Project description:Molecular basis of transition to addiction in vulnerable individuals is largely unknown. We hypothesized that human susceptibility genes can be identified on the basis of conserved molecular mechanisms in rodent brains. We used a short-term cocaine-dependent conditioned place preference (CPP) to identify genetic hallmarks of early steps of reward memory in basal ganglia including accumbens nucleus (NAc), globus pallidus (GP) and subthalamic nucleus (STN). Using genome-wide microarray analysis and CPP as a quantitative trait, we found that synaptic plasticity-related genes are deregulated in these three structures. A significant enrichment in bona fide transcripts involved in dendritic spine local translation was evidenced. mGluR5 is transcriptionally deregulated in Acc and GP of cocaine-treated animals. Grin3a that encodes a NMDA receptor subunit involved in Ca++ permeability is deregulated in NAc. Furthermore, Orexin/Hcrt transcript level is decreased in STN, a region known to be involved in discriminating addictive drugs and natural rewards. We also found that mGluR5 and Grin3a expression deregulation is sufficient to induce changes in synaptic plasticity-related genes. Altogether, these results suggest that a combined deregulation of mGluR5 and Grin3A pathway in NAc, mGluR5 in GP and orexin system in STN may generate an incentive memory contrasted between addictive drugs and natural rewards. Such pathways may include clusters of genes that are potential susceptibility genes for transition to addiction.
Project description:Molecular basis of transition to addiction in vulnerable individuals is largely unknown. We hypothesized that human susceptibility genes can be identified on the basis of conserved molecular mechanisms in rodent brains. We used a short-term cocaine-dependent conditioned place preference (CPP) to identify genetic hallmarks of early steps of reward memory in basal ganglia including accumbens nucleus (NAc), globus pallidus (GP) and subthalamic nucleus (STN). Using genome-wide microarray analysis and CPP as a quantitative trait, we found that synaptic plasticity-related genes are deregulated in these three structures. A significant enrichment in bona fide transcripts involved in dendritic spine local translation was evidenced. mGluR5 is transcriptionally deregulated in Acc and GP of cocaine-treated animals. Grin3a that encodes a NMDA receptor subunit involved in Ca++ permeability is deregulated in NAc. Furthermore, Orexin/Hcrt transcript level is decreased in STN, a region known to be involved in discriminating addictive drugs and natural rewards. We also found that mGluR5 and Grin3a expression deregulation is sufficient to induce changes in synaptic plasticity-related genes. Altogether, these results suggest that a combined deregulation of mGluR5 and Grin3A pathway in NAc, mGluR5 in GP and orexin system in STN may generate an incentive memory contrasted between addictive drugs and natural rewards. Such pathways may include clusters of genes that are potential susceptibility genes for transition to addiction. Agilent Whole Mouse Genome oligomicroarrays (GEO accession no. GPL2872, Agilent Technologies, Palo Alto, CA) were used. They contain 60-mer DNA probes synthesized in situ in a 44k format. Of 44,290 spots, 2756 are controls. The remaining 41,534 spots represent 33,661 unique transcripts which correspond to 20,202 unique human genes. Five independent (five accumbens nuclei from mice treated with cocaine and having a low score of conditioned place preference compared to five accumbens nuclei from mice treated with saline solution) measurements were carried out for each group of biological conditions using exchanged dye-labeled RNA targets (i.e., Cy3 and Cy5 dyeswapping experiments).
Project description:Substance use disorder emerges in a small proportion of drug users and has the characteristics of a chronic relapsing pathology. The objective of our study was to demonstrate and characterize the variability in the expression of the reinforcing effects of cocaine in the conditioned place preference (CPP) paradigm. An unbiased cocaine-CPP paradigm in Sprague-Dawley rats with an extinction period of 12 days and reinstatement was conducted. We developed a statistical model to distinguish rats that express or do not express cocaine-induced place preference. Two groups of rats were identified: rats that did express reinforcing effects (CPP expression (CPPE), score > 102 s) and rats that did not (no CPP expression (nCPPE), score between −85 and 59 s). These two groups did not show significant differences in a battery of behavioral tests. To identify differentially expressed genes in the CPPE and nCPPE groups, we performed a whole-transcriptome RNA-sequencing analysis in the nucleus accumbens (Nac) 24 h after the CPP test. Four immediate early genes (Fos, Egr2, Nr4a1 and Zbtb37) were differentially expressed in the Nac of CPPE rats after CPP memory retrieval. Variability in cocaine-induced place preference persisted in the CPPE and nCPPE groups after the extinction and reinstatement phases. Transcriptomic differences observed after reinstatement were distinct from those observed immediately after CPP memory retrieval. These new findings provide insights into the identification of mechanisms underlying interindividual variability in the response to cocaine's reinforcing effects.
Project description:Molecular basis of transition to addiction in vulnerable individuals is largely unknown. We hypothesized that human susceptibility genes can be identified on the basis of conserved molecular mechanisms in rodent brains. We used a short-term cocaine-dependent conditioned place preference (CPP) to identify genetic hallmarks of early steps of reward memory in basal ganglia including accumbens nucleus (NAc), globus pallidus (GP) and subthalamic nucleus (STN). Using genome-wide microarray analysis and CPP as a quantitative trait, we found that synaptic plasticity-related genes are deregulated in these three structures. A significant enrichment in bona fide transcripts involved in dendritic spine local translation was evidenced. mGluR5 is transcriptionally deregulated in Acc and GP of cocaine-treated animals. Grin3a that encodes a NMDA receptor subunit involved in Ca++ permeability is deregulated in NAc. Furthermore, Orexin/Hcrt transcript level is decreased in STN, a region known to be involved in discriminating addictive drugs and natural rewards. We also found that mGluR5 and Grin3a expression deregulation is sufficient to induce changes in synaptic plasticity-related genes. Altogether, these results suggest that a combined deregulation of mGluR5 and Grin3A pathway in NAc, mGluR5 in GP and orexin system in STN may generate an incentive memory contrasted between addictive drugs and natural rewards. Such pathways may include clusters of genes that are potential susceptibility genes for transition to addiction.
Project description:Drug-induced alterations in gene expression play an important role in the development of addictive behavior. Methionine has been proven to inhibit addictive behaviors of cocaine dependence. However, the mechanisms underlying how methionine use corresponds to drug-induced behaviors still remain unclear. We performed mRNA and miRNA high-throughput sequencing of the prefrontal cortex in a mouse model of cocaine CPP combined with L-methionine in order to identify L-methionine target miRNAs and genes that participate in the cocaine conditioned place preference (CPP). We found that the L-methionine inhibits cocaine CPP. Sequencing data analysis showed that L-methionine down-regulates genes enriched in the Glutamatergic Synapse pathways and significantly reversed the cocaine-induced expression changes of the substance dependence pathways (Morphine addiction and Nicotine addiction) and the neurotransmitter synapse pathways (Glutamatergic Synapse, Cholinergic Synapse and GABAergic Synapse). Furthermore, the Glutamatergic synapse was either overlapped between DEGs with DEGs-miRNA induced by cocaine CPP, or with the MET effects on cocaine CPP. Nineteen targeted genes were investigated and five were identified (Gria4, Grid1, Grik4, Grik5 and Grin3a) to belong to iGluR family. Interestingly, there were several miRNAs that had the same sequence which targets the iGluR family: Mmu-miR-30e-50p and mmu-miR-380-5p share UUGAC motif and targets Grik4; mmu-miR-6940-3p and mmu-miR-212-5p both share UGGCU motif which targets Gria4 and Grid1 respectively. Thus, we demonstrated the efficacy of L-methionine in counteracting the effects of cocaine CPP and identified specific genes of synaptic plasticity pathways, especially the Glutamatergic synapse pathway, which is modulated by L-methionine in response to cocaine dependence.
Project description:Substance use disorder emerges in a small proportion of drug users and has the characteristics of a chronic relapsing pathology. The objective of our study was to demonstrate and characterize the variability in the expression of the reinforcing effects of cocaine in the conditioned place preference (CPP) paradigm. An unbiased cocaine-CPP paradigm in Sprague-Dawley rats with an extinction period of 12 days and reinstatement was conducted. We developed a statistical model to distinguish rats that express or do not express cocaine-induced place preference. Two groups of rats were identified: rats that did express reinforcing effects (CPP expression (CPPE), score > 102 s) and rats that did not (no CPP expression (nCPPE), score between −85 and 59 s). These two groups did not show significant differences in a battery of behavioral tests. To identify differentially expressed genes in the CPPE and nCPPE groups, we performed a whole-transcriptome RNA-sequencing analysis in the nucleus accumbens (Nac) 24 h after the CPP test. Four immediate early genes (Fos, Egr2, Nr4a1 and Zbtb37) were differentially expressed in the Nac of CPPE rats after CPP memory retrieval. Variability in cocaine-induced place preference persisted in the CPPE and nCPPE groups after the extinction and reinstatement phases. Transcriptomic differences observed after reinstatement were distinct from those observed immediately after CPP memory retrieval. These new findings provide insights into the identification of mechanisms underlying interindividual variability in the response to cocaine's reinforcing effects.
Project description:Molecular basis of transition to addiction in vulnerable individuals is largely unknown. We hypothesized that human susceptibility genes can be identified on the basis of conserved molecular mechanisms in rodent brains. We used a short-term cocaine-dependent conditioned place preference (CPP) to identify genetic hallmarks of early steps of reward memory in basal ganglia including accumbens nucleus (NAc), globus pallidus (GP) and subthalamic nucleus (STN). Using genome-wide microarray analysis and CPP as a quantitative trait, we found that synaptic plasticity-related genes are deregulated in these three structures. A significant enrichment in bona fide transcripts involved in dendritic spine local translation was evidenced. mGluR5 is transcriptionally deregulated in Acc and GP of cocaine-treated animals. Grin3a that encodes a NMDA receptor subunit involved in Ca++ permeability is deregulated in NAc. Furthermore, Orexin/Hcrt transcript level is decreased in STN, a region known to be involved in discriminating addictive drugs and natural rewards. We also found that mGluR5 and Grin3a expression deregulation is sufficient to induce changes in synaptic plasticity-related genes. Altogether, these results suggest that a combined deregulation of mGluR5 and Grin3A pathway in NAc, mGluR5 in GP and orexin system in STN may generate an incentive memory contrasted between addictive drugs and natural rewards. Such pathways may include clusters of genes that are potential susceptibility genes for transition to addiction. Agilent Whole Mouse Genome oligomicroarrays (GEO accession no. GPL2872, Agilent Technologies, Palo Alto, CA) were used. They contain 60-mer DNA probes synthesized in situ in a 44k format. Of 44,290 spots, 2756 are controls. The remaining 41,534 spots represent 33,661 unique transcripts which correspond to 20,202 unique human genes. Five independent (four accumbens nuclei from mice treated with cocaine compared to four accumbens nuclei from mice treated with saline solution) measurements were carried out for each group of biological conditions using exchanged dye-labeled RNA targets (i.e., Cy3 and Cy5 dyeswapping experiments). Each hybridization was numerized hybridization by a GenePix 4000B Microarray Scanner and an Agilent G6525 Microarray Scanner.
Project description:Drug-paired cues inducing memory retrieval by expressing drug-seeking behaviors present a major challenge to drug abstinence. How neural circuits coordinate for drug memory retrieval remains unclear. Here, we report that exposure of the training chamber where cocaine-conditioned place preference (CPP) was performed increased neuronal activity in the core of nucleus accumbens (AcbC), ventral CA1 (vCA1), and medial prefrontal cortex (mPFC), as shown by elevated pERK and c-Fos levels. Chemogenetic inhibition of neuronal activity in the vCA1 and AcbC, but not mPFC, reduced the time spent in the cocaine-paired compartment, suggesting that the vCA1 and AcbC are required for the retrieval of cocaine-CPP memory and are key nodes recruited for cocaine memory storage. Furthermore, chemogenetic inhibition of the AcbC-projecting vCA1 neurons, but not the AcbC-projecting mPFC neurons, decreased the expression of cocaine-CPP. Optogenetic inhibition of the vCA1-AcbC projection, but not the mPFC-AcbC projection, also reduced the preference for the cocaine-paired compartment. Taken together, the cue-induced natural recall of cocaine memory depends on vCA1-AcbC circuits. The connectivity from the vCA1 to the AcbC may store the information of the cue-cocaine reward association critically required for memory retrieval. These data thus provide insights into the neural circuit basis of retrieval of drug-related memory.
Project description:Molecular basis of transition to addiction in vulnerable individuals is largely unknown. We hypothesized that human susceptibility genes can be identified on the basis of conserved molecular mechanisms in rodent brains. We used a short-term cocaine-dependent conditioned place preference (CPP) to identify genetic hallmarks of early steps of reward memory in basal ganglia including accumbens nucleus (NAc), globus pallidus (GP) and subthalamic nucleus (STN). Using genome-wide microarray analysis and CPP as a quantitative trait, we found that synaptic plasticity-related genes are deregulated in these three structures. A significant enrichment in bona fide transcripts involved in dendritic spine local translation was evidenced. mGluR5 is transcriptionally deregulated in Acc and GP of cocaine-treated animals. Grin3a that encodes a NMDA receptor subunit involved in Ca++ permeability is deregulated in NAc. Furthermore, Orexin/Hcrt transcript level is decreased in STN, a region known to be involved in discriminating addictive drugs and natural rewards. We also found that mGluR5 and Grin3a expression deregulation is sufficient to induce changes in synaptic plasticity-related genes. Altogether, these results suggest that a combined deregulation of mGluR5 and Grin3A pathway in NAc, mGluR5 in GP and orexin system in STN may generate an incentive memory contrasted between addictive drugs and natural rewards. Such pathways may include clusters of genes that are potential susceptibility genes for transition to addiction.