing genes Msx-1 and Msx-2 and homeoprotein Msx-2 expression during chick craniofacial development.

The expression pattern of chick Msx-1 and Msx-2 homeobox genes in craniofacial primordia was examined by in situ hybridization using cRNA probes. Both genes were expressed in the distal region of the facial primordia, where the distribution of Msx-2 expression was restricted distally within the Msx-1 expression domain. On the contrary, Msx-2 expression in the lateral choroid plexus and cranial skull was broader and more intensive than Msx-1 expression. Our findings suggest that these two genes cooperate to play differential roles in craniofacial development. Msx-2 protein was detected immunohistochemically, and its localization essentially corresponded to the mRNA expression pattern, substantiating the involvement of Msx-2 protein as a transcriptional regulator in developing limb and face.

Animals↗

PubMed1994

[Bone metabolic markers in osteoporosis].

Since osteoporosis has been defined as "state of low bone mass", the bone mineral measurement has been utilized as a golden standard. However some limitations in bone mineral measurement such as expensive machine, very small extent in bone mineral change and/or required long term observation to detect significant change in bone mass, are prohibited extensive use. On the other hand, recent advances in the measurement of bone metabolic markers arrows us to utilize in the diagnosis of osteoporosis as well as in the monitoring of drug efficacy for osteoporosis. Especially in the monitoring of osteoporosis under some treatment, the magnitude of the change in bone metabolic markers are about 10 times higher than that in bone mineral density. Therefore, the measurement of bone metabolic markers may be utilized more widely in the clinical field of not only osteoporosis but also the other metabolic bone diseases in near future.

Amino Acids↗

PubMed1994

Cellular and subcellular localization of NMDA-R1 subunit immunoreactivity in the visual cortex of adult and neonatal rats.

NMDA receptor activation can alter synaptic strength, cause cell death, and may modulate the release of glutamate and other neurotransmitters. Using a specific and selective antiserum directed against the R1 subunit of the NMDA receptor, we examined (1) whether NMDA receptors in the adult rat visual cortex are exclusively postsynaptic or also presynaptic and (2) whether NMDA-R1 subunits are incorporated into the plasma membrane prior to, contemporaneously, or following the formation of synapses during postnatal development. By light microscopy, NMDA-R1 immunoreactivity in the adult visual cortex is easily detectable within perikarya and proximal dendrites in laminae 2-6. Many of them have the morphological features of pyramidal neurons. In addition, fine punctate labeling is evident throughout the neuropil. Electron microscopy reveals these puncta to reside at postsynaptic densities of axospinous junctions and at fine astrocytic processes and axon terminals. In the deeper laminae, the majority of labeled profiles are astrocytic. Visual cortices of animals in their first postnatal week show concentrated immunoreactivity in a few nonpyramidal neurons within laminae that have just differentiated from the cortical plate. Electron microscopy reveals diffuse labeling along the plasma membrane of dendritic shafts lacking morphologically identifiable synaptic junctions or appositions to axons. Immunoreactivity is detectable in dendritic processes by postnatal day (PND) 2, in axonal processes by PND 4, and in astrocytic profiles by PND 14. Immunoreactivity also is detectable along the postsynaptic membrane of presumably transient axosomatic junctions. At all ages, the prevalence of NMDA-R1-immunoreactive profiles is lamina 1 > 4/5 > 6/6B. These results provide the cellular basis for NMDA receptors' participation in (1) postsynaptic membrane excitability, (2) regulation of transmitter release, (3) and, in the deeper laminae, astrocyte responses. During development, NMDA-R1 subunits are associated with the plasma membrane prior to axons' arrival while clustering of receptors to junctions may be promoted by axonal contact. Finally, spatial segregation of axonal growth cones may be mediated by NMDA-R1 subunits on these axonal processes.

Aging↗

PubMed1993

Nitric oxide synthase in the visual cortex of monocular monkeys as revealed by light and electron microscopic immunocytochemistry.

Recent results indicate that nitric oxide (NO) can play an important role in neuronal excitability by modifying the strength of activated synapses and regulating local cerebral blood flow. We sought to determine whether the level of NO synthase (NOS) could, in turn, also be regulated by neural activity. Results using a polyclonal anti-NOS antibody showed that, in cortical area V1 of monocular monkeys, NOS-immunoreactivity is diminished in lamina 4C neuropil of the deprived ocular dominance columns relative to the immediately adjacent non-deprived columns. Closer examination of lamina 4C indicated that the intercolumnar difference in NOS-immunoreactivity does not reflect differences in the distribution of NOS-labeled perikarya, since relatively few neurons were immunoreactive for NOS in lamina 4C of either monocular or normal binocular monkeys. Electron microscopy revealed that the majority (> 80%) of NOS-immunoreactive profiles in lamina 4C are axon terminals. NOS-immunoreactive spines and dendritic shafts also are present but these are more prevalent in the superficial laminae. In order to determine whether the intercolumnar differences in lamina 4C neuropil correspond to altered densities of NOS cells in the superficial laminae, we performed a series of quantitative analyses. In the superficial laminae, NOS-cells occur as two distinguishable classes: a few that are large and intensely NOS-immunoreactive and many more (ca. 24-fold) that are small and lightly immunoreactive. Analysis of the distribution of 559 small and 105 large NOS-immunoreactive cells within 40-microns-thick tangential sections spanning laminae 2-3 showed that the number of cells (large and small together) associated with each blob is approximately 14 for both deprived (lighter) and non-deprived (darker) blobs. These cells are distributed evenly from the center to periphery of columns. Analysis of the distribution of NOS-cells in the infragranular laminae also did not reveal any columnar differences. These observations suggest that local neural activity may be coupled to NO release via alteration of NOS protein levels specifically within distal axonal processes of neurons. This mechanism could operate in conjunction with the more instantaneous catalytic activation of NOS. Ultrastructural analyses further suggest that NO may act as an anterograde and retrograde messenger arising from terminals in addition to its proposed role as a retrograde messenger arising from dendrites.

Amino Acid Oxidoreductases↗

PubMed1993

Differential immunohistochemical localization of inositol 1,4,5-trisphosphate- and ryanodine-sensitive Ca2+ release channels in rat brain.

Ca2+ release from inositol 1,4,5-trisphosphate (IP3)-sensitive and ryanodine-sensitive intracellular Ca2+ stores is mediated by distinct proteins identified as IP3 receptors (IP3R) and ryanodine receptors (RyR), respectively. We have compared the immunohistochemical localizations of IP3R and RyR in the brain at the light and electron microscopic levels and have also evaluated the distribution of the major brain intracellular Ca(2+)-pumping ATPase. IP3R and RyR occur in overlapping populations of neurons in widespread areas of the brain, but labeling is distinct in a number of areas. For example, IP3R is enriched in cerebellar Purkinje cells and hippocampal CA1 pyramidal cells, while RyR is present at relatively low levels in these cells. RyR is most enriched in the dentate gyrus and CA3/4 areas of the hippocampus, where IP3R levels are low. In the cortex, IP3R is found in pyramidal cell bodies and proximal dendrites, whereas RyR is located predominantly in long, thin apical dendrites of pyramidal cells. In deep cerebellar nuclei, RyR is located in cell bodies that appear devoid of IP3R, whereas IP3R is enriched in terminals surrounding cell bodies. Electron microscopy in the hippocampus reveals RyR in axons, dendritic spines, and dendritic shafts near dendritic spines while IP3R is primarily identified in dendritic shafts and cell bodies. These results suggest that the IP3- and ryanodine-sensitive Ca2+ pools have largely distinct roles in controlling intracellular Ca2+ levels, though in some sites they may interact to varying degrees.

Animals↗