The rabbit retina: a long-term model system for aluminum-induced neurofibrillary degeneration

Aluminum (Al) was injected into the rabbit eye as a potential long-term model system for Al-induced neurofibrillary degeneration (NFD). Neurofibrillary tangles made up of 10 nm phosphorylated neurofilaments were observed in a subpopulation of retinal ganglion cells, located primarily in the peripheral retina. The distribution of affected cells suggested a differential susceptibility of ganglion cells to Al intoxication. Importantly, none of the animals demonstrated any of the central neurological dysfunctions characteristic of previous Al intoxication models. The retinal model should allow for long-term studies of Al intoxication and its potential relationship to neurofibrillary degenerative disorders such as Alzheimer's disease.     

Association of ATP synthase alpha-chain with neurofibrillary degeneration in Alzheimer's disease

Amyloid deposits and neurofibrillary tangles (NFT) are the two hallmarks that characterize Alzheimer's disease (AD). In order to find the molecular partners of these degenerating processes, we have developed antibodies against insoluble AD brain lesions. One clone, named AD46, detects only NFT. Biochemical and histochemistry analyses demonstrate that the labeled protein accumulating in the cytosol of Alzheimer degenerating neurons is the alpha-chain of the ATP synthase. The cytosolic accumulation of the alpha-chain of ATP synthase is observed even at early stages of neurofibrillary degenerating process. It is specifically observed in degenerating neurons, either alone or tightly associated with aggregates of tau proteins, suggesting that it is a new molecular event related to neurodegeneration. Overall, our results strongly suggest the implication of the alpha-chain of ATP synthase in neurofibrillary degeneration of AD that is illustrated by the cytosolic accumulation of this mitochondrial protein, which belongs to the mitochondrial respiratory system. This regulatory subunit of the respiratory complex V of mitochondria is thus a potential target for therapeutic and diagnostic strategies.     

Chronic model of neurofibrillary changes induced in mature rabbits by metallic aluminum

—A slurry of aluminum powder injected into the brains of mature rabbits produced neurofibrillary changes in neurons of spinal cord and cerebrum similar to those produced by aluminum chloride, and with similar topography and rates of formation. The major difference observed with this preparation was that many rabbits survived several weeks or months before having any obvious seizures, compared to 2 to 3 weeks with aluminum chloride, and some survived with no obvious symptoms, apparently indefinitely (12 months being the longest time before sacrifice). This chronic animal model of neurofibrillary changes, induced in a mature nervous system, will allow better investigations of alterations in the biochemistry, pathology, behavior and cognition which may occur.     

Antigenic characteristics of neurofibrillary tangles in progressive supranuclear palsy

The antigenic components of neurofibrillary tangles in the basal forebrain and brainstem were studied in 4 cases of progressive supranuclear palsy (PSP) at the light and electron microscopic levels, using antibodies to neurofilaments (in the phosphorylated and non-phosphorylated forms); the high, middle and low molecular weight neurofilament subunits; ubiquitin; the microtubule associated proteins MAP1, MAP2 and tau; isolated Alzheimer paired helical filaments and to tubulin, in the tyrosinated and detyrosinated forms. Although PSP neurofibrillary tangles appear to have most antigenic sites in common with those of Alzheimer disease, PSP tangles share epitopes with tyrosinated and detyrosinated tubulin, which has not been demonstrated in Alzheimer neurofibrillary tangles.     

Molecular analysis of neurofibrillary degeneration in Alzheimer's disease. An immunohistochemical study.

Antibodies directed against three regions of tau, ubiquitin, and B-amyloid were used in a histologic study of neurofibrillary degeneration in Alzheimer's disease to distinguish two populations of neurofibrillary tangles. Intracellular tangles were immunolabeled exclusively by two antibodies raised against antigens in the fuzzy coat of the paired helical filament (PHF). Extracellular tangles were distinguished by selective immunolabeling with a monoclonal antibody raised against antigens in the PHF core. This was associated with removal of the fuzzy coat and exposure of PHF-core epitopes. In the transition from intracellular to extracellular compartments in vivo, tangles appeared to undergo changes similar to protease digestion in vitro. The transition was associated with the appearance of amyloid immunoreactivity. These findings suggest that tangle degradation occurs in a series of distinct stages, including ubiquitination of some unknown molecule, a change in tau immunoreactivity, and partial proteolysis of tangle-bound tau in extracellular tangles.     

Aluminum-induced neurofibrillary degeneration disrupts acquisition of the rabbit's classically conditioned nictitating membrane response

Rabbits received intraventricular injections of aluminum chloride, hydrochloric acid, or served as unoperated controls. On the 6th day postsurgery, they underwent 4 days (100 trials per day) of classical conditioning of the nictitating membrane response (NMR) to a tone conditioned stimulus and an air-puff unconditioned stimulus. Unoperated and hydrochloric acid control animals readily acquired the conditioned response. Aluminum intoxicated rabbits, in contrast, did not acquire the conditioned response over the 4 days of testing. This disruption of conditioning in aluminum-treated rabbits could not be attributed to deficits in sensory or motor processes or to illness. Neuropathological analysis revealed widespread neurofibrillary tangle formation in aluminum-treated animals. Furthermore, the degree of neurofibrillary degeneration was significantly negatively correlated with the degree of conditioning. The results are considered in the context of using the rabbit NMR preparation as a model system for studying age-related conditioning disorders.     

Locus coeruleus neurofibrillary degeneration in aging, mild cognitive impairment and early Alzheimer's disease

Neurofibrillary degeneration in the nucleus basalis and a loss of its cortical cholinergic projections are prominent components of the neuropathology in Alzheimer's disease (AD). The AD brain is also associated with a degeneration of the noradrenergic projections arising from the nucleus locus coeruleus (LC), but the time course of this lesion is poorly understood. To determine whether the LC displays neurofibrillary abnormalities early in the course of events leading to AD, we examined tissue specimens from seven cognitively normal controls and five subjects at the stages of mild cognitively impairment (MCI) or early AD. Tyrosine hydroxylase immunochemistry was used as a marker of LC neurons while AT8 immunolabeling visualized abnormal tau associated with neurofibrillary tangles and their precursors. Thioflavine-S was used as a marker for fully developed tangles. We found that AT8-positive labeling and thioflavine-S positive tangles were present in both groups of specimens. However, the percentage of neurons containing each of these markers was significantly higher in the cognitively impaired group. The MMSE scores displayed a negative correlation with both markers of cytopathology. These results indicate that cytopathology in the LC is an early event in the age-MCI-AD continuum and that it may be listed among the numerous factors that mediate the emergence of the cognitive changes leading to dementia.     

Aluminum induced neurofibrillary degeneration, brain electrical activity and alterations in acquisition and retention

In the early stages of an aluminum induced dementia model a positive correlation exists between the occurrence of neurofibrillary degeneration (NFD) in hippocampus, entorhinal and neocortex and the rate of conditioned avoidance response acquisition. Quantitative measurements from appropriate electronmicrographs indicate that the density of microtubules in a region of NFD is profoundly reduced. At the stage in the encephalopathy in which short-term retention and acquisition are impaired the EEG and averaged visual evoked potentials were normal. The observations suggest that a nonelectrical activity of neurons, important to the learning-memory mechanism, may be altered by the effects of aluminum chloride. The disorganization of the dendritic microtubular system is postulated to alter dendroplasmic flow and supports the hypothesis that the translocation of synaptically active agents by the cytoplasmic streaming mechanism may subserve a component of the associative learning mechanism.     

Co-localization of glycogen synthase kinase-3 with neurofibrillary tangles and granulovacuolar degeneration in transgenic mice

Transgenic mice expressing human tau with P301L missense mutation (JNPL3) develop progressive amyotrophy, neurofibrillary degeneration, and neuronal loss. Mating of JNPL3 with transgenic mice expressing mutant amyloid precursor protein (Tg2576) leads to bigenic (TAPP) mice with enhanced neurofibrillary pathology. TAPP and JNPL3 mice were studied with immunocytochemistry and immunoblotting with antibodies to glycogen synthase kinase-3 (GKS3) to determine whether the development of tauopathy is associated with activation or increased expression of GSK3, and when the observed changes occur with respect to neurofibrillary tangle (NFT) formation. Accumulation of GSK3alpha/beta phosphorylated at Y279/216 was observed in neurons containing NFTs and granulovacuolar degeneration (GVD), but not in normal neurons or neurons with pretangles. More GSK3 immunoreactive NFTs were detected in TAPP than JNPL3 mice, especially in the amygdala. These differences were notable only in old animals. There was no significant difference between animals with and without NFTs in the level of total, inactive, or Y216-phosphorylated (pY216)GSK3beta. No apparent GSK3 accumulation was detected in neurons in Tg2576 mice. There was also no significant difference in the distribution of GSK3 in lysates fractionated based on their solubility in various reagents, including the sarkosyl-insoluble fraction. The results suggest that the pY216 GSK3beta accumulates in NFT and GVD due to redistribution rather than increased expression or activation, and that pre-existence of tau abnormalities is required for APP/Abeta to exert their effects on tau pathology in TAPP mice.     

Regional distribution of amyloid-Bri deposition and its association with neurofibrillary degeneration in familial British dementia

Familial British dementia (FBD), pathologically characterized by cerebral amyloid angiopathy (CAA), amyloid plaques, and neurofibrillary degeneration, is associated with a stop codon mutation in the BRI gene resulting in the production of an amyloidogenic fragment, amyloid-Bri (ABri). The aim of this study was to assess the distribution of ABri fibrillar and nonfibrillar lesions and their relationship to neurofibrillary pathology, astroglial and microglial response using immunohistochemistry, confocal microscopy, and immunoelectron microscopy in five cases of FBD. Abnormal tau was studied with immunoblotting. We present evidence that ABri is deposited throughout the central nervous system in blood vessels and parenchyma where both amyloid (fibrillar) and pre-amyloid (nonfibrillar) lesions are formed. Ultrastructurally amyloid lesions appear as bundles of fibrils recognized by an antibody raised against ABri, whereas Thioflavin S-negative diffuse deposits consist of amorphous electron-dense material with sparse, dispersed fibrils. In contrast to nonfibrillar lesions, fibrillar ABri is associated with a marked astrocytic and microglial response. Neurofibrillary tangles and neuropil threads occurring mainly in limbic structures, are found in areas affected by all types of ABri lesions whereas abnormal neurites are present around amyloid lesions. Immunoblotting for tau revealed a triplet electrophoretic migration pattern. Our observations confirm a close link between ABri deposition and neurodegeneration in FBD.     

Monoclonal antibodies to Alzheimer neurofibrillary tangles. 2. Demonstration of a common antigenic determinant between ANT and neurofibrillary degeneration in progressive supranuclear palsy.

Neurofibrillary degeneration is an argyrophilic intraneuronal lesion found in several unrelated neurologic conditions. The relationship between different types of neurofibrillary tangles is investigated with two monoclonal antibodies raised against Alzheimer neurofibrillary tangles (anti-ANT). Using the peroxidase-antiperoxidase technique, the authors demonstrate that neurofibrillary tangles of progressive supranuclear palsy, containing 15-nm straight filaments, share an antigenic determinant with ANTs. Ultrastructural studies localize the antigenic determinant to filamentous elements in the parakarya. The determinant is not present in normal brain, aluminum-induced experimental tangles in the rabbit, Lewy bodies, Hirano bodies, or axonal filamentous inclusions of amyotrophic lateral sclerosis and giant axonal neuropathy. It is, however, present in ANTs regardless of the pathologic condition in which they are found, including Alzheimer's disease, Down's syndrome, and postencephalitic Parkinson's disease.     

Hypothalamic gangliocytoma. Selective appearance of neurofibrillary changes, granulovacuolar degeneration, and argentophilic bodies

A hamartomatous gangliocytoma was observed in the hypothalamus of a 54-year-old woman. The ganglion cells were atypical, highly pleomorphic and often multinucleated, and they possessed neurofibrillary changes, granulovacuolar degeneration, and argentophilic bodies. The neuronal changes were highly selective and were not found in other parts of the brain. The tumor was also characterized by the presence of angiomatous blood vessels having such degenerative changes as fibrosis and thrombosis. The angiomatous blood vessels were found only in the lesion. The ultrastructural features of the neurofibrillary changes were similar to those observed in Alzheimer's disease. Vascular alterations have been suggested to be a possible contributor to the morphogenesis of neurofibrillary changes. In this case the exact etiology of these neuronal changes remains unclear, however, the possibility of a regional vascular role is considered with respect to their morphogenesis.     

Alterations in short-term retention, conditioned avoidance response acquisition and motivation following aluminum induced neurofibrillary degeneration

Aluminum chloride induced neurofibrillary degeneration may provide a useful model for the study of a human dementia process. This possibility was assessed in cats trained to perform on a delayed-response task, a conditioned avoidance task, visual and temporal discrimination tasks and a motivational task involving rewarding intracranial electrical stimulation. After an initial asymptomatic period short term retention and acquisition of a conditioned avoidance response were selectively impaired. The associated ultrastructural abnormalities plausibly implicate the cytoplasmic streaming mechanism in the cellular substrate for some retention and acquisition phenomena.     

Staging of neurofibrillary degeneration caused by human tau overexpression in a unique cellular model of human tauopathy

The hyperphosphorylation of human tau and its aggregation into neurofibrillary tangles are central pathogenic events in familial tauopathies and Alzheimer's disease. However, the cellular consequences of neurofibrillary tangle formation in vivo have not been directly studied because cellular models of human neurofibrillary degeneration have been unavailable until recently. Incorporation of human tau into filaments in vivo and the association of filamentous tau with cytodegeneration were first demonstrated experimentally with the overexpression of human tau in identified neurons (anterior bulbar cells) in the lamprey central nervous system. In this system, filamentous tau deposits are associated with the loss of dendritic microtubules and synapses, plasma membrane degeneration, and eventually the formation of extracellular tau deposits and cell death. Here we show that human tau hyperphosphorylation in anterior bulbar cells is spatiotemporally correlated with a highly stereotyped sequence of degenerative stages closely resembling those seen in human neurofibrillary degeneration. Hyperphosphorylated tau deposits first appear in the distal dendrites and somata, together with degenerative changes that begin in distal dendrites and progress proximally over time. This sequence is independent of the tau isoform used, the presence of epitope tags and the method used to overexpress tau, and thus has important implications for the cytopathogenesis of human neurofibrillary disease.     

Lysosomal cathepsin D is upregulated in Alzheimer's disease neocortex and may be a marker for neurofibrillary degeneration

Alzheimer's disease (AD) is characterized by accumulation of β‐amyloid plaques (AP) and neurofibrillary tangles (NFT) in the cortex, together with synaptic loss and amyloid angiopathy. Perturbations in the brain lysosomal system, including the cathepsin family of proteases, have been implicated in AD where they may be involved in proteolytic clearance of misfolded and abnormally aggregated peptides. However, the status of cathepsin D (catD) is unclear in Lewy body dementia, the second most common form of neurodegenerative dementia after AD, and characterized by Lewy bodies (LB) containing aggregated α‐synuclein. Furthermore, earlier reports of catD changes in AD have not been entirely consistent. We measured CatD immunoreactivities in the temporal (Brodmann area BA21) and parietal (BA40) cortices of well characterized AD brains as well as two clinical subtypes of Lewy body dementia, namely Parkinson disease dementia (PDD) and dementia with Lewy bodies (DLB), known to show varying degrees of concomitant AD pathology. Increased catD immunoreactivities in AD were found for both neocortical regions measured, where they also correlated with neuropathological NFT scores and phosphorylated pSer396 tau burden, and appeared to co‐localize at least partly to NFT‐containing neurons. In contrast, catD was increased only in BA40 in DLB and not at all in PDD, did not correlate with LB scores, and did not appreciably co‐localize with α‐synuclein inclusions. Our study suggests that catD upregulation may be an adaptive response to AD‐related processes leading to neurofibrillary degeneration, but may not be directly associated with formation of α‐synuclein inclusions in Lewy body dementia.     

Aluminum-induced neurofibrillary degeneration affects a subset of neurons in rabbit cerebral cortex, basal forebrain and upper brainstem

Neurofibrillary tangles in Alzheimer's disease show a predilection for cortical pyramidal and subcortical projection neurons. The antigenic composition, neuronal specificity and distribution of aluminum-induced neurofibrillary degeneration were examined in regions of rabbit brain analogous to those that develop neurofibrillary tangles in Alzheimer's disease. Neurofibrillary degeneration was induced by intraventricular instillation of aluminum chloride. In aluminum-treated rabbits, intensely immunoreactive filamentous aggregates were seen in affected neuronal perikarya after staining with an antiphosphorylated neurofilament antibody (SMI 31), while in controls immunoreactivity was confined to axon-like elements. Monoclonal antibodies against Microtubule-associated protein 2 and tau, which stain human neurofibrillary tangles, did not stain aluminum-induced neurofibrillary degeneration. Pyramidal neurons exhibiting neurofibrillary degeneration formed a discrete linear pattern in layers III and V of cortex. Cortical somatostatin and nicotinamide adenine dinucleotide phosphate diaphorase-reactive neurons identified in double-stained sections were unaffected. Large perikarya in the vicinity of the globus pallidus, some of which contained acetylcholinesterase, were frequently SMI 31-immunoreactive. Among the cell groups affected in the upper brainstem were the nucleus raphe dorsalis and locus coeruleus. These findings show that aluminum-induced neurofibrillary degeneration differs antigenically from neurofibrillary tangles in Alzheimer's disease. Nevertheless, many neuronal subsets that are particularly susceptible to Alzheimer's disease, including cortical pyramidal neurons, basal forebrain cholinergic neurons and upper brainstem catecholaminergic neurons, are also affected by aluminum-induced neurofibrillary degeneration.     

维骨力预防骨关节炎软骨退变的实验研究

目的:观察维骨力(viartrils)对兔实验性早中期骨关节炎(OA)病变发生发展是否有预防作用及其对OA软骨细胞增殖的影响。方法:24只新西兰兔用切断膝关节前、后交叉韧带的方法复制兔OA模型,随机分为对照组和实验组各12只,实验组术后即加服维骨力(主要成份为硫酸氨基葡萄糖)每天2粒,对照组常规饲养。术后第10周处死动物,取股骨髁负重面软骨标本进行HE、safranin’O/fast green组织化学染色及骨关节炎评分、分级,采用免疫组化方法观察软骨细胞增殖状况。结果:切断兔前后交叉韧带成功复制出OA早、中期模型,第10周时实验组(维骨力组)骨关节炎病理评分显著低于对照组(P<0.05),软骨细胞增殖指数显著高于对照组(P<0.05)。结论:维骨力对兔膝骨关节炎软骨细胞有刺激增殖的作用,可以较好地预防OA的发生发展。