Involvement of nucleus accumbens dopamine D1 receptors in ethanol drinking, ethanol-induced conditioned place preference, and ethanol-induced psychomotor sensitization in mice

Abstract

Rationale Dopamine D1 receptor (D1R) signaling has been associated to ethanol consumption and reward in laboratory animals. Objectives Here, we hypothesize that this receptor, which is located within the nucleus accumbens (NAc) neurons, modulates alcohol reward mechanisms. Methods To test this hypothesis, we measured alcohol consumption and ethanol-induced psychomotor sensitization and conditioned place preference (CPP) in mice that received bilateral microinjections of small interference RNA (siRNA)-expressing lentiviral vectors (LV-siD1R) producing D1R knock-down. The other group received control (LV-Mock) viral vectors into the NAc. Results There were no differences in the total fluid consumed and also no differences in the amount of ethanol consumed between groups prior to surgery. However, after surgery, the LV-siD1R group consumed less ethanol than the control group. This difference was not associated to taste neophobia. In addition, results have shown that downregulation of endogenous D1R using viral-mediated siRNA in the NAc significantly decreased ethanol-induced behavioral sensitization as well as acquisition, but not expression, of ethanol-induced place preference.Conclusions We conclude that decreased D1R expression into the NAc led to reduced ethanol rewarding properties, thereby leading to lower voluntary ethanol consumption. Together, these findings demonstrate that the D1 receptor pathway within the NAc controls ethanol reward and intake.

Lentiviral Delivery of a Vesicular Glutamate Transporter 1 (VGLUT1)-Targeting Short Hairpin RNA Vector Into the Mouse Hippocampus Impairs Cognition

“…Finally, VGLUT1 expression was quantified and glutamatergic signaling examined (by microdialysis and microsensoring) at timepoints corresponding to the key cognitive alterations. The timing of behavioral and neurochemical evaluations was similar to previous studies employing lentiviral shRNA delivery (Bahi and Dreyer, 2012a) and commenced 7 days after intrahippocampal administration, as stable shRNA expression (Kim et al, 2012) and target mRNA (Bahi and Dreyer, 2012b) and protein (Nielsen et al, 2009) knockdown have been reported at this timepoint and importantly appear to be sustained beyond the 30-day duration of the current study.…”

Impairment of acquisition of intravenous cocaine self-administration by RNA-interference of dopamine D1-receptors in the nucleus accumbens shell

“…The construction of Drd1a-siRNA expressing lentiviruses has been described previously in detail (Bahi and Dreyer, 2012;Ortiz et al, 2010). In brief, three 19-nucleotide Drd1a-siRNA sequences were added to the U6 promoter by PCR.…”

“…Vectors were resuspended in PBS-BSA and stored at À80 C until use (Bahi, 2013;Bahi and Dreyer, 2013). The three distinct Drd1a-siRNA sequences were successfully used to knock-down the expression Drd1a mRNA in the NAc (Bahi and Dreyer, 2012) and proteins in the hippocampus (Ortiz et al, 2010).…”

“…RNAi is triggered in eukaryotic cells by double-stranded RNAs having 19e21 nucleotides (short interfering RNA, siRNA; Fire et al, 1998), which, when recognized as aberrant, induce a polyenzymatic process leading to degradation of homologous mRNAs (Hannon, 2002). For in vivo application, viral mediated expression of siRNAs, which takes place a few days after transduction (Bahi and Dreyer, 2012;Ortiz et al, 2010), allows stable long term RNAi, thus silencing the expression of the relative genes (Bahi et al, 2004(Bahi et al, , 2005Bahi and Dreyer, 2012;Ortiz et al, 2010;Scherr et al, 2003;Van den Haute et al, 2003). Viral mediated silencing of targeted proteins offers higher temporal (RNAi starts right after transduction of targeted cells) and spatial control (inoculation of defined volumes and concentrations of viral vectors restricts silencing to targeted areas) of manipulations, compared to conventional knockout or pharmacological strategies.…”

Chronic psychosocial stress causes delayed extinction and exacerbates reinstatement of ethanol-induced conditioned place preference in mice

“…The CPP apparatus used in the current study has been previously described (Bahi 2012(Bahi , 2013aBahi and Dreyer 2012b;Bahi et al 2013b). In brief, it consists of two equalsized compartments (30×30×30 cm) with a sliding guillotine door in the center of the base.…”