RSDP impairs GABAB receptor-mediated inhibition of
spontaneous glutamate release in dissociated hippocampal neurons in
culture. A, the percentage of inhibition of the mEPSC frequency
by baclofen (100 μm) was assessed in individual neurons under
control condition (ACSF, n = 5) and after incubation with 4
nm (n = 5) or 40 nm (n = 7) RSDP for
the times indicated (for values, see supplemental Table S1). B, time
course of the RSDP effect on the baclofen-induced mEPSC frequency inhibition
in individual neurons (n = 5 per condition). C, summary
histograms illustrating that incubation with 40 nm RSDP for 1 h
impairs baclofen (bac)-but not adenosine (adeno)-mediated
mEPSC frequency inhibition. Values are means ± S.E. of the percentage
of inhibition of the mEPSC frequency (100 μm baclofen, ACSF,
88.6 ± 2.4% n = 5; RSDP, 15.7 ± 3.2%, n = 5,
***, p < 0.001, Kolmogorov-Smirnov; 100
μm adenosine, ACSF, 70.2 ± 4.0%, n = 5; RSDP,
78.6 ± 2.7%, n = 5). D, representative mEPSC
recordings under baseline conditions, during adenosine application, after
washing with ACSF (wash), during baclofen application, and after
antagonizing GABAB receptors with CGP54626. Recordings from one
cell each incubated with ACSF or RSDP are shown.