Figure 3
GABAB receptors inhibit both L-type VDCC and pacemaker activity in DRN serotonergic neurons. (a,b) Representative traces (a) and peak current density (b) of high voltage activated (HVA) VDCC current in serotonergic neurons. The recordings were performed in the presence of DNQX (20 μM), APV (50 μM), bicuculline (20 μM), and tetrodotoxin (1 μM). HVA VDCC current was evoked by voltage step from −110 mV to −10 mV. CGP52432 (CGP; 10 μM) was bath-applied. KT5720 (KT; 1 μM) and D890 (0.5 mM) were applied through a patch pipette. *P < 0.05, **P < 0.01. (Control, n = 5 neurons from 2 mice; CGP, n = 8 neurons from 4 mice; CGP + KT, n = 8 neurons from 2 mice; CGP + D890, n = 7 neurons from 2 mice; one-way ANOVA; F(3, 24) = 6.767, P = 0.018; Tukey’s Multiple Comparison Test; Control vs. CGP, P < 0.05, CGP vs. CGP + KT, P < 0.05, CGP vs. CGP + D890, P < 0.01). (c,d) Representative traces (c) and average spontaneous firing rate (d) in serotonergic neurons. Recordings were performed in the presence of DNQX (20 μM), APV (50 μM), bicuculline (20 μM), WAY100635 (0.1 μM), and GR127935 (1 μM) to minimize the effects of presynaptic GABAB receptor inhibition. CGP52432 (CGP; 10 μM) was bath-applied. KT5720 (KT; 1 μM) and D890 (0.5 mM) were applied through a recording pipette. *P < 0.05, **P < 0.01. (Control, n = 8 neurons from 4 mice; CGP, n = 11 neurons from 2 mice; CGP + KT, n = 10 neurons from 2 mice; CGP + D890, n = 12 neurons from 2 mice; one-way ANOVA; F(3, 37) = 5.112, P = 0.0046; Tukey’s Multiple Comparison Test; Control vs. CGP, P < 0.05, CGP vs. CGP + KT, P < 0.05, CGP vs. CGP + D890, P < 0.01). Each representative trace shows the data from different cell. Data are presented as the mean ± S.E.M.
