In particular, Gs versus Gi/o activation by DREADDs during training produced opposite effects on retention of a decision-making strategy over time, but had no effect on responding during acquisition of the task nor on task performance following acquisition [13•]. Cell-type specific Gi/o-coupled DREADDs have also been used to examine the role of glutamatergic neurons in the basolateral nucleus of the amygdala NVP-BGJ398 ic50 (BLA) in the development of locomotor sensitization to cocaine. It was found that increasing Gi/o signaling in the BLA during repeated cocaine treatment attenuated the development of

locomotor sensitization without altering basal levels of locomotion [14•]. This manipulation was also sufficient to block cocaine-induced increases in the frequency of miniature excitatory post-synaptic currents (mEPSCs) in dopamine D1 MSNs in the nucleus accumbens shell, suggesting that BLA regulation of MSN plasticity is probably an important mechanism regulating sensitization [14•]. In addition to behavioral sensitization, DREADDS have been used successfully in drug self-administration models to examine the circuitry underlying drug-taking behaviors, including motivation to take Trametinib mouse drugs under a progressive ratio schedule of reinforcement. Interestingly, using targeted injections of a conditional hM4Di viral vector into adora2a-Cre

mice, Bock et al. [15••] found that increasing Gi/o signaling in indirect pathway MSNs in the nucleus accumbens core had no effect on responding for cocaine when it was available under low effort conditions (fixed ratio 1; FR1) but enhanced motivation for cocaine as

evidenced Branched chain aminotransferase by higher breakpoints in progressive ratio schedules. This effect was region-specific, as the same manipulation in the dorsal striatum had no impact on motivation for cocaine. In addition, these results cannot be attributed to non-discriminative effects on motivation, as increasing Gi/o signaling in indirect pathway MSNs in nucleus accumbens core had no effect on breakpoints for food reward [15••]. Thus, together with the sensitization findings, this series of DREADD experiments demonstrates that the plasticity that occurs in indirect pathway MSNs following drug use likely regulates the processes that govern the transition to addiction. Although most work with DREADDs has centered on understanding behaviors produced by psychostimulant drugs, DREADDs have also been utilized as an effective tool for studying addiction processes in other drug classes. For example, although increasing Gq signaling throughout the nucleus accumbens had no effect on ethanol consumption in a limited access paradigm, increasing Gi/o signaling in the same region reduced ethanol consumption without altering either water or sucrose intake or effecting basal levels of locomotor activity [16].