Ikuo Tooyama

Immunohistochemical study of α2 Macroglobulin receptor in Alzheimer and control postmortem human brain

Localization of the alpha 2 macroglobulin receptor (alpha 2MR) was studied in postmortem human brain tissue of Alzheimer disease (AD) and age-matched control cases with a monoclonal antibody (A2MR alpha 2) to the receptor. In control cases alpha 2MR was detected in neurons, glia, and some capillaries. Neuronal staining was most conspicuous in the hippocampus and entorhinal cortex. In AD, alpha 2MR immunoreactivity was enhanced. The staining intensity of some neurons was increased, as was the number of positive glial cells. In addition, senile plaques, tangles, and dystrophic neurites were strongly stained. These results suggest that alpha 2MR is involved in AD pathology.

Morphological diversities of CD44 positive astrocytes in the cerebral cortex of normal subjects and patients with Alzheimer's disease.

The localization of CD44 was investigated immunohistochemically in postmortem human brain tissue of control subjects and patients with Alzheimers disease. CD44 is a multifunctional cell surface glycoprotein that serves as a receptor for hyaluronic acid, collagen types I and VI, and mucosal vascular addressin. In gray matter, it was found to be associated with some astrocytes of both protoplasmic and fibrous morphology. These positively stained astrocytes were most frequently observed in association with blood vessels, and had morphologies that were highly comparable to those described with the Golgi technique. Double immunostaining for CD44 and glial fibrillary acidic protein (GFAP) revealed that a significant number of these astrocytes were positive for both antigens. However, GFAP staining was mostly confined to the cell somata and proximal processes, while CD44 staining extended to a rich and extensive array of processes. Occasional CD44 positive cells of spherical morphology with a few thin varicose processes were observed. Their processes formed thick terminations on blood vessels, suggesting that these cells are a special class of astrocyte. In Alzheimers disease brain, the number of CD44 positive astrocytes increased dramatically. These data suggest that astrocytes have very extensive branching patterns, which are reflected by CD44 staining patterns. CD44 may be an important adhesion molecule for these astrocytic processes.

Retention of basic fibroblast growth factor immunoreactivity in dopaminergic neurons of the substantia nigra during normal aging in humans contrast with loss in Parkinson's disease

A count of pigmented neurons per mm3 in sections of the substantia nigra at the level where the oculomotor nerve emerges in 11 neurologically normal controls aged 15-82 showed the expected slow loss of such neurons with age. Most (82 +/- 3.8%) of the pigmented neurons showed immunoreactivity for basic fibroblast growth factor (bFGF) and this percentage was unaffected by age. This is in marked contrast to the case in Parkinsons disease where only some 12.7 +/- 2.6% of the remaining dopaminergic neurons showed bFGF-like immunoreactivity, providing further evidence against the hypothesis that Parkinsons disease is due to some early insult followed by age-related attrition of the remaining neurons.

Subcellular localization of the low density lipoprotein receptor-related protein (α2-macroglobulin receptor) in human brain

The subcellular localization of the alpha 2-macroglobulin receptor, also known as the low density lipoprotein receptor-related protein (LRP), was studied in postmortem human brain tissue by light and electron microscopic immunocytochemistry. A specific monoclonal antibody (A2MR2) against the extracellular alpha-chain of the molecule was utilized. Light microscopically, LRP was detected strongly in neurons, weakly in some glial cells and discontinuously along capillary membranes. At the electron microscopic level, positive reaction products were found to be associated with plasma membranes, ribosomes, lysosomes and lipofuscin granules of neurons, glial cells and pericytes. The results suggest that LRP may have a function, particularly in neurons, of receptor-mediated endocytosis with subsequent lysosomal uptake and degradation of ligands such as alpha 2-macroglobulin proteinase complexes and apolipoprotein E.

High molecular weight basic fibroblast growth factor-like protein is localized to a subpopulation of mesencephalic dopaminergic neurons in the rat brain ☆

A rabbit antiserum (R917) was raised to a purified fraction of bovine brain basic fibroblast growth factor (bFGF). On Western blots of rat midbrain extract, the antiserum did not recognize low molecular weight forms of bFGF. Instead, it recognized a single band of 27-28 kDa. Immunohistochemically, the antiserum preferentially stained a subpopulation of calbindin-negative mesencephalic dopaminergic neurons. The positive somata were mainly packed in a ventral portion of the tegmentum including the A10 region, the ventral tegmental area and the pars compacta of the medial substantia nigra, but were also scattered in both the pars compacta and reticulata portions of the lateral substantia nigra. Processes of dendrites and axons were clearly visible. Terminal fields were located in striosomes, the dorsolateral rim of the neostriatum, the anterodorsal aspect of the nucleus accumbens shell, the infralimbic cortex, and the medial prefrontal cortex. These results suggest that trophic specialization in subpopulations may occur in all three of these dopaminergic projection systems, i.e. the nigrostriatal, mesolimbic and mesocortical pathways.

Acidic and basic fibroblast growth factor-like immunoreactivity in the striatum and midbrain in Huntington's disease

The immunohistochemical localizations of acidic and basic fibroblast growth factor (aFGF and bFGF) were investigated in the striatum and midbrain of Huntingtons disease (HD) and control cases using specific antibodies. In the striatum of control cases, the ependymal cell layer was stained for aFGF and bFGF. In addition, a few subependymal astrocytes were positive for aFGF, and some neurons stained weakly for bFGF. In HD striatum, many astrocytes and remaining neurons were strongly stained for aFGF. aFGF-positive astrocytes were particularly conspicuous in the subependymal region of the caudate but appeared throughout the caudate and putamen. The number of bFGF-positive astrocytes was slightly increased. In contrast to the caudate/putamen, the globus pallidus, nucleus of the oculomotor nerve and substantia nigra showed very similar patterns for both aFGF and bFGF in control and most HD brains. Reports that FGF can protect against glutamate neurotoxicity, and that the FGF receptor (FGFR3), with its gene located in the HD region on chromosome 4, appears in striatal neurons, make it tempting to speculate on a possibly important role for FGF-FGFR3 interactions in HD pathology.

Immunohistochemical study of A2B5-positive ganglioside in postmortem human brain tissue of Alzheimer disease, amyotrophic lateral sclerosis, progressive supranuclear palsy and control cases

Localization of gangliosides positively stained by the monoclonal antibody A2B5 was investigated in postmortem brain tissue of Alzheimer disease, amyotrophic lateral sclerosis (ALS), progressive supranuclear palsy (PSP) and control cases. In control cases, A2B5-staining was granular, appearing in selective neuronal populations. In the neocortex, the A2B5-positive neurons were distributed mainly in deep cortical layers. In the cerebellum, A2B5-positive structures were detected in processes extending from the Purkinje cell layer into the molecular layer. In Alzheimer cases, many neurofibrillary tangles, neuropil threads and dystrophic neurites were strongly A2B5-positive. In addition, aggregations of A2B5-positive granules were detected in some neurons lacking neurofibrillary tangles. Alterations of A2B5-positive gangliosides were also detected in ALS and PSP cases. In ALS cases, A2B5-positive granules were aggregated in Betz cells of the precentral gyrus. In PSP cases, globose-type neurofibrillary tangles were also strongly A2B5-positive. The results indicate that A2B5-positive gangliosides are widely but selectively distributed in human brain and may be involved in several neuropathological processes.

Columnar arragement of β-amyloid protein deposits in the cerebral cortex of patients with Alzheimer's disease

SummaryThe spatial pattern of β-amyloid protein (BAP) deposits in Alzheimers disease cerebral cortex was investigated. In cortical areas where the accumulation of BAP was relatively sparse, the deposits tended to accumulate vertically in a columnar arrangement. Typically, these aggregates consisted of both consolidated and diffuse deposits approximately 200 to 600 μm in width. Blood vessels running perpendicularly to the pial surface were sometimes observed penetrating the center of these colunms, but this was not a consistent finding. These BAP extracellular aggregates might be related to the columnar organization of the cerebral cortex.