Figure 9. Synthetic L-MEN1 rescues deficits in synapse formation induced by L-EGFR knockdown in situ.

(a) Intact VD4 and LPeD1 neurons were simultaneously impaled with intracellular electrodes to confirm whether or not a synapse was present. Trains of action potentials triggered in VD4 induced a corresponding excitatory response in LPeD1 (n = 7). (ai) Control, LPeD1 transplants re-formed excitatory, cholinergic synapses with intact, host VD4 neurons (n = 17). (aii) LPeD1 neurons pre-treated with L-AChBP dsRNA (negative control; 200 ng/ml) prior to transplantation established excitatory synapses with host VD4 neurons (n = 9). (aiii) Incubation of LPeD1 neurons with L-EGFR dsRNA (200 ng/ml) prior to transplantation prevented excitatory synapse formation with host VD4 neurons (n = 17). (b) Whole CRG were pre-treated with L-EGFR dsRNA prior to isolation of the LPeD1 transplants. 4–6 hours later, LPeD1 was injected with L-MEN1 mRNA. 2–3 hours following injection, the LPeD1 neurons were isolated and transplanted into host CRG, where they re-formed excitatory synapses with VD4 (n = 13). (c–d) Summary of the percentage of pairs that formed an excitatory synapse with a significance of P<0.01, as determined using Pearson's Chi-squared test. (e) Summary of mean EPSP amplitude (mV) with a significance of P<0.05, as determined using a univariate ANOVA with Tukey's post hoc test. Error bars represent standard error of the mean (SEM).