Fig. 5: Knockdown of CRTC1 in the NAcsh decreases cocaine reinforcement and motivation and blocks the enhancing effects of AMPK inhibition.

A Timeline of the experiment. Four weeks after the injection of AAV-Scramble or AAV-shCRTC1 in the NAcsh, the rats were trained to self-administer intravenous injections of cocaine under an FR1 schedule in daily 3 h sessions. The response requirement was gradually increased to FR5, and training continued until cocaine intake stabilized. Following acquisition and stabilization, the rats received intra-NAcsh infusions of vehicle or the AMPK inhibitor compound C. The rats then underwent a between-session dose-response test and progressive-ratio test. Infusions (B), active nosepokes (C), and inactive nosepokes (D) during daily 3 h self-administration sessions. E The knockdown of CRTC1 shifted dose-response curves downward, which was rescued by compound C treatment (n = 8–12/group). F The knockdown of CRTC1 decreased breakpoints during the progressive ratio test, which was prevented by compound C treatment (n = 8–12/group). G A hypothesized working model of AMPK-CRTC1 signaling in the NAcsh in modulating cocaine reinforcement behaviors. In basal level, phosphorylated CRTC-1 was maintained by high level of AMPK and is sequestered in the cytoplasm. After repeated cocaine self-administration (SA) training, AMPK activity was decreased, promoting the dephosphorylation of CRTC-1. Dephosphorylated CRTC-1 translocates to the nucleus to promote CREB-dependent gene transcription, ultimately contributing to the cocaine reinforcement behaviors. The data are expressed as mean ± SEM. Post hoc analyses were performed using the Tukey test. *p < 0.05, compared with Scramble + vehicle group; ^#p < 0.05, compared with shCRTC1 + comp C group.