Figure 4. Silexan does neither share the binding site of pregabalin, nor inhibits VOCCs via G_i-coupled receptors.

(A) Displacement studies conducted with [³H]-gabapentin in partially purified synaptic membranes. Synaptic membranes were incubated with [³H]-gabapentin in presence of pregabalin (A, 0.001–100 µM) or Silexan (B, 0.1–100 µM; n = 3). (C) Primary hippocampal neurons were incubated in the presence or absence of PTX (200 ng/ml) for 18 h. Afterwards cells were treated with Silexan (1 µg/ml) or AEA (1 µM) for 10 min and then stimulated with KCl (60 mM; n = 11–12). (D) Additive inhibitory effects of P/Q-type and N-type channel blockers on KCl-induced Ca²⁺-influx in murine synaptosomes. Synaptosomes were preincubated with ω-agatoxin IVA (100 nM), ω-conotoxin GVIA (30 nM) or a combination of both inhibitors for 10 min. Afterwards, they were stimulated with KCl (80 mM). Silexan (1 µg/ml) causes no significant additive effects when combined with the N-type VOCCs inhibitor ω-conotoxin GVIA (30 nM, E), or the P/Q-type inhibitor ω-agatoxin IVA (100 nM, F; n = 9–12). All data presented are mean values ± SEM (paired t-test).