Koichi Wakabayashi

Neuropathology of Autonomic Nervous System in Parkinson's Disease

Lewy body formation has been considered to be a marker for neuronal degeneration, because postmortem studies of Parkinsons disease (PD) patients have shown loss of neurons in the predilection sites for Lewy bodies. We systemically studied the autonomic nervous system in patients with PD. Lewy bodies were widely distributed in the hypothalamus, sympathetic system (intermediolateral nucleus of the thoracic cord and sympathetic ganglia) and parasympathetic system (dorsal vagal and sacral parasympathetic nuclei). The number of neurons in the intermediolateral nucleus was significantly reduced. Furthermore, Lewy bodies were also found in the enteric nervous system of the alimentary tract, cardiac plexus, pelvic plexus and adrenal medulla. These findings indicate that both central and peripheral autonomic nervous systems are involved in the disease process in PD.

Parkinson's disease: the presence of Lewy bodies in Auerbach's and Meissner's plexuses

SummaryWe systematically studied the enteric nervous system of the alimentary tract in seven patients with Parkinsons disease. In all patients, characteristic inclusions histologically and ultrastructurally identical to Lewy bodies were found in Auerbachs and Meissners plexuses. They were most frequent in the Auerbachs plexus of the lower esophagus. Lewy bodies were found in 8 out of 24 age-matched nonparkinsonian patients. However, they were obviously small in number. These findings clearly indicate that the plexuses are also involved in Parkinsons disease.

Abnormal expression of brain-derived neurotrophic factor and its receptor in the corticolimbic system of schizophrenic patients.

Previous neuropathological studies have revealed that the corticolimbic system of schizophrenic patients expresses abnormal levels of various synaptic molecules, which are known to be influenced by the neuronal differentiation factors, neurotrophins. Therefore, we determined levels of neurotrophins and their receptors in the postmortem brains of schizophrenic patients and control subjects in relation to molecular impairments in schizophrenia. Among the neurotrophins examined, levels of brain-derived neurotrophic factor (BDNF) were elevated specifically in the anterior cingulate cortex and hippocampus of schizophrenic patients, but levels of nerve growth factors and neurotrophin-3 showed no change in any of the regions examined. In parallel, the expressions of TrkB receptor and calbindin-D, which are both influenced by BDNF, were reduced significantly in the hippocampus or the prefrontal cortex. However, neuroleptic treatment did not appear to mimic the neurotrophic change. Neither withdrawal of drug treatment in patients nor chronic administration of haloperidol to rats altered levels of BDNF. These findings suggest that neurotrophic abnormality is associated with the corticolimbic structures of schizophrenic patients and might provide the molecular substrate for pathological manifestations of the illness.

Accumulation of α-synuclein/NACP is a cytopathological feature common to Lewy body disease and multiple system atrophy

Abstract Recently, we have shown that the precursor of the non-Aβ component of Alzheimer’s disease amyloid (NACP), also known as α-synuclein, is a major component of Lewy bodies (LBs) as well as neuronal and glial cytoplasmic inclusions in multiple system atrophy (MSA). To elucidate whether the accumulation of NACP is specific to LB disease and MSA, we further studied 83 autopsied cases with various neurological disorders, using anti-NACP antibodies. In LB disease, NACP immunoreactivity was present in all of the LBs and Lewy neurites in both the central and peripheral nervous systems, the pale bodies in the substantia nigra, and dystrophic neurites in the hippocampal CA2/3 region. Immunoelectron microscopy revealed that the reaction product was localized within filamentous structures and associated granular structures. In MSA, NACP immunoreactivity was found in the intracytoplasmic inclusions of both neuronal and oligodendroglial cells, neuronal intranuclear inclusions, and swollen neuronal processes. No NACP immunoreactivity was found in a variety of other neuronal or glial inclusions in other disorders, including Alzheimer’s disease, Pick’s disease, progressive supranuclear palsy, corticobasal degeneration, motor neuron disease and triplet-repeat diseases. These findings strongly suggest that the accumulation of NACP is a cytopathological feature common to LB disease and MSA.

NACP, a presynaptic protein, immunoreactivity in Lewy bodies in Parkinson's disease

NACP, originally identified as a precursor of the non-Abeta component of Alzheimers disease amyloid (NAC), is now known to be identical to alpha-synuclein, a presynaptic protein in the human brain. Recently, a mutation in the alpha-synuclein gene in families with autosomal dominant Parkinsons disease (PD) was identified. We carried out immunohistochemical examinations of the brains of sporadic PD patients using anti-NACP and anti-ubiquitin antibodies. Consistent with previous studies, the anti-NACP antibody immunostained the neuropil in a punctate pattern throughout the brain. Moreover, much stronger NACP immunoreactivity was found in Lewy bodies and degenerating neurites in the brainstem. Serial sections immunolabeled with anti-ubiquitin or anti-NACP showed that all ubiquitin-immunoreactive LBs were also NACP-immunoreactive. These findings suggest that alteration of NACP metabolism is involved in the pathogenesis of PD, particularly in Lewy body formation, leading to neurodegeneration.

Phosphorylated α-Synuclein Is Ubiquitinated in α-Synucleinopathy Lesions

α-Synuclein is one of the major components of intracellular fibrillary aggregates in the brains of a subset of neurodegenerative disorders, including Parkinsons disease, dementia with Lewy bodies, multiple system atrophy, and Hallervorden-Spatz disease, which are referred to as α-synucleinopathies. We have shown previously (Fujiwara, H., Hasegawa, M., Dohmae, N., Kawashima, A., Masliah, E., Goldberg, M. S., Shen, J., Takio, K., and Iwatsubo, T. (2002) Nat. Cell Biol. 4, 160–164) that α-synuclein deposited in synucleinopathy brains is extensively phosphorylated at Ser-129 and migrates at 15 kDa. Here we examined the biochemical characteristics of the additional, higher molecular mass species of phosphorylated α-synuclein-positive polypeptides that also are recovered in the Sarkosyl-insoluble fraction of synucleinopathy and migrate at about 22 and 29 kDa. These 22 and 29 kDa bands were positive for three different anti-ubiquitin antibodies and comigrated perfectly with in vitro ubiquitinated α-synuclein that may correspond to mono- and diubiquitinated α-synuclein, respectively. Furthermore, cyanogen bromide cleavage of the 22 and 29 kDa polypeptides shifted the mobility to 19 and 26 kDa, respectively, and they retained immunoreactivity for both ubiquitin and α-synuclein. Finally, protein sequence analysis showed that the 19 kDa band contained two amino-terminal sequences of α-synuclein and ubiquitin. These results strongly suggest that phosphorylated α-synuclein is targeted to mono- and diubiquitination in synucleinopathy brains, which may have implications for mechanisms of these diseases.

Synphilin‐1 is present in Lewy bodies in Parkinson's disease

α‐Synuclein is believed to play an important role in Parkinsons disease (PD). Mutations in the α‐synuclein gene are responsible for familial forms of PD and α‐synuclein protein is a major component of Lewy bodies in patients with sporadic PD. Synphilin‐1 is a novel protein that we have previously found to associate in vivo with α‐synuclein. We now show that synphilin‐1 is present in Lewy bodies of patients with PD. Our data suggest that synphilin‐1 could play a role in Lewy body formation and the pathogenesis of PD. Ann Neurol 2000;47:521–523.

NACP/α-synuclein-positive filamentous inclusions in astrocytes and oligodendrocytes of Parkinson's disease brains

Abstract The precursor of the non-Aβ component of Alzheimer’s disease amyloid (NACP), also called α-synuclein, is a major component of Lewy bodies in Parkinson’s disease (PD) as well as of neuronal and oligodendroglial cytoplasmic inclusions in multiple system atrophy. We previously reported argyrophilic, tau-negative glial inclusions in the midbrains of patients with PD and have now conducted immunocytochemical and ultrastructural examinations. The PD glial inclusions also are immunoreactive for NACP/α-synuclein, but not for β-synuclein, and ultrastructurally are composed of filamentous structures about 25–40 nm in diameter. Double immunolabeling showed that the inclusions were present in both astrocytic and oligodendroglial cells. They were located within the substantia nigra in 13 of 30 patients with PD and outside the nigra in 24. The number of inclusions was correlated with the severity of nigral neuronal loss. These findings indicate that abnormal accumulation of NACP/α-synuclein in glial cells is a pathological feature of PD related to its progression.

Selective Insolubility of α-Synuclein in Human Lewy Body Diseases Is Recapitulated in a Transgenic Mouse Model

α-Synuclein (α-SYN) is deposited in intraneuronal cytoplasmic inclusions (Lewy bodies, LBs) characteristic for Parkinson’s disease (PD) and LB dementias. α-SYN forms LB-like fibrils in vitro, in contrast to its homologue β-SYN. Here we have investigated the solubility of SYNs in human LB diseases and in transgenic mice expressing human wild-type and PD-associated mutant [A30P]α-SYN driven by the brain neuron-specific promoter, Thy1. Distinct α-SYN species were detected in the detergent-insoluble fractions from brains of patients with PD, dementia with LBs, and neurodegeneration with brain iron accumulation type 1 (formerly known as Hallervorden-Spatz disease). Using the same extraction method, detergent-insolubility of human α-SYN was observed in brains of transgenic mice. In contrast, neither endogenous mouse α-SYN nor β-SYN were detected in detergent-insoluble fractions from transgenic mouse brains. The nonamyloidogenic β-SYN was incapable of forming insoluble fibrils because amino acids 73 to 83 in the central region of α-SYN are absent in β-SYN. In conclusion, the specific accumulation of detergent-insoluble α-SYN in transgenic mice recapitulates a pivotal feature of human LB diseases.

Parkinson's disease : an immunohistochemical study of Lewy body-containing neurons in the enteric nervous system

SummaryWe performed immunohistochemical analysis of specimens from three autopsied patients with Parkinsons disease, using antibodies to tyrosine hydroxylase (TH), vasoactive intestinal polypeptide (VIP), somatostatin, met-enkephalin, leu-enkephalin and substance P in an attempt to reveal the types of neurons that contain Lewy bodies (LBs) in the paravertebral and celiac sympathetic ganglia and in the enteric nervous system of the alimentary tract. In the sympathetic ganglia, almost all LB-containing neuronal cell bodies and processes were immunoreactive for TH. In the alimentary tract, however, most LBs were found in the VIP-immunoreactive (VIP-IR) neuronal cell bodies and processes. In spite of the significant presence of TH-IR neuronal cell bodies and processes in the alimentary tract, LB-containing TH-IR neuronal elements were rarely encountered. These findings indicate that in the alimentary tract, the VIP neuron system is mainly involved in the disease process of Parkinsons disease.