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C Aoki

Publications and source records attributed to C Aoki.

At least 37 records · Page 2Linked to original sources
PubMed1988

Neuropeptide Y-containing neurons in the rat striatum: ultrastructure and cellular relations with tyrosine hydroxylase- containing terminals and with astrocytes.

The ultrastructural localization of neuropeptide Y (NPY) was comparatively examined in the dorsal (caudate-putamen) and ventral (nucleus accumbens) striatum using the peroxidase-antiperoxidase (PAP) method. In both striatal regions, NPY-like immunoreactivity (IR) was detected in perikarya, dendrites and axons. The labeled perikarya were 15-25 microns in a diameter and contained large, deeply and multiply indented nuclei and prominent Nissl bodies. The labeled dendrites contained a few large (80-150 nm) dense-core vesicles, lacked detectable spines and received few afferents. These morphological characteristics of NPY-IR neurons in both areas are in close accord with previous descriptions for the medium aspiny intrinsic neurons. Axon terminals with terminals with NPY-like IR contain primarily small clear round vesicles, as seen in single or serial sections. These terminals formed junctions that lacked recognizable pre- or post- synaptic densities, but showed parallel spacing between apposed plasmalemmas at presumed synaptic clefts. Targets of the axon terminals with NPY-like IR included unlabeled somata, unlabeled proximal dendrites and labeled and unlabeled distal dendrites. The NPY-IR neurons in the caudate-putamen differed from those in the nucleus accumbens in that (1) there were no recognized appositions between labeled dendrites and labeled terminals, and (2) fewer terminals contained large dense-core vesicles. These findings are consistent with the concept that in the nucleus accumbens, the excitability of the NPY-IR neurons may be more directly modulated by NPY or another transmitter co-existing in the terminals. Catecholamines are known to co-exist with NPY in certain rostrally projecting brainstem nuclei. Therefore, in the two striatal regions, we additionally sought to determine (1) whether the NPY-IR neurons might be modulated by catecholaminergic afferents and (2) whether NPY might co-exist with catecholamines in terminals. Goat antiserum against NPY and rabbit antiserum against tyrosine hydroxylase (TH), the catecholamine-synthesizing enzyme, were simultaneously localized in single sections by PAP and immunoautoradiographic methods, respectively. Quantitative analysis in dually labeled sections from both striatal areas revealed few, if any, direct synaptic contacts between TH-labeled terminals and dendrites containing NPY-like IR. However, there was convergence of separate NPY- and TH-IR terminals on unlabeled dendrites. A few terminals in the nucleus accumbens, but not in the dorsal striatum, showed immunoreactivity methods, to TH and also contained dense-core vesicles with NPY-like IR.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Effects of dobutamine and terbutaline on the secretion of glycoproteins from the acinar cells of the rat submandibular gland.

The actions of dobutamine (DOB) and terbutaline (TER) on the secretion of marker glycoprotein (GP) from the secretory cells of the glands and secretion of fluid from rat submandibular gland (SMG) were investigated in combination with two antagonists, metoprolol (MET) and ICI-118551 (ICI). The ED50 value of fluid secretion was 8.7 mg/kg for DOB and 5.9 mg/kg for TER. MET, administered prior to either agonists at a dose of 40 mg/kg, inhibited the fluid secretion. However, the blocking effects of ICI were considerably lower than those of MET. The electrophoretic profiles of GP in DOB-evoked saliva were similar to those in TER-evoked saliva, and included two characteristic main bands of GP I (130 KDa) and GP IV (21.5 KDa) from the acinar cells and a minor band of GP III (31 KDa) which originated in the cells of the granular tubules. When MET was administered at a dose of 5 mg/kg prior to DOB, the intensity of band I decreased, whereas that of band III did not change. These results showed that the SMG of rats contains both beta 1- and beta 2-adrenoceptors and that beta-receptors which mediate the secretion of GP from the acinus and fluid from the gland are mainly of the beta 1-subtype.

Adrenergic beta-Antagonists↗
PubMed1988

A comparative study of the effects of four choline esters on the secretion of fluid and glycoprotein from rat submandibular glands.

The actions of four choline esters, acetylcholine (ACH), methacholine (MET), carbachol (CAR) and bethanechol (BET), on the secretion of saliva and the specific glycoprotein (GP) contained in the secretory cells of the submandibular gland (SMG) of the rat were compared under conditions with and without physostigmine (PHY). The ED50 values with respect to salivation were 17 mg/kg for ACH, 1060 micrograms/kg for BET, 810 micrograms/kg for MET and 75 micrograms/kg for CAR, whereas after pretreatment with PHY, ED50 values were lowered to 7.5 mg/kg for ACH and 212 micrograms/kg for MET, but remained unchanged for CAR and BET. SDS-polyacrylamide gel electrophoresis demonstrated that the saliva from the SMG elicited by the four choline esters contained GP I (130 KDa) and GP IV (21.5 KDa), characteristic of the acinus, and a band of GP III (31 KDa), which originates from the granular tubules. The order of intensity of these bands was band I much greater than band III = band IV. Among these bands, band I increased in intensity in a dose-dependent manner. These results suggest that the four choline esters act mainly on the acinar cells, but exert some effects on the granular tubules of the rat SMG.

Acetylcholine↗
PubMed1987

Ultrastructural localization of beta-adrenergic receptor-like immunoreactivity in the cortex and neostriatum of rat brain.

We sought to quantitatively examine the processes containing beta-adrenergic receptor-like immunoreactivity (beta-AR-LI) in the cerebral cortex and neostriatum using a previously characterized rabbit antiserum to frog erythrocyte beta-ARs under optimized immunolabeling conditions. Quantitative assessments of the laminar distribution of beta-AR-LI in the cortex was achieved by computer-assisted image analysis of immunoautoradiographs and by quantitative electron microscopic analysis of peroxidase-antiperoxidase (PAP) labeling in aldehyde-fixed sections and unfixed synaptosomes. In the somatosensory and anterior cingulate cortical areas, light microscopy of aldehyde-fixed sections immunolabeled by the PAP method revealed small (0.5-1.0 micron) punctate processes in all layers. In the deeper layers, rims of immunoreactivity around the plasmalemma of a population of neuronal perikarya and processes were also observed. By immunoautoradiography, labeling was seen in distinct, laminar distributions resembling the reported autoradiographic patterns using radioligands. By electron microscopy, the immunoreactive profiles in all cortical layers were primarily thick and thin postsynaptic densities (PSDs), comprising 4% of all identifiable PSDs in fixed sections and 12% in unfixed synaptosomal preparations. Also labeled were saccules of smooth endoplasmic reticulum and pinocytotic vesicles in dendrites, glial processes and lightly myelinated axons. In the neostriatum, the density of autoradiographic immunoreactivity was equivalent to the heavily labeled laminae of the cerebral cortex. Immunoreactivity detectable by light microscopy included punctate processes and rims of perikarya, as was seen in the cerebral cortex. The PAP reaction was shown by electron microscopy to be localized to the cytoplasmic surface of plasmalemma of a few proximal dendrites, but was most prominently associated with PSDs of dendritic spines. Preadsorption of the antiserum with a partially purified beta-AR preparation abolished all detectable immunoreactivity. These results provide further support for the specificity of the antiserum for beta-ARs, and are the first quantitative ultrastructural evidence for association of beta-AR-LI with PSDs in the cerebral cortex. The neostriatum, whose major catecholaminergic innervation is dopaminergic, and not noradrenergic, is also confirmed to exhibit high levels of beta-AR-LI within subcellular structures analogous to those seen in the cerebral cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Benzodiazepine ([3H]flunitrazepam) binding in cat visual cortex: ontogenesis of normal characteristics and the effects of dark rearing.

[3H]Flunitrazepam (FNZ) binding sites were characterized in homogenates of cat visual cortex during normal postnatal development and following dark rearing from birth. In parallel experiments, the distribution and density of [3H]FNZ binding sites were examined by in vitro autoradiographic or 'scrape' methods. In homogenates, Bmax measurements showed low early values, rising to a peak in receptor density at about 60 days postnatal, followed by a decline in adulthood. At all ages, gamma-aminobutyric acid (GABA) altered the Kd, but not the Bmax of [3H]FNZ binding sites. Kd values showed a general increase with age, parallelled by an increased sensitivity to GABA. Receptor autoradiography revealed that the highest density of [3H]FNZ binding sites was in layer IV of cats of all ages. Deafferentation of extrinsic inputs to the visual cortex by surgical undercutting did not alter this pattern of laminar distribution, indicating that the receptors were associated with intrinsic cortical elements rather than subcortical inputs. Dark rearing had no effect on [3H]FNZ laminar distribution in the visual cortex. The Bmax was higher at 30 days postnatal, but did not differ significantly thereafter. Modulation by GABA was concomitantly higher at 30 days, but lower than normal in dark-reared animals at ages greater than 30 days postnatal. The results are discussed in relation to the normal and abnormal development of GABA receptors in the cat visual cortex.

Animals↗
PubMed1987

Differential glucose utilization in the parafascicular region during slow-wave sleep, the still-alert state and locomotion.

Regional cerebral glucose utilization (CGU), detectable by the uptake of 2-deoxy-[14C]glucose [( 14C]2DG), was examined during 3 behavioral states--slow-wave sleep (SWS), the still-alert state (SAL) and locomotion (LOC). Examination of the autoradiograms, generated by exposing the [14C]2DG incorporated brain sections to Kodak Royal X Pan film revealed a high level of uptake bilaterally and discretely in the parafascicular (PF) region during these behaviors. This pattern of [14C]2DG uptake does not correspond to any of the anatomical structures previously identified by histo- and cytochemical methods, including the [14C]2DG method. Further, optical density measurements of this region indicated that the [14C]2DG uptake was significantly lower during SWS than during SAL or LOC. The present finding is compatible with the interpretations of previous physiological and behavioral studies that there is an inhibition by cells at the PF relay to the dentate gyrus that is lowered during the SWS compared to the SAL state, thus allowing preferential brain-stem activation of the dentate gyrus.

Animals↗
PubMed1987

Glial glutamate dehydrogenase: ultrastructural localization and regional distribution in relation to the mitochondrial enzyme, cytochrome oxidase.

Glutamate dehydrogenase (GDH) is primarily a mitochondrial enzyme involved in the metabolism of glutamate. We have recently shown by light microscopic immunocytochemistry that, within detergent-permeabilized brain tissue, GDH is enriched in glial cells, particularly in regions utilizing L-glutamate as a neurotransmitter. In this study, we used immunogold labeling to quantitatively establish that the form of the enzyme recognized by the presently used GDH antiserum is associated primarily with a subpopulation of mitochondria in ultrathin, plastic-embedded sections of the rat cortex and striatum. Permeabilization with detergents was omitted in these studies, so as to preserve the ultrastructure. As expected, labeled mitochondria occurred both in neurons and glia. Furthermore, light microscopic comparisons of the regional distributions of peroxidase immunoreactivity for GDH and a histochemical reaction product for a second mitochondrial enzyme, cytochrome oxidase (CO), were used to demonstrate that high levels of GDH in glia of glutamate-receptive areas do not necessarily reflect the areas' demand for elevated oxidative metabolism. While all regions showing intense labeling for glial GDH also exhibited high levels of CO activity, many additional regions showing high levels of CO activity contained no detectable immunoreactivity for glial GDH. These light-microscopic comparisons reveal that the energy requirements are not the only factors accounting for the regional heterogeneity of the enzyme. We conclude that glial mitochondria are heterogeneous with respect to their GDH content and that GDH is enriched in areas exhibiting chronically active glutamatergic transmission.

Animals↗
PubMed1987

Effects of dopamine on the secretion of glycoproteins from the functional segments of the rat submandibular gland.

The action of dopamine (DA) on salivation and the secretion of marker glycoproteins (GP) from secretory cells of the rat submandibular gland (SMG) was investigated using various blockers at doses of 1 or 2 mg/kg (i.v.). DA at doses from 5 to 40 mg/kg (i.p.) dose-dependently increased salivation and the concentration of protein in SMG saliva. The order of inhibitory potency on salivation was propranolol (PPR) greater than phentolamine (PHN) much greater than haloperidol (HAL) when DA was administered i.p. at a dose of 10 mg/kg and PHN much greater than HAL much greater than PPR when the dose of DA was 40 mg/kg. The concentration of protein in saliva after pretreatment with HAL or PHN increased significantly at a dose of 40 mg/kg of DA, but did not increase at a dose of 10 mg/kg of DA. Moreover, pretreatment with PPR decreased it at both doses of DA. The electrophoretic profiles of GP in DA-evoked saliva showed two characteristic main bands of GP I (130 KDa) and GP IV (21.5 KDa) contained in the acinar cells (AC) and a minor band of GP III (31 KDa) which originated from the granular tubular cells (GT). The profile was not changed by pretreatment with PHN and HAL when DA was administered at a dose of 10 mg/kg, but at a dose of 40 mg/kg, the intensity of band I increased. Pretreatment with PPR, when DA was administered at 40 mg/kg, caused an increase in the intensity of band III and a reduction in that of band I. These results suggest that DA, at low doses, affects the AC, whereas at a higher dose, it affects both the AC and GT.

Animals↗
PubMed1987

Regional distribution of astrocytes with intense immunoreactivity for glutamate dehydrogenase in rat brain: implications for neuron-glia interactions in glutamate transmission.

The principally mitochondrial enzyme glutamate dehydrogenase (GDH) exhibited low-intensity, uniform immunoreactivity in neurons and intense heterogeneous labeling of glial cells of rat brain. Simultaneous peroxidase labeling for GDH and immunoautoradiography for glial fibrillary acidic protein (GFAP) confirmed the astrocytic localization of the enzyme. Immunoreactivity in astrocytes, but not in neurons, required the presence of Triton X-100 as a solubilizing agent. Most of the intensely labeled glial processes were localized to regions previously reported as containing moderate to high densities of binding sites for the excitatory amino acids, L-glutamate or L-aspartate, and glutamatergic fibers. These included several forebrain regions, such as the superficial layers of the rostral neocortex, dorsal neostriatum, nucleus accumbens, septohippocampal nucleus, intralaminar thalamic nuclei, and external capsules. However, the central gray of the midbrain, the nuclei of the reticular formation, brain stem regions projecting to the cerebellum, and cranial nuclei of the trigeminal and vagal nerves also exhibited intense glial labeling for GDH, even though some of these regions are known to receive only weak glutamatergic projections. A second factor determining the distribution of GDH appeared to be neuronal activity, as assessed by correspondence with reported high densities of cytochrome oxidase. We conclude that GDH enriched in glial populations exists in a subcellular compartment distinct from that of neurons and may serve as one of the enzymes involved in glutamatergic transmission. Deficiencies of glial GDH and the consequent cytotoxic effects of high levels of excitatory amino acids may contribute to a number of neurodegenerative disorders.

Animals↗
PubMed1987

Light microscopic immunocytochemical localization of pyruvate dehydrogenase complex in rat brain: topographical distribution and relation to cholinergic and catecholaminergic nuclei.

Pyruvate dehydrogenase complex (PDHC; EC 1.2.4.1, EC 2.3.1.12 and EC 1.6.4.3) includes 3 catalytically active mitochondrial enzymes involved in the formation of cellular energy through the tricarboxylic acid cycle and in the synthesis of ACh. We sought to determine whether immunocytochemically detected PDHC was enriched in neurons of the rat CNS, and, if so, whether the perikarya containing higher levels of PDHC immunoreactivity were differentially distributed with respect to their size or location within nuclear groups containing ACh, catecholamines or other unidentified transmitters. Under the labeling conditions used in this study, the peroxidase-antiperoxidase immunoreaction product for PDHC was detectable principally in neuronal perikarya. The intensity of immunoreactivity within perikarya was variable as judged visually and by cellular, computer-assisted densitometry. In the forebrain, the most intensely labeled perikarya were seen in the medial septal nuclei, the nuclei of the diagonal band, the nuclei basalis, the dorsal and ventral striatum, and the entorhinal cortex. More caudally, intense immunoreactivity was detected in perikarya in the supraoptic hypothalamic nuclei, reticular thalamic nuclei, lateral substantia nigra, most of the tegmental nuclei, lateral nuclei of the trapezoid body, raphe pontis and obscuris, and the caudal part of the lateral reticular nuclei. In addition, many of the motor nuclei of the cranial nerves, including the dorsal motor nuclei of the vagus and the hypoglossal nuclei, and the nucleus ambiguus contained perikarya with intense PDHC labeling. Densitometry revealed no differences in intensity of immunoreactivity in soma of varying sizes. However, the intensity of neuronal labeling for PDHC was significantly greater in several nuclear groups that were shown in adjacent sections to contain cholinergic, but not catecholaminergic, enzymes. In contrast, the primary olfactory cortex, pyramidal cell layer of the regio inferior of hippocampus, and the Purkinje cell layer of the cerebellum were regions having perikarya with intense PDHC immunoreactivity but lacking both the synthetic and the degradative enzymes for ACh. These results provide the first morphological evidence that PDHC, a general metabolic enzyme complex, is enriched in selective perikarya that are heterogeneously distributed in brain and are especially abundant in many of the regions containing cholinergic neurons. The heterogeneity of PDHC immunoreactivity suggests that certain cholinergic as well as noncholinergic nuclei may be selectively vulnerable to mitochondrial diseases involving pyruvate utilization.

Animals↗
PubMed1986

The ontogeny of the laminar distribution of beta-adrenergic receptors in the visual cortex of cats, normally reared and dark-reared.

Patterns of distribution of beta 1 and beta 2 adrenergic receptors were examined autoradiographically in slide-mounted sections from the visual cortical areas of 22 developing cat brains, using [125I]iodopindolol as the ligand in combination with displacers specific for beta 1 and beta 2 subtypes of adrenergic receptors. Within visual cortical areas 17 and 18 of adult brains, the density of beta 1 and beta 2 adrenergic receptors was highest in laminae I-III, lowest in lamina IV, and intermediate in laminae V-VI. For beta 1 adrenergic receptors, this laminar distribution was also seen in visual area 19 as well as in the non-visual area 7 that is lateral to area 19. By contrast, the distribution of beta 2 adrenergic receptors varied across cortical areas, such that its density was more homogeneous across the laminae in area 19, and decreased in all laminae in area 7. This pattern of distribution in adult brains was already formed at the beginning of the critical period and was not disturbed by dark-rearing.

Animals↗
PubMed1986

The laminar distributions and postnatal development of neurotransmitter and neuromodulator receptors in cat visual cortex.

We review efforts to further understand the development and nature of sensory processing mechanisms in the cat visual cortex. In vitro autoradiographic and homogenate assay techniques have been employed to determine the laminar distribution and characteristics of various neurotransmitter and neuromodulator receptor populations during postnatal development. Each receptor population shows a distinct laminar-specific pattern of binding, which, in most cases, is age-dependent. Changes in receptor number and affinity are also observed during postnatal development. These findings indicate that major alterations in the basic chemical circuitry of cat visual cortex are a normal feature of postnatal maturation and may play a role in plasticity mechanisms.

Aging↗
PubMed1986

Effects of substance P on glycoprotein secretion from acinar cells of the rat submandibular gland.

The action of substance P on glycoprotein secretion from acinar cells of the rat submandibular gland was described in this report. Salivation elicited by i.v. injection of 0.5 to 20 micrograms/kg of substance P was increased dose-dependently, and its flow rate was highest at the first 1 min. Major glycoprotein species secreted into saliva by substance P-stimulus were shown to be electrophoretically identical with those found in acini, but not granular convoluted tubules. These results support the view that substance P acts on acinar cells of the submandibular gland and stimulates secretion of saliva from the cells.

Animals↗
PubMed1985

Modification of neurotransmitter receptor sensitivity in cat visual cortex during the critical period.

We have examined the characteristics of various receptors in cat visual cortex during postnatal development. These included beta-adrenergic, GABA, benzodiazepine and acetylcholine receptors. For each population of receptor the number (Bmax) and affinity (Kd) were examined as a function of postnatal age (3 days-adult). For all receptors examined, the Bmax increased during development from low early values to a peak within the critical period. The Kd also changed during development for most receptors. The simultaneous alterations in Bmax and Kd necessitate defining a term which takes both of these receptor properties into consideration. This term, called receptor sensitivity (RS), provides a more comprehensive measure of receptor function than either Bmax or Kd alone. Using this measure, we find that receptor sensitivity is low near birth for the 4 receptor populations studied, rises to a peak within the first two months of life, and then declines to near-neonatal levels for 3 of the 4 receptor populations.

Animals↗
PubMed1985

Development of the A1 adenosine receptors in the visual cortex of cats, dark-reared and normally reared.

The ontogeny of the distribution of the binding sites for [3H]chlorohydroxyladenosine, an A1 adenosine receptor-specific ligand, was visualized autoradiographically within coronal sections of the visual cortical areas of developing cats. In adults, the A1 adenosine receptors were found in all lamina except for lamina IV, and in particularly high concentration within laminas I-III. In brains of kittens 2 months old and younger who were within the critical period for the development of visual neural function, the receptor distribution was less defined and sparser, except that in contrast to adults, it was found in relatively high concentration within lamina VI. Animals dark-reared from birth, so that the critical period was postponed, exhibited an ontogenetic pattern identical to that of the normally reared animals. These results indicate that, at least with respect to ocular dominance determination, A1 adenosine receptors are probably not involved in determining the state of plasticity that is seen during the critical period.

Animals↗
PubMed1985

Comparison of proteins involved with cyclic AMP metabolism between synaptic membrane and postsynaptic density preparations isolated from canine cerebral cortex and cerebellum.

Synaptic membrane and postsynaptic density (PSD) fractions isolated from canine cerebral cortex and cerebellum were assayed for the following proteins: adenylate cyclase and phosphodiesterase (PDE) activities against cyclic AMP and cyclic GMP, the regulatory subunit of the cyclic AMP-dependent protein kinase, and the substrate proteins for this kinase. The results were expressed on the basis of both the protein content of the fractions and the number of synapses in the synaptic membrane fractions. The number of synapses on a constant protein content basis was about three times higher in the cerebral cortex synaptic membrane fraction than in the comparable cerebellar fraction. Adenylate cyclase activity was from 3.4 to 5.6 times higher in the cerebral cortex membrane fraction than in the cerebellar membrane fraction based on protein content but only slightly higher based on synapse counts. PSD fractions had no adenylate cyclase activity. The cyclic AMP-PDE activity was from 17 to 27 times higher in the cerebral cortex membrane fraction than in the cerebellar membrane fraction based on protein content, and about five times higher based on synapse counts. By doing PDE histochemistry at the electron microscopy level it was found that all the cerebral cortex PSDs in the isolated fraction contained PDE activity, none being found associated with the broken-up material in the fraction. The amount of the regulatory subunit of the cyclic AMP-dependent protein kinase was about equal in the two fractions based on protein, but about one-third lower in cerebral cortex fraction than in cerebellar fractions. In the cerebral cortex membrane fraction the primary substrate for the cyclic AMP-dependent protein kinase is synapsin I, with much lower amounts in the cerebellar membrane fraction. The PSD fraction from the two sources also showed these differences in synapsin I content. In the cerebellar membrane fraction, the primary substrate for the enzyme is a approximately 245,000 Mr protein not found in the cerebral cortex membrane fraction. The findings that the turnover of cyclic AMP is much higher in cerebral cortex synapses than in cerebellar synapses, and that differences are found between the cerebral cortex and cerebellum with regard to the substrate proteins for the cyclic AMP-dependent protein kinase indicate a divergence in the effect of cyclic AMP between cerebral cortex and cerebellar synapses.

3',5'-Cyclic-AMP Phosphodiesterases↗