Characterization of prefrontal cortex neuronal ensembles in cue-induced heroin seeking using FACS and neural inactivation

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NIDA	NEURO/BEHAV/SENSYS-11

* FARE Award Winner

Authors

• S Fanous
• D Guez-Barber
• E Goldart
• R Schrama
• F Theberge
• J Bossert
• Y Shaham
• B Hope

Abstract

Cue-induced heroin seeking persists long after heroin withdrawal and is associated with sparse activation of medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) neurons. To identify gene expression alterations within these selectively activated neurons, we trained rats to self-administer heroin. Two or four weeks after training, test rats underwent extinction tests while control rats remained in their home cages. Ninety minutes after testing, pooled mPFC and OFC neurons were dissociated and double-immunolabeled for the neuronal marker NeuN and the neural activity marker Fos. We used fluorescent-activated cell-sorting (FACS) to separate Fos-positive and Fos-negative neurons from extinction test rats while all neurons were collected from control rats due to low Fos expression. Extinction tests increased mRNAs of immediate early genes fosB, arc, egr1, and egr2, as well as npy and map2k6 in Fos-positive, but not Fos-negative, neurons. Thus unique gene expression alterations are induced in neurons activated during heroin seeking. Current experiments assess whether activated neurons mediate heroin seeking. Here, we implanted rats with cannulae aimed at mPFC or OFC and trained them to self-administer heroin. Two weeks after training, GABA agonists muscimol+baclofen or vehicle were injected immediately prior to 90-min extinction tests. Results from OFC and mPFC inactivation are pending.

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