Biomedical subjects

O Yasuhara

Publications and source records attributed to O Yasuhara.

At least 19 recordsLinked to original sources

PubMed2003

Expression of a splice variant of choline acetyltransferase in magnocellular neurons of the tuberomammillary nucleus of rat.

A splice variant of choline acetyltransferase mRNA has recently been identified in the pterygopalatine ganglion of rat. An antibody against this variant protein (designated pChAT) was demonstrated to immunolabel peripheral cholinergic neurons. In the present study, we investigated the expression of pChAT in rat brain. Amongst the brain regions examined, magnocellular neurons in the tuberomammillary nucleus of the posterior hypothalamus were immunohistochemically labelled with anti-pChAT antibody, whilst no immunolabelling was detected in cholinergic neurons in the basal forebrain or striatum. RT-PCR analysis confirmed the expression of pChAT mRNA in the posterior hypothalamus. The distribution of pChAT-positive neurons in the tuberomammillary nucleus was compared with that of neurons positive for adenosine deaminase, which is contained in all neurons of this nucleus. After colchicine treatment to inhibit axonal transport of enzyme, virtually all pChAT-positive cells contained adenosine deaminase. Conversely, about 85% of adenosine deaminase-positive cells contained pChAT in the ventral area, whilst 19% of adenosine deaminase-positive cells were pChAT-positive in the dorsal area. Long axonal projections of pChAT-positive cells in the tuberomammillary nucleus were shown by retrograde labelling of these cells after injection of cholera-toxin B subunit into the cerebral cortex. This study demonstrates that a splice variant of choline acetyltransferase is expressed in the tuberomammillary nucleus of rat. The results raise the possibility that some of the known diverse projection areas of this nucleus may have a cholinergic component.

Acetylcholine↗

PubMed2000

Immunohistochemical demonstration of choline acetyltransferase of a peripheral type (pChAT) in the enteric nervous system of rats.

Using a recently developed antiserum against a splice variant (pChAT) of choline acetyltransferase, the enzyme which synthesizes acetylcholine, we carried out an immunohistochemical examination in the digestive canal of rats. Positive staining was exclusively localized to neuronal cells and fibers. Positive somata were distributed widely in the intramural ganglia throughout the digestive tract from the esophagus to the rectum. Double staining indicated that, in the rat, virtually all pChAT immunoreactive somata exhibited histochemical activity for acetylcholinesterase but not for NADPH-diaphorase. In the guinea pig, however, there were a few neurons possessing both pChAT and NADPH-diaphorase. We also found a few neuronal somata which were positive for acetylcholinesterase but not for pChAT. The results suggest that pChAT immunohistochemistry is useful for studying the enteric cholinergic system.

Acetylcholinesterase↗

PubMed2000

Enhancement of progenitor cell division in the dentate gyrus triggered by initial limbic seizures in rat models of epilepsy.

PURPOSE: Mitogenic effects of seizures on granule cell progenitors in the dentate gyrus were studied in two rat models of epilepsy. We investigated which stage of epileptogenesis is critical for eliciting progenitor cell division and whether seizure-induced neuronal degeneration is responsible for the enhancement of progenitor cell division. METHODS: Seizures were induced by either kainic acid (KA) administration or electrical kindling. Neurogenesis of dentate granule cells was evaluated using the bromodeoxyuridine (BrdU) labeling method, and neuronal degeneration was assessed by in situ DNA fragmentation analysis. RESULTS: After injection of KA, the number of BrdU-positive granule cells began to increase at day 3 after the treatment, peaked at day 5, and returned to baseline at day 10. By day 13, the values were lower than control. After kindling, the number of BrdU-positive cells began to increase after five consecutive experiences of stage I seizures. The increase occurred from day 1 to day 3 after the last electrical stimulation, but returned to baseline by day 7. After generalized seizures were well established, repeated stimulation did not facilitate division of granule cell progenitors. DNA fragmentation was noted in pyramidal neurons in the CA1, CA3, and hilus regions at 18 h after KA injection, but not in the kindling model. CONCLUSIONS: These observations indicate that a mechanism in epileptogenesis boosts dentate progenitor cell division, but progenitor cells may become unreactive to prolonged generalized seizures. Pyramidal neuronal degeneration is not necessary for triggering the upregulation. It is suggested that newly born granule cells may play a role in the network reorganization that occurs during epileptogenesis.

Animals↗

PubMed1999

Two modes of corticospinal reinnervation occur close to spinal targets following unilateral lesion of the motor cortex in neonatal hamsters.

Although it has been shown that unilateral neonatal cortical ablation induces bilateral corticospinal projections, the explanation for the pathways responsible for this bilateral innervation remains controversial. We hypothesized that such reinnervation may be supplied from newly formed fibers sprouting at the level rostral to, or at, or caudal to the pyramidal decussation. In order to test our hypothesis, we examined the brain and spinal cord of young hamsters which had a unilateral ablation of the right motor cortex at six days postnatally, and then received an injection of an anterograde neuronal lectin tracer, Phaseolus vulgaris-leucoagglutinin, into the hindlimb area of the left motor cortex at 21 days postnatally. For the identification of motoneurons in the lumbar spinal cord, some of these animals also received an injection of cholera toxin subunit B, a retrograde tracer, into the gastrocnemius muscle. A quantitative analysis in the left gray matter of the lumbar spinal cord indicated that the lectin labeling was two to eight times higher in cortically ablated animals than in intact animals. Immunohistochemical detection of the lectin revealed that innervation of the left spinal cord occurred close to targets at lower levels in the spinal cord. Two modes of reinnervation (types I and II) by the intact corticospinal tract were recognized. The type I fibers consisted of recrossing axon collaterals sprouted from the intact dorsal funiculus near their targets, while the type II fibers were recrossing parent axons which entered the intact, right gray matter several levels rostral to their targets, and then changed direction toward the targets. The recrossing at lower spinal levels yielded a large number of ipsilaterally labeled axons and their terminals in the gray matter of the denervated lumbar cord, with a distribution pattern similar to that seen on the intact side. The present results indicate that such ipsilateral innervation may play an important role in the sparing and recovery of function following neonatal hemicortical injury.

Animals↗

PubMed1999

Immunohistochemical localization of choline acetyltransferase of a peripheral type in the rat larynx.

As shown in the accompanying paper, choline acetyltransferase, so far the best histochemical marker for identifying cholinergic structures, has at least one alternative splice variant. The variant, termed pChAT because of its preferential expression in peripheral organs, encouraged us to study peripheral, probably cholinergic, cells and fibers by immunohistochemistry using an antiserum against a peptide specific for pChAT. We chose the larynx of the rat, since cholinergic innervation in this organ has been well established by physiological studies, but not sufficiently by chemical neuroanatomy. Neuronal somata positive for pChAT were found in the intralaryngeal ganglia. Our double staining study indicated that these somata always possessed acetylcholinesterase activity, while the reverse did not hold true. Nerve fibers positive for pChAT were distributed widely in the intrinsic laryngeal muscles, laryngeal glands, blood vessels and laryngeal mucosa. In the intrinsic laryngeal muscles, pChAT-positive terminals were apposed closely to motor end-plates which were stained positively for acetylcholinesterase activity. Denervation experiments revealed that there were three types of pChAT-positive fibers in the larynx: (1) special visceral efferent fibers to the intrinsic laryngeal muscles, which decreased dramatically in number after vagotomy; (2) parasympathetic postganglionic fibers near the laryngeal glands and blood vessels, which appeared unaffected after vagotomy or cervical sympathectomy: and (3) afferent fibers innervating the laryngeal mucosa, which reduced markedly in number after vagotomy performed distal, but not proximal, to the nodose ganglion. Such afferent fibers remained unchanged following the neonatal capsaicin treatment, suggesting their independence from those containing substance P.

Afferent Pathways↗

PubMed1997

Expression of interleukin-1 receptor antagonist protein in post-mortem human brain tissues of Alzheimer's disease and control cases.

The immunohistochemical localization of interleukin-1 receptor antagonist protein (Il-1ra) was examined in brain tissues of neurologically normal controls as well as in cases of Alzheimer's disease (AD) and Pick's disease. In all control cases, immunoreactivity was observed in some normal-appearing neurons in the neocortex and hippocampus. In AD, there appeared to be increased numbers of positively staining neurons, and the staining of individual neurons was somewhat more intense. Il-1ra was additionally expressed in globular deposits in senile plaques and, weakly, in some extracellular neurofibrillary tangles. In Pick's disease, there was similar staining of normal-appearing neurons and intense staining in some degenerating neurons. Using reverse transcriptase-polymerase chain reaction techniques, the mRNA for IL-1ra was detected in cultured IMR-32 human neuroblastoma cells following differentiation with dibutyryl cAMP and bromodeoxyuridine. Taken together, these data suggest that IL-1ra is a product of normal neurons which may be upregulated in some pathological circumstances.

Aged↗

PubMed1997

Immunohistochemical localization of low-affinity nerve growth factor receptor in the enteric nervous system of adult rats.

The localization of low-affinity nerve growth factor receptor in the enteric nervous system of adult rats has been studied by immunohistochemistry using a monoclonal antibody (clone 192) against the rat receptor. Cryostat and whole-mount sections were stained. By light and confocal microscopy, positive staining in neural structures was found in every part of the gut. In the ganglionic plexus, dense staining was detected in the neuropil surrounding neuronal cell bodies that were themselves devoid of immunoreactivity. Immunoelectron microscopy revealed deposition of reaction products on the outer plasma membranes of both perikarya and processes of neuronal as well as glial cells. Such a selective localization of the receptor in the plasma membrane, but not the cytoplasm, suggests that the mechanisms of receptor-ligand interaction in the gut may differ from those in the brain, where internalization of the receptor is observed in cholinergic cells. The present study provides the morphological basis for future studies designed to elucidate the functional significance of this enteric nervous system receptor. Since it is found in both neuronal and glial cells, it is probably under the influence of a number of trophic factors, including nerve growth factor.

Animals↗

PubMed1996

Pancreastatin-like immunoreactivity in globular dystrophic neurites of senile plaques in brains of patients with Alzheimer's disease.

The immunohistochemical localization of pancreastatin (PST) was examined in brains of Alzheimer's disease (AD) and control cases using three different antisera to PST, and was compared with the staining for chromogranin A (CgA), the precursor of PST. In control brains, CgA-like immunoreactivity was observed in the cytoplasm and fibers of certain neuronal populations, which were not immunostained with any of the PST antisera. In AD brains, dystrophic neurites of globular shape located in senile plaques were immunostained with each of the PST antisera, as well as with the CgA antibody. PST-positive and CgA-positive dystrophic neurites showed similar profiles. The present study indicates that CgA is probably cleaved to produce PST in some globular dystrophic neurites in senile plaques.

Aged↗

PubMed1996

Reactive microglia specifically associated with amyloid plaques in Alzheimer's disease brain tissue express melanotransferrin.

Several investigations have implicated the involvement of metals in neuropathologies. In particular, the disruption of iron metabolism and iron transport molecules have been demonstrated in Alzheimer's disease (AD). We have identified a novel pathway of iron uptake into mammalian cells involving melanotransferrin, or p97, which is independent of the transferrin receptor. Here we investigated whether there is a possible link between this molecule and the pathology of AD. The distributions of melanotransferrin, transferrin and the transferrin receptor were studied immunohistochemically in brain tissues from AD cases. In brain tissues from AD, melanotransferrin and the transferrin receptor were highly localized to capillary endothelium, while transferrin itself was mainly localized to glial cells. In brain tissue derived from AD patients, melanotransferrin was additionally detected in a subset of reactive microglia associated with senile plaques. Our demonstration that melanotransferrin mediates iron uptake through a pathway independent of the transferrin receptor indicates that this mechanism may have a role in AD.

Aged↗

PubMed1996

Coincident expression and distribution of melanotransferrin and transferrin receptor in human brain capillary endothelium.

One method of iron transport across the blood brain barrier (BBB) involves the transferrin receptor (TR), which is localized to the specialized brain capillary endothelium. The melanotransferrin (MTf) molecule, also called p97, has been widely described as a melanoma specific molecule, however, its expression in brain tissues has not been addressed. MTf has a high level of sequence homology to transferrin (Tf) and lactoferrin, but is unusual because it predominantly occurs as a membrane bound, glycosylphosphatidylinositol (GPI) anchored molecule, but can also occur as a soluble form. We have recently demonstrated that GPI-anchored MTf provides a novel route for cellular iron uptake which is independent of Tf and its receptor. Here we consider whether MTf may have a role in the transport of iron across the BBB. The distributions of MTf, Tf and the TR were studied immunohistochemically in human brain tissues. The distributions of MTf and TR were remarkably similar, and quite different from that of Tf. In all brain tissues examined, MTf and the TR were highly localized to capillary endothelium, while Tf itself was mainly localized to glial cells. These data suggest that MTf may play a role in iron transport within the human brain.

Animals↗

PubMed1996

Midkine-like immunoreactivity in extracellular neurofibrillary tangles in brains of patients with parkinsonism-dementia complex of Guam.

Midkine (MK) has been shown to be present in amyloid deposits in Alzheimer's disease (AD). In the present study, expression of midkine was examined immunohistochemically in brains of patients with the parkinsonism-dementia complex of Guam, lytico bodig disease (LB), using an affinity purified antibody to midkine. Positive staining was identified on some extracellular neurofibrillary tangles. The relative prevalence was somewhat less than for beta-amyloid protein (Abeta)-positive extracellular tangles. The results demonstrate that expression of MK and Abeta is not an exclusive feature of amyloid deposits in Alzheimer brain, but is also found in LB brain.

Antibody Specificity↗

PubMed1995

Complement C1 inhibitor is produced by brain tissue and is cleaved in Alzheimer disease.

C1 inhibitor was identified in human brain tissue by Western blotting and by immunohistochemistry using multiple antibodies to the native protein. The presence of C1 inhibitor mRNA was identified by reverse transcriptase-polymerase chain reaction analysis of brain mRNA extracts. The mRNA was also detected in cultured postmortem human microglia and in the IMR-32 human neuroblastoma cell line. Immunohistochemically, the native protein was detected in residual serum of capillaries and pyramidal neurons of both control and Alzheimer disease cases, as well as in occasional senile plaques of Alzheimer tissue. The reacted protein was detected on dystrophic neurites and neuropil threads in Alzheimer tissue by 4C3 monoclonal antibody, which recognizes a neoepitope following suicide inhibition. These data indicate that C1 inhibitor, a regulatory molecule controlling multiple inflammatory proteolytic cascades, is produced in normal brain. In Alzheimer disease, C1 inhibitor undergoes a prominent reaction in abnormal neuronal processes, such as dystrophic neurites and neuropil threads.

Alzheimer Disease↗

PubMed1995

Pick's disease immunohistochemistry: new alterations and Alzheimer's disease comparisons.

Pick's disease (PD) brains were examined immunohistochemically for the expression of antigens known to be associated with Alzheimer's disease (AD) lesions. Most antibodies which label intracellular neurofibrillary tangles (NFTs) in AD were found to stain Pick bodies (PBs). Among them was the monoclonal antibody A2B5, which is known to recognize neuronal surface gangliosides. This result indicates that membrane proteins are probably incorporated into PBs as into NFTs. However, PBs, in contrast to NFTs, showed a paucity of staining for heparan sulfate glycosaminoglycan and basic fibroblast growth factor (bFGF). Staining for midkine, seen in senile plaques in AD, was not seen in PD. The relative lack of staining for these two neurotrophic factors in PD brain may reflect underlying mechanisms which are distinct from those in AD. We also describe two glial abnormalities in PD: glial fibrillary tangles and clusters of granules positive for the complement protein C4d in the hippocampal dentate fascia. These are presumably related to complement-activated oligodendroglia, and both pathological structures are more abundant in advanced cases, suggesting that they may be hallmarks of the disease progression.

Aged↗

PubMed1994

Acidic fibroblast growth factor-like immunoreactivity in rat brain following cerebral infarction.

Expression of acidic fibroblast growth factor (aFGF) was studied by immunocytochemistry in the rat brain with or without cerebral infarction. In a model of infarction produced by occlusion of the middle cerebral artery, aFGF-positive staining that was not seen in controls appeared in both neurons and macrophages. Positive neurons were distributed mainly in the periventricular region of the hypothalamus. The neuronal aFGF began to be detectable about 24 h after the occlusion. The staining intensity for such neuronal aFGF increased until about 14 days after the surgery, but decreased gradually and was undetectable after more than 30 days. Positive macrophages first appeared on the 3rd day after the occlusion and were persistently seen up to the 7th day, but were no longer visible after 14 days. The present results suggest that aFGF may be involved in the repair processes following brain infarction.

Animals↗

PubMed1994

Hageman factor and its binding sites are present in senile plaques of Alzheimer's disease.

Hageman factor (HF) or factor XII participates in several defense systems of the body. These include coagulation, fibrinolysis and complement activation. We investigated the expression of HF and its mRNA in control and Alzheimer's disease (AD) brain, using immunohistochemistry and polymerase-chain reaction (PCR) techniques. HF mRNA was detected in control and AD brain extracts, indicating that HF can be produced by endogenous brain cells. HF-like immunoreactivity was present in residual serum of capillaries in both control and AD brain, consistent with its known presence in the circulation. In addition, AD senile plaques were stained. The staining was dramatically enhanced when AD sections were incubated with solutions containing HF, indicating that plaques contain not only HF but also binding sites for HF. The enhanced staining was eliminated by pretreatment of solutions with the HF-binding agent kaolin. It was also eliminated by pretreatment of sections with protamine, an agent which strongly binds to negative surfaces. These data suggest that negatively charged surfaces in plaques might bind HF in vivo. Since HF can be activated by contact with negative surfaces, locally released HF could be playing a role in initiating a variety of inflammatory responses in AD brain.

Aged↗

PubMed1994

Expression of the complement membrane attack complex and its inhibitors in Pick disease brain.

The immunohistochemical localization of the complement membrane attack complex (MAC) was examined in Pick disease brain and compared with the distribution of three of its inhibitors, vitronectin, protectin and clusterin. Pick bodies were stained intensely for both the MAC and protectin, weakly for vitronectin, but negatively for clusterin. However, the clusterin antibody intensely stained some pyramidal neurons in affected cortical areas, including ballooned neurons. The present study indicates that a complement-mediated attack is associated with the formation of Pick bodies, and provides further suggestive evidence that clusterin may be a marker for active neuronal degeneration.

Aged↗

PubMed1994

Accumulation of amyloid precursor protein in brain lesions of patients with Pick disease.

The expression of amyloid precursor protein (APP) was examined immunohistochemically in Pick disease brain using several antibodies to various segments of APP. Some neurons, including ballooned neurons, were intensely stained with antibodies to all but the N-terminal APP segment. However, Pick bodies were labeled with the antibody to that segment as well as the antibody to intermediate segment of APP. The pattern was similar to that previously observed for Alzheimer neurofibrillary tangles. These data provide additional evidence that Pick bodies and neurofibrillary tangles share some immunohistochemical characteristics.

Aged↗

PubMed1994

Two types of dystrophic neurites in senile plaques of Alzheimer disease and elderly non-demented cases.

Senile plaques (SPs) occur profusely in brain tissue of Alzheimer disease (AD) cases, and sparsely in brain tissue of elderly normals. Two types of dystrophic neurites (DNs) have been identified in SPs. Type 1 are the classically described elongated forms. Type 2 are globular in shape. Type 1 DNs are stained immunohistochemically by antibodies to A68 protein, other forms of phosphorylated tau, and N-terminal epitopes of amyloid precursor protein (APP), as well as an antibody which preferentially recognized conjugated ubiquitin. Type 2 DNs are stained immunohistochemically by antibodies to chromogranin A and C-terminal epitopes of APP, as well as an antibody which preferentially recognizes free ubiquitin. SPs of AD cases usually contain a mixture of type 1 and type 2 DNs. However, in the neocortex of elderly normals, which have few neurofibrillary tangles and neuropil threads, the DNs in the SPs are restricted to type 2. These data suggest that SPs containing only type 2 DNs may be benign, and independent of neurofibrillary pathology.

Aged↗