Context-Induced Reinstatement of Methamphetamine Seeking Is Associated with Unique Molecular Alterations in Fos-Expressing Dorsolateral Striatum Neurons

Abstract

Context-induced reinstatement of drug seeking is a well established animal model for assessing the neural mechanisms underlying context-induced drug relapse, a major factor in human drug addiction. Neural activity in striatum has previously been shown to contribute to context-induced reinstatement of heroin, cocaine, and alcohol seeking, but not yet for methamphetamine seeking. In this study, we found that context-induced reinstatement of methamphetamine seeking increased expression of the neural activity marker Fos in dorsal but not ventral striatum. Reversible inactivation of neural activity in dorsolateral but not dorsomedial striatum using the GABA agonists muscimol and baclofen decreased context-induced reinstatement. Based on our previous findings that Fos-expressing neurons play a critical role in conditioned drug effects, we assessed whether context-induced reinstatement was associated with molecular alterations selectively induced within context-activated Fos-expressing neurons. We used fluorescence-activated cell sorting to isolate reinstatement-activated Fos-positive neurons from Fos-negative neurons in dorsal striatum and used quantitative PCR to assess gene expression within these two populations of neurons. Context-induced reinstatement was associated with increased expression of the immediate early genes Fos and FosB and the NMDA receptor subunit gene Grin2a in only Fos-positive neurons. RNAscope in situ hybridization confirmed that Grin2a, as well as Grin2b, expression were increased in only Fos-positive neurons from dorsolateral, but not dorsomedial, striatum. Our results demonstrate an important role of dorsolateral striatum in context-induced reinstatement of methamphetamine seeking and that this reinstatement is associated with unique gene alterations in Fos-expressing neurons.

Incubation of Methamphetamine Craving Is Associated with Selective Increases in Expression ofBdnfandTrkb, Glutamate Receptors, and Epigenetic Enzymes in Cue-Activated Fos-Expressing Dorsal Striatal Neurons

“…These results extend previous studies on the changes of these epigenetic enzymes in ventral striatum (accumbens) after cocaine exposure LaPlant et al, 2010;Maze et al, 2010;Robison and Nestler, 2011;Taniguchi et al, 2012;Rogge and Wood, 2013). The findings of a selective increase of Dnmt3a mRNA in Fos-positive DS neurons extend previous finding showing increased Dnmt3a mRNA in accumbens 28 d after chronic cocaine exposure (LaPlant et al, 2010).…”

“…The sessions began with the extension of the active lever and the illumination of the red house light, which remained on for the duration of the session. Active lever presses during testing (the operational measure of cue-induced drug seeking in incubation of craving studies (Lu et al, 2004a;Pickens et al, 2011) resulted in contingent presentations of the tone/light cue, previously paired with methamphetamine infusions, but not the drug.…”

“…The third class included genes encoding epigenetic enzymes involved in chromatin remodeling or DNA methylation (Kouzarides, 2007). These genes were chosen because of their roles in cocaine's physiological and behavioral effects (Robison and Nestler, 2011;Rogge and Wood, 2013;Schmidt et al, 2013;SadriVakili, 2014).…”

The Anterior Insular Cortex→Central Amygdala Glutamatergic Pathway Is Critical to Relapse after Contingency Management

“…We performed RNA in situ hybridization (ISH) for Fos , Drd1 , and Drd2 mRNAs as described previously (Caprioli et al, 2017; Li et al, 2015a; Rubio et al, 2015; Warren et al, 2016). Sixty min after the beginning of the test session, we briefly anesthetized the rats with isoflurane and decapitated them.…”

Genome-wide DNA hydroxymethylation identifies potassium channels in the nucleus accumbens as discriminators of methamphetamine addiction and abstinence

“…26,31 Rats were anesthetized with ketamine (50 mg kg , intraperitoneal) and inserted with silastic catheters into the jugular vein. The catheters were attached to a modified 22-gauge cannula that was mounted to the rats' skulls with dental cement.…”