Figure 6.

Endogenous ACh enhances GABA release from A17 cells and increases inhibition in RB cells. (A,B) Traces show the effect of the AChE inhibitor neostigmine (Neo, 2 μM) on responses to ACh (1 mM, 1 s) in (A) A17 cells and (B) RB cells. (C) Bar plot summing up the effects of neostigmine or phenserine (Phen, 5 μM) application on the electrical charge transferred after ACh stimulation. (D) In A17 cells, perfusion of neostigmine (2 μM) produced a long lasting depolarization that could be reverted by blocking nAChRs with TMPH (10 μM). Horizontal bars below traces show duration of both treatments. (E) Summary of the changes in resting membrane potential induced by an initial perfusion of Neo and subsequent addition of TMPH. (F) In a different subset of A17 cells, the holding current (V_hold = −60 mV) was measured in control conditions, after adding AChE inhibitors Neo or Phen, and after TMPH application. Thin lines denote individual cells and thick lines display average values. Gray lines correspond to experiments with Phen, black lines show experiments using Neo. (G) representative traces showing the increase in the frequency of spontaneous IPSCs after neostigmine perfusion in RB cells. (H) Bar plot summarizing the enhancement in IPSC frequency by Neo. (I) Summary plot showing the marked increase in frequency of IPSCs after perfusion of nicotine (25 μM) in the presence of TTX (1 μM). ^*p < 0.05, ^**p < 0.01, and ^***p < 0.001. Two-tailed paired t-tests were used, except in panels E, F (Phenserine) where repeated measures ANOVA followed by Bonferroni-corrected pairwise comparison was used.