Figure 5.

α1-ARs-mediated effect on GABA_A IPSCs amplitude is not affected in VTA DA neurons after one saline or cocaine injection. (A) A bar graph showing the total locomotor activity recorded from saline- (0.9%, white bar; n = 7) and cocaine- (15 mg/kg i.p., black bar; n = 7) treated animals. The locomotion of cocaine treated animals was significantly increased compared to saline-treated controls (Unpaired t-test, p < 0.0001). (B,C) Representative recordings from saline- and cocaine-treated animals, respectively, show that phenylephrine superfusion (10 μM, 10 min) induces a significant decrease in GABA_A IPSCs amplitude in VTA DA neurons from both groups. (D) The time course summary of phenylephrine effects on GABA IPSCs recorded from VTA DA neurons from saline- (n = 13) and cocaine- (n = 12) treated animals at 8 min of control (2 min intervals), 5 and 10 min phenylephrine (10 μM), and 5 and 10 min washout. A 10 min phenylephrine application decreases the GABA_A IPSCs amplitude in neurons from saline- and cocaine-treated animals (One-way ANOVA, Newman-Keuls post hoc test, p < 0.0001). (E) A bar graph showing that phenylephrine application results in a ~30% decrease in GABA_A IPSCs amplitude in VTA DA neurons from saline- (n = 13/7) and cocaine- (n = 12/7) treated animals (One-way ANOVA, Newman-Keuls post-hoc, p < 0.0001). **** p < 0.0001. n = the number of cells recorded/number of animals.