Reduced neuronal size in posterior hippocampus of schizophrenic patients

The hippocampus, an integral component of the corticolimbic circuitry of the brain, has been recently implicated in the pathophysiology of schizophrenia. This article has employed quantitative morphometric techniques to determine whether abnormalities of posterior hippocampal cross-sectional area, as well as the number, size, and degree of disarray of pyramidal neurons were present in 9 control and 14 schizophrenic subjects. Seven schizophrenic patients showed evidence of superimposed mood disturbance (schizoaffective type), while the remaining seven were a mixture of paranoid, undifferentiated, and catatonic types. All morphometric measurements were conducted under strictly blind conditions; stepwise multiple regression and analyses of covariance were used to evaluate the effects of various confounding variables. There were no differences in the cross-sectional size of the hippocampus or degree of neuronal disarray between the two groups. Similarly, the number of pyramidal neurons was also the same in sectors Cornu Ammonis (CA) 2, CA 3, and CA 4 for the controls and schizophrenic subjects. In CA 1, the schizophrenic subjects without mood disturbances showed a significant reduction (36%) of pyramidal neuron numbers when compared with those of both controls and patients with mood disturbance. Pyramidal neurons were smaller in all sectors of the schizophrenic specimens, CA 1 (p less than or equal to 0.01), CA 2 (p less than or equal to 0.01), CA 3 (p less than or equal to 0.01), and CA 4 (p less than or equal to 0.005), but there were no differences with respect to the presence of mood disturbances. Corrections for the effects of age, postmortem interval, fixation interval, hypoxia, and neuroleptic exposure did not alter the pattern in the data. The significance of a smaller size of hippocampal pyramidal neurons in this group of schizophrenic specimens is unclear, but it is consistent with the suggestions of other laboratories that there may be altered function of this brain region in chronically psychotic individuals.

Evidence for axonal loss in regions occupied by senile plaques in Alzheimer cortex

The studies described have sought to determine what, if any, relationship exists between axons and the senile plaque, a hallmark histopathological feature of Alzheimer's disease. A double stain was performed on both early and late Alzheimer frontal cortex tissues in order to examine the interaction between axons stained with antibodies against the 200,000 mol. wt neurofilament subunit (NFP-200) of the axon cytoskeleton and Thioflavin-S, a fluorescent dye that stains plaques. Serial photomicrographs of plaques were taken and axon and plaque profiles were three-dimensionally reconstructed. Analysis of computer-processed images revealed that there were fewer axons within plaques than in regions lying one and two plaque distances away. When axons were observed passing through plaques, swelling and disruption of normal morphology was frequently present. Statistical analyses of axon counts within and around placques showed a gradient of axon density, with increased numbers occurring at progressive distances from the placque. Similar patterns were seen for early and late stages of the disease. The results of this study indicate that disruption of the axonal cytoskeleton may occur within the regions occupied by plaques.

Kynurenine pathway measurements in Huntington's disease striatum: evidence for reduced formation of kynurenic acid

Recent evidence suggests that there may be overactivation of the N-methyl-D-aspartate (NMDA) subtype of excitatory amino acid receptors in Huntington's disease (HD). Tryptophan metabolism by the kynurenine pathway produces both quinolinic acid, an NMDA receptor agonist, and kynurenic acid, an NMDA receptor antagonist. In the present study, multiple components of the tyrosine and tryptophan metabolic pathways were quantified in postmortem putamen of 35 control and 30 HD patients, using HPLC with 16-sensor electrochemical detection. Consistent with previous reports in HD putamen, there were significant increases in 5-hydroxyindoleacetic acid, 5-hydroxytryptophan, and serotonin concentrations. Within the kynurenine pathway, the ratio of kynurenine to kynurenic acid was significantly (p less than 0.01) increased twofold in HD patients as compared with controls, consistent with reduced formation of kynurenic acid in HD. CSF concentrations of kynurenic acid were significantly reduced in HD patients as compared with controls and patients with other neurologic diseases. Because kynurenic acid is an endogenous inhibitor of excitatory neurotransmission and can block excitotoxic degeneration in vivo, a relative deficiency of this compound could directly contribute to neuronal degeneration in HD.

Basic fibroblast growth factor in Alzheimer's disease

We have examined the presence of basic fibroblast growth factor (FGF) in normal and in Alzheimer brains, studied the distribution of the mitogen by immunohistochemical techniques, measured the quantities of growth factor in selected areas of the brain (Brodmann areas 10/11 and 20/21), characterized the molecular forms by Western blotting and determined its sites of synthesis by in situ hybridization. Although the same molecular forms of basic FGF are found in control and Alzheimer brains, basic FGF is increased in the brains of Alzheimer's patients. Furthermore, basic FGF is not distributed in an identical fashion to normal and Alzheimer brains, but is found in association with the lesions that characterize this disease. In normal controls (n = 5), basic FGF was found to be widely distributed throughout the three brain regions examined (prefrontal cortex, hippocampus, and hypothalamus). Immunoreactivity was observed within astrocytes in both the grey and white matter, as well as within neuronal perikarya. Brain tissues that were obtained from Alzheimer patients (N = 4) showed a substantial increase in the overall specific staining of astrocytes and neurons, particularly in areas of reactive gliosis. Focal concentration of immunoreactive basic FGF was evident within the neuritic plaques, and could be clearly seen in association with the neurofibrillary tangles present within neuronal perikarya. The possibility that basic FGF expression in the CNS is linked to the pathogenesis of the disease is discussed.

Lysosomal proteinase antigens are prominently localized within senile plaques of Alzheimer's disease: evidence for a neuronal origin

To investigate the role of proteolysis in amyloid formation, we studied the localization of the proteolytic enzymes, cathepsin D and cathepsin B, in the prefrontal cerebral cortex and hippocampus of human postmortem brains from patients with Alzheimer's disease and from individuals free of neurological disease. In control and Alzheimer brains, cathepsin immunoreactivity within cells was localized to lysosome-related structures, which were particularly abundant in neuronal perikarya. In Alzheimer brain, cathepsin immunoreactivity was also heavily concentrated extracellularly within senile plaques. Cathepsin immunoreactivity associated with plaques was not confined to lysosomes and was distributed throughout the plaque. Isolated amyloid cores, however, were not immunostained. Cathepsin-laden perikarya of degenerating neurons were frequently seen within senile plaques and, in the more advanced stages of degeneration, cathepsin immunoreactivity was present throughout the cytoplasm. Other identified constituents of senile plaques appeared to be less significant sources of cathepsin immunoreactivity, including astrocytes, degenerating neurites, microglia and macrophages. These results demonstrate that lysosomal proteinases are major constituents of the senile plaque and that degenerating neuronal perikarya are a principal source of the cathepsin immunoreactivity. We propose that the unregulated action of extracellular cathepsins liberated from degenerating neurons may lead to abnormal processing of the amyloid precursor protein and to the formation of amyloid locally within senile plaques in Alzheimer's disease.

Laminar distributions of muscarinic acetylcholine, serotonin, GABA and opioid receptors in human posterior cingulate cortex

Experimental animal studies have demonstrated a number of receptor localizations on specific cortical afferents and neurons. The present study of human posterior cingulate cortex evaluates the laminar distributions of particular receptors and their likely association with components of the neuropil. Coverslip autoradiographic and single grain counting techniques were used followed by heterogeneity analysis in which the layer of peak binding and an index of heterogeneity were determined for each ligand. The index was calculated by determining specific binding by layer as a percentage of binding in all layers. The differences from an absolutely homogeneous distribution, i.e. 11.1% for each of nine layers, were subtracted and the absolute laminar differences summed to form the index. High indices of over 15 reflected heterogeneous binding patterns in neocortex. The binding of ligands for muscarinic acetylcholine, serotonin, opioid, GABA and beta adrenoceptors was evaluated. Pirenzepine binding peaked in layer II of area 23a but was extremely homogeneous with an index of heterogeneity of 8.9. In contrast, oxotremorine-M binding had a peak in layer IIIc and an index of 16.4, while AF-DX 116 binding peaked in layer IIIa-b and had an index of 30.6. Of the ligands for serotonin uptake and receptor binding paroxetine binding was evenly distributed in layers I-III and had a low index of heterogeneity of 9.8. Ketanserin binding was also homogeneous and, since it had an index of 8.9, this pattern was virtually the same as that for paroxetine. In contrast, serotonin and 8-hydroxy-2-(di-n-propylamino)tetralin binding peaked in layer II and had very high indices of 20.8 and 50.3, respectively, suggesting only a limited association with that of the paroxetine distribution. Finally, there were three layers which contained peaks in binding for ligands for opioid, GABA and beta adrenoceptors. Firstly, layer Ia had peak dynorphin-A binding, the latter of which had an index of 22.6. Secondly, Tyr-D-Ala-Gly-MePhe-Gly-ol and 2-D-penicillamine-5-D-penicillamine-enkephalin binding peaked in layer II and had indices of 8.6 and 17.4, respectively. Thirdly, muscimol and (-)-cyanopindolol binding peaked in layer IIIa-b and had indices of 29.6 and 11.1, respectively. When viewed in the context of experimental animal studies, it is likely that heterogeneities in oxotremorine-M and paroxetine binding are associated with the termination of the thalamic and raphe nuclei, respectively. While serotonin 2 receptors are co-distributed with serotonin uptake sites, serotonin 1A receptors have a significant mismatch with these sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Phenotypic variation in 2 Huntington's disease families with linkage to chromosome 4

Variability of expression of the Huntington's disease (HD) gene is illustrated in 2 families with linkage of DNA restriction fragment length polymorphism to the short arm of chromosome 4. In 1 family, affected persons from 3 generations show 50-year variation of onset age. The member with the latest onset age (67) died at 91 with autopsy-confirmed HD. The next generation had hypotonic chorea beginning in the 4th decade with death in the 5th. In the 3rd generation, a rigid patient, inheriting the illness from an affected father, had a much earlier onset at 16, while her siblings had chorea beginning in the 3rd decade. In the 2nd family, several members had cerebellar signs, chorea, and dementia. MRI and CT revealed olivoponto-cerebellar and striatal atrophy. These phenotypes may be the result of different allelic genes at the HD locus or unlinked autosomal modifying loci influencing the expression of the HD gene.

Uptake of gamma-aminobutyric acid and L-glutamic acid by synaptosomes from postmortem human cerebral cortex: multiple sites, sodium dependence and effect of tissue preparation

The uptake of gamma-aminobutyric acid (GABA) and L-glutamic acid by synaptosomes prepared from frozen postmortem human brain was shown to be effected via distinct high and low affinity sites. At approximately 17 h postmortem delay, the kinetic parameters for GABA uptake were: high affinity site, Km 7.1 +/- 2.5 microM, Vmax 18.7 +/- 4.8 nmol.min-1 per 100 mg protein; low affinity site, Km 2 +/- 1 mM, Vmax 425 +/- 250 nmol.min-1 per 100 mg protein (means +/- S.E.M., n = 13). Kinetic parameters for L-glutamate uptake were: high affinity site, Km 7.5 +/- 1.0 microM, Vmax 85 +/- 8 nmol.min-1 per 100 mg protein; low affinity site, Km 1.8 +/- 1.2 mM. Vmax 780 +/- 175 nmol.min-1 per 100 mg protein (n = 11). A detailed kinetic analysis of high affinity GABA uptake was performed over a range of sodium ion concentrations. The results were consistent with a coupling ratio of one Na+ ion to one GABA molecule; a similar result was found with rat brain synaptosomes. However, rat and human synaptosomes differed in the degree to which the substrate affinity of the high affinity GABA uptake site varied with decreasing Na+ ion concentration. High affinity GABA uptake was markedly affected by the method used to freeze and divide the tissue, but did not vary greatly in different cortical regions. There was some decline of high affinity GABA uptake activity with postmortem delay, apparently due to a loss of sites rather than a change in site affinity.

Brain gangliosides in dementia of the Alzheimer type

Gangliosides GM1, GD1a, GD1b, and GT1b were measured in nine brain regions of five patients, clinically and neuropathologically diagnosed as having dementia of the Alzheimer type (DAT), and of three control patients. Analysis of variance revealed that mean concentrations of all gangliosides analyzed were significantly lower in DAT than in control brains. The areas affected in DAT included the nucleus basalis, and entorhinal, posterior cingulate, visual, and prefrontal cortices. A significant interaction between ganglioside type and brain area indicated unequal ganglioside concentrations. Individual gangliosides had significantly different concentrations in the hippocampal, entorhinal, posterior cingulate, visual, and prefrontal cortices. Analysis of ratios of "a"-ganglioside (GM1 and GD1a) and "b"-ganglioside (GD1b and GT1b) subtypes indicated that DAT preferentially affected "b"-gangliosides. Ganglioside concentrations in nucleus basalis did not correlate with age at disease onset, age at death, or postmortem interval. Changes in gangliosides, observed in this study, were not correlated with classic DAT neuropathology.

Localization of the growth-associated phosphoprotein GAP-43 (B-50, F1) in the human cerebral cortex

The growth-associated phosphoprotein GAP-43 is a component of the presynaptic membrane that has been linked to the development and functional modulation of neuronal connections. A monospecific antibody raised against rat GAP-43 was used here to study the distribution of the protein in cortical and subcortical areas of the human brain. On Western blots, the antibody recognized a synaptosomal plasma membrane protein that had an apparent molecular weight and isoelectric point similar to GAP-43 of other species. In brain tissue reacted with the antibody, the heaviest immunoreactivity was found in associative areas of the neocortex, particularly within layers 1 and 6, in the molecular layer of the dentate gyrus, the caudate putamen, and the amygdala. In contrast, primary sensory or motor regions of the cortex, portions of dorsal thalamus, and cerebellum showed only light staining. Staining was generally confined to the neuropil, which showed punctate labeling, whereas most neuronal somata and fiber bundles were unreactive. The pronounced variations in GAP-43 immunostaining among various areas of the human brain may reflect different potentials for functional and/or structural remodeling.

Receptor affinity, neurochemistry and behavioral characteristics of the enantiomers of thioridazine: evidence for different stereoselectivities at D1 and D2 receptors in rat brain

The binding characteristics of the enantiomers of thioridazine were assessed in the brain of the rat using competitive radioreceptor assays with tritiated ligands selective for dopamine D1 (SCH-23390), D2 (spiperone), norepinephrine alpha-1 (prazosin) and muscarinic (quinuclinidinyl benzilate) receptors. (+)-Thioridazine was shown to have 2.7 and 4.5 times higher affinity than (-)-thioridazine for D2 and alpha-1 receptors, respectively. In contrast, (-)-thioridazine had 10 times higher affinity for the D1 receptor. Both enantiomers showed similar affinities for the muscarinic receptor. In a second experiment, thioridazine, dopamine, norepinephrine, serotonin and their metabolites were assayed in the brain of the rat after acute administration of the enantiomers of thioridazine and the assessment of catalepsy. (+)-Thioridazine was 4.1 times as potent as (-)-thioridazine in elevating the turnover of dopamine in the striatum, but neither enantiomer affected the other monoamines. The concentration of thioridazine and its metabolites in the brain, for a given dose, was similar for both enantiomers. (-)-Thioridazine induced slightly more catalepsy than (+)-thioridazine and appeared to be more toxic at large doses. While racemic thioridazine had an intermediate effect between that of its two enantiomers in the binding and neurochemical assays, it appeared to induce more catalepsy than either enantiomer, suggesting a synergistic effect in this behavioral assay. It was concluded that (+)- and (-)-thioridazine act as partially selective D2 and D1 antagonists, respectively. Therefore, clinical administration of only one enantiomer of thioridazine, rather than the currently prescribed racemate, may result in an improved therapeutic profile and so be worthy of further investigation.

Amino acid and neuropeptide neurotransmitters in Huntington's disease cerebellum

Several neuropathologic studies have suggested that there may be pathologic involvement of the cerebellum in Huntington's disease (HD). To investigate this further, we measured concentrations of neurotransmitter amino acids and the neuropeptides, somatostatin, neuropeptide Y and substance P, in HD cerebellar cortex and dentate nucleus. Twenty-seven pathologically confirmed cases of HD were compared with 20 controls. There were no significant changes in concentrations were significantly increased by 21% in HD cerebellar cortex. In the dentate nucleus, there were small significant increases of neuropeptide Y-like immunoreactivity and substance P-like immunoreactivity. The meaning of the neurotransmitter changes found is unclear: however, the lack of change in GABA and glutamate concentrations argues against a substantial loss of intrinsic cerebellar neurons.

Somatostatin and neuropeptide Y concentrations in pathologically graded cases of Huntington's disease

Somatostatin and neuropeptide Y concentrations have previously been reported to be increased in the basal ganglia in Huntington's disease (HD). In the present study we have extended these findings by examining both somatostatin-like immunoreactivity (SLI) and neuropeptide Y-like immunoreactivity (NPYLI) in cases of HD, which were graded according to the severity of pathological degeneration in the striatum. In addition, we surveyed a large number of subcortical nuclei and cortical regions for alterations. Both SLI and NPYLI were significantly increased about threefold in the caudate, putamen, and the nucleus accumbens. Increases in mild and severe grades were similar, which is consistent with a relative but not absolute sparing of striatal aspiny neurons in which somatostatin and neuropeptide Y are colocalized. Significant increases of NPYLI were also found in the external pallidum, subthalamic nucleus, substantia nigra compacta, claustrum, anterior and dorsomedial thalamus, bed nucleus of the stria terminalis, and locus ceruleus. SLI was significantly increased in the external pallidum, red nucleus, and locus ceruleus. Measurements of both neuropeptides were made in 24 regions of the cerebral cortex. Significant increases in both NPYLI and SLI were found in the frontal cortex (Brodmann areas 6, 8, 9, 10, 11, and 45) and temporal cortex (Brodmann area 21), whereas NPYLI was also increased in Brodmann areas 12, 20-22, 25, and 42. Alterations in the cerebral cortex were as pronounced in cases with mild striatal pathological changes as in those with severe striatal pathological changes. These alterations may occur early in HD and could reflect a selective sparing of somatostatin-neuropeptide Y cortical neurons combined with cortical atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth-associated protein GAP-43 is expressed selectively in associative regions of the adult human brain

GAP-43 is a neuron-specific phosphoprotein that has been linked with the development and functional modulation of synaptic relationships. cDNAs for the human GAP-43 gene were used to reveal high overall levels of GAP-43 mRNA in a number of integrative areas of the neocortex, but low levels in cortical areas involved in the initial processing of sensory information, in several brainstem structures, and in caudate-putamen. Neurons expressing highest levels of GAP-43 mRNA were found by in situ hybridization to be concentrated in layer 2 of association cortex and in hippocampal pyramidal cells. Control studies showed that several other RNAs had regional distributions that were different from GAP-43, although the mRNA encoding the precursor of the Alzheimer amyloid beta protein followed a similar pattern of expression. These results suggest that a restricted subset of cortical and hippocampal neurons may be specialized for synaptic remodeling and might play a role in information storage in the human brain.

Predictive testing for Huntington's disease with use of a linked DNA marker

The probability of carrying the gene for Huntington's disease can in many cases be estimated in the children of affected persons by identifying a specific DNA marker that is genetically linked to the gene. We studied 47 persons at 50 percent risk of inheriting Huntington's disease who requested a presymptomatic or prenatal genetic-linkage test between September 1986 and January 1988. The participants were given pre-test counseling and psychological and neurologic evaluations. Nineteen persons later voluntarily withdrew from the protocol, including one who would have been excluded anyway, and one person was from a family that was too small to allow testing. Three D4S10 restriction-fragment-length polymorphisms produced by the HindIII, EcoRI, and Bg/I enzymes were used for all tests, and the probability that a subject was a Huntington's disease carrier was calculated. The accuracy of the test was compromised by a 4 percent recombination frequency between D4S10 and the Huntington's disease gene. Fifteen presymptomatic tests and one prenatal test were completed. Four yielded positive results, seven yielded negative results, and five were uninformative; seven persons are awaiting test results. All participants with positive tests experienced intermittent depression, but none required hospitalization, and no suicide threats were reported. Five participants received a diagnosis of Huntington's disease on the basis of the neurologic assessment. We conclude that some persons in the early stages of Huntington's disease may seek presymptomatic testing rather than neurologic evaluations.

A detailed examination of substance P in pathologically graded cases of Huntington's disease

Substance P concentrations have been found to be reduced in the basal ganglia in Huntington's disease (HD). In order to further examine this finding in the present study we measured substance P-like immunoreactivity (SPLI) in cases of HD which had been graded as to the severity of pathological changes in the striatum. Marked significant reductions of SPLI were found in all striatal nuclei which were significantly correlated with the percentage of neuronal loss in the varying pathologic grades. Similar changes were found in the projection sites of striatal substance P neurons, the globus pallidus interna and the substantia nigra. These changes are consistent with a loss of striatal substance P containing projection neurons in HD. Significant reductions in SPLI were also found in the external pallidum, bed nucleus of the stria terminalis and the subthalamic nucleus. Small significant increases in SPLI (20-30%) were found in 3 frontal cortical regions (Brodmann areas 6, 8 and 9). The finding of neurochemical changes in the subthalamic nucleus is of particular interest since lesions in this nucleus are known to result in chorea and therefore might contribute to the chorea which is a cardinal symptom of HD.

Clinical and neuropathologic assessment of severity in Huntington's disease

Clinical records were evaluated for 163 Huntington's disease patients in whom postmortem brain specimens had been graded for degree of neuropathologic involvement in the striatum. Juvenile/adolescent onset (4 to 19 years of age) was associated with very severe neuropathologic involvement produced by an apparent rapid degenerative process. Cases of early (20 to 34 years) and midlife (35 to 49 years) onset had respectively less severe striatal involvement, suggesting a slower degenerative progression. High correlations among the grade of neuropathologic involvement, cell counts of neurons, and a rating of physical disability suggest that each represents a common underlying degenerative process of the disease. The relationship between the age at onset and the extent of neuropathologic involvement suggests that a single mechanism may determine both onset and rate of degenerative disease progression.

Concentration and distribution of thioridazine and metabolites in schizophrenic post-mortem brain tissue

Thioridazine (THD) and its major metabolites, mesoridazine (MES), sulforidazine (SULF), and northioridazine (norTHD) accumulate at a predictable rate in human brain tissue after chronic medication. Although the concentration of THD is normally lower than or the same as its major metabolite, MES, in the plasma, it was found to be up to five times as concentrated in the brain tissue of treated patients. THD and its metabolites were evenly distributed throughout all regions of the brain in chronically medicated patients. Brain concentrations of THD were also compared with those of chlorpromazine (CPZ) when both drugs had been given at the same dose before death, and were shown to be up to 10 times more concentrated in brain at doses greater than 300 mg/day. Because some of the metabolites of THD are pharmacologically active, it is important to know how they accumulate in the brain in relation to the parent compound to understand how this drug mediates its clinical effect.

The spatial distribution of neurons and glia in human cortex based on the poisson distribution

A method was devised that employs deviations from the Poisson distribution to analyze the spatial arrangement of neurons and glia in human cerebral cortex. A field of randomly distributed points equal in number of a sample field of neuronal or glial cells is generated by computer, and the proportion of cells in the sample field that are closer to the nearest neighboring cells than to the nearest randomly distributed point is determined. We call this proportion the "Poisson ratio." When the cells are randomly distributed, the Poisson ratio is equal to 0.5. If the Poisson ratio is less than 0.5, the cells are farther away from one another than a random distribution would predict (exclusionary pattern); if the Poisson ratio is greater than 0.5, the cells are closer to one another than a random distribution would predict (clustering). A simple nonparametric statistical test is used to determine the significance of differences in the ratios. This method was applied to samples of human cerebral cortex in order to test the hypothesis that patients with schizophrenic psychosis may have an altered pattern of neuronal clustering. The analysis revealed that there is no difference in the nearest-neighbor distribution of either neurons or glia between psychotic patients and controls. It was found, however, that there is a highly significant difference in the spatial distribution of neurons versus glia in human cerebral cortex. Neurons of layers II to VI in the human cortex show greater-than-expected distances among them and are distributed according to an exclusionary pattern, while neurons in layer I show a clustering pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acid neurotransmitter abnormalities in Huntington's disease and the quinolinic acid animal model of Huntington's disease

Concentrations of gamma-aminobutyric acid (GABA), glutamate, aspartate, and taurine were measured in postmortem tissue from the brains of patients with Huntington's disease (HD) and in the quinolinic acid (QA) lesioned rat striatum. The aim of the study was to assess further the ability of the QA model of HD to reproduce the neurochemical features of the disease. Nine cortical and 9 subcortical regions were examined from 17 pathologically graded cases of HD and 10 controls. Significant reductions in both GABA and glutamate were found in HD striatum. The reductions were greater in the more severely affected grades of HD, and there was a gradient of amino acid loss across the striatal nuclei (caudate greater than putamen greater than nucleus accumbens) which was consistent with the known pattern of pathological involvement. Taurine and aspartate concentrations showed no significant change. GABA reductions were found in both segments of the globus pallidus (external greater than internal) and both parts of the substantia nigra (reticulata greater than compacta). In advanced cases of HD, there were significant reductions in glutamate in Brodmann cortical areas 3-1-2, 6, 9, and 17, but GABA, aspartate, and taurine were unaltered in the cortex. The QA lesions reproduced the striatal deficits of both GABA and glutamate but, in contrast to HD, there was a decrease in taurine, possibly due to species differences. Chronic QA lesions resulted in a secondary dying back of corticostriatal glutamatergic terminals, but did not produce a change in cortical glutamate concentration. This suggests that reductions in cortical glutamate in HD may reflect a primary loss of glutamatergic neurons. Our findings extend previous observations on amino acid neurotransmitters in HD and, with the exception of taurine, confirm the general applicability of the QA model.

Human brain D1 and D2 dopamine receptors in schizophrenia, Alzheimer's, Parkinson's, and Huntington's diseases

Because dopamine D2 receptors are known to be elevated in schizophrenic brain striata, this study examined whether a similar dopamine receptor elevation occurred in other diseases including neuroleptic-treated Alzheimer's and Huntington's diseases. The average D1 density in postmortem striata from Alzheimer's patients was 17.6 +/- 0.1 pmol/g, similar to an age-matched control density of 16.6 +/- 0.4 pmol/g. The average D1 density in schizophrenia patients was 19.0 +/- 0.6 pmol/g, similar to the age-matched control density of 17.9 +/- 0.6 pmol/g. In Parkinson's disease patients, however, the D1 receptor density was elevated, with values of 22.8 +/- 1.2 pmol/g (in patients not receiving L-DOPA) and 19.6 +/- 1.5 pmol/g (in patients receiving L-DOPA) compared to the age-matched control density of 16.0 +/- 0.4 pmol/g. The D2 receptors in Alzheimer's striata averaged 13.4 +/- 0.6 pmol/g (in patients who had not received neuroleptics), almost identical to the control density of 12.7 +/- 0.3 pmol/g. The average D2 density in neuroleptic-treated Alzheimer's striata was 16.7 +/- 0.7 pmol/g, an elevation of 31%, the individual values of which had a normal distribution. In Parkinson's disease patients, the D2 densities were elevated in tissues from patients not receiving L-DOPA (19.9 +/- 1.5 pmol/g in putamen and 14.8 +/- 1.2 pmol/g in striatum) compared to the age-matched control values of 13.0 +/- 0.4 pmol/g and 12.6 +/- 0.3 pmol/g, respectively. In Huntington's disease patients, the D2 density averaged 7.5 +/- 0.4 pmol/g in patients who had not received neuroleptics, but was 10.3 +/- 0.6 pmol/g in those who had. Although all of the D1 and D2 densities in each of the above diseases and subgroups revealed a normal distribution pattern, the D2 densities in schizophrenia displayed a bimodal distribution pattern, with 48 striata having a mode at 14 pmol/g, and the other 44 striata having a mode at 26 pmol/g. Thus, compared to the neuroleptic-induced and unimodal elevations in D2 of 31% in Alzheimer's disease and 37% in Huntington's disease, the schizophrenic striata with a mode of 26 pmol/g (105% above control) appear to contain more D2 receptors than can be accounted for by the neuroleptic administration alone.

Increased vertical axon numbers in cingulate cortex of schizophrenics

Data generated from an earlier study have suggested a model in which greater numbers of long, vertical, associative axons may occur in the anterior cingulate cortex of schizophrenic patients relative to control subjects. This hypothesis has now been tested using neuron-specific antibodies raised against the 200-kilodalton neurofilament subunit, a component of neuronal cytoskeleton, to immunostain axons of human postmortem cingulate cortex. A manual method for counting axons in the region of layer II and sublamina IIIA has been designed and applied blindly to parallel control and schizophrenic immunoprocessed specimens. The results show that there are 25% more vertical axons in the schizophrenic than in the control specimens. Preferentially higher numbers of both long vertical axons (62%) and axons associated with blood vessels (52%) have also been noted in the schizophrenic specimens. By contrast, the number of large-caliber horizontal axons was the same in the two groups; therefore, the greater number of vertical axons in schizophrenic specimens does not appear to represent a nonspecific effect. When these data are corrected for the effects of several confounding variables using analysis of covariance, the overall pattern of the results persists. These findings suggest the possibility that there might be an increase of associative inputs into the anterior cingulate cortex of schizophrenic patients, although it is not clear at present whether the differences noted, if replicative, may be primarily or perhaps only secondarily related to the disorder.

The amyloid beta protein gene is not duplicated in brains from patients with Alzheimer's disease

Complementary DNAs (cDNAs) encoding portions of the amyloid beta protein were used to investigate possible amyloid gene duplication in sporadic Alzheimer's disease. A strategy employing two Eco RI restriction fragment length polymorphisms (RFLPs) detected by the amyloid cDNAs was used. RFLPs allow the detection of a 2:1 gene dosage in the DNA of any individual who is heterozygous for a particular RFLP. The amyloid gene regions homologous to the cDNAs used were not duplicated in the DNA from brains of individuals with sporadic Alzheimer's disease. Similar results were also obtained with a strategy employing a test for 3:2 gene dosage.

EC array sensor concepts and data

The use of multiple parameter assays of entire metabolic pathways is potentially a powerful tool for unraveling mechanisms of disorders or drug action and classification of neurological diseases. Coulometric electrode series array sensors, coupled with liquid chromatography (n-ELC), provide a route to multiplying the resolving power of conventional LC by factors of 10 to 50. Since the original description of the n-ELC concept by Matson et al. (1), fundamental issues of optimizing sensor design and integration with computer controlled LC systems have been addressed. Femtogram level potential time (ET) separations can now be performed for multiple components in both isocratic and gradient modes. A 56-component isocratic method for the study of the kynurenine system in Huntington's Disease (HD) is presented as an indication of the analytical definitions and nomenclature used to qualify an n-ELC procedure, and an indication of the implications of multiparameter data bases on data handling and experimental design.