Partial blockage of sterol biosynthesis with a squalene synthase inhibitor in early postnatal Niemann-Pick type C npcnih null mice brains reduces neuronal cholesterol accumulation, abrogates astrogliosis, but may inhibit myelin maturation

Niemann-Pick C disease (NPC) is a fatal, neurovisceral genetic disorder. Cell culture studies showed that NPC1 or NPC2 mutations cause malfunctions in cellular cholesterol trafficking and lead to accumulation of cholesterol and other lipids in the late endo/lysosomes. Previous work showed that neuronal cholesterol accumulation occurs in the brains of young postnatal NPC1-/- mice. Here, to evaluate the potential of partial blockage of cholesterol biosynthesis as a therapy for the NPC disease, we first developed a simple method to monitor the relative rates of lipid biosynthesis in mice brains. We next administered squalene synthase inhibitor (SSI) CP-340868 to young mice. The results show that treating 8-day-old NPC1-/- mice with CP-340868 for 6 days significantly inhibits cholesterol biosynthesis in the mice brains. It reduces neuronal cholesterol accumulation, reduces GM3 ganglioside accumulation, and diminishes astrogliosis in the brain. These results suggest that neuronal cholesterol accumulation contributes to early pathogenesis in the NPC1-/- mice brains. The SSI treatment also reduced brain galactolipid content, suggesting that blocking endogenous cholesterol synthesis in the young mice brains may disrupt the normal myelin maturation processes. The methods described in the current work have general applicability for lipid metabolism studies in mice brains in various pathophysiological conditions.     

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.     

Cognitive correlates of Abeta deposition in male and female mice bearing amyloid precursor protein and presenilin-1 mutant transgenes

Several transgenic mouse models of Alzheimer's disease (AD) have been developed that exhibit beta-amyloid (Abeta) neuropathology and behavioural deficits. However, not all studies have investigated the relationship between the development of cognitive impairment and neuropathology. Therefore, temporal changes in cognition were investigated in male and female double-mutant APPswexPS1.M146V (TASTPM) transgenic mice using an object recognition test and correlated with the development of cerebral Abeta neuropathology. Both male and female TASTPM mice exhibited similar significant cognitive impairment at 6, 8 and 10 months of age in the object recognition test, compared to wild-type littermates. There was no such cognitive impairment at 3 or 4 months of age. Quantitative immunohistochemistry using a battery of Abeta antibodies demonstrated that cerebral Abeta deposition was first apparent in 3-month-old mice, and it increased with age. The early appearance of cerebral Abeta deposits in the double-transgenic TASTPM mice supports the evidence that mutations in the PS1 gene accelerate Abeta deposition. The cerebral Abeta load was greater in female than in male TASTPM mice at all ages investigated. In the electron microscope, mature Abeta plaques comprising a fibrillar core surrounded by degenerating neurites and reactive glia were first observed in the cortex of TASTPM mice at 6 months of age, the same age at which cognitive impairment became apparent. These results suggest that the cognitive impairment in TASTPM mice is related to the disruption of neural connectivity and not simply Abeta deposition, which first occurs 3 months earlier.     

Controversial neuropsychological issues in Alzheimer's disease: influence of onset-age and hemispheric asymmetry of impairment

A battery of 21 standardized neuropsychological tests was used in a retrospective study carried out on 52 mildly demented Alzheimer patients to analyse the relationship between age at onset of disease and the progress of cognitive impairment. Early onset was found to be associated with a more severe impairment. Possible sampling biases are discussed. Forty-seven patients were also tested for hemisphere asymmetry of cognitive impairment with two subsets of tests predominantly tapping left and right hemisphere abilities, respectively. We found a significant predominance of left-sided impairment which was not related to age at onset of disease. Possible relationship of this finding to healthy brain asymmetries is discussed.     

Frontotemporal dementia: patient characteristics,cognition, and behaviour

OBJECTIVES: To describe sociodemographic data of patients with frontotemporal dementia (FTD), to compare the cognitive profile of patients with FTD with that of severity-matched patients with Alzheimer's disease using the CERAD neuropsychological battery (CERAD-NP), to investigate the frequency of behavioural disturbances, and to examine the relation between FTD-specific non-cognitive behavioural symptoms of patients with FTD with age and sex. METHODS: Fifty outpatients were diagnosed with FTD according to the Lund-Manchester consensus criteria. Cognitive impairment was assessed in 30 patients using the CERAD-NP. Severity of dementia was rated on the Clinical Dementia Rating (CDR). Eleven non-cognitive symptoms were rated by severity. To compare CERAD-NP results between patients with FTD and AD, 30 patients with AD were matched for age, sex, and global severity of cognitive performance. RESULTS: The average age at onset of first symptoms was 57.8 years. Eighteen patients (36%) had a positive family history of dementia. On the CERAD-NP patients with FTD performed significantly better than patients with AD on word list learning, delayed verbal recall and visuoconstruction (p < 0.05). There were no significant differences between FTD and AD on naming and verbal fluency tasks. The most frequent non-cognitive behavioural symptoms in FTD were loss of insight, speech abnormality, and apathy. Non-cognitive behavioural symptoms were more frequent in younger and in male than in older patients and in female patients. CONCLUSIONS: The CERAD-NP is a valuable clinical instrument for the cognitive evaluation of patients with suspected FTD. Complementary short tests of attention and executive function may be recommended. To enhance diagnostic sensitivity informant interviews should focus on non-cognitive behavioural changes, taking advantage of standardised questionnaires.     

Differences in behavioural test battery performance between mice with hippocampal and cerebellar lesions

Effects of hippocampal or cerebellar lesions have been described extensively, but the ability of behavioural tests for laboratory mice to distinguish between such lesions has not been studied in detail. We compared the behavioural consequences of large bilateral hippocampal and hemispheric cerebellar lesions with eight commonly used tests that included elements of neuromotor performance, exploratory behaviour, and learning and memory ability. Dissociation between the effects of the different lesions was most obviously demonstrated by neuromotor impairment in cerebellum-lesioned mice (typically in the rotarod task) and hyperactivity in hippocampus-lesioned mice (typically in cage activity recordings). Several of the behavioural variables derived from the test battery correlated differently with the size of the hippocampal and cerebellar lesions. In contrast, no absolute dissociation between the effects of these lesions was found in the Morris maze, a reportedly hippocampus-dependent learning and memory task. The contextual fear conditioning task, on the other hand, did reveal a selective decrease of context-dependent freezing in hippocampus-lesioned mice, whereas cerebellum-lesioned animals displayed an increase in freezing responses. By and large, the present battery of tests does allow differentiation between the effects of cerebellar and hippocampal lesions in laboratory mice.     

Early glial activation, synaptic changes and axonal pathology in the thalamocortical system of Niemann-Pick type C1 mice

Niemann-Pick disease type C (NPC) is an inherited lysosomal storage disease characterised by accumulation of cholesterol and glycosphingolipids. NPC patients suffer a progressive neurodegenerative phenotype presenting with motor dysfunction, mental retardation and cognitive decline. To examine the onset and progression of neuropathological insults in NPC we have systematically examined the CNS of a mouse model of NPC1 (Npc1(-/-) mice) at different stages of the disease course. This revealed a specific spatial and temporal pattern of neuropathology in Npc1(-/-) mice, highlighting that sensory thalamic pathways are particularly vulnerable to loss of NPC1 resulting in neurodegeneration in Npc1(-/-) mice. Examination of markers of astrocytosis and microglial activation revealed a particularly pronounced reactive gliosis in the thalamus early in the disease, which subsequently also occurred in interconnected cortical laminae at later ages. Our examination of the precise staging of events demonstrate that the relationship between glia and neurons varies between brain regions in Npc1(-/-) mice, suggesting that the cues causing glial reactivity may differ between brain regions. In addition, aggregations of pre-synaptic markers are apparent in white matter tracts and the thalamus and are likely to be formed within axonal spheroids. Our data provide a new perspective, revealing a number of events that occur prior to and alongside neuron loss and highlighting that these occur in a pathway dependent manner.     

High early case fatality after ischaemic stroke in Poland: exploration of possible explanations in the International Stroke Trial

Several authors have recently reported a broad cognitive impairment in autosomal dominant cerebellar ataxias (ADCAs) patients. However, only a few studies on neuropsychological features in spinocerebellar ataxia type 2 (SCA2) patients are present in the current literature. The aim of this study is to evaluate the cognitive impairment in a wide sample of SCA2 patients and to verify the role of different disease-related factors (age of onset, disease duration, and clinical severity) on intellectual abilities. We administered a battery of neuropsychological tests assessing handedness, attention, short- and long-term verbal and visuo-spatial memory, executive functions, constructive abilities, general intellectual abilities and depression to 18 SCA2 patients belonging to eight families who came to our observation. Evidence of impaired verbal memory, executive functions and attention was found. The cognitive status was partially related to clinical severity rather than to disease duration or age at onset of symptoms. We partially confirmed data on cognitive defects already reported by others but we also found defective attention skills as well as significant lower performances in a nonverbal intelligence task.     

Peripheral nerve pathology in Niemann-Pick type C mouse

The sciatic nerve of the mouse mutant with Niemann-Pick type C disease (NPC mouse) was investigated using light and electron microscopy, and teased-fiber preparations. As early as postnatal day 20, when clinical symptoms were not yet apparent, focal paranodal swellings with an accumulation of small myelin figures in the Schwann cell cytoplasm were noted. These paranodal changes were more pronounced in the distal segment and became progressively conspicuous with increasing age. The morphometric analysis revealed a hypomyelination of large myelinated fibers in the NPC nerves at 70 days, whereas an essentially similar histogram pattern was noted in both control and NPC nerves at 20 days, suggesting progressively defective utilization of cholesterol in the NPC nerves with age. Intraxonal accumulation of dense bodies was noted in older mice, but no segmental demyelination or Wallerian type of axonal degeneration was observed at any age. The changes noted in the paranodal regions in the NPC mouse closely resemble those found in rats treated with an inhibitor of cholesterol biosynthesis, as well as those seen in remodeling fibers during an early stage of peripheral nerve development. Thus, the morphological changes seen in the sciatic nerve of the NPC mouse may be an expression of perturbation in myelin maintenance as a result of defective cholesterol metabolism.Preliminary findings were presented at the Annual Meeting of the American Association of Neuropathologists, Baltimore, Maryland, June 1991     

Mice lacking leukocyte common antigen-related (LAR) protein tyrosine phosphatase domains demonstrate spatial learning impairment in the two-trial water maze and hyperactivity in multiple behavioural tests

Leukocyte common antigen-related (LAR) protein is a cell adhesion molecule-like receptor-type protein tyrosine phosphatase. We previously reported that in LAR tyrosine phosphatase-deficient (LAR-Delta P) mice the number and size of basal forebrain cholinergic neurons as well as their innervation of the hippocampal area was reduced. With the hippocampus being implicated in behavioural activity aspects, including learning and memory processes, we assessed possible phenotypic consequences of LAR phosphatase deficiency using a battery of rodent behaviour tests. Motor function and co-ordination tests as well as spatial learning ability assays did not reveal any performance differences between wildtype and LAR-Delta P mice. A spatial learning impairment was found in the difficult variant of the Morris water maze. Exploration, nestbuilding and activity tests indicated that LAR-Delta P mice were more active than wildtype littermates. The observed hyperactivity in LAR-Delta P mice could not be explained by altered anxiety or curiosity levels, and was found to be persistent throughout the nocturnal period. In conclusion, behavioural testing of the LAR-Delta P mice revealed a spatial learning impairment and a significant increase in activity.     

LMN diet, rich in polyphenols and polyunsaturated fatty acids, improves mouse cognitive decline associated with aging and Alzheimer's disease

We examined whether LMN diet, reported to induce neurogenesis in adult mice, was able to antagonize the age-related behavioural impairment and neuropathology in wild type (WT) mice and Tg2576 mice, a mouse model of Alzheimer's disease (AD). Thirteen-month-old mice (once the amyloid (Aβ) plaques were formed) were fed with the LMN diet for 5 months, and in the last 2 months of the regimen they received a battery of behavioural tests. In general, both aging and (to a higher extent) Tg2576 genotype deteriorated sensorimotor reflexes, exploratory behaviour in the hole board, activity (but not anxiety) in the elevated plus-maze, ambulation in the home cage during the dark phase, and spatial learning in the Morris water maze. LMN diet did not affect the detrimental effects observed in sensorimotor reflexes, but clearly reversed the effects of both aging and Tg2576 genotype. This behavioural amelioration was correlated with a 70% increase in cellular proliferation in subventricular zone (SVZ) of the brain, but did not correlate with a decrease of amyloid plaques. In contrast, administration of LMN diet to 10 months old mice (before the plaques are formed) strongly suggested a putative delay in the formation of plaques, as indicated by a decreasing tendency of soluble and fibrillar Aβ levels in hippocampus which correlated with a decrease in Aβ (1-40, 1-42) plasma content. Herein we describe for the first time that LMN diet rich in polyphenols, dry fruits and cocoa, was able to decrease behavioural deterioration caused by aging and Tg2576 genotype and to delay the Aβ plaque formation. These results corroborate the increasing importance of polyphenols as human dietary supplements in amelioration of the cognitive impairment during aging and neurological disorders such as AD.     

Perturbed myelination process of premyelinating oligodendrocyte in Niemann-Pick type C mouse

Niemann-Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage disease caused by a loss of NPCI function, which results in perturbation of intracellular cholesterol transport. In BALB/c npc(nih) mice, the murine ortholog of NPCI gene is mutated. In NPC mouse, hypomyelination is conspicuous in the cerebral white matter and corpus callosum in addition to neuronal storage. However, the pathogenesis on hypomyelination is not well elucidated. We hypothesized that the hypomyelination in NPC mice resulted from either defective differentiation of oligodendrocyte lineage cells or a failure of proper axon-glial interaction. Myelin basic protein immunohistochemistry disclosed severe hypomyelination of cerebral cortex as well. NG2- or O4-positive progenitor cells and premyelinating oligodendrocytes (OLs) were abundant. However, pi-glutathione-S-transferase-positive mature OLs were considerably reduced. In hypomyelinated white matter, strong immunoreactivity of polysialylated-neural cell adhesion molecule, a negative regulator of myelination, was observed in axons. Given the fact that neuro-axonal degeneration has been observed in NPC mouse as early as 9 days of age prior to the commencement of myelination in the corpus callosum and that axonal signals are essential for the proper myelination, subtle axonal injury might be contributing to the pathogenesis of disturbed myelination in the NPC mouse.     

Psychosis as a presentation of physical disease in adolescence: a case of Niemann–Pick disease, type C

This study reports the case of a 16-year-old male who presented with a history of prominent psychotic symptoms and paranoid delusions which overshadowed subtle signs and symptoms of cognitive and motor dysfunction. Intensive neurobehavioral and biochemical investigations eventually led to the diagnosis of Niemann–Pick disease, type C (NPC), an autosomal recessively inherited storage disease that is associated with the accumulation of cholesterol in lysosomes and difficulties in the processing of exogenously derived cholesterol. Clues to the presence of a neurological disorder included: a history of insidiously declining academic and athletic performance which antedated the onset of psychosis; abnormalities on mental status examination, including psychomotor slowing, memory difficulties, and impairment of higher attentional functions; physical findings of subtle downgaze impairment, mild symmetrical hyperreflexia, and lower-extremity hypertonia with flexor plantar responses, marked impairment of upper-extremity rapid alternating movements, action tremor, and bilateral posturing with stress gait maneuvers. This case demonstrates the importance of careful and persistent neurodiagnostic evaluation in adolescents with psychotic presentations, particularly when cognitive and motor deterioration is suspected, and even when head CT and MRI scans are judged to be normal.     

The heterozygous reeler mouse: behavioural phenotype

The aim of this study was to investigate whether heterozygous reeler mice (+/rl) could be used as a genetic mouse model of schizophrenia, as previously suggested [J. Med. Chem. 44 (2001) 477]. The behavioural phenotype of male and female +/rl mice (young adult: 50-70 days old, and fully adult: >75 days old) was compared to their wild type (+/+) littermates. A complex behavioural test battery was employed: Irwin test, rotarod, spontaneous locomotor activity, social behaviour, light-dark transition test, startle response and prepulse inhibition, and hot-plate test. Overall, +/rl mice did not differ from their +/+ littermates at either age, although fully adult +/rl male mice spent more time engaged in social investigation. Some of the behavioural measures investigated were influenced by gender. Young female mice were more active in the light/dark transition test than males, while males were more aggressive than females during social interaction. In addition, performance on the rotarod was shown to deteriorate with age. Our data are in agreement with previous findings [Soc. Neurosci. Abst. 27 (2001) 238; J. Psychopharmacol. 17 (2003) A43], but contrary to those of Costa et al. [Curr. Opin. Pharmacol. 2 (2002) 56], although mice used in the present and previous studies were derived from the same genetic stock at Jackson Laboratories, USA. The present study clearly shows that, compared to its +/+ littermates, the +/rl mouse (young/fully adult) exhibits normal behaviour in a wide range of behavioural measures and suggest that these mice may not be suitable for use as a genetic animal model of schizophrenia.     

Central cholinergic dysfunction in the adult form of Niemann Pick disease type C: a further link with Alzheimer’s disease?

Adult patients with Niemann-Pick disease type C (NPC) usually develop cognitive impairment progressing to dementia, whose pathophysiology remains still unclear. Noteworthy parallels exist in cognitive impairment and cellular pathology of NPC and Alzheimer’s disease (AD). In particular, alterations of cholinergic system, which represent one of the pathological hallmarks and contribute to cognitive deterioration in AD, have recently been demonstrated in a human brain autopsy and in an experimental model of NPC. This finding raised the issue that central cholinergic circuits dysfunction may contribute to pathophysiology of cognitive impairment in NPC as well, and prompted us to evaluate the cholinergic functional involvement in NPC patients by applying a neurophysiologic technique, named short-latency afferent inhibition (SAI). We describe clinical, biochemical, molecular and neuropsychological features, and SAI findings in three patients affected by NPC. Diagnosis of NPC was assessed by molecular analysis of the NPC1 gene in all patients. In two of them, biochemical analysis of intracellular accumulation of unesterified cholesterol was also performed. The main clinical features were cerebellar ataxia, vertical supranuclear gaze palsy and a variable degree of cognitive impairment ranging from only memory impairment to severe dementia. Electrophysiological evaluation revealed a reduced SAI in all three patients. Our SAI findings provide evidence of cholinergic dysfunction in patients with the adult form of NPC, supporting that cholinergic alterations may play a role in cognitive impairment in NPC, and strengthening the similarities between NPC and AD.     

Is early‐onset clinically different from late‐onset frontotemporal dementia?

Background and purpose: Frontotemporal dementia (FTD) is the second most common neurodegenerative dementia in the young age after Alzheimer disease. Recent improvement in diagnostic assessment suggests that it is more common than previously, although with a great heterogeneity in clinical presentation. The different clinical patterns related to age of disease onset in behavioural variant FTD (bvFTD) have been fairly studied. Aim of the study was to evaluate whether age at disease onset modulate the heterogeneity of either cognitive impairment or behavioural disturbances in patients affected by bvFTD. Methods: One hundred and thirty‐four patients with bvFTD entered the study. Age at onset and demographic characteristics were carefully recorded. Each patient underwent a wide neuropsychological and behavioural standardized assessment, as well as a brain SPECT perfusion imaging study. Results: Behavioural variant FTD were subdivided into four groups according to the age at onset. The four quartile groups did not differ for demographic characteristics and family history for dementia. Global cognitive impairment as well as analysis of the different cognitive domains and behavioural patterns were comparable. Conclusions: These findings provide evidence that the clinical heterogeneity of bvFTD is not explained by age at disease onset. Further studies are needed.     

Transient caloric restriction in early adulthood hastens disease endpoint in male, but not female, Cu/Zn-SOD mutant G93A mice

Long-term caloric restriction (CR) prolongs the lifespan in healthy insects, rodents, and nonhuman primates. We previously reported that long-term CR improves motor performance but hastens clinical onset of disease in an animal model of amyotrophic lateral sclerosis (G93A mice). G93A mice overexpress the mutant human Cu/Zn-SOD gene and show progressive lower motor neuron weakness and increased oxidative stress. To study short-term (15 days) CR in the same animal model, we investigated the effect of transient caloric restriction (TCR) on paw grip endurance, clinical onset, disease progression (time from clinical onset to endpoint), and lifespan. Starting at age 40 days, 32 separately caged G93A mice were randomly divided into two groups: ad libitum (AL, n = 17; 10 females, 7 males) and TCR (n = 15; 6 females, 9 males) with a diet equal to 60% of AL. When the TCR mice lost 30% of their weight they were offered food AL until endpoint, otherwise all TCR mice were provided food AL from age 55 days until endpoint (i.e., range of TCR = 13-15 days). Paw grip endurance started to decrease significantly at age 96 days compared with baseline values for all the groups. TCR males reached clinical onset 5 days sooner than TCR females. Disease progression was 8 days faster in TCR mice than AL mice and 6 days faster in male mice than female mice. The probability of survival was significantly different between the groups, with the TCR males having a faster rate of reaching endpoint than TCR females, AL males, and AL females. We conclude that TCR hastens clinical onset of disease and shortens the lifespan in male, but not female, G93A mice. Moreover, TCR hastens progress of disease but has no effect on paw grip endurance. The female sex is protective against the detrimental effects of short-term CR in G93A mice. Assuming we can extrapolate these results to humans, short-term CR should be avoided in patients with amyotrophic lateral sclerosis, especially men.     

The neuropsychology of de novo patients with idiopathic Parkinson's disease: the effects of age of onset

One hundred de novo patients with Parkinson's disease (PD) were classified into two groups according to age of onset of symptoms. Seventy two patients were under 70 years and 28 were 70 years and over. All patients were given neurological and neuropsychological assessments, and the severity of the signs was rated on a modified Columbia scale. The neuropsychological assessment was also administered to 50 age-and-education-matched controls. The neuropsychological test battery included tests of verbal learning, visual memory, verbal fluency, visuospatial skill, simple and choice reaction time, language and maze learning. The late-onset patients had significant impairment in nonverbal reasoning, auditory verbal learning, visual memory and choice reaction time in contrast to early-onset patients and controls. A relationship was found between bradykinesia and widespread cognitive impairment. Severity of tremor was found to be significantly correlated with impairment in auditory verbal learning, visual memory and increased choice reaction time, while rigidity was found to be associated with cognitive impairment in verbal fluency and visuospatial skill. Using DSM II criteria, 39% of the late-onset and 8% of the early-onset group were classified as demented. Dementia was more common in patients with bilateral symmetrical disease and in those patients with marked tremor and bradykinesia. The pattern of cognitive impairment in PD was consistent with that associated with a subcortical dementia. This study confirms that the expression of PD is markedly influenced by the age of onset.