Fig. 4: Rats with punishment-resistant and punishment-sensitive phenotypes responded differently to chemogenetic activation of DRN 5-HT neurons in FR and punishment as well as lowering the dose of heroin during punishment.
From: Role of serotonin neurons in the dorsal raphe nucleus in heroin self-administration and punishment
A In FR self-administration, activating DRN 5-HT neurons increased heroin intake in punishment-resistant rats only. A1 Number of heroin infusions during FR sessions in saline- vs. CNO-treated animals in punishment-resistant and punishment-sensitive phenotypes. Asterisks indicate a significant difference between saline vs CNO in punishment-sensitive phenotype (***p ≤ 0.001, Fisher’s PLSD). A2 Suppression ratio on the punishment day 3 correlated with the magnitude of change caused by activation of DRN 5-HT neurons in FR. B Suppression ratio on the punishment day 3 correlated with a number of heroin infusions in PR. C Activation of the DRN 5-HT neurons increased heroin intake in punishment-resistant but not punishment-sensitive rats in punishment. Number of heroin infusions in punishment sessions in saline- vs. CNO-treated animals in punishment-resistant and punishment-sensitive phenotypes. Asterisks indicate a significant difference between saline vs CNO in punishment-resistant phenotype (** p ≤ 0.01, Fisher’s PLSD). D Lowering the dose of heroin produced divergent effects in punishment-resistant and punishment-sensitive rats, increasing the suppression ratio in punishment-resistant rats but decreasing the suppression ratio in punishment-sensitive rats (*p ≤ 0.05, Fisher’s PLSD).
