Project description:Methamphetamine (METH) addiction is associated with a plethora of neuropsychiatric symptoms. In rodents, administration of the drug is accompanied by complex changes in gene expression in the dorsal striatum. Very little is known about the effects of the drug on gene expression and epigenetic modifications in the nucleus accumbens (NAc). The present study was conducted in order to investigate the effects of a single injection of METH on gene expression in that structure. We also queried whether changes in transcript levels were accompanied by alterations in histone acetylation as well as in the expression of the histone acetyltransferase (HAT), ATF2, and of the histone deacetylases (HDACs), HDAC1 and HDAC2. Microarray analyses revealed that METH caused significant time-dependent increases in the expression of several genes that had previously been implicated in the acute and longterm effects of psychostimulants in the brain. These include several immediate early genes (c-fos, Egrs, c-jun, and Nurr1) and corticotropin-releasing factor (Crf). There were also increases in the levels of neuromedin U, Tnf-alpha, and Kcnk18, among others. In contrast, the METH injection caused decreases in the expression of many genes including Npas4 and cholecystokin (Cck). Pathway analyses showed that differentially affected genes participate in behavioral performance, cell-to-cell signaling and interactions, and regulation of gene expression. Other differentially affected genes are known to be involved in cellular compromise and death pathways. PCR analyses were used to confirm the changes in the expression of c-fos, fosB, c-jun, junB, Crf, NmU, Cck, and Npas4 transcripts. Western blot analyses also identified METH-mediated decreases in the acetylation of histone H3 at lysine 9 (H3K9) and lysine 18 (H3K18) as well as in histone 4 at lysine 16 (H4K16). In contrast, the METH injection caused time-dependent increases in the acetylation of H4K8 and H4K12. The changes in histone acetylation were also accompanied by decreased expression of HDAC1 but increased expression of ATF2 and of HDAC2. These results suggest that METH-induced alterations in global gene expression might be due, in part, to diverse effects of METH-induced histone acetylation secondary to changes in HAT and HDAC expression. At the indicated time after the METH or saline injections, rats (n = 5 per group) were euthanized and the NAc was dissected and immediately put on dry ice. The tissues were kept at -70 oC until RNA extraction. Total RNA was isolated from the nucleus accumbens according to the manufacturer’s manual using Qiagen RNeasy mini kit (Qiagen, Valencia, CA, USA). RNA integrity was detected using an Agilent 2100 Bioanalyzer (Agilent, Palo Alto, CA, USA).

Project description:Drug-induced alterations in transcriptional regulation play a central role in establishing the persistent neuroplasticities that occur during drug addiction. Additionally, changes in gene expression associated with drug administration provide valuable insight into the molecular basis of drug abuse. The molecular mechanisms that underlie susceptibility to psychostimulant addiction remain unknown. Identifying the common gene transcriptional responses to psychostimulants can provide a mechanistic insight to elucidate the molecular nature of drug dependence. Male Wistar rats (4 weeks old) were acclimatized for a week to their housing conditions prior to experiments. Thereafter, they were divided into two groups: (cohort 1) 4 groups of rats (n=12 rats per group) given saline only (i.p., "drug-naive" rats); and (cohort 2): 3 groups of rats given either methamphetamine, amphetamine or methylphenidate (5 mg/kg,i.p., M-CM-"M-bM-^BM-,M-EM-^Sdrug-pretreated") for 7 days (2x daily) prior to behavioral assays. Conditioned place preference (CPP) tests were conducted a day after the final drug administration. Rats which showed CPP were evaluated for self-administration of the psychostimulants. [Cohort 1] A day after the final self-administration test, brains of 2-3 rats from each subgroups (i.e. those which showed the most robust self-administration), as well as 5 rats from the control group were removed for microarray analysis. The striatum (rostral part of the caudate putamen and the nucleus accumbens [NAc]) and the prefrontal cortex were dissected and immediately frozen at -70M-CM-^BM-BM-0C. Total RNA was isolated and gene expression profiling was conducted on independent pools of total RNA from 2-5 animals per group. [Cohort 2] A day after the final self-administration test, brains of 3 rats from each subgroups (i.e. those which showed the most robust self-administration), as well as 3 rats from the control group were removed for microarray analysis. The striatum (rostral part of the caudate putamen and the nucleus accumbens [NAc]) and the prefrontal cortex were dissected and immediately frozen at -70M-BM-0C. Total RNA was isolated and gene expression profiling was conducted on independent pools of total RNA from three animals per group.

Project description:Many of the long-term effects of cocaine on the brain's reward circuitry have been shown to be mediated by alterations in gene expression. Several chromatin modifications, including histone acetylation and methylation, have been implicated in this regulation, but the effect of other histone modifications remains poorly understood. Poly(ADP-ribose) polymerase-1 (PARP-1), a ubiquitous and abundant nuclear protein, catalyzes the synthesis of a negatively charged polymer called poly(ADP-ribose) or PAR on histones and other substrate proteins and forms transcriptional regulatory complexes with several other chromatin proteins. Here, we identify an essential role for PARP-1 in cocaine-induced molecular, neural, and behavioral plasticity. Repeated cocaine administration, including self-administration, increased global levels of PARP-1 and its mark PAR in mouse nucleus accumbens (NAc), a key brain reward region. Using PARP-1 inhibitors and viral-mediated gene transfer, we established that PARP-1induction in NAc mediates enhanced behavioral responses to cocaine, including increased self-administration of the drug. Using chromatin immunoprecipitation sequencing, we demonstrated a global, genome-wide enrichment of PARP-1 in NAc of cocaine-exposed mice and identified several PARP-1 target genes that could contribute to the lasting effects of cocaine. Specifically, we identified sidekick-1-important for synaptic connections during development-as a critical PARP-1 target gene involved in cocaine's behavioral effects as well as in its ability to induce dendritic spines on NAc neurons. These findings establish the involvement of PARP-1 and PARylation in the long-term actions of cocaine. c57bl/6 mice were given IP injections of chronic cocaine 20mg/kg once per day for 7 days and sacrificed 30 minutes after the final dose of cocaine. Control animals were given saline for 7 days and sacrificed 30 minutes after the final dose of saline. Nucleus accumbens (NAc) tissue was collected and then PARP-1 ChIP-seq was performed. Three sequencing replicates were performed on each group.

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