Spiral analysis in Niemann‐Pick disease type C

Spiral analysis is a computerized method of analyzing upper limb motor physiology through the quantification of spiral drawing. The objective of this study was to determine whether spirals drawn by patients with Niemann‐Pick disease type C (NPC) could be distinguished from those of controls, and to physiologically characterize movement abnormalities in NPC. Spiral data consisting of position, pressure, and time were collected from 14 NPC patients and 14 age‐matched controls, and were analyzed by the Mann‐Whitney U test. NPC spirals were characterized by: lower speed (2.67 vs. 9.56 cm/s, P < 0.001) and acceleration (0.10 vs. 2.04 cm/s², P < 0.001), higher loop width variability (0.88 vs. 0.28, P < 0.001), tremor (5/10 vs. 0/10 trials in the dominant hand, P < 0.001), and poor overall spiral rating (2.53 vs. 0.70, P < 0.005). NPC spirals also exhibited sustained drawing pressure profiles that were abnormally invariant with time. Other features, such as the tightness of loop widths, were normal. Our findings reveal that differing aspects of tremor, Parkinsonism, ataxia, and dystonia are quantifiable in NPC patients. © 2009 Movement Disorder Society     

Severe demyelination in a patient with a late infantile form of Niemann‐Pick disease type C

Niemann‐Pick disease type C (NPC) is a cholesterol storage disease caused by defective cellular cholesterol transportation. The onset and progression of NPC are variable, and autopsy findings have mainly been reported for the adult and juvenile forms of this disease. Here we report the clinical and pathological findings from a 9‐year‐old female patient with the late infantile form of NPC due to NPC1 gene mutation. She had notable splenomegaly at 4 months of age. She lost the ability to speak at 18 months of age. She learned to walk, but often fell and could no longer walk after 30 months. At 3 years of age, she was diagnosed with NPC. Sequence analysis of the NPC1 gene revealed compound heterozygous mutation of T2108C (F703S) and C2348G (S813X) (both novel). Thereafter, the patient suffered repeated respiratory infections and died of respiratory failure at 9 years of age. Pathological findings included cerebral atrophy (particularly of white matter), severe demyelination, and the loss of neurons from the cerebrum and from the nuclei of the brain stem. Remnant neuronal cells and microglia in the cerebrum, cerebellum, and brain stem had become swollen and foamy. Neurons of the hippocampal CA1 and Purkinje cells were relatively spared, and senile plaques and axonal spheroids were not present. Foamy cells were also observed in other organs, especially the spleen and bone marrow. The F703S mutation in this patient was localized in a sterol‐sensing domain (SSD). Severe neurological phenotypes have been previously reported in patients with missense mutations in an SSD. It is considered that the combination of a nonsense mutation and missense mutation in an SSD was responsible for the severe neurological phenotype of our present patient. While pathological findings of adult/juvenile forms of NPC have included swollen neurons and glia, neuronal cell loss, and NFTs, demyelination may be a predominant finding in the infantile form of NPC.     

Deletion of the L‐type calcium channel CaV1.3 but not CaV1.2 results in a diminished sAHP in mouse CA1 pyramidal neurons

Trains of action potentials in CA1 pyramidal neurons are followed by a prolonged calcium‐dependent postburst afterhyperpolarization (AHP) that serves to limit further firing to a sustained depolarizing input. A reduction in the AHP accompanies acquisition of several types of learning and increases in the AHP are correlated with age‐related cognitive impairment. The AHP develops primarily as the result of activation of outward calcium‐activated potassium currents; however, the precise source of calcium for activation of the AHP remains unclear. There is substantial experimental evidence suggesting that calcium influx via voltage‐gated L‐type calcium channels (L‐VGCCs) contributes to the generation of the AHP. Two L‐VGCC subtypes are predominately expressed in the hippocampus, Ca_V1.2 and Ca_V1.3; however, it is not known which L‐VGCC subtype is involved in generation of the AHP. This ambiguity is due in large part to the fact that at present there are no subunit‐specific agonists or antagonists. Therefore, using mice in which the gene encoding Ca_V1.2 or Ca_V1.3 was deleted, we sought to determine the impact of alterations in levels of these two L‐VCGG subtypes on neuronal excitability. No differences in any AHP measure were seen between neurons from Ca_V1.2 knockout mice and controls. However, the total area of the AHP was significantly smaller in neurons from Ca_V1.3 knockout mice as compared with neurons from wild‐type controls. A significant reduction in the amplitude of the AHP was also seen at the 1 s time point in neurons from Ca_V1.3 knockout mice as compared with those from controls. Reductions in both the area and 1 s amplitude suggest the involvement of calcium influx via Ca_V1.3 in the slow AHP (sAHP). Thus, the results of our study demonstrate that deletion of Ca_V1.3, but not Ca_V1.2, significantly impacts the generation of the sAHP. © 2009 Wiley‐Liss, Inc.     

Motion analysis of a child with Niemann–Pick disease type C treated with miglustat

Niemann–Pick disease type C (NPC) is a progressive neurodegenerative disorder for which there is no effective treatment other than supportive therapy. Recently, the oral medication miglustat has been offered as a possible therapy aimed at reducing pathological substrate accumulation. This article describes the use of computerized three‐dimensional motion analysis to evaluate a 3‐year‐old child with NPC treated with miglustat for 12 months. Motion analysis provided quantitative data on the patient's gait. However, dementia and motor dysfunction progressed despite the treatment, and the patient lost the ability to walk between 9 and 12 months of the study. Motion analysis should be considered among the tools for measuring functional outcomes in future therapeutical trials of patients with neurodegenerative diseases. It is not possible to draw conclusions about miglustat therapy in NPC from a single patient experience. © 2007 Movement Disorder Society     

Amelioration of enteric neuropathology in a mouse model of Niemann‐Pick C by Npc1 expression in enteric glia

Niemann‐Pick C (NPC) disease is an autosomal recessive, lethal, neurodegenerative disorder caused by mutations in NPC1. By using the glial fibrillary acidic protein (GFAP) promoter, we demonstrated previously that astrocyte‐specific expression of Npc1 decreased neuronal storage of cholesterol in Npc1^?/? mice; reduced numbers of axonal spheroids; and produced less degeneration of neurons, reactive astrocytes, and loss of myelin tracts in the central nervous system. GFAP‐Npc1, Npc1^?/? mice exhibited markedly enhanced survival, and death was not associated with the severe terminal weight loss observed in Npc1^?/? mice. Intestinal transit is delayed in Npc1^?/? mice but is normal in GFAP‐NPC1, Npc1^?/? until late in the course of their disease. Because glia play an important role in the enteric nervous system, we studied morphology and cholesterol content of intestines from Npc1^?/? mice and examined the effect of GFAP‐promoted restoration of Npc1 in enteric glia. Although the number of neurons was not altered, the total amount of cholesterol stored in the small intestine was decreased, as were the number of neurons with inclusions and the number of inclusions per neuron. We conclude that expression of Npc1 by enteric glial cells can ameliorate the enteric neuropathology, and we speculate that dysfunction of the enteric nervous system contributes to the retarded intestinal transit, weight loss, and demise of Npc1^?/? mice. © 2009 Wiley‐Liss, Inc.     

Intracerebroventricular infusion of acid sphingomyelinase corrects CNS manifestations in a mouse model of Niemann–Pick A disease

Niemann–Pick A (NPA) disease is a lysosomal storage disorder (LSD) caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously, we showed that the storage pathology in the ASM knockout (ASMKO) mouse brain could be corrected by intracerebral injections of cell, gene and protein based therapies. However, except for instances where distal areas were targeted with viral vectors, correction of lysosomal storage pathology was typically limited to a region within a few millimeters from the injection site. As NPA is a global neurometabolic disease, the development of delivery strategies that maximize the distribution of the enzyme throughout the CNS is likely necessary to arrest or delay progression of the disease. To address this challenge, we evaluated the effectiveness of intracerebroventricular (ICV) delivery of recombinant human ASM into ASMKO mice. Our findings showed that ICV delivery of the enzyme led to widespread distribution of the hydrolase throughout the CNS. Moreover, a significant reduction in lysosomal accumulation of sphingomyelin was observed throughout the brain and also within the spinal cord and viscera. Importantly, we demonstrated that repeated ICV infusions of ASM were effective at improving the disease phenotype in the ASMKO mouse as indicated by a partial alleviation of the motor abnormalities. These findings support the continued exploration of ICV delivery of recombinant lysosomal enzymes as a therapeutic modality for LSDs such as NPA that manifests substrate accumulation within the CNS.     

Reduced cerebellar neurodegeneration after combined therapy with cyclodextrin/allopregnanolone and miglustat in NPC1: A mouse model of Niemann‐Pick type C1 disease

Niemann‐Pick type C1 (NPC1) disease is a lysosomal storage disease characterized by a deficiency of NPC1 gene function. The malfunction of protein results in a progressive accumulation of lipids in many organs. A combined approach with substrate‐reduction therapy (SRT) and byproduct therapy (BPT) has been shown to ameliorate the disease course in a mutant mouse model (NPC1^–/–). The present study examines the morphological parameters underlying these changes. For the combined SRT/BPT treatment, NPC1^–/– mutant mice (NPC1^{–/–SRT/BPT}) were injected with allopregnanolone/cyclodextrin weekly, starting at postnatal day (P) 7. Starting at P10, a miglustat injection was administered daily until P23. Thereafter, miglustat was added to the powdered chow. For the sham treatment, both mutant NPC1^–/– (NPC1^–/–sham) and wild‐type (NPC1^+/+sham) mice received an NaCl injection and were fed powdered chow without miglustat. Analysis was performed on cerebellar slices by histology and immunohistochemistry. The volumes and cell counts of cerebellar structures were quantified. Additionally, ultrastructural analysis was performed with transmission electron microscopy. In agreement with previous studies, the current study demonstrates Purkinje cell degeneration in the mutant mice, which was partially abrogated by SRT/BPT. The volumes of cerebellar white matter and molecular layer were reduced as well. Also, the number of neurons was reduced in granular and molecular layers. However, only the molecular layer benefited from the therapy, as shown by an increase in the volume and the amount of neurons. The volume and number of neurons of the deep cerebellar nuclei were significantly decreased in mutant mice; an appreciable therapeutic benefit could be demonstrated for the nucleus interpositus. © 2014 Wiley Periodicals, Inc.     

Pontine‐to‐midbrain ratio indexes ocular‐motor function and illness stage in adult Niemann–Pick disease type C

Background and purpose: Niemann–Pick disease type C (NPC) is a progressive neurovisceral disorder associated with dystonia, ataxia and a characteristic gaze palsy. Neuropathological studies have demonstrated brainstem atrophy associated with neuronal inclusions and loss, and neurofibrillary tangles, although it is not known whether this pathology can be detected in vivo or how these changes relate to illness variables, particularly ocular‐motor changes. Our aim was to utilize a method for brainstem atrophy, validated in progressive supranuclear palsy (PSP), in a group of adult patients with NPC, and explore its relationship to illness variables and ocular‐motor functioning. Methods: We calculated the midbrain and pontine area, and pontine‐to‐midbrain ratio (PMR) from midsagittal images of 10 adult patients with NPC and 27 age‐ and gender‐matched controls. Measures were correlated with illness variables, and measures of horizontal saccadic functioning. Results: Pontine‐to‐midbrain ratio was 14% higher in the NPC group, but this difference was not significant. However, PMR showed a significant positive correlation with duration of illness and a measure of illness severity. Furthermore, PMR was significantly negatively correlated with saccadic peak velocity and gain, and self‐paced saccadic performance. Conclusions: Pontine‐to‐midbrain ratio was increased in adult patients with NPC compared to controls, although not to the same degree as previously described in PSP, which also presents with significant gaze palsy. These changes were driven predominantly by progressive midbrain atrophy. The strong correlation with illness and ocular‐motor variables suggests that it may be a useful marker for illness progression in NPC.     

Decreased estradiol release from astrocytes contributes to the neurodegeneration in a mouse model of Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is a deadly neurodegenerative disease often caused by mutation in a gene called NPC1, which results in the accumulation of unesterified cholesterol and glycosphingolipids in the endosomal-lysosomal system. Most studies on the mechanisms of neurodegeneration in NPC have focused on neurons. However, the possibility also exists that NPC1 affects neuronal functions indirectly by acting on other cells that are intimately interacting with neurons. In this study, using a heterotypic neuron-glia coculture system, we found that wild-type neurons cultured on a layer of NPC1-/- astrocytes showed decreased neurite growth compared with those cultured on wild-type astrocytes. RT-PCR and immunohistochemical assessments showed significantly lower expression of neurosteroid enzymes and StAR (steroidogenic acute regulatory protein) in NPC1-/- astrocyte cultures than in wild-type cultures. Furthermore, a reduced level of estradiol was measured from both astrocyte culture medium and whole brains from NPC1-/- mice. Administration of 17beta-estradiol to neonatal NPC1-/- mice significantly delayed the onset of neurological symptoms, increased Purkinje cell survival, and extended the animals' life span. Our findings suggest that astrocyte dysfunction contributes to the neurodegeneration of NPC and estradiol treatment may be useful in ameliorating progression of the disease.     

Altered levels and distribution of amyloid precursor protein and its processing enzymes in Niemann‐Pick type C1‐deficient mouse brains

Niemann‐Pick type C (NPC) disease is an autosomal recessive neurodegenerative disorder characterized by intracellular accumulation of cholesterol and glycosphingolipids in many tissues including the brain. The disease is caused by mutations of either NPC1 or NPC2 gene and is accompanied by a severe loss of neurons in the cerebellum, but not in the hippocampus. NPC pathology exhibits some similarities with Alzheimer's disease, including increased levels of amyloid β (Aβ)‐related peptides in vulnerable brain regions, but very little is known about the expression of amyloid precursor protein (APP) or APP secretases in NPC disease. In this article, we evaluated age‐related alterations in the level/distribution of APP and its processing enzymes, β‐ and γ‐secretases, in the hippocampus and cerebellum of Npc1^−/− mice, a well‐established model of NPC pathology. Our results show that levels and expression of APP and β‐secretase are elevated in the cerebellum prior to changes in the hippocampus, whereas γ‐secretase components are enhanced in both brain regions at the same time in Npc1^−/− mice. Interestingly, a subset of reactive astrocytes in Npc1^−/− mouse brains expresses high levels of APP as well as β‐ and γ‐secretase components. Additionally, the activity of β‐secretase is enhanced in both the hippocampus and cerebellum of Npc1^−/− mice at all ages, while the level of C‐terminal APP fragments is increased in the cerebellum of 10‐week‐old Npc1^−/− mice. These results, taken together, suggest that increased level and processing of APP may be associated with the development of pathology and/or degenerative events observed in Npc1^−/− mouse brains. © 2010 Wiley‐Liss, Inc.     

Astrocytic poly(ADP‐ribose) polymerase‐1 activation leads to bioenergetic depletion and inhibition of glutamate uptake capacity

Poly(ADP‐ribose) polymerase‐1 (PARP‐1) is a ubiquitous nuclear enzyme involved in genomic stability. Excessive oxidative DNA strand breaks lead to PARP‐1‐induced depletion of cellular NAD⁺, glycolytic rate, ATP levels, and eventual cell death. Glutamate neurotransmission is tightly controlled by ATP‐dependent astrocytic glutamate transporters, and thus we hypothesized that astrocytic PARP‐1 activation by DNA damage leads to bioenergetic depletion and compromised glutamate uptake. PARP‐1 activation by the DNA alkylating agent, N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG), caused a significant reduction of cultured cortical astrocyte survival (EC₅₀ = 78.2 ± 2.7 μM). HPLC revealed MNNG‐induced time‐dependent reductions in NAD⁺ (98%, 4 h), ATP (71%, 4 h), ADP (63%, 4 h), and AMP (66%, 4 h). The maximal [³H]glutamate uptake rate (V_max) also declined in a manner that corresponded temporally with ATP depletion, falling from 19.3 ± 2.8 in control cells to 2.1 ± 0.8 nmol/min/mg protein 4 h post‐MNNG. Both bioenergetic depletion and loss of glutamate uptake capacity were attenuated by genetic deletion of PARP‐1, directly indicating PARP‐1 involvement, and by adding exogenous NAD⁺ (10 mM). In mixed neurons/astrocyte cultures, MNNG neurotoxicity was partially mediated by extracellular glutamate and was reduced by co‐culture with PARP‐1^−/− astrocytes, suggesting that impairment of astrocytic glutamate uptake by PARP‐1 can raise glutamate levels sufficiently to have receptor‐mediated effects at neighboring neurons. Taken together, these experiments showed that PARP‐1 activation leads to depletion of the total adenine nucleotide pool in astrocytes and severe reduction in neuroprotective glutamate uptake capacity. © 2009 Wiley‐Liss, Inc.     

Neurotoxic effects of high-dose piperine on hippocampal synaptic transmission and synaptic plasticity in a rat model of memory impairment

In recent years, piperine has attracted much attention due to its various biological effects as a neuroprotective agent. Therefore, clarification of the possible side effects of piperine is important to identify its potential pharmacological action. Thus, the effects of piperine on the long-term plasticity of perforant pathway to dentate gyrus synapses were studied in hippocampus of an animal model of Alzheimer's disease (AD).Adult male rats were injected with intracerebroventricular (ICV) streptozotocin (STZ) bilaterally, on days 1 and 3 (3 mg/kg). The STZ-injected rats were treated with different doses of piperine for 4 weeks before being used in behavioral, electrophysiological and histopathological experiments. The passive-avoidance test was conducted on all animals in order to determine the cognitive performance. Rats were placed in a stereotaxic frame to implant a recording electrode in the hippocampal dentate gyrus and a stimulating electrode in the perforant path. Additionally, we assessed the density of survived neurons stained by cresyl violet.In this study, chronic administration of piperine low dose improved the ICV-STZ induced learning and long-term potentiation (LTP) impairments with no significant effect on baseline synaptic activity. In contrast, remarkable learning and long-term plasticity impairments were observed in rats treated by high dose of piperine in comparison to the other groups. Interestingly, this impaired hippocampal LTP was accompanied by an obvious alteration in baseline activity and significantly decreased neuronal numbers within the hippocampus. Therefore, our data provides a new understanding of the piperine supplementation effects on hippocampal electrophysiological profile although the consequences may be either beneficial or detrimental.     

Niemann‐Pick disease type C1 predominantly involving the frontotemporal region,with cortical and brainstem Lewy bodies: An autopsy case

Niemann‐Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage disorder. Two disease‐causing genes (NPC1 and NPC2) have been identified. NPC is characterized by neuronal and glial lipid storage and NFTs. Here, we report a man with juvenile‐onset progressive neurological deficits, including pyramidal signs, ataxia, bulbar palsy, vertical supranuclear ophthalmoplegia, and psychiatric symptoms; death occurred at age 37 before definitive clinical diagnosis. Post mortem gross examination revealed a unique distribution of brain atrophy, predominantly in the frontal and temporal lobes. Microscopically, lipid storage in neurons and widely distributed NFTs were observed. Lipid storage cells appeared in systemic organs and filipin staining indicated intracellular cholesterol accumulation in hepatic macrophages. Electron microscopy revealed accumulation of lipids and characteristic oligolamellar inclusions. These findings suggested an NPC diagnosis. Neuronal loss and gliosis were frequently accompanied by NFTs and occurred in the frontal and temporal cortices, hippocampus, amygdala, basal forebrain, basal ganglia, thalamus, substantia nigra and brain stem nuclei. Lewy bodies (LBs) were observed in most, but not all, regions where NFTs were evident. In contrast, neuronal lipid storage occurred in more widespread areas, including the parietal and occipital cortices where neurodegeneration with either NFTs or LBs was minimal. Molecular genetic analysis demonstrated that the patient had compound heterozygous mutations in the cysteine‐rich loop (A1017T and Y1088C) of the NPC1 gene. To our knowledge there has been no previous report of the A1017T mutation. The pathological features of this patient support the notion that NPC has an aspect of α‐synucleinopathy, and long‐term survivors of NPC may develop a frontotemporal‐predominant distribution of brain atrophy.     

Reward memory relieves anxiety‐related behavior through synaptic strengthening and protein kinase C in dentate gyrus

Anxiety disorders are presumably associated with negative memory. Psychological therapies are widely used to treat this mental deficit in human beings based on the view that positive memory competes with negative memory and relieves anxiety status. Cellular and molecular processes underlying psychological therapies remain elusive. Therefore, we have investigated its mechanisms based on a mouse model in which food reward at one open‐arm of the elevated plus‐maze was used for training mice to form reward memory and challenge the open arms. Mice with the reward training showed increased entries and stay time in reward open‐arm versus neutral open‐arm as well as in open‐arms versus closed‐arms. Accompanying with reward memory formation and anxiety relief, glutamatergic synaptic transmission in dentate gyrus in vivo and dendritic spines in granule cells became upregulated. This synaptic up‐regulation was accompanied by the expression of more protein kinase C (PKC) in the dendritic spines. The inhibition of PKC by chelerythrine impaired the formation of reward memory, the relief of anxiety‐related behavior and the up‐regulation of glutamate synapses. Our results suggest that reward‐induced positive memory relieves mouse anxiety‐related behavior by strengthening synaptic efficacy and PKC in the hippocampus, which imply the underlying cellular and molecular processes involved in the beneficial effects of psychological therapies treating anxiety disorders. © 2015 Wiley Periodicals, Inc.