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

Abstract

Cue-induced methamphetamine seeking progressively increases after withdrawal (incubation of methamphetamine craving), but the underlying mechanisms are largely unknown. We determined whether this incubation is associated with alterations in candidate genes in dorsal striatum (DS), a brain area implicated in cue-and context-induced drug relapse. We first measured mRNA expression of 24 candidate genes in whole DS extracts after short (2 d) or prolonged (1 month) withdrawal in rats following extended-access methamphetamine or saline (control condition) self-administration (9 h/d, 10 d). We found minimal changes. Next, using fluorescence-activated cell sorting, we compared gene expression in Fos-positive dorsal striatal neurons, which were activated during "incubated" cue-induced drug-seeking tests after prolonged withdrawal, with nonactivated Fos-negative neurons. We found significant increases in mRNA expression of immediate early genes (Arc, Egr1), Bdnf and its receptor (Trkb), glutamate receptor subunits (Gria1, Gria3, Grm1), and epigenetic enzymes (Hdac3, Hdac4, Hdac5, GLP, Dnmt3a, Kdm1a) in the Fos-positive neurons only. Using RNAscope to determine striatal subregion and cell-type specificity of the activated neurons, we measured colabeling of Fos with Drd1 and Drd2 in three DS subregions. Fos expression was neither subregion nor cell-type specific (52.5 and 39.2% of Fos expression colabeled with Drd1 and Drd2, respectively). Finally, we found that DS injections of SCH23390 (C 17 H 18 ClNO), a D 1 -family receptor antagonist known to block cue-induced Fos induction, decreased incubated cue-induced methamphetamine seeking after prolonged withdrawal. Results demonstrate a critical role of DS in incubation of methamphetamine craving and that this incubation is associated with selective gene-expression alterations in cue-activated D 1 -and D 2 -expressing DS neurons.

BAZ1B in Nucleus Accumbens Regulates Reward-Related Behaviors in Response to Distinct Emotional Stimuli

“…There was a strong positive correlation between BAZ1B and SMARCA5 binding (r ϭ 0.873), suggesting that BAZ1B is at least partly working with SMARCA5 to exert its regulation. Agreeing with the previously reported transcriptionally activating role of BAZ1B in other systems (Vintermist et al, 2011;Culver-Cochran and Chadwick, 2013;Lundqvist et al, 2013;Sarshad et al, 2013;Takada, 2015), we found positive correlations between BAZ1B binding and three activating histone marks, H3K4me3 (r ϭ 0.117), H3K4me1 (r ϭ 0.279), and H3K27Ac (r ϭ 0.332), and a negative correlation between BAZ1B and two repressive marks, H3K9me2 (r ϭ Ϫ0.165) and H3K9me3 (r ϭ Ϫ0.101). Surprisingly, BAZ1B had a significant positive correlation with the repressive mark H3K27me3 (r ϭ 0.168).…”

“…The related ISWI subunit, BAZ1B (also known as WSTF, or Williams Syndrome Transcription Factor), was first discovered by mapping the deletion region of patients with the developmen-tal disorder Williams-Beuren syndrome (Lu et al, 1998;Peoples et al, 1998). The BAZ family of proteins contain a BAZ type of bromodomain (Jones et al, 2000) and BAZ1B in particular is implicated in several chromatin remodeling/transcriptional complexes (including associating with the ISWI subunit, SMARCA5) with diverse roles in regulating DNA replication, DNA repair, and transcription (Bozhenok et al, 2002;Poot et al, 2004;Cavellán et al, 2006;Percipalle et al, 2006;Xiao et al, 2009;Vintermist et al, 2011;Culver-Cochran and Chadwick, 2013;Lundqvist et al, 2013;Sarshad et al, 2013;Takada, 2015).…”

Role of Dorsomedial Striatum Neuronal Ensembles in Incubation of Methamphetamine Craving after Voluntary Abstinence

“…We implanted bilateral guide cannulae (23 gauge; Plastics One) 1 mm above the DMS. The Paxinos and Watson (2008) coordinates (nose bar set at Ϫ3.3 mm) for DMS were as follows: distance from bregma: anteroposterior, ϩ1.2 mm; mediolateral, Ϯ2.4 mm (8°angle); and dorsoventral, Ϫ4.3 mm Li et al, 2015c). We anchored the cannulas to the skull with jeweler's screws and dental cement.…”

“…We performed RNA ISH for Fos, Drd1, and Drd2 mRNAs as described previously (Li et al, 2015c;Rubio et al, 2015;. Sixty minutes after the beginning of the test session, we briefly anesthetized the rats with isoflurane (Ͻ30 s) and decapitated them.…”

“…Studies using animal models of relapse/reinstatement demonstrated a role of these two striatal subregions in relapse to heroin , cocaine (Fuchs et al, 2006;Pacchioni et al, 2011), alcohol (Wang et al, 2010), and methamphetamine (Rubio et al, 2015) seeking. Additionally, we recently found that incubation of methamphetamine craving after forced abstinence is associated with increased expression of the activity marker Fos (Morgan and Curran, 1991) in both DLS and DMS, and that blockade of D 1 family receptors in these subregions decrease "incubated" drug seeking after 30 d of forced abstinence (Li et al, 2015c).…”