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Tuesday, May 22, 2012

Coordinated dysregulation of mRNAs and microRNAs in the rat medial prefrontal cortex following a history of alcohol dependence

Long-term changes in brain gene expression have been identified in alcohol dependence, but underlying mechanisms remain unknown. Here, we examined the potential role of microRNAs (miRNAs) for persistent gene expression changes in the rat medial prefrontal cortex (mPFC) after a history of alcohol dependence.

Two-bottle free-choice alcohol consumption increased following 7-week exposure to intermittent alcohol intoxication.

A bioinformatic approach using microarray analysis, quantitative PCR (qPCR), bioinformatic analysis and microRNA–messenger RNA (mRNA) integrative analysis identified expression patterns indicative of a disruption in synaptic processes and neuroplasticity. About 41 rat miRNAs and 165 mRNAs in the mPFC were significantly altered after chronic alcohol exposure.

A subset of the miRNAs and mRNAs was confirmed by qPCR. Gene ontology categories of differential expression pointed to functional processes commonly associated with neurotransmission, neuroadaptation and synaptic plasticity. microRNA–mRNA expression pairing identified 33 miRNAs putatively targeting 89 mRNAs suggesting transcriptional networks involved in axonal guidance and neurotransmitter signaling.

Our results demonstrate a significant shift in microRNA expression patterns in the mPFC following a history of dependence. Owing to their global regulation of multiple downstream target transcripts, miRNAs may have a pivotal role in the reorganization of synaptic connections and long-term neuroadaptations in alcohol dependence. MicroRNA-mediated alterations of transcriptional networks may be involved in disrupted prefrontal control over alcohol drinking observed in alcoholic patients.

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