Izuru Matsumoto

Adolescent rats find repeated Delta(9)-THC less aversive than adult rats but display greater residual cognitive deficits and changes in hippocampal protein expression following exposure.

The current study examined whether adolescent rats are more vulnerable than adult rats to the lasting adverse effects of cannabinoid exposure on brain and behavior. Male Wistar rats were repeatedly exposed to Δ-9-tetrahydrocannabinol (Δ9-THC, 5 mg/kg i.p.) in a place-conditioning paradigm during either the adolescent (post-natal day 28+) or adult (post-natal day 60+) developmental stages. Adult rats avoided a Δ9-THC-paired environment after either four or eight pairings and this avoidance persisted for at least 16 days following the final Δ9-THC injection. In contrast, adolescent rats showed no significant place aversion. Adult Δ9-THC-treated rats produced more vocalizations than adolescent rats when handled during the intoxicated state, also suggesting greater drug-induced aversion. After a 10–15 day washout, both adult and adolescent Δ9-THC pretreated rats showed decreased social interaction, while only Δ9-THC pretreated adolescent rats showed significantly impaired object recognition memory. Seventeen days following their last Δ9-THC injection, rats were euthanased and hippocampal tissue processed using two-dimensional gel electrophoresis proteomics. There was no evidence of residual Δ9-THC being present in blood at this time. Proteomic analysis uncovered 27 proteins, many involved in regulating oxidative stress/mitochondrial functioning and cytoarchitecture, which were differentially expressed in adolescent Δ9-THC pretreated rats relative to adolescent controls. In adults, only 10 hippocampal proteins were differentially expressed in Δ9-THC compared to vehicle-pretreated controls. Overall these findings suggest that adolescent rats find repeated Δ9-THC exposure less aversive than adults, but that cannabinoid exposure causes greater lasting memory deficits and hippocampal alterations in adolescent than adult rats.

Alcohol‐responsive genes in the frontal cortex and nucleus accumbens of human alcoholics

The molecular processes underlying alcohol dependence are not fully understood. Many characteristic behaviours result from neuroadaptations in the mesocorticolimbic system. In addition, alcoholism is associated with a distinct neuropathology. To elucidate the molecular basis of these features, we compared the RNA expression profile of the nucleus accumbens and prefrontal cortex of human brain from matched individual alcoholic and control cases using cDNA microarrays. Approximately 6% of genes with a marked alcohol response were common to the two brain regions. Alcohol-responsive genes were grouped into 11 functional categories. Predominant alcohol-responsive genes in the prefrontal cortex were those encoding DNA-binding proteins including transcription factors and repair proteins. There was also a down-regulation of genes encoding mitochondrial proteins, which could result in disrupted mitochondrial function and energy production leading to oxidative stress. Other alcohol-responsive genes in the prefrontal cortex were associated with neuroprotection/apoptosis. In contrast, in the nucleus accumbens, alcohol-responsive genes were associated with vesicle formation and regulation of cell architecture, which suggests a neuroadaptation to chronic alcohol exposure at the level of synaptic structure and function. Our data are in keeping with the previously reported alcoholism-related pathology characteristic of the prefrontal cortex, but suggest a persistent decrease in neurotransmission and changes in plasticity in the nucleus accumbens of the alcoholic.

A proteome analysis of the anterior cingulate cortex gray matter in schizophrenia

The Anterior Cingulate Cortex (ACC, Brodmans Area 24) is implicated in the pathogenesis of schizophrenia due to its normal functions and connectivity together with reports of structural, morphological and neurotransmitter aberrations within this brain area in the disease state. Two-dimensional gel electrophoresis (2DE) was employed to scan and compare the ACC gray matter proteomes between schizophrenia (n=10) and control (n=10) post-mortem human tissue. This proteomic approach has detected 42 protein spots with altered levels in the schizophrenia cohort, which to our knowledge is the first proteomic analysis of the ACC in schizophrenia. Thirty nine of these proteins were subsequently identified using mass spectrometry and functionally classified into metabolism and oxidative stress, cytoskeletal, synaptic, signalling, trafficking and glial-specific groups. Some of the identified proteins have previously been implicated in the disease pathogenesis and some offer new insights into schizophrenia. Investigating these proteins, the genes encoding these proteins, their functions and interactions may shed light on the molecular mechanisms underlying the heterogeneous symptoms characteristic of schizophrenia.

Alcohol-responsive genes in the frontal cortex and nucleus accumbens of human alcoholics: Alcohol responsive genes in human brain

The molecular processes underlying alcohol dependence are not fully understood. Many characteristic behaviours result from neuroadaptations in the mesocorticolimbic system. In addition, alcoholism is associated with a distinct neuropathology. To elucidate the molecular basis of these features, we compared the RNA expression profile of the nucleus accumbens and prefrontal cortex of human brain from matched individual alcoholic and control cases using cDNA microarrays. Approximately 6% of genes with a marked alcohol response were common to the two brain regions. Alcohol‐responsive genes were grouped into 11 functional categories. Predominant alcohol‐responsive genes in the prefrontal cortex were those encoding DNA‐binding proteins including transcription factors and repair proteins. There was also a down‐regulation of genes encoding mitochondrial proteins, which could result in disrupted mitochondrial function and energy production leading to oxidative stress. Other alcohol‐responsive genes in the prefrontal cortex were associated with neuroprotection/apoptosis. In contrast, in the nucleus accumbens, alcohol‐responsive genes were associated with vesicle formation and regulation of cell architecture, which suggests a neuroadaptation to chronic alcohol exposure at the level of synaptic structure and function. Our data are in keeping with the previously reported alcoholism‐related pathology characteristic of the prefrontal cortex, but suggest a persistent decrease in neurotransmission and changes in plasticity in the nucleus accumbens of the alcoholic.

Differential protein expression in the prefrontal white matter of human alcoholics: a proteomics study.

Neuroimaging and post-mortem studies indicate that chronic alcohol use induces global changes in brain morphology, such as cortical and subcortical atrophy. Recent studies have shown that frontal lobe structures are specifically susceptible to alcohol-related brain damage and shrinkage in this area is largely due to a loss of white matter. This may explain the high incidence of cognitive dysfunction observed in alcoholics. Using a proteomics-based approach, changes in protein expression in the dorsolateral prefrontal region (BA9) white matter were identified in human alcoholic brains. Protein extracts from the BA9 white matter of 25 human brains (10 controls; eight uncomplicated alcoholics; six alcoholics complicated with hepatic cirrhosis; one reformed alcoholic) were separated using two-dimensional gel electrophoresis. Overall, changes in the relative expression of 60 proteins were identified (P<0.05, ANOVA) in the alcoholic BA9 white matter. In total, 18 protein spots have been identified using MALDI-TOF; including hNP22, α-internexin, transketolase, creatine kinase chain B, ubiquitin carboxy-terminal hydrolase L1 and glyceraldehyde-3-phosphate dehydrogenase. Several of these proteins have been previously implicated in alcohol-related disorders and brain damage. By identifying changes in protein expression in this region from alcoholics, hypotheses may draw upon more mechanistic explanations as to how chronic ethanol consumption causes white matter damage.

Abnormal pathways in the genu of the corpus callosum in schizophrenia pathogenesis: a proteome study

Abnormalities within the corpus callosum (CC) have been identified in schizophrenia brains and are thought to affect inter‐hemispheric communication, which in‐turn is postulated to underlie some schizophrenia symptoms. Furthermore, hemisphere asymmetry of fractional anisotropy, detected by diffusion tensor imaging, left‐higher‐than‐right‐ has been observed in normal individuals in the CC genu. This asymmetry is significantly reduced in the left CC genu of first‐episode and chronic schizophrenia subjects. We examined the protein expression profile of the CC genu, including the profiles from the left and right hemisphere, in schizophrenia brains compared to controls using two‐dimensional gel electrophoresis and mass spectrometry techniques. Proteins involved in cytoskeletal structure and function, neuroprotective function and energy metabolism were identified as differentially expressed, suggesting these proteins may underlie abnormal CC genu structure and function. Proteins in these functional categories also displayed different expression levels in the left CC genu compared to the right in both control and schizophrenia brains and therefore may be involved in normal CC asymmetry and reduced asymmetry in schizophrenia individuals. This initial pool of protein candidates and abnormal functional pathways opens up avenues for further investigation of molecular mechanisms involving the CC in schizophrenia pathogenesis and symptoms.

Failure to support a genetic contribution of AKT1 polymorphisms and altered AKT signaling in schizophrenia

The protein kinase v‐akt murine thymoma viral oncogene homolog (AKT) gene family comprises three human homologs that phosphorylate and inactivate glycogen synthase kinase 3β (GSK3β). Studies have reported the genetic association of AKT1 with schizophrenia. Additionally, decreased AKT1 protein expression and the reduced phosphorylation of GSK3β were reported in this disease, leading to a new theory of attenuated AKT1‐GSK3β signaling in schizophrenia pathogenesis. We have evaluated this theory by performing both genetic and protein expression analyses. A family based association test of AKT1 did not show association with schizophrenia in Japanese subjects. The expression levels of total AKT, AKT1 and phosphorylated GSK3β detected in the schizophrenic brains from two different brain banks also failed to support the theory. In addition, no attenuated AKT‐GSK3β signaling was observed in the lymphocytes from Japanese schizophrenics, contrasting with previous findings. Importantly, we found that the level of phosphorylated GSK3β at Ser9 tended to be inversely correlated with postmortem intervals, and that the phosphorylation levels of AKT were inversely correlated with brain pH, issues not assessed in the previous study. These data introduce a note of caution when estimating the phosphorylation levels of GSK3β and AKT in postmortem brains. Collectively, this study failed to support reduced signaling of the AKT‐GSK3β molecular cascade in schizophrenia.

Protein expression profile in the striatum of acute methamphetamine-treated rats.

PURPOSE Methamphetamine (MAP) is an addictive drug with psychostimulant effects. It is known that MAP induces behavioral changes, including hyperlocomotion and stereotypical movements in rodents. These behavioral changes induced by MAP have been compared with behavioral changes in patients with MAP addiction and MAP psychosis. However, little is known about the underlying mechanisms of MAPs effects on global protein expression. 2-DE proteomics allows us to examine global changes in protein expression in complex biological systems and to propose possible hypotheses of the underlying mechanisms in various pathological conditions. In the present study, we aim to identify protein expression profiles in the striatum (ST) of acute low dose MAP (1 mg/kg)-treated rats using 2-DE proteomics. MATERIALS AND METHODS Rats were given an intraperitoneal injection of MAP (1 mg/kg) or saline. Locomotor activity was monitored. Proteins were extracted from the ST of MAP-treated and saline-treated control rats then separated and analyzed using 2-DE. RESULTS. Low dose MAP administration significantly increased locomotor activity. 2-DE analysis revealed 36 protein spots differentially regulated in the ST of acute MAP-treated rats compared to a vehicle-treated control. 26 protein spots have been identified using MALDI-TOF, including phosphoglycerate kinase 1, Dihydrolipoamide dehydrogenase, Voltage-dependent anion-selective channel protein 1, Rho GDP dissociation inhibitor alpha, peroxiredoxin 2, ubiquitin carboxy-terminal hydrolase L1, and actin beta, N-tropomodulin. DISCUSSION These proteins could be related to underlying mechanisms of acute low dose MAP effects, indicating mitochondrial dysfunction, oxidative damages, lysosomal degradation, degenerative processes, and neuronal modification.

Increased TUNEL positive cells in human alcoholic brains

Alcohol-sensitive neuronal cell loss, which has been reported in the superior frontal cortex and hippocampus, may underlie the pathogenesis of subsequent cognitive deficits. In the present study, we have used the TUNEL labeling to detect the DNA damage in human alcoholic brains. Seven out of eleven alcoholics exhibited TUNEL-positive cells in both superior frontal cortex and hippocampus, which were co-localized with GFAP immunoreactivity. In contrast, almost no positive cells were detected in the non-alcoholic controls. None of the TUNEL-positive cells showed any typical morphological features of apoptosis or necrosis. TUNEL-positive cells observed in the present study may indicate DNA damage induced by ethanol-related overproduction of reactive oxygen species.

5-HT2A and muscarinic receptors in schizophrenia: a postmortem study.

Although evidence suggests that 5-HT(2A) and muscarinic M1/M4 receptors are implicated in the pathology of schizophrenia, the results are not conclusive. In the present study we tested the hypothesis that binding of 5-HT(2A) and M1/M4 receptors is altered in the postmortem brain of schizophrenia subjects. Quantitative autoradiography was employed to measure [(3)H]ketanserin binding to 5-HT(2A) receptors and [(3)H]pirenzepine binding to both M1 and M4 receptors in Brodmanns area 9 (BA9), caudate/putamen, and the hippocampal formation from six schizophrenic and six control subjects. A significant reduction in the density of 5HT(2A) receptors in BA 9 of schizophrenic subjects was observed (p=0.036). No significant difference was observed in the density of 5HT(2A) receptors in the hippocampus or caudate/putamen between the two groups. No significant changes in the density of M1/M4 receptors was observed in these three regions between the two groups. These findings support a possible involvement of the serotonergic system in the pathology of schizophrenia.