Adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) and Nasu-Hakola disease: lesion staging and dynamic changes of axons and microglial subsets.

The brains of 10 Japanese patients with adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) encompassing hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD) and eight Japanese patients with Nasu-Hakola disease (N-HD) and five age-matched Japanese controls were examined neuropathologically with special reference to lesion staging and dynamic changes of microglial subsets. In both diseases, the pathognomonic neuropathological features included spherically swollen axons (spheroids and globules), axon loss and changes of microglia in the white matter. In ALSP, four lesion stages based on the degree of axon loss were discernible: Stage I, patchy axon loss in the cerebral white matter without atrophy; Stage II, large patchy areas of axon loss with slight atrophy of the cerebral white matter and slight dilatation of the lateral ventricles; Stage III, extensive axon loss in the cerebral white matter and dilatation of the lateral and third ventricles without remarkable axon loss in the brainstem and cerebellum; Stage IV, devastated cerebral white matter with marked dilatation of the ventricles and axon loss in the brainstem and/or cerebellum. Internal capsule and pontine base were relatively well preserved in the N-HD, even at Stage IV, and the swollen axons were larger with a higher density in the ALSP. Microglial cells immunopositive for CD68, CD163 or CD204 were far more obvious in ALSP, than in N-HD, and the shape and density of the cells changed in each stage. With progression of the stage, clinical symptoms became worse to apathetic state, and epilepsy was frequently observed in patients at Stages III and IV in both diseases. From these findings, it is concluded that (i) shape, density and subsets of microglia change dynamically along the passage of stages and (ii) increase of IBA-1-, CD68-, CD163- and CD204-immunopositive cells precedes loss of axons in ALSP.

A family with hereditary diffuse leukoencephalopathy with spheroids caused by a novel c.2442+2T>C mutation in the CSF1R gene.

Clinical phenotypes of hereditary diffuse leukoencephalopathy with spheroids (HDLS), a familial progressive neurodegenerative disorder affecting the white matter of the brain, are heterogenous and may include behavioral and personality changes, memory impairment, parkinsonism, seizure, and spasticity. Thus, HDLS is frequently unrecognized and misdiagnosed. Heterozygous mutations located within the kinase domain of the gene encoding the colony-stimulating factor 1 receptor (CSF1R), a cell surface receptor with key roles in development and innate immunity, have been shown in HDLS. These different gene mutations may be related to the various clinical phenotypes. We report here a newly identified family with HDLS harboring a mutation in the CSF1R gene. We examined clinical and neuropathological features in three members of this family. These patients presented with affective incontinence, memory impairment, and executive dysfunction at onset, and revealed nonfluent aphasia, parkinsonism, and seizure as the disease progressed. We identified a novel CSF1R splice site mutation (c.2442+2T>C) in intron 18 for two of the patients. MRI of these patients revealed progressive, frontotemporal-predominant, confluent leukoencephalopathy. We also observed severe myelin loss, axonal degeneration, and abundant axonal spheroids, astrocytes, and microglia in the cerebral white matter, consistent with HDLS neuropathological features. Additionally, we identified atypical neuropathological findings for HDLS, including neuronal loss and gliosis with ballooned neurons and central chromatolysis in the frontal cortex and hippocampus. This report provides further evidence for the clinical and neuropathological heterogeneity of HDLS.

EPR evidence of hydroxyl radical generation as an initiator of lipid peroxidation in amyloid beta-protein-stimulated PC12 cells.

Recent data from several groups suggest that the primary mechanism of amyloid beta-protein (Abeta) neurotoxicity may be mediated by free radicals. To evaluate this hypothesis, our aim is to make the mechanism of Abeta neurotoxicity clear, especially in the formation of free radicals. In this study, rat pheochromocytoma (PC12) cells were exposed to Abeta25-35 and confirmed free radical generations using two kinds of spin trap agents, 5,5-dimethyl-1-pyrroline-N-oxide; DMPO and alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; POBN. DMPO spin adduct revealed that hydroxyl radical (OH), while POBN spin adduct identified a lipid radical (L) as electron paramagnetic resonance (EPR) evidence of lipid peroxidation in the process of cell damage by Abeta25-35 exposure. An Abeta cytotoxicity assay also was performed by using WST-8 reduction system and histochemical analysis. These analyses showed cell damage induced by Abeta. This study provides EPR evidence that Abeta neurotoxicity is derived from hydrogen abstraction from polyunsaturated lipid acid by hydroxyl radical as a cause of lipid peroxidation.

Conditioned-fear stress increases Fos expression in monoaminergic and GABAergic neurons of the locus coeruleus and dorsal raphe nuclei.

Many studies have demonstrated that physical or psychological stress can increase Fos expression in brainstem monoaminergic nuclei. Little is known, however, about the extent to which stress increases the expression of Fos in monoaminergic and nonmonoaminergic neurons in the brainstem. We examined the effects of conditioned-fear (CF) stress following mild footshock (FS) as unconditioned stress on Fos expression in the monoaminergic and GABAergic neurons of the ventral tegmental area (VTA), locus coeruleus (LC), and dorsal raphe nucleus (DR) in rats. The CF stress significantly increased the number of Fos-positive (Fos+) cells in both the LC and DR, whereas it did not increase the number in the VTA. Using a double-labeling technique, we combined Fos immunostaining with that for tyrosine hydroxylase (TH), serotonin (5-HT), or GABA for histochemical identification of the CF stress-induced Fos+ neurons. The percentage of TH/Fos double-labeled cells resulting from CF stress was 63% of the Fos+ cells in the LC, whereas 52% of the Fos+ cells contained 5-HT in the DR. We also found that approximately 60% of the CF stress-induced Fos+ cells were GABAergic neurons in these brain regions. These results indicate that CF stress induces intense Fos expression in the noradrenergic LC and serotonergic DR neurons, but not in the dopaminergic VTA neurons. They also indicate that not only monoaminergic neurons but also GABAergic neurons within the LC and DR are activated by the stress.

Nitric oxide and hydroxyl radicals initiate lipid peroxidation by NMDA receptor activation.

In this experiment, we used direct electron paramagnetic resonance (EPR) spectra to measure lipid peroxidation by hydroxyl radical (.OH), nitric oxide (.NO) and lipid radical (.L). NMDA-receptor associated lipid peroxidation is thought to act through .OH in induction of neurotoxicity. The origin of .OH generation was found to arise mainly from peroxynitrite anion produced from O(2)(-) and .NO rather than from Fenton's reaction. This study verified that .OH generation from interactive reactions between .NO and O(2)(-) initiates NMDA-induced lipid peroxidation of PC12 cells.