Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A high proportion of neurons in the cerebellum and in cholinergic brainstem nuclei stain positive for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd), which is a nitric oxide synthase (NOS). Recent evidence suggests that schizophrenia may involve increased numbers of NADPHd-stained neurons in different areas of the subcortex. This led us to examine the actual concentration of NOS in postmortem brain specimens of cerebellum, and the relevant regions of brainstem tegmentum, to see if NOS concentrations were also increased in schizophrenia. Postmortem brain tissue was obtained at autopsy from schizophrenics and controls who did not have other brain disease. In patients with schizophrenia, NOS concentration was higher.
Mol Chem Neuropathol 1996 Apr
PMID:Nitric oxide synthase (NOS) in schizophrenia: increases in cerebellar vermis. 914 13

Twin, adoption and family studies have provided overwhelming but indirect evidence for a significant genetic contribution to the etiology of schizophrenia. More recent studies exploiting a plethora of highly polymorphic genetic markers provide a more direct approach to the identification and localization of genes. Current investigative efforts to identify schizophrenia susceptibility genes include diverse approaches such as linkage analysis, association studies, search for chromosomal abnormalities, analysis of disorders or syndromes with simple inheritance that overlap phenotypically with schizophrenia, studies of genetic anticipation and efforts to facilitate genetic analysis by reducing the phenotypic complexity of the disease. For the first time, after many years, there are now several promising findings, as well as replication efforts that inspire a certain degree of confidence in them.
Mol Psychiatry 1997 May
PMID:Dissecting the genetic complexity of schizophrenia. 915 85

The hypothesis of a neurodevelopmental dysfunction being involved in the etiology of schizophrenia is suggested by the observation of morphological alterations in the brains of schizophrenia patients. These alterations may be caused by defects in neural cell differentiation or migration, which could lead to disrupted neuronal circuitry and to the schizophrenia symptomatology. The neural cell adhesion molecule (NCAM) plays a major role in cell migration and axon outgrowth, and is involved in synaptic plasticity mechanisms implicated in adult cognitive functions. Altered levels of the NCAM polysialylated form, PSA-NCAM, in the brain of schizophrenia patients have been reported, and are supportive of a role for this molecule in the disorder. To investigate the possible involvement of the NCAM gene in schizophrenia, we conducted a comprehensive genetic study, which included linkage analysis and an association study employing the Haplotype Relative Risk (HRR) design in nuclear families. Our results indicate that structural alterations in the NCAM gene are unlikely to play a major role in schizophrenia, although a function for the NCAM molecule in the etiology of the disease remains an intriguing hypothesis.
Mol Psychiatry 1997 Jan
PMID:NCAM and schizophrenia: genetic studies. 915 19

Hallucinations in schizophrenia represent an important clinical problem, an interesting neuropsychological enigma, and a significant challenge for neuroscientific research. Functional neuroimaging techniques allow the in vivo, systems-level study of brain dysfunction underlying this debilitating symptom. Clinical and scientific vantage points that can inform the design and interpretation of functional neuroimaging studies of schizophrenic hallucinations are outlined. These include considerations of the phenomenology of hallucinations, the relationship of hallucinations to other symptoms of schizophrenia, and the neuropsychological functions that are thought to be disrupted in hallucinations. They also include the anatomical and chemical brain systems in which abnormalities are implicated in schizophrenia, the neurologic conditions in which hallucinations may occur, the neurochemical contexts that are associated with hallucinations, and the methodologic details of the functional neuroimaging techniques employed. Bottom-up and top-down functional neuroimaging strategies for the investigation of schizophrenic hallucinations with positron emission tomography (PET), single photon emission computed tomography (SPECT) and functional magnetic resonance imaging (fMRI) are reviewed. Bottom-up approaches start with or measure the biology associated with hallucinations. Top-down approaches start from the specific neuropsychological dysfunctions thought to be associated with hallucinations. The distributed brain regions, systems and functions implicated in schizophrenic hallucination formation are then discussed in the context of an integration of bottom-up and top-down approaches. Focus is placed upon abnormalities in the functions of, and interactions among, auditory-linguistic association cortices, caudal and rostral limbic/paralimbic systems, prefrontal cortices, ventral striatum and (non-specific projection and associative) thalamic nuclei, as well as upon the glutamatergic, GABAergic and ventral tegmental dopaminergic modulation of these systems.
Mol Psychiatry 1996 Nov
PMID:Functional neuroimaging of hallucinations in schizophrenia: toward an integration of bottom-up and top-down approaches. 915 29

In this article, recent information from neuropathological studies in humans and behavioural and electrophysiological/pharmacological studies in rats is used to examine the hypothesis that the subiculum, the major output region of the hippocampal formation, may contain sites of action for novel antipsychotic drugs. In the first section, the possible interactions between subicular neurons and the sites at which existing antipsychotic drugs act are discussed. These include the interaction implied by convergence of subicular and dopaminergic inputs to the nucleus accumbens. The second section concentrates upon subicular involvement in animal behaviours that are thought to be relevant to schizophrenia, which, in rats, include Latent inhibition and Pre-pulse inhibition of Acoustic Startle. Involvement of the subiculum in the neuropathology of schizophrenia is discussed in the third section. However, few neuropathological studies comment specifically on the subiculum. Those which suggest involvement tend to be recent and, as yet, have not all been replicated. Finally, there is discussion of the possibility that the subiculum contains chemical sites at which drugs could act specifically to produce appropriate physiological effects. Potential sites include, but are not necessarily restricted to, particular ion channels in electrophysiologically defined subclasses of subicular pyramidal neurons, the receptors for neuromodulatory peptides such as somatostatin and cholecystokinin, and the enzyme nitric oxide synthase. It is concluded that a wide range of clinical and basic neuroscience disciplines has provided evidence which, especially when viewed as a whole, is consistent with the hypothesis that the subiculum is a potential site of action for novel antipsychotic drugs.
Mol Psychiatry 1996 Nov
PMID:The subiculum: a potential site of action for novel antipsychotic drugs? 915 31

In the present study, we evaluated the possible contribution of genetic variation of the serotonin 5-HT7 receptor to the development of schizophrenia and bipolar affective disorder. Cloning and characterization of exon-flanking intronic sequences enabled us to investigate the whole coding region and the exon-intron boundaries of the human 5-HT7 receptor gene. Using single-strand conformational analysis, we screened for presence of DNA sequence variation in a sample of 137 unrelated individuals including 45 schizophrenic and 46 bipolar affective patients, as well as 46 healthy controls. We detected two rare naturally occurring receptor variants (Pro-279-Leu, Thr-92-Lys) and a silent nucleotide substitution (A-->G) at position +1233. The occurrence of the Pro-279-Leu and Thr-92-Lys substitutions was studied in an extended sample of patients (n = 462) and controls (n = 335). The Leu-279 variant was found in similar frequency in all groups, indicating that presence of this variant is not causally related to the development of schizophrenia or bipolar affective disorder. The Lys-92 variant was found in a single individual who suffered from bipolar affective disorder. Investigation of the patient's family revealed independent segregation between the Lys-92 variant and psychiatric illness. Our data suggests that genetic variation of the 5-HT7 receptor does not play a major role in the development of bipolar affective disorder and schizophrenia.
Mol Psychiatry 1996 Nov
PMID:The human serotonin 7 (5-HT7) receptor gene: genomic organization and systematic mutation screening in schizophrenia and bipolar affective disorder. 915 33

We have previously described an allelic variant of the human H2R, nominated the H2R649G allele. This allele contains an adenine-->guanidine substitution at base 649, which introduces an additional TaqI restriction endonuclease site into the gene. With this in mind, we have investigated allelic polymorphism of this receptor and its association with schizophrenia. H2R DNA from 47 schizophrenic patients and 46 control subjects was amplified by the polymerase chain reaction (PCR). These PCR products were analyzed by observing TaqI cleavage patterns and single-stranded conformational polymorphisms. It was found that the H2R649G allele was 1.8 times more frequent in the schizophrenic population (chi 2 test P < 0.01). In addition, schizophrenic individuals were 2.8 times more likely to be homozygous for the H2R649G allele than the control population, (chi 2 test P < 0.05). These data place the attributable fraction for possession of the H2R649G allele at 28.4%.
Mol Psychiatry 1996 Dec
PMID:Individuals with schizophrenia have an increased incidence of the H2R649G allele for the histamine H2 receptor gene. 915 48

Cell and tissue damage in respiratory chain disorders have been related to increased production of reactive oxygen species (ROS). We measured telomere lengths in such disorders since ROS have also been implicated with telomere shortening. We investigated whole blood cell DNA of 14 patients with MELAS-related mitochondriopathy and two patients with the LHON-associated G11778A mutation of the mitochondrial genome. The phenotypes were variable and included an unusual case of schizophrenia-like psychosis associated with the A3243G mutation. As compared to healthy controls telomere shortening in the patient group was advanced (P < or = 0.006). We compare this finding with the accelerated telomere shortening in Down's syndrome and in chromosomal breakage syndromes. We discuss possible relations between advanced telomere shortening and selective constraints that act on proliferating cells with respiratory chain dysfunction.
Hum Mol Genet 1997 Jun
PMID:Advanced telomere shortening in respiratory chain disorders. 917 37

The present study used in situ hybridization to c-fos mRNA to compare the effects of an 'ampakine' (a positive modulator of AMPA type glutamate receptors) with those of methamphetamine on the balance of aggregate neuronal activity in the cortex versus striatum. Methamphetamine (n = 11) induced a marked increase in c-fos mRNA in the dorsomedial quadrant of the striatum and a 21% smaller, but still reliable, increase in the ventrolateral quadrant. The drug also elevated c-fos mRNA levels in the ventral and medial segments of the orbitofrontal cortex but had no detectable effects in motor and somatosensory neocortices. The ampakine (n = 11) caused a near inverse pattern of changes; i.e. a sizable increase in somatosensory labeling and a significant decrease in striatal labeling with statistically insignificant effects in motor and orbitofrontal cortex. Within-rat cortical and striatal values were correlated in both the vehicle (n = 11) and ampakine groups, and appropriate comparisons established that the ampakine caused 27-55% increases in the ratio of cortical to striatal labeling. These results are in accord with the idea that facilitation of glutamatergic transmission has 'network level' effects that are opposite in nature to those resulting from enhanced dopaminergic transmission. The potential relevance of ampakines alone or in conjunction with dopamine antagonists for the treatment of schizophrenia is discussed.
Brain Res Mol Brain Res 1997 Jun
PMID:Comparison of the effects of an ampakine with those of methamphetamine on aggregate neuronal activity in cortex versus striatum. 919 Oct 86

Dopamine is the neurotransmitter most often implicated in the pathogenesis of schizophrenia. However, glutamatergic antagonists can cause psychotic symptoms in otherwise normal humans, and exacerbate these symptoms in schizophrenics. These findings have led to a model of dopamine-glutamate interactions in limbic cortex and striatum as a potential substrate for symptom production in schizophrenia. From this model, we might expect that cortical and striatal expression of non-NMDA ionotropic glutamate receptors would be differentially regulated by antipsychotic treatment. To begin to address this question, we examined the regulation of mRNA levels of the AMPA (gluR1-gluR4), low affinity kainate (gluR5-gluR7), and high affinity kainate (KA1-KA2) receptor subunits by clozapine (20 mg/kg/day) and haloperidol (2 mg/kg/day) treatment for 2 weeks. Both clozapine and haloperidol caused region-specific alterations in the mRNA levels of these subunits, but there was no differential regulation in the cortex vs. the striatum. Haloperidol caused a decrease in gluR2 and gluR4 mRNA levels in both cortex and striatum and an increase in KA2 mRNA levels in the striatum only. However, clozapine treatment caused an increase in gluR7 mRNA expression, and a decrease in gluR3 mRNA expression, in both cortex and striatum while causing an increase in KA2 mRNA levels, and a decrease in gluR4 mRNA levels, in the striatum only. These dissimilarities may represent an interesting mechanism for some of the differential therapeutic or toxic effects of clozapine and haloperidol, and also may be relevant to our understanding of dopamine-glutamate interactions in schizophrenia.
Brain Res Mol Brain Res 1997 Jul
PMID:Clozapine and haloperidol differentially affect AMPA and kainate receptor subunit mRNA levels in rat cortex and striatum. 922 32


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