Tissue was fixed overnight in 4% PFA and cut into 30 μm sections on a SM2010R freezing microtome (Leica, Wetzler, Germany). Tissue beta-catenin inhibitor was blocked with 10% normal donkey serum and permeabilized with 0.1% Triton X-100. Primary antibody incubation was performed at 4°C for 24 hr, using rabbit anti-TH (1:200; Pel-Freeze, Rogers, AR, USA). Secondary antibody, goat anti-rabbit (1:500, Vector Labs, Burlingame, CA, USA) was incubated for 1 hr at room temperature. Images were taken on a 6D epifuorescent microscope (Nikon, Shinjuku, Tokyo, Japan) and quantified using ImageJ software. We thank R.

Taussig, T. Golde, C. Ceballos, Y. Chen, B. Sabatini, S. Finkbeiner, E. LaDow, E. Korb, L. Shoenfeld, N. Hammack, A. Kravitz, G. Hang, and other members of the Kreitzer Lab for helpful advice on experiments, comments on the manuscript, technical assistance, and reagents. We also thank N. Devidze and B. Masatsugu of the Gladstone Institutes’ Behavioral Core for help obtaining the

behavioral data. The Gladstone Institutes received support from a National Center for Research Resources grant (RR18928-01). This work was supported by the National Institutes Venetoclax cost of Health (R01 NS064984), the Pew Biomedical Scholars Program, the W.M. Keck Foundation, and the McKnight Foundation. “
“The neural mechanisms responsible for the pursuit of rewards in the environment are essential for the survival of the organism (Nesse and Berridge, 1997 and Schultz et al., 1997). Environmental stimuli that predict the

availability of reward develop incentive-motivational properties that energize the seeking of future rewards (Bindra, 1968). The NAc is a neural substrate that is critically involved in integrating interoceptive and environmental information with emotional information to initiate reward seeking (Kelley, 1999 and Mogenson et al., 1980). When reward seeking is maintained in a controlled experimental setting in which environmental stimuli predict reward availability, transient dopamine surges in the NAc begin to occur in response to the predictive stimuli (i.e., conditioned not cues) following the attribution of incentive salience (Berridge and Robinson, 1998 and Flagel et al., 2011). These transient increases in dopamine have been detected in the NAc when animals are presented with cues predicting various rewards—including drugs of abuse (Phillips et al., 2003), food (Roitman et al., 2004), and brain stimulation reward (Cheer et al., 2007a)—and are required to promote reward-directed behavior (Nicola, 2010). The brain endocannabinoid system, formed by metabotropic cannabinoid receptors (CB1 and CB2) and their endogenous ligands (e.g., anandamide and 2AG), is important for the regulation of dopamine signaling during reinforcement processing (Lupica and Riegel, 2005 and Solinas et al., 2008).