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Gene expression evidence for remodeling of lateral hypothalamic circuitry in cocaine addiction

ABSTRACT: By using high-density oligonucleotide arrays, we profiled gene expression in reward-related brain regions of rats that developed escalated cocaine intake after extended access to cocaine (6 h per day). Rats allowed restricted daily access to cocaine (only 1 h) that displayed a stable level of cocaine intake and cocaine naive rats were used for controls. Four analysis methods were compared: Affymetrix microarray suite 4 and microarray suite 5, which use perfect-match-minus-mismatch models, and dchip and rma, which use perfect-match-only models to generate expression values. Results were validated by RT-PCR in individual animals from an independent replication of the experiment. A small number of genes was associated with escalated cocaine intake (ESC genes). Unexpectedly, of the brain regions examined [prefrontal cortex, nucleus accumbens, septum, lateral hypothalamus (LH), amygdala, and ventral tegmental area], the LH was the most transcriptionally responsive in escalation of cocaine intake. Most of the ESC genes identified are also expressed during synaptogenesis and synaptic plasticity and include genes that code for several presynaptic and postsynaptic proteins involved in neurotransmission. These results suggest that LH intrinsic circuitry undergoes a structural reorganization during escalation of cocaine use. This remodeling of LH circuitry could contribute to the chronic deficit in reward function that has been hypothesized to drive the transition to drug addiction. Results also support the value of using multiple analysis strategies to identify the most robust changes in gene expression and to compensate for the biases that affect each strategy. Keywords: cocaine addiction

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE3016 | GEO | 2006/01/26

SECONDARY ACCESSION(S): PRJNA93199

REPOSITORIES: GEO

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Project description:By using high-density oligonucleotide arrays, we profiled gene expression in reward-related brain regions of rats that developed escalated cocaine intake after extended access to cocaine (6 h per day). Rats allowed restricted daily access to cocaine (only 1 h) that displayed a stable level of cocaine intake and cocaine naive rats were used for controls. Four analysis methods were compared: Affymetrix microarray suite 4 and microarray suite 5, which use perfect-match-minus-mismatch models, and dchip and rma, which use perfect-match-only models to generate expression values. Results were validated by RT-PCR in individual animals from an independent replication of the experiment. A small number of genes was associated with escalated cocaine intake (ESC genes). Unexpectedly, of the brain regions examined [prefrontal cortex, nucleus accumbens, septum, lateral hypothalamus (LH), amygdala, and ventral tegmental area], the LH was the most transcriptionally responsive in escalation of cocaine intake. Most of the ESC genes identified are also expressed during synaptogenesis and synaptic plasticity and include genes that code for several presynaptic and postsynaptic proteins involved in neurotransmission. These results suggest that LH intrinsic circuitry undergoes a structural reorganization during escalation of cocaine use. This remodeling of LH circuitry could contribute to the chronic deficit in reward function that has been hypothesized to drive the transition to drug addiction. Results also support the value of using multiple analysis strategies to identify the most robust changes in gene expression and to compensate for the biases that affect each strategy. Experiment Overall Design: The experimental design for this study comprised three groups of rats (n = 8) with different daily access to a continuous schedule of i.v. cocaine self-administration (0.25 mg per injection): 0 h access per day (drug-naive control rats), 1 h access per day (ShA rats), or 6 h access per day (LgA rats). Experiment Overall Design: Gene expression profiling was then performed for each dissected brain region by using Affymetrix rat neurobiology arrays.

Project description:MicroRNAs (miRNAs) regulate many basic aspects of cell biology including neuronal plasticity, but little is known of their roles in drug addiction. Extended access to cocaine can trigger the emergence of compulsive drug-seeking behaviors, but molecular mechanisms regulating this process remain unclear. Here we report that microRNA-212 (miR-212) is upregulated in the dorsal striatum of rats with extended access to cocaine. Striatal overexpression of miR-212 decreases, whereas its inhibition increases cocaine intake in rats with extended but not restricted drug access, suggesting that miR-212 serves as a protective factor against the development of compulsive drug seeking. The transcription factor CREB (cAMP response element-binding protein) is considered a core regulator of cocaine reward. We show that miR-212 controls responsiveness to cocaine by dramatically amplifying striatal CREB signaling. This action occurs through miR-212-enhanced Raf-1 activity, resulting in adenylyl cyclase sensitization and increased expression of the essential CREB co-activator TORC (Transducer of Regulated CREB; also known as CRTC). Our findings suggest that striatal miR-212 signaling plays a key role in vulnerability to addiction, and that noncoding RNAs such as the miRNAs may serve as novel targets for the development of anti-addiction therapeutics. To identify potential targets for miR-212, we transfected cells with a vector to overexpress miR-212 or an empty vector. We then analyzed profiled gene expression using Affymetrix arrays. Human Affymetrix Study: Cells were transfected with a vector to overexpress miR-212 or an empty vector. We then analyzed profiled gene expression using Affymetrix arrays. The complete, unfiltered set of signal intensity data for Samples miR-212 and pMIF, including miR-212/pMIF ratios, are in the supplementary file at the foot of the record. Probes excluded from analysis (pMIF intensity <100) are indicated in the supplementary file by a no in the far-right column, 'Passed data filtering and included in analysis: no/yes'. Probes that were included in the analyses (pMIF intensity >100) are indicated in the supplementary file by a yes in the 'Passed data filtering and included in analysis: no/yes' column. Rat miRNA Study: Rats were permitted access to intravenous cocaine self-administration (0.5 mg/kg/infusion) for 7 consecutive days during restricted (1-h) or extended (6-h) daily sessions. Control rats remained coaine-naïve throughout. 24-h after the last session the dorsal striatum from each rats was removed, and RNA extracted for microarray profiling. There was a total of n=6 rats per access condition. RNA from 2 rats per access condition were pooled on to arrays, for a total of 3 arrays per access condition, and 9 arrays in total.

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Gene expression evidence for remodeling of lateral hypothalamic circuitry in cocaine addiction

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