Excitotoxic brain lesion modifies binding to a USF binding site acting as a negative regulatory element in the Protease nexin-1 promoter

The expression of the serine protease inhibitor Protease nexin-1 (PN-1) is upregulated in glial cells following different types of lesion in the nervous system. A strong negative regulatory element has been shown by the missing nucleoside technique to be a CACGTG site (E-box) in the proximal part of the PN-1 promoter. The factor binding to this site is specifically recognized by antibodies directed against the human upstream stimulatory factor (USF). Point mutations in the E-box binding site which abolish USF binding in vitro increase the transcriptional activity of the PN-1 promoter. Cotransfection of a PN-1 promoter/reporter construct together with an expression vector for human USF1 confirms the negative regulatory function of this site. Finally, we show that the binding to this USF site changed after ibotenic acid-induced lesion of the caudate putamen in the rat brain.

Presynaptic dopaminergic deficits in Lesch-Nyhan disease

BACKGROUND

Lesch-Nyhan disease is a rare, devastating, X-linked recessive disorder of purine synthesis. Patients present with hyperuricemia, choreoathetosis, dystonia, and aggressive and self-injurious behavior. Although the genetic and biochemical abnormalities have been identified, the causes of the neuropsychiatric syndrome remain unclear.

METHODS

We used positron-emission tomography to measure presynaptic accumulation of fluorodopa F 18 tracer in the dopaminergic regions of the brains of 12 patients with Lesch-Nyhan disease (age, 10 to 20 years) and 15 healthy controls (age, 12 to 23). The results were expressed as ratios of specific to nonspecific radioactive counts. A low ratio indicates decreased dopa decarboxylase activity and dopamine storage.

RESULTS

The fluorodopa F 18 ratio was significantly lower in the putamen (31 percent of control values), caudate nucleus (39 percent), frontal cortex (44 percent), and ventral tegmental complex (substantia nigra and ventral tegmentum; 57 percent) in the patients with Lesch-Nyhan disease than in the controls. Uptake of the tracer was abnormally low even in the youngest patients tested, and there was no overlap in the values between patients and controls.

CONCLUSIONS

Patients with Lesch-Nyhan disease have abnormally few dopaminergic nerve terminals and cell bodies. The abnormality involves all dopaminergic pathways and is not restricted to the basal ganglia. These dopaminergic deficits are pervasive and appear to be developmental in origin, which suggests that they contribute to the characteristic neuropsychiatric manifestations of the disease.

Distribution of follistatin messenger ribonucleic acid in the rat brain: implications for a role in the regulation of central reproductive functions

Follistatin (FS), which binds to the inhibin/activin beta A- or beta B-subunit is localized with and modulates the biological actions of activin in many systems. However, in contrast to the wide distribution of the activin beta-subunit proteins and messenger RNAs (mRNA) in the brain, demonstration of FS mRNA signal has been limited to the olfactory tubercle and layer II of the frontal cortex. We have hypothesized a more extensive distribution of central FS gene expression and localization in regions coinciding with inhibin/activin beta-subunits and possible activin-mediated effects. In the present study, we examined the central distribution of FS mRNA expression in the normal adult male rat. With in situ hybridization analysis, using a 33P-labeled RNA probe specific for rat FS, gene expression is shown to be widely distributed throughout the brain. Abundant FS mRNA expression is localized in several areas of the olfactory bulb as well as the frontal cortex, a few thalamic nuclei, and in septal regions. Moderate FS mRNA is observed in the caudate putamen and various hypothalamic areas including the paraventricular, ventromedial, dorsomedial, and arcuate nuclei. Several brain stem regions are also found to express FS mRNA, including the medial vestibular and solitary tract nuclei. Notably, FS mRNA, including the medial vestibular and solitary septal/diagonal band region is localized in patterns that are highly correlative with those of GnRH gene expression and hence may serve to regulate possible activin-mediated effects in these areas. FS mRNA is also expressed in areas associated with the activin-oxytocin pathway (solitary tract nucleus and paraventricular nucleus) and is therefore in a position to modulate the role of activin in the solitary tract nucleus-paraventricular nucleus pathway (afferent system mediating the milk-ejection reflex). The results suggest that FS is centrally localized in sites compatible with a role in the regulation of central reproductive functions.

Dopamine deficits in the brain: the neurochemical basis of parkinsonian symptoms in AIDS

We sought to determine whether the motor dysfunctions and neuroleptic sensitivity that can occur in patients with AIDS relates to a deficit of striatal dopamine innervation similar to that of Parkinson's disease. For this purpose we measured concentrations of dopamine and its major metabolite homovanillic acid (HVA) in caudate nucleus tissue taken post-mortem from patients with AIDS and from appropriate age-matched control subjects. Dopamine and HVA concentrations were both significantly reduced in the AIDS group, with 20 of 34 patients exhibiting dopamine concentrations below the control range. This finding is consistent with a loss of nigrostriatal dopaminergic neurones, and may underlie the motor dysfunction and neuroleptic sensitivity that can occur in AIDS patients, indicating the potential value of antiparkinsonian therapy in such patients.

The density of muscarinic M1 receptors is decreased in the caudate-putamen of subjects with schizophrenia

Changes in cholinergic neurons have been implicated in the pathology of schizophrenia. Clozapine, an atypical anti-psychotic drug, has been shown to bind with high affinity to the muscarinic1 (M1) receptor suggesting this receptor could be involved in the therapeutic efficacy of the drug. Because of this we measured the density of M1 receptors in the caudate-putamen, obtained at autopsy, from 19 schizophrenic subjects and 19 non-schizophrenic subjects. The density of M1 receptors was decreased in the caudate-putamen from the schizophrenic subjects (181 +/- 20 vs 287 +/- 10 fmol mg-1 TE; mean +/- s.e.m.; P < 0.001). Furthermore, preliminary studies would not suggest that the change in the density of M1 receptors in the tissue from the schizophrenic subjects had resulted from drug treatment prior to death. These data raise the possibility that changes in muscarinic receptors may be involved in the pathology of schizophrenia.

Somatostatin and the patch/matrix compartments of the rat caudate-putamen

In the caudate-putamen of the rat, two subpopulations of medium aspiny neurons exist that contain somatostatin. The first subpopulation contains somatostatin 14, somatostatin 28, and somatostatin 28(1-12). The other subpopulation contains only somatostatin 28. To examine the relationship between somatostatin-containing neurons and the patch/matrix compartments, a series of double-labelling experiments using antisera directed against different somatostatin peptides and calbindin were used. Sections stained in this manner were examined with the aid of a confocal microscope. The results of these experiments indicate that somatostatin 28(1-12)-containing neurons may play a role in matrix integration, with some input directed from the patch compartment. In addition, somatostatin 28-containing neurons are more numerous in the patch compartment than somatostatin 28(1-12)-containing neurons, suggesting a possible role for these neurons in patch integration.

Chronic haloperidol-induced changes in regional dopamine release and metabolism and neurotensin content in rats

Chronic neuroleptic administration has previously been shown to alter in vivo measures of dopaminergic function and lead to regionally selective increases in neurotensin levels. In the current study, female rats were administered chronic haloperidol for 6 months via subcutaneous silastic implants. After 24 weeks of administration, microdialysis probes were inserted into the lateral caudate putamen and the medial prefrontal cortex. Basal samples were collected prior to infusion of a high K+ concentration (100 mM KCl). Extracellular concentrations of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid were assessed using HPLC. Chronic haloperidol-treated rats showed increased basal dopamine metabolite levels in the caudate putamen and an altered response to the effects of high K+ on 3,4-dihydroxyphenylacetic acid; no significant differences were seen with other analytes in the caudate putamen. Although basal concentrations were not different between groups in the prefrontal cortex, haloperidol-treated rats showed a significant attenuation of response to the effects of high K+ infusion on dopamine metabolite concentrations. Radioimmunoassay measurement of tissue neurotensin content showed highly significant elevations of neurotensin concentrations in the caudate putamen and nucleus accumbens, but not in other brain regions analyzed. These results suggest a confluence of altered dopamine and neurotensin function in the caudate putamen which may be related to motor side effects of haloperidol, whereas changes in prefrontal dopamine function are not associated with altered neurotensin levels.

Dopamine receptor mRNA expression patterns by opioid peptide cells in the nucleus accumbens of the rat: a double in situ hybridization study

Colocalization of proenkephalin and prodynorphin mRNAs with each other as well as with D1, D2, and D3 dopamine receptor mRNAs was analyzed in the nucleus accumbens of the rat. Distinct combinations were detected in the rostral pole, core, and shell subdivisions of the nucleus accumbens. Proenkephalin and prodynorphin mRNAs were principally localized in separate cells in the core. All detectable prodynorphin cells in the core expressed D1 mRNA but not D2 mRNA. Conversely, approximately 95% of the proenkephalin-positive cells in this region expressed D2 mRNA but not D1 mRNA. This pattern was identical to that observed in the caudate putamen. In the rostral pole and the shell, embedded in a background of this "typical" colocalization pattern, clusters of cells expressing a distinct configuration were found. In these clusters, proenkephalin-positive cells expressed both prodynorphin and D1 mRNAs, but they did not express D2 mRNA. D3 and prodynorphin mRNAs were colocalized in "limbic" striatal areas, including the ventromedial caudate putamen, the rostral pole, and the medial shell. In contrast, D3 mRNA was not detected in any proenkephalin-positive cells. Together with the prodynorphin/D1 data, this suggests that a subset of prodynorphin cells expresses both D1 and D3 mRNAs. It is concluded that 1) clusters of cells that coexpress proenkephalin, prodynorphin, and D1 mRNAs overlap extensively with previously defined cytoarchitectural cell clusters in the nucleus accumbens and 2) a subset of the prodynorphin cells in the ventromedial caudate putamen and the nucleus accumbens contains both D1 and D3 mRNAs.

Regional quantification of D1, D2, and D3 dopamine receptor mRNA in rat brain using a ribonuclease protection assay

We describe ribonuclease protection assays for dopamine D1, D2, and D3 receptors, and regional quantitation of mRNA levels for these receptors in rat brain. Both D1 and D2 mRNA levels were highest in caudate putamen, where they were found in approximately equal levels. Of the brain regions examined, D3 mRNA was most abundant in hippocampus, hypothalamus, and nucleus accumbens. Levels of D3 mRNA were significantly lower than values for D1 and D2 mRNA in all brain regions studied. Variability was observed between animals for expression of both D1 and D2 mRNA in caudate putamen, with a significant correlation between D1 and D2 mRNA levels in neostriatum (r = 0.942, P < 0.001). This suggests a functional interaction between D1 and D2 receptor mRNA levels in this brain region. Our results are generally consistent with regional distributions previously reported using other methods. These results suggest that DA D2 receptors function both as an auto and as a postsynaptic receptor, while D1 receptors are restricted to a postsynaptic function. Our results demonstrate the utility of this method in studying possible relationships between individual animal variation in regional mRNA expression and behavioral response to pharmacological and other experimental treatments.

The distribution of splice variants of the NMDAR1 subunit mRNA in adult rat brain

Regional variation in the alternative splice forms of the NMDAR1 subunit mRNA was investigated by in situ hybridization in the adult rat brain, using radiolabelled splice-specific oligonucleotide probes. Each splice variant was detected in an individual distribution. The NMDAR1-a and NMDAR1-2 forms were widely and abundantly distributed throughout the brain, except for the inferior colliculus. The NMDAR1-b and NMDAR1-4 variants were located in similar patterns in fewer areas (e.g. parietal cortex, hippocampus CA3, thalamus, inferior colliculus, cerebellar granule cells). In contrast, the NMDAR1-1 forms were distributed in a pattern approximately complementary in the forebrain to that of NMDAR1-4 (weakly expressed in thalamus and inferior colliculus). The NMDAR1-3 variants were not abundant in any structure. Considerable overlap of the in situ hybridization images was noted, so all eight splice combinations are possible in heterogenous distributions. Correlation of the distribution of NMDAR1 mRNA splice forms with functional analyses of heteromeric recombinant receptors will be necessary to ascertain if alternative splicing of the NMDAR1 subunit can account for some of the known heterogeneity of endogenous NMDA receptors.

In vivo D2 dopamine receptor density in psychotic and nonpsychotic patients with bipolar disorder

BACKGROUND

A prior positron emission tomographic study from The Johns Hopkins University, Baltimore, Md, using N-methylspiperone labeled with carbon 11 reported elevated basal ganglia D2 dopamine receptor density (Bmax) values in neuroleptic-naive schizophrenic patients compared with controls. We have now extended these studies to include patients with bipolar disorder.

METHODS

Patients with bipolar disorder (n = 14) either had never received neuroleptic medication or had been neuroleptic-free for more than 6 months, and they met DSM-III criteria for currently symptomatic affective disorder. Patients with bipolar disorder were compared with matched schizophrenic patients and normal controls. All received two positron emission tomographic scans, the second of which was preceded by oral administration of haloperidol lactate, to permit the calculation of D2 dopamine receptor Bmax.

RESULTS

Diagnostic groups differed in Bmax by analysis of variance (P < .0001); post hoc tests showed higher Bmax values for psychotic patients with bipolar disorder and schizophrenic patients compared with normal controls and for schizophrenic patients and psychotic patients with bipolar disorder compared with nonpsychotic patients with bipolar disorder. Among patients with bipolar disorder, Bmax values correlated significantly with the severity of psychotic symptoms (r = .63) on the Present State Examination but not with the severity of nonpsychotic mood symptoms.

CONCLUSIONS

We conclude that, like schizophrenic patients, patients with psychotic bipolar disorder have elevations of D2 dopamine receptor Bmax values and that such elevations in affective disorder are more closely associated with the presence of psychosis than with mood abnormality. Elevations in dopamine receptor values thus may occur in psychiatric states that are characterized by psychotic symptoms rather than being specific to schizophrenia.

Quantification of the serotonin hyperinnervation in adult rat neostriatum after neonatal 6-hydroxydopamine lesion of nigral dopamine neurons

Light microscope autoradiography after uptake and storage of tritiated serotonin (5-HT) in brain slices was used to count 5-HT axon terminals (varicosities) in the 5-HT-hyperinnervated neostriatum of adult rats subjected to neonatal 6-hydroxydopamine treatment and age-matched, normal controls. After correction for incomplete autoradiographic exposure and for section thickness, the results were expressed in millions of varicosities per mm3 of tissue. Control values ranged from 4.8 in the rostral to 6.3 in the caudal neostriatum (5.8 at intermediate level), for an average of 5.6. The corresponding values in 5-HT-hyperinnervated tissue ranged from 9.7 to 7.7 (8.8 at intermediate level), for an average of 8.7 and increases of 102%, 52% and 22% above control in the rostral, intermediate and caudal neostriatum, respectively (average increase of 55%). These data confirmed the predilection of the 5-HT hyperinnervation for the rostral neostriatum and demonstrated its presence in the caudal neostriatum also.

Characterization of neurotensin-like immunoreactivity in human basal ganglia: increased neurotensin levels in substantia nigra in Parkinson's disease

A method that combines high performance liquid chromatography with radioimmunoassay (HPLC/RIA) has been used to characterize neurotensin-like immunoreactivity (NT-IR) in the basal ganglia from control subjects and Parkinson's disease (PD) patients. In samples from the caudate nucleus and putamen, NT-IR eluted as two HPLC peaks. One was indistinguishable from the synthetic tridecapeptide, while the other peak corresponded to oxidized NT, as judged by its chromatographic behaviour and its reaction with the antiserum employed. There were marked discrepancies between the IR detected in crude extracts and that in HPLC purified samples. NT levels (HPLC/RIA) were unaltered in the caudate nucleus, putamen and both segments of the globus pallidus in the parkinsonian brain. In contrast, there was a two-fold increase in NT content in both zona compacta and zona reticulata of the substantia nigra in PD patients compared to controls. Degeneration of the nigrostriatal pathway and/or prolonged antiparkinsonian treatment in PD appears to alter neurotensin levels in an attempt to activate the dopaminergic nigrostriatal pathway.

Differential effects of 3-PPP enantiomers on extracellular dopamine concentration in the caudate-putamen and nucleus accumbens of rats

The ability of the enantiomers of 3-PPP (3-(3-hydroxyphenyl)-N-n-propylpiperidine) to modify the extracellular concentration of dopamine (DA) in the caudate-putamen and the nucleus accumbens of awake rats was assessed using intracranial microdialysis. The enantiomers and the racemate were directly infused at 3 incremental concentrations (1-100 microM) or systematically administered by subcutaneous injection (10 mg/kg). Both systemic administration and direct infusion of (-)3-PPP at the highest concentration (100 microM) significantly increased extracellular DA in both brain regions. This increase was also seen in the presence of higher extracellular DA levels following reuptake inhibition by nomifensine (10 microM). In contrast to the effects of (-)3-PPP, systemic administration of both (+)3-PPP and (+/-)3-PPP decreased DA levels. Infusion of (+/-)3-PPP led to slight increases in DA levels in both brain regions at the highest concentration (100 microM), while (+)3-PPP at 100 microM also produced a significant increase in the caudate-putamen, but not in the nucleus accumbens. However, in the presence of nomifensine-induced elevations in extracellular DA, (+)3-PPP produced a significant decrease in DA concentrations in both brain regions. These results support previous findings that the enantiomers of 3-PPP show unique profiles in their in vivo effects on DA terminal functions. Furthermore, these effects are dependent on the mode of 3-PPP administration, the brain region in which DA overflow is measured, and the level of basal extracellular DA.

The distribution of cholinergic perikarya with respect to enkephalin-rich patches in the caudate nucleus of the adult cat

The distribution of cholinergic interneurons with respect to enkephalin-rich patches in the caudate nucleus of the cat was examined using both computer-assisted 3-D reconstruction and immunocytochemical techniques. Examination of the 3-D distribution of perikarya staining for choline acetyltransferase (ChAT) revealed that these cells were not evenly distributed within the caudate nucleus but exhibited areas of increased and decreased density. Comparison of the 3-D distribution of cholinergic perikarya to that of the enkephalin-rich patches indicated that areas of increased ChAT+ cell density often corresponded to the positions of enkephalin-rich patches within the dorsal-lateral caudate nucleus. At more ventral regions, there was no clear correspondence between areas of increased ChAT+ cell density and enkephalin-rich patches. In agreement with these observations, a quantitative analysis of sections double-labeled for ChAT and enkephalin revealed that the density of cholinergic neurons within enkephalin-rich patches was twice that in the surrounding tissue in the dorsal region of the caudate nucleus. In contrast at more ventral levels, the difference in the density of ChAT+ cells in enkephalin-rich patches did not significantly differ from that in the surrounding striatal tissue. Both the results of the 3-D and the double-labeling analysis suggest that cholinergic neurons are not evenly distributed within the caudate nucleus of the cat but form loose clusters which are associated dorsally with the enkephalin-rich patches. These results also provide further evidence of heterogeneity within the striosomal compartment in the cat.

Identification of a 12.5-kD protein from caudate-putamen nucleus as a dopaminergic neuronotrophic factor

The effect of the extract from caudate-putamen nucleus of newborn rats (CPe) on the dopaminergic (DA) neurons has been studied. An MTT colorimetric microassay measuring optical densities for the growth of DA neuron cultures reveals a significant increase in growth for cultures with CPe as compared to those without CPe (p < 0.05). Rhodamine retrograde-prelabelled DA neurons were cultured on a Phastgel containing all the electrophoretically separated protein bands from CPe, and able to fish out from it their own trophic factor, a 12.5-kD protein band. The survived neurons at the 12.5-kD protein band were immunostained positive with anti-dopamine antibody. Co-culturing the 12.5 kD-containing gel strip with explants from substantia nigra at a close distance for a week revealed anti-dopamine immunopositive neurites outgrowing from the explants only towards the 12.5-kD gel strip. These results indicate that a 12.5-kD protein from the CPe is capable of maintaining the survival of DA neurons of the substantia nigra and promoting their neurite outgrowth.

D2 dopamine receptor mRNA distribution in cholinergic and somatostatinergic cells of the rat caudate-putamen and nucleus accumbens

An in situ hybridization procedure that identifies cells expressing D2 dopamine receptor mRNA was combined in double-labelling studies with immunohistochemical procedures that identify cells expressing either choline acetyltransferase (ChAT) or somatostatin. D2 receptor mRNA was detected in almost all of the ChAT positive caudate-putamen cells, approximately half of the ChAT positive nucleus accumbens cells and none of the somatostatin-positive cells in either brain region.

Interleukin-1 beta, interleukin-6, epidermal growth factor and transforming growth factor-alpha are elevated in the brain from parkinsonian patients

Interleukin (IL)-1 beta, IL-6, epidermal growth factor (EGF), and transforming growth factor-alpha (TGF-alpha) were measured for the first time in the brain (caudate nucleus, putamen and cerebral cortex) from control and parkinsonian patients by highly sensitive sandwich enzyme immunoassays. The concentrations of IL-1 beta, IL-6, EGF, and TGF-alpha in the dopaminergic, striatal regions were significantly higher in parkinsonian patients than those in controls, whereas those in the cerebral cortex did not show significant differences between parkinsonian and control subjects. Since these cytokines and growth factors may play important roles as neurotrophic factors in the brain, the present results suggest that they may be produced as compensatory responses in the nigrostriatal dopaminergic regions in Parkinson's disease, and may be related, at least in part, to the process of neurodegeneration in Parkinson's disease.

Localisation of parvalbumin-immunoreactive structures in primate caudate-putamen

To investigate the morphology, distribution, and connections of parvalbumin-containing neurones in the caudate-putamen of primates, perfuse-fixed sections were stained to reveal parvalbumin immunoreactivity. In agreement with previous observations, the caudate-putamen was rich in parvalbumin-positive neurones and neuropil. The neuropil staining was uneven such that the dense background staining was interspersed with zones of relatively weak staining. The distribution corresponded to the striosome/matrix system as defined by substance P or met-enkephalin immunostaining in adjacent sections. Because parvalbumin-positive neurones are present in regions known to project to the caudate-putamen and the majority of parvalbumin-positive terminals in the matrix formed asymmetric synapses, it is concluded that the uneven staining is probably due to afferents of the neostriatum. The morphology of the parvalbumin-immunoreactive neurones varied between the striosomes and matrix; those in the matrix were smaller and possessed dendritic arborisations that were relatively uniform, whereas those in the striosomes were generally more extensively stained and possessed a greater variation in their dendritic branching patterns. The dendrites frequently crossed the boundary between the striosomes and matrix. A population of giant parvalbumin-immunoreactive neurones was also observed in the putamen. Electron microscopic analysis revealed that, in addition to terminals forming asymmetric synapses, a smaller population formed symmetric synaptic specialisations and are presumed to be derived from the local parvalbumin-immunoreactive neurones. Terminals of the latter group formed synapses with medium-sized spiny neurones. Because parvalbumin-positive neurones receive input from the cortex, they may transmit cortical information to spiny neurones.

The effects of typical and atypical antipsychotic drugs on neurotensin-containing neurons in the central nervous system

Several lines of evidence, including the effect of antipsychotic drugs on neurotensin-containing neurons, have implicated the neurotensin system in the mechanism of action of antipsychotic drugs. Thus far, all clinically efficacious antipsychotics have been found to increase neurotensin concentrations in the nucleus accumbens; "typical" antipsychotic drugs increase neurotensin concentrations in both the nucleus accumbens and the caudate nucleus, whereas "atypical" antipsychotics increase neurotensin concentrations only in the nucleus accumbens. The effects of antipsychotic drugs on neurotensin-containing neurons in the nucleus accumbens may be predictive of clinical antipsychotic efficacy whereas the effects on neurotensin in the caudate nucleus may be predictive of extrapyramidal side effects. In addition to this evidence that antipsychotic drugs may act at least in part on neurotensin-containing neurons to produce their clinical effects is a considerable data base indicating that there are alterations in neurotensin-containing neurons in schizophrenia.

Compartmental organization of the peptide network in the human caudate nucleus

The mammalian striatum may be divided into a striosomal compartment and a surrounding matrix region. We have examined the distribution of leucine enkephalin (LENK) and substance P (SP) immunoreactivity in relation to striosomes defined by calbindin-D (CABD) staining in alternate 70 microns serial sections from the human caudate nucleus. The distribution of LENK immunoreactivity showed a transition from dorsal to ventral striatum: dorsally, LENK-rich patches were present in a lightly stained matrix; mid-ventrally, annular patches of LENK staining with a lighter core were seen. These patches corresponded to striosomal regions defined by CABD-poor zones. In contrast, in the ventral caudate and nucleus accumbens, LENK-poor zones matched CABD-defined striosomes. CABD staining in the matrix was intense in the dorsal caudate, diminishing ventrally. SP-rich zones in dorsal caudate and SP-poor areas in the mid-ventral region overlapped striosomes. In the ventromedial sector, the SP staining pattern was complex and did not consistently correlate with striosomes. Computer-assisted three-dimensional reconstruction of the striosomal system in the human, based on regions of either high LENK or low CABD immunoreactivity, revealed the existence of considerable long-range order. Patches appeared aligned over several millimeters to form long, horizontal structures in the caudate nucleus, with occasional orthogonal interconnecting crossbridges. Our results are in accord with previous work in the human and in other species. These three-dimensional networks are strikingly similar across individuals and may relate to the segregation of and interactions between striatal circuits.

Reduced concentrations of the alpha-subunit of GTP-binding protein Go in schizophrenic brain

Concentrations of the alpha-subunits of GTP-binding protein, Go (Go alpha) and of Gi2 (Gi2 alpha) in 6 areas (the hippocampus, parahippocampus, putamen, caudate head, orbital frontal cortex, and lateral temporal cortex) of control and schizophrenic postmortem brains were investigated using the highly sensitive enzyme immunoassay method. There was a significant decrease in Go alpha in the hippocampus and caudate head of the right hemisphere in schizophrenic patients compared to controls; the ANOVA (a general linear model; SAS Type II) demonstrated a significant diagnosis x side interaction only in the hippocampus. In other areas of the brain, analysis by grouping under diagnosis, side, age, gender, and postmortem delay showed no significant deviations in Go alpha between controls and schizophrenics. The concentrations of Gi2 alpha did not differ significantly in any area. These findings contrasted with the results yielded by ADP-ribosylation, which showed decreased pertussis toxin ADP-ribosylated amounts in the hippocampus and putamen of the contralateral (left) hemisphere. Some abnormal receptor-Go or Gi 1 signalling in hippocampus, putamen or caudate head may be involved in the pathogenesis of schizophrenia.

Human striatum: chemoarchitecture of the caudate nucleus, putamen and ventral striatum in health and Alzheimer's disease

The morphology and distribution of perikarya positive for choline acetyltransferase, somatostatin, calcium binding protein (calbindin D28K) and nicotinamide adenine dinucleotide phosphate diaphorase were surveyed in the human striatum. Choline acetyltransferase and somatostatin antibodies labeled separate populations of large striatal interneurons. Somatostatin immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (nitric oxide synthase) activity were completely co-localized. Calbindin antibody identified two distinct groups of striatal neurons: (1) numerous medium-sized, lightly stained neurons, probably analogous to striatopallidal projection neurons in the rat, and (2) much less numerous, large, darkly stained neurons. Half of the latter group, but none of the former, were also nicotinamide adenine dinucleotide phosphate diaphorase-positive. Somatostatin-positive and medium-sized, calbindin-positive neurons were more numerous in the caudate nucleus than in the putamen or ventral striatum. By contrast, large calbindin-immunoreactive neurons were more frequently encountered in the putamen. Choline acetyltransferase-positive neurons were evenly distributed across striatal components. In aged control subjects, the size of large, darkly stained calbindin-positive neurons was reduced relative to young subjects. Aging had no effect on somatostatin-, medium-sized calbindin-, or choline acetyltransferase-positive neurons. However, in histologically confirmed cases of Alzheimer's disease, there was a selective, 75% loss of choline acetyltransferase-immunoreactive perikarya from the ventral striatum, but not from the dorsal striatum, compared to aged controls. Furthermore, the remaining cholinergic neurons in the ventral striatum of Alzheimer's disease cases were significantly smaller than similar neurons in controls. These results indicate that various striatal components which have been shown to differ in their anatomical connectivity and functional specialization, also differ in their neurochemical signatures. The specific and marked loss of choline acetyltransferase-positive neurons from the ventral striatum in Alzheimer's disease is consistent with the characteristic cholinergic and 'limbic' pathology in this disease.

In vivo evaluation of brain iron in Alzheimer's disease and normal subjects using MRI

Magnetic resonance imaging (MRI) can measure transverse relaxation rate (R2) of tissues. Although R2 is increased by tissue iron levels, R2 is not a specific measure of iron. A new method, based on the fact that ferritin (the primary tissue iron storage protein) affects R2 in a field-dependent manner, can quantify tissue iron with specificity by measuring the Field Dependent R2 Increase (FDRI). Using the FDRI method, we compared brain iron stores in frontal white matter, caudate nucleus, putamen, and globus pallidus of five male patients with Alzheimer disease (AD) and eight age and gender-matched normal controls. FDRI values were significantly higher among AD patients in the caudate and globus pallidus. The data suggest that AD may involve disturbances in brain iron metabolism and that the involvement of iron in the pathophysiology of age-related neurodegenerative disorders can be investigated in vivo using MRI.

Chemical compartmentation and relationships between calcium-binding protein immunoreactivity and layer-specific cortical caudate-projecting cells in the anterior intralaminar nuclei of the cat

Neurons projecting to the parietal cortex or striatum and neurons showing immunoreactivity for the calcium-binding proteins parvalbumin and 28KD-calbindin were examined in the anterior intralaminar nuclei (IL) of the cat. Retrograde tracing from deep or superficial parietal cortical layers or from the caudate nucleus was coupled with immunohistochemistry to determine which of these proteins were expressed in the projection neurons. It was found that IL neurons project to deep as well as to superficial layers of the parietal cortex, that IL-cortical neurons could be differentiated into two populations according to their cortical projection pattern and their soma size, and that IL neurons projecting to the parietal cortex or to the striatum express 28KD calbindin immunoreactivity but not parvalbumin immunoreactivity. The distribution of immunoreactivity to 28KD calbindin and parvalbumin in the neuropil showed a consistent complementary distribution pattern in the IL. The compartments based on differential parvalbumin and 28KD calbindin expression may indicate the presence of functionally segregated units in IL.