Pick's disease with neuronal four‐repeat tau accumulation in the basal ganglia,brain stem nuclei and cerebellum

It is very rare that cases of Pick's disease, a representative three‐repeat (3R) tauopathy, also have significant four‐repeat (4R) tau accumulation. Here, we report a Pick's disease case that clinically showed behavioral variant frontotemporal dementia without motor disturbance during the course, and pathologically had 3R tau‐positive Pick bodies as well as numerous 4R tau‐positive neuronal cytoplasmic inclusions (NCIs). Abundant 3R tau‐positive 4R tau‐negative spherical or horseshoe‐shaped Pick bodies were found in the frontotemporal cortex, limbic region, striatum and pontine nucleus. On the other hand, many 4R tau‐positive, 3R tau‐negative, Gallyas‐negative dot‐, rod‐ or intertwined skein‐like NCIs were found mainly in the subthalamic nucleus, pontine nucleus, inferior olivary nucleus and cerebellar dentate nucleus. Tufted astrocytes, astrocytic plaques, argyrophilic grains or globular glial inclusions were absent. Double‐labeling immunofluorescence demonstrated that 3R tau was hardly accumulated in 4R tau‐positive inclusions. On tau immunoblotting, while 60 and 64 kDa bands were demonstrated in the frontal cortex, 60, 64 and 68 kDa bands, as well as the 33 kDa tau fragments that are reported to be characteristic of progressive supranuclear palsy brains, were found in the basal ganglia and cerebellum. No mutation was identified in the tau gene. The present case suggests that, although probably rare, some Pick's disease cases have non‐negligible 4R tau pathology in the subcortical nuclei, and that such 4R tau pathology can affect the evaluation of the distribution of AT8‐positive tau pathology in Pick's disease cases.     

Distribution of basal ganglia lesions in Pick's disease with Pick bodies: A topographic neuropathological study of eight autopsy cases

The distribution of the basal ganglia lesions, including the amygdala, striatum, and pallidum, were investigated neuropathologically in eight Japanese autopsy cases of Pick's disease with Pick bodies. The lesions were classified as mild, moderate or severe. The degree and distribution of basal ganglia lesions in all eight cases were uniform: the amygdala showed severe to moderate lesions, the caudate nucleus and putamen showed moderate to mild lesions, and the pallidum showed mild lesions. Furthermore, the lesions in the amygdala were more prominent in the basolateral group than in the corticomedial group. In Pick's disease with Pick bodies, the degree and distribution of the lesions within the basal ganglia differs from those reported in both ‘Pick's disease without Pick bodies’ and corticobasal degeneration (CBD), in which severe lesions were present in the pallidum. These neuropathological findings may contribute to the morphological differential diagnosis among Pick's disease with Pick bodies, ‘Pick's disease without Pick bodies’, and CBD.     

Sensory stimulation accelerates dopamine release in the basal ganglia

We report herein the modulation of dopamine release in the basal ganglia during peripheral electrical stimulation in animals. The endogenous dopamine release during electrical stimulation was measured in anesthetized cats by positron emission tomography (PET) using the D2 receptor agonist [11C]-raclopride. Binding potential (BP) parametric maps were calculated using a simplified reference region model. The regional dopamine release evoked by electrical stimulation was estimated both by region of interest (ROI) analysis and statistical parametric mapping (SPM 99). Both ROI analysis and statistical parametric mapping showed significant release of endogenous dopamine in the nucleus accumbens and the striatum contralateral to the stimulated side as compared to the resting condition as well as the ipsilateral side. Accordingly, we suggest that the activity of the dopaminergic neurons in the midbrain projecting to the nucleus accumbens and the striatum is modulated by the input from the afferent nerves. This provides an in vivo evidence for the importance of the basal ganglia in the processing of peripheral information required for normal movement. This may also explain the clinically observed sensory system abnormalities in patients with movement disorders.     

Distribution of basal ganglia lesions in generalized variant of Pick's disease: a clinicopathological study of four autopsy cases

We investigated four Japanese autopsy cases of the generalized variant of Pick's disease ("basophilic inclusion body disease") both clinically and pathologically, and examined the degree and distribution of the basal ganglia lesions, including the amygdala, striatum, pallidum, and substantia nigra. The lesions in the amygdala, striatum, and pallidum were classified into three categories (slight, moderate, and severe). The lesions in the substantia nigra were qualitatively judged, compared with normal controls. Extrapyramidal signs, not noticed in the generalized variant of Pick's disease, were evident in all four cases, in addition to dementia. The degree and distribution of basal ganglia lesions in all four cases were uniform: the caudate nucleus showed severe lesions, the amygdala and putamen severe to moderate lesions, and the pallidum moderate to slight lesions. The substantia nigra in all our cases showed prominent neuronal loss, probably being one of the lesions responsible for extrapyramidal signs. In the generalized variant of Pick's disease, the degree and distribution of the alterations within the basal ganglia differs from those reported in Pick's disease with Pick bodies (PDPB) and corticobasal degeneration (CBD). In PDPB, severe lesions are present in the amygdala with relative sparing of the substantia nigra, compatible with rare extrapyramidal signs in PDPB, while in CBD, severe lesions are found in the pallidum and substantia nigra. These clinicopathological findings may contribute not only to the elucidation of clinicopathological hallmarks, but also to the progress of neuroimaging, in the generalized variant of Pick's disease.     

Glutamate/dopamine D1/D2 balance in the basal ganglia and its relevance to Parkinson' disease

The recent availability of selective ligands for NMDA and AMPA receptors has enabled neuroscientists to test the hypothesis that Parkinson' disease is a glutamate hyperactivity; disorder and hence treatable with glutamate antagonists. This review takes a critical look at the motor characteristics of this new class of drugs in rodent and primate models of parkinsonism and assesses the clinical potential and pitfalls of this radical new approach. Monotherapy of Parkinson's disease with glutamate antagonists appears impractical at the present time, due to their low efficacy and unacceptable side effects, but polypharmacy with L-DOPA and a glutamate antagonist as adjuvant is a more realistic prospect. This review will focus on the ways in which glutamate receptor blockade facilitates motor recovery with L-DOPA and will examine whether the basis for this beneficial effect can be traced to a specific interaction with dopamine at D₁ or D₂ receptors, and therefore to discrete motor pathways within the basal ganglia © 1995 Wiley-Liss, Inc.     

Ventricular somatostatin-like immunoreactivity in patients with basal ganglia disease

Summary The concentrations of somatostatin-like immunoreactivity (SLI) in lateral ventricular fluid of patients with extrapyramidal motor disease were determined by specific radio-immunoassay. Mean SLI levels were significantly lower in patients with Parkinson's disease (mean ± SEM); 42.9±2.9 fmol/ml) and in patients with dystonic syndromes (39.4±3.2) than in patients with benign essential tremor (65.3±9.7). The lowest levels were found in patients with athetosis (34.7±5.4). In parkinsonian patients somatostatin levels correlated with the degree of akinesia, rigidity and autonomic disturbances.     

Glutamate-dopamine interactions in the basal ganglia: relationship to Parkinson's disease

Summary Current antiparkinsonian therapies focus on either replacing dopamine via precursor (L-DOPA) administration, or directly stimulating postsynaptic dopamine receptors with dopamine agonists. Unfortunately, this approach is associated with numerous side effects and these drugs lose efficacy with disease progression. This article reviews recent evidence which suggests that negative modulation of glutamatergic neurotransmission has antiparkinsonian effects in a variety of rodent and primate models of parkinsonism. The pronounced synergism between dopaminergic agents and glutamate receptor antagonists may provide a means of using very low doses of the two drug classes in concert to treat Parkinson's disease effectively and minimize dose-related drug side effects.     

High levels of dopamine activity in the basal ganglia of cigarette smokers

OBJECTIVE: The authors' goal was to study presynaptic dopamine activity in smoking and nonsmoking human subjects in vivo. METHOD: [(18)F]Fluorodopa ([(18)F]DOPA) uptake K(i) values in the basal ganglia of nine smoking and 10 nonsmoking healthy men were measured with positron emission tomography. RESULTS: Significantly higher [(18)F]DOPA uptake was observed in both the putamen (average 17.3% higher) and the caudate (average 30.4% higher) of smokers than in those of nonsmokers. CONCLUSIONS: Smoking is related to greater dopamine activity in the human basal ganglia. Nicotine-induced dopamine activity may be a relevant mechanism in dependence on cigarette smoking.     

Distribution of secretagogin-containing neurons in the basal forebrain of mice,with special reference to the cholinergic corticopetal system

Cholinergic and GABAergic corticopetal neurons in the basal forebrain play important roles in cortical activation, sensory processing, and attention. Cholinergic neurons are intermingled with peptidergic, and various calcium binding protein-containing cells, however, the functional role of these neurons is not well understood. In this study we examined the expression pattern of secretagogin (Scgn), a newly described calcium-binding protein, in neurons of the basal forebrain. We also assessed some of the corticopetal projections of Scgn neurons and their co-localization with choline acetyltransferase (ChAT), neuropeptide-Y, and other calcium-binding proteins (i.e., calbindin, calretinin, and parvalbumin). Scgn is expressed in cell bodies of the medial and lateral septum, vertical and horizontal diagonal band nuclei, and of the extension of the amygdala but it is almost absent in the ventral pallidum. Scgn is co-localized with ChAT in neurons of the bed nucleus of the stria terminalis, extension of the amygdala, and interstitial nucleus of the posterior limb of the anterior commissure. Scgn was co-localized with calretinin in the accumbens nucleus, medial division of the bed nucleus of stria terminalis, the extension of the amygdala, and interstitial nucleus of the posterior limb of the anterior commissure. We have not found co-expression of Scgn with parvalbumin, calbindin, or neuropeptide-Y. Retrograde tracing studies using Fluoro Gold in combination with Scgn-specific immunohistochemistry revealed that Scgn neurons situated in the nucleus of the horizontal limb of the diagonal band project to retrosplenial and cingulate cortical areas.     

Development of the nigrostriatal dopamine neuron and the pathways in the basal ganglia

The nigrostriatal (NS) dopamine (DA) neuron and the basal ganglia show marked functional age variation in the first three decades. Neurohistochemical studies revealed marked age variation of activities of tyrosine hydroxylase at the terminal of the NS-DA neuron, which show exponential decremental variation from early childhood and subside in the fourth decade. DA-D2 receptors, examined by PET scan, are in high levels in the third decade which decrease dramatically to the bottom or 'adult' levels in the fourth decade. The examination of voluntary saccade suggested the striatal indirect pathways are functionally immature in the childhood and attain adult levels in around the middle of the second decade, while the striatal direct pathways have already been functionally matured in childhood. Clinical evidence suggests that among efferents of the basal ganglia those descending to the brainstem and the midbrain mature earlier while those ascending to the thalamus later. These developmental variation of the NS-DA neurons and the basal ganglia could modulate the ages at onset and clinical courses of the diseases with abnormalities in the NS-DA neuron or the basal ganglia which occur in these age periods.     

Cerebrospinal fluid markers of pathogenetic processes in vascular dementia, with special reference to the subcortical subtype

There is a need for improvement of the diagnosis of vascular dementia (VaD). Today, the clinician has to rely on clinical examination, history, and, possibly, brain imaging to identify cerebrovascular damage and other signs of VaD. The clinical diagnosis of subcortical VaD may be difficult because the clinical manifestation of this disorder is often similar to that of Alzheimer disease. There are also mixed forms of the two disorders. Biochemical diagnostic markers, which reflect the pathogenetic processes in the brain, would add to the accuracy of the diagnosis. There are some interesting candidate markers: the cerebrospinal fluid (CSF)/serum albumin ratio could be used to identify blood-brain barrier damage to the small intracerebral vessels, CSF sulfatide to identify ongoing demyelination of the white matter, CSF neuron-specific enolase to identify ongoing neuronal degeneration, and CSF tau protein and CSF neurofilament light protein to identify ongoing axonal degeneration. None of these potential markers is specific to subcortical VaD, but together and used in conjunction with the conventional diagnostic workup, they may be of diagnostic value.     

Stereotactic microdialysis of the basal ganglia in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an efficacious treatment in patients with advanced Parkinson's disease, yet the mechanisms of STN DBS are poorly understood. The aims of this study were to develop a useful method for studying neurotransmitter alterations during DBS and for the pharmacokinetics of L-dopa in brain tissue. Ten patients with Parkinson's disease participated, whereof two had no previous L-dopa medication. The electrodes and catheters were placed using MRI-guided stereotaxic targeting. Two microdialysis probes were placed, one in the right internal globus pallidus, and one in a brachial vein. The quadripolar deep brain electrodes were placed in the right STN. Microdialysates from brain tissue and blood were collected in 15-min fractions at baseline and during DBS. After stimulation new baseline fractions were taken and finally three fractions during continuous intravenous infusion of L-dopa. Clinical evaluation showed that both DBS and L-dopa infusion gave good relief of rigidity and tremor in all ten patients. During DBS the L-dopa levels in the brain increased in some of the patients but did not persist during the whole stimulation period. The concentration in brain increased substantially during intravenous L-dopa infusion. A number of catecholamines and their metabolites were analysed with high pressure liquid chromatography (HPLC). With our study we could show that this model is suitable for the monitoring of neurotransmitters and for pharmacokinetic studies in human brain, although we found that the sampling time was too short to follow the possible alterations in brain activity caused by DBS.     

The effect of manganese inhalation on basal ganglia dopamine concentrations in rhesus monkey

Manganese (Mn) may produce neurotoxicity in man through inhalation of Mn dust. Animals exposed to excessive Mn develop neurological abnormalities, and neuropathological lesions in the brain mainly in the globus pallidus with decreased concentrations of the neurotransmitter, dopamine (DA), in the brain. Monkeys exposed to Mn by inhalation did not produce any abnormal movements. After two years, the animals were sacrificed and certain brain areas were compared to controls. There were significant decreases in DA concentration in caudate and globus pallidus, and there was a 60-80% increase in Mn concentration in the basal ganglia of the brain. The DA system in the basal ganglia is vulnerable to the effects of Mn, but the amount of Mn inhaled and the period of exposure would appear to determine whether abnormal neurological signs develop.