A heritable phenotype resulting from the self-administration of cocaine in rats was delineated. We observed delayed acquisition and reduced maintenance of cocaine self-administration in male, but not female, offspring of sires that self-administered cocaine. Brain-derived neurotrophic factor (BDNF) mRNA and protein were increased in the medial prefrontal cortex (mPFC) and there was an increased association of acetylated histone H3 with BDNF promoters only in the male offspring of cocaine-experienced sires. Administration of a BDNF receptor antagonist (the TrkB receptor antagonist ANA-12) reversed the diminished cocaine self-administration in male cocaine-sired rats. In addition, the association of acetylated histone H3 with BDNF promoters was increased in the sperm of sires that self-administered cocaine. Collectively, these findings indicate that voluntary paternal ingestion of cocaine results in epigenetic reprograming of the germline resulting in profound effects on mPFC gene expression and resistance to cocaine reinforcement in male offspring.

Accumbal deep brain stimulation (DBS) is a promising therapeutic modality for the treatment of addiction. Here, we demonstrate that DBS in the nucleus accumbens shell, but not the core, attenuates cocaine priming-induced reinstatement of drug seeking, an animal model of relapse, in male Sprague Dawley rats. Next, we compared DBS of the shell with pharmacological inactivation. Results indicated that inactivation using reagents that influenced (lidocaine) or spared (GABA receptor agonists) fibers of passage blocked cocaine reinstatement when administered into the core but not the shell. It seems unlikely, therefore, that intrashell DBS influences cocaine reinstatement by inactivating this nucleus or the fibers coursing through it. To examine potential circuit-wide changes, c-Fos immunohistochemistry was used to examine neuronal activation following DBS of the nucleus accumbens shell. Intrashell DBS increased c-Fos induction at the site of stimulation as well as in the infralimbic cortex, but had no effect on the dorsal striatum, prelimbic cortex, or ventral pallidum. Recent evidence indicates that accumbens DBS antidromically stimulates axon terminals, which ultimately activates GABAergic interneurons in cortical areas that send afferents to the shell. To test this hypothesis, GABA receptor agonists (baclofen/ muscimol) were microinjected into the anterior cingulate, and prelimbic or infralimbic cortices before cocaine reinstatement. Pharmacological inactivation of all three medial prefrontal cortical subregions attenuated the reinstatement of cocaine seeking. These results are consistent with DBS of the accumbens shell attenuating cocaine reinstatement via local activation and/or activation of GABAergic interneurons in the medial prefrontal cortex via antidromic stimulation of cortico-accumbal afferents.

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Introduction-Neuregulin-1 (NRG1) is one of susceptibility genes for schizophrenia and plays critical roles in glutamatergic, dopaminergic and GABAergic signaling. Using mutant mice heterozygous for Nrg1 (Nrg1 +/− ) we studied the effects of Nrg1 signaling on behavioral and electrophysiological measures relevant to schizophrenia.Experimental Procedure-Behavior of Nrg1 +/− mice and their wild type littermates was evaluated using pre-pulse inhibition, contextual fear conditioning, novel object recognition, locomotor, and social choice paradigms. Event-related potentials (ERPs) were recorded to assess auditory gating and novel stimulus detection.Results-Gating of ERPs was unaffected in Nrg1 +/− mice, but mismatch negativity in response to novel stimuli was attenuated. The Nrg1 +/− mice exhibited behavioral deficits in contextual fear conditioning and social interactions, while locomotor activity, pre-pulse inhibition and novel object recognition were not impaired.Summary-Nrg1 +/− mice had impairments in a subset of behavioral and electrophysiological tasks relevant to the negative/cognitive symptom domains of schizophrenia that are thought to be influenced by glutamatergic and dopaminergic neurotransmission. These mice are a valuable tool for studying endophenotypes of schizophrenia, but highlight that single genes can not account for the complex pathophysiology of the disorder.