Protein expression in the nucleus accumbens of rats exposed to developmental vitamin D deficiency.

INTRODUCTION: Developmental vitamin D (DVD) deficiency is a candidate risk factor for schizophrenia. Animal models have confirmed that DVD deficiency is associated with a range of altered genomic, proteomic, structural and behavioural outcomes in the rat. Because the nucleus accumbens has been implicated in neuropsychiatric disorders, in the current study we examined protein expression in this region in adult rats exposed to DVD deficiency METHODS: Female Sprague Dawley rats were maintained on a vitamin D deficient diet for 6 weeks, mated and allowed to give birth, after which a diet containing vitamin D was reintroduced. Male adult offspring (n = 8) were compared to control male (n = 8). 2-D gel electrophoresis-based proteomics and mass spectroscopy were used to investigate differential protein expression. RESULTS: There were 35 spots, mapped to 33 unique proteins, which were significantly different between the two groups. Of these, 22 were down-regulated and 13 up-regulated. The fold changes were uniformly small, with the largest FC being -1.67. Within the significantly different spots, three calcium binding proteins (calbindin1, calbindin2 and hippocalcin) were altered. Other proteins associated with DVD deficiency related to mitochondrial function, and the dynamin-like proteins. CONCLUSIONS: Developmental vitamin D deficiency was associated with subtle changes in protein expression in the nucleus accumbens. Disruptions in pathways related to calcium-binding proteins and mitochondrial function may underlie some of the behavioural features associated with animal models of developmental vitamin D deficiency.

Protein expression profile in the amygdala of rats with methamphetamine-induced behavioral sensitization.

Repeated exposure to methamphetamine (MAP) results in a progressively enhanced and enduring behavioral response to the drug. This phenomenon is known as behavioral sensitization. MAP-induced sensitization has been suggested to underlie certain aspects of MAP psychosis and schizophrenia. The mesolimbic dopamine system including the ventral tegmental area, nucleus accumbens (NAc) and associated brain regions such as the amygdala (AMG) are proposed to be involved in the behavioral sensitization. However, the molecular mechanisms underlying this protracted alteration of behavior are almost unknown. Here we examined protein expression profiles in the AMG of acute MAP-treated and MAP-sensitized rats using 2-DE-based proteomics. Analysis revealed that 64 and 43 protein spots were differentially regulated in the AMG of acute MAP-treated and MAP-sensitized rats, respectively, when compared to control rats. A total of 48 and 34 proteins were identified in these two models, respectively using MALDI-ToF-MS. When the results were compared between acute and chronic MAP-treated groups, only 9 proteins were identified in common. These proteins could be related to acute MAP effects and/or non-specific effects. It is therefore suggested that AMG react differently to the acute and repeated administration of MAP at least at the protein expression level. A number of proteins in the categories of synaptic, cytoskeletal, oxidative stress, apoptosis, and mitochondria related proteins were differentially expressed in the AMG of sensitized animals. Changes of these protein expressions in the AMG could be associated with the mechanism underlying behavioral sensitization.

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 Delta-9-tetrahydrocannabinol (Delta(9)-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 Delta(9)-THC-paired environment after either four or eight pairings and this avoidance persisted for at least 16 days following the final Delta(9)-THC injection. In contrast, adolescent rats showed no significant place aversion. Adult Delta(9)-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 Delta(9)-THC pretreated rats showed decreased social interaction, while only Delta(9)-THC pretreated adolescent rats showed significantly impaired object recognition memory. Seventeen days following their last Delta(9)-THC injection, rats were euthanased and hippocampal tissue processed using two-dimensional gel electrophoresis proteomics. There was no evidence of residual Delta(9)-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 Delta(9)-THC pretreated rats relative to adolescent controls. In adults, only 10 hippocampal proteins were differentially expressed in Delta(9)-THC compared to vehicle-pretreated controls. Overall these findings suggest that adolescent rats find repeated Delta(9)-THC exposure less aversive than adults, but that cannabinoid exposure causes greater lasting memory deficits and hippocampal alterations in adolescent than adult rats.

CNS proteomes in alcohol and drug abuse and dependence.

Drugs of abuse, including alcohol, can induce dependency formation and/or brain damage in brain regions important for cognition. 'High-throughput' approaches, such as cDNA microarray and proteomics, allow the analysis of global expression profiles of genes and proteins. These technologies have recently been applied to human brain tissue from patients with psychiatric illnesses, including substance abuse/dependence and appropriate animal models to help understand the causes and secondary effects of these complex disorders. Although these types of studies have been limited in number and by proteomics techniques that are still in their infancy, several interesting hypotheses have been proposed. Focusing on CNS proteomics, we aim to review and update current knowledge in this rapidly advancing area.

Protein expression profile in the striatum of rats with methamphetamine-induced behavioral sensitization.

Repeated administration of methamphetamine (MAP) results in an increased behavioral response to the drug during subsequent exposure. This phenomenon is called behavioral sensitization. Sensitization is an enduring phenomenon, and suggests chronic alterations in neuronal plasticity. MAP-induced sensitization has been proposed and widely investigated as an animal model of MAP psychosis and schizophrenia. However, little is known about the molecular mechanisms underlying MAP-induced sensitization. 2-DE-based proteomics allows us to examine global changes in protein expression in complex biological systems and to propose hypotheses concerning the mechanisms underlying various pathological conditions. In the present study, we examined protein expression profiles in the striatum of MAP-sensitized rats using 2-DE-based proteomics. Repeated administration of MAP (4.0 mg/kg, once a day, intraperitoneal (i.p.)) for 10 days significantly augmented the locomotor response to an MAP challenge injection (1.0 mg/kg, i.p.) on day 11. This enhanced activity was maintained even after a week of drug abstinence. 2-DE analysis revealed 42 protein spots were differentially regulated in the striatum of MAP-sensitized rats compared to control. Thirty-one protein spots were identified using MALDI-TOF, including synapsin II, synaptosomal-associated protein 25 (SNAP-25), adenylyl cyclase-associated protein 1 (CAP1), and dihydropyrimidinase-related protein 2 (DRP2). These proteins can be related to underlying mechanisms of MAP-induced behavioral sensitization, indicating cytoskeletal modification, and altered synaptic function.

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.

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 Brodmann's 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.

Selective reduction of chromogranin A-like immunoreactivities in the prefrontal cortex of schizophrenic subjects: a postmortem study.

It is suggested that secretogranins/chromogranins play a role in regulating secretion of various proteins and amines, including neurotransmitters from secretory granules. Several studies have implicated the importance of altered synaptic connectivity in schizophrenia. We employed immunohistochemical techniques to determine if the level of chromogranin A (CgA)-immunoreactivity (IR) was altered in the subjects with schizophrenia. Nine subjects with schizophrenia and nine age- and sex-matched control subjects were selected for this study. Immunohistochemistry using specific antibody against CgA was performed on sections of prefrontal cortex and hippocampus. Images of CgA-IR were analyzed by computer-based image analyzing software. CgA-IR was significantly decreased in layers III-V of the prefrontal cortex in schizophrenic subjects compared with control subjects. In the hippocampus, no significant difference was observed between two groups. The results indicate that there may be a decrease in the number of CgA positive large dense-core vesicles per terminal, and/or in the number of CgA positive terminals, suggesting possible functional impairment of prefrontal synaptic contact in schizophrenia.