Project description:Background: Methamphetamine (METH) is one of the most widely abused illicit substances worldwide; unfortunately, its addiction mechanism remains unclear. Based on accumulating evidence, changes in gene expression and chromatin modifications might be related to the persistent effects of METH on the brain. In the present study, we took advantage of METH-induced behavioral sensitization as an animal model that reflects some aspects of drug addiction and examined the changes in gene expression and histone acetylation in the prefrontal cortex (PFC) of adult rats. Methods: We conducted mRNA microarray and chromatin immunoprecipitation (ChIP) coupled to DNA microarray (ChIP-chip) analyses to screen and identify changes in transcript levels and histone acetylation patterns. Functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, were performed to analyze the differentially expressed genes. We then further identified alterations in ANP32A (acidic leucine-rich nuclear phosphoprotein-32A) and POU3F2 (POU domain, class 3, transcription factor 2) using qPCR and ChIP-PCR assays. Results: In the rat model of METH-induced behavioral sensitization, METH challenge caused 275 differentially expressed genes and a number of hyperacetylated genes (821 genes with H3 acetylation and 10 genes with H4 acetylation). Based on mRNA microarray and GO and KEGG enrichment analyses, 24 genes may be involved in METH-induced behavioral sensitization, and 7 were confirmed using qPCR. We further examined the alterations in the levels of the ANP32A and POU3F2 transcripts and histone acetylation at different periods of METH-induced behavioral sensitization. H4 hyperacetylation contributed to the increased levels of ANP32A mRNA and H3/H4 hyperacetylation contributed to the increased levels of POU3F2 mRNA induced by METH challenge-induced behavioral sensitization, but not by acute METH exposure. Conclusions: The present results revealed alterations in transcription and histone acetylation in the rat PFC by METH exposure and provided evidence that modifications of histone acetylation contributed to the alterations in gene expression caused by METH-induced behavioral sensitization.

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:Histone acetylation and other modifications of the chromatin are important regulators of gene expression and, consequently, may contribute to drug-induced behaviors and neuroplasticity. Previous studies have shown that a reduction on histone deacetylase (HDAC) activity results on the enhancement of some psychostimulant-induced behaviors. In the present study, we extend those seminal findings by showing that the administration of the HDAC inhibitor sodium butyrate enhances morphine-induced locomotor sensitization and conditioned place preference. In contrast, this compound has no effects on the development of morphine tolerance and dependence. Similar effects were observed for cocaine and ethanol-induced behaviors. These behavioral changes were accompanied by a selective boosting of a component of the transcriptional program activated by chronic morphine administration that included circadian clock genes and other genes relevant in addictive behavior. Our results support an specific role for histone acetylation and the epigenetic modulation of transcription at a reduced number of biologically relevant loci on non-homeostatic, long lasting, drug-induced behavioral plasticity. To further investigate the molecular bases of sodium butyrate action on long-lasting behavioral responses to morphine, we screened for potential substrates of their interaction by performing a genome-wide comparison of the striatal transcriptome after chronic administration of morphine in the absence or presence of sodium butyrate. Striatal tissue was dissected from two months-old Swiss-Albino male mice subjected to behavioral sensitization. Behavioural sensitization: Locomotor sensitization induced by morphine was evaluated using a protocol divided into two phases: induction and challenge. The induction phase involved six trials on alternate days, one trial per day. On each one of these trials, mice received and injection of saline or sodium butyrate (300 mg/kg) immediatedly followed by a second injection of morphine (20 mg/kg). The challenge phases consisted of a single trial conducted 7 days after the last test of the induction phase. In this case, all animals received a single injection of morphine (20 mg/kg). Striatal RNA was extracted 1h after the morphine challenge in groups of four animals that received either saline (N=6) or morphine (N=3), or the sodium butyrate-morphine (N=3) co-treatment during the sensitization induction phase.

Dataset Information

Behavioral Sensitization Induced by Methamphetamine Causes Differential Alterations in Gene Expression and Histone Acetylation of the Prefrontal Cortex in Rats (Histone acetylation dataset)

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