Figure 4

From: Functional Status of the Serotonin 5-HT2C Receptor (5-HT2CR) Drives Interlocked Phenotypes that Precipitate Relapse-Like Behaviors in Cocaine Dependence

Figure 4

Genetic loss of 5-HT2CR in medial prefrontal cortex (mPFC) confers aggregate impulsive action/cue reactivity. (a) The shRNA expression plasmid targeting the 5-HT2CR efficiently silenced 5-HT2CR mRNA in a cell line transiently expressing 5-HT2CR (*p<0.05 vs LI). (b) The 5-HT2CR shRNA-eGFP AAV knocked down 5-HT2CR protein levels in the mPFC (50% decrease) relative to the NSC-eGFP AAV. (c) Stereotaxic placement and NSC-eGFP AAV infection (green) in mPFC (left). The NSC-eGFP AAV (green) did not alter 5-HT2CR protein expression (red) in infected neurons (yellow arrows) relative to non-AAV infected neurons (white arrows) (right). (d) Stereotaxic placement and 5-HT2CR shRNA-eGFP AAV infection (green) in mPFC (left). The 5-HT2CR shRNA-eGFP AAV (green) induced a significant knockdown of 5-HT2CR protein (red) in infected neurons (yellow arrows) relative to non-infected neurons (white arrows) (right). (e) Following intra-mPFC transgene delivery and stable viral vector expression, control and 5-HT2CR knockdown rats were subjected to the one-choice serial reaction time (1-CSRT) task. The 5-HT2CR knockdown rats expressed significantly higher premature responses vs control rats on the final 1-CSRT task training stage (0.5 s stimulus duration, 5 s limited hold and 5 s intertrial interval (ITI5)) (*p<0.05 vs NSC-eGFP AAV). Upon completion of 1-CSRT task assessments, control and 5-HT2CR knockdown rats were retained in their home cages and allowed to free-feed for 7 days before surgical implantation of a jugular catheter. Cocaine self-administration commenced 7 days post catheterization. (f) On forced abstinence (FA) day 14, 5-HT2CR knockdown rats exhibited higher cue-reinforced lever presses (*p<0.05 vs NSC-eGFP AAV), but not inactive, lever presses (n.s.), during a cue reactivity test session vs control rats. (g) There was a positive correlation between premature responses and cue-reinforced lever presses during the cue reactivity test session for individual subjects (r=0.577; p<0.01).