Research Paper Volume 11, Issue 14 pp 5008—5034

Ginsenoside Rb1 regulates prefrontal cortical GABAergic transmission in MPTP-treated mice

Figure 7. Rb1 modulates GABAB receptor in the PFC of MPTP-treated mice. (A) Overall map of Rb1 interaction with GABABR1 receptor. (B) Interaction between Rb1 with the extracellular domain of 4MS1, agonist conformation of GABABR1 receptor. Note that when Rb1 (indicted by green stick) was docked in the extracellular domain of 4MS1, four hydrogen bonds formed with the amino group of main chain and hydroxyl group of side chain of Ser130 sites, the amino group of main chain of Ser131 site, and the side chain of Asp104 site (indicated by red dotted line). Besides, Rb1 also formed a hydrophobic interaction with multiple hydrophobic amino acids or hydrophobic parts of polar amino acids in the extracellular domain of 4MS1 (Cys103, Cys129, Trp65, His170, Ser153, Tyr250, Val201) (indicated by blue stick). (C and D) The effect of Rb1 on the GABAB receptor expression in the synaptosome and PSD fraction of the PFC of MPTP-treated mice was determined by western blotting. Western blotting results are from two of the six mice in each group and are expressed as the mean ± SEM of three experiments. (E) Representative traces of GABA receptor-mediated mIPSCs in the presence of Rb1 and GABAB-receptor agonist Baclofen. All mIPSCs were recorded at a holding potential of −65 mV. (F) Cumulative frequency plots of the inter-event interval (left) and quantitative analysis of the frequency of GABA receptor-mediated mIPSCs (right) in the presence of Rb1 and presence of Baclofen. (G) Cumulative frequency plots (left) and quantitative analysis (right) of the amplitude of GABA receptor-mediated mIPSCs in the presence of Rb1 and presence of Baclofen. n = 14–20 per group. **P < 0.01 and *P < 0.05 vs. control; ##P < 0.01 and #P < 0.05 vs. MPTP group; &P < 0.05 vs. MPTP+Rb1 group. Statistical significance was determined by one-way ANOVA and the Bonferroni post-hoc test for pairwise comparisons.