Figure 7.

CAPS2 indirectly regulates synaptic transmission. Synaptic transmission measured in WT DRG/SC neurons co-cultures pre-incubated or not (control) with 10 nM olcegepant, 10 μM L-703,606 oxalate salt hydrate, and 10 μM cyclotraxin B, inhibiting the receptors for calcitonin gene-related peptide (CGRP) calcitonin receptor-like receptor (CLR), Substance P (SP; NK-1R), and BDNF tropomyosin receptor kinase B (TRKB), respectively. Two co-cultures were generated using two adult mice for DRG neurons and 12 P0 mice for SC neurons, N_{DRG neurons} = 29 and 50, n_synapses = 241 and 101 for control and treated neurons, respectively. Error bars are SEM, and Mann-Whitney test was applied, ns = non-significant, *p < 0.5, **p < 0.01 and ***p < 0.001. (A) The recording protocol is shown on the left. The images correspond to an overlay of the SypHy MIP over time in DRG/SC neurons acquired prior to (white) and during superfusion with NH₄Cl (red) in control (left) and inhibition (right) conditions. White vs. red images indicate active vs. SypHy-labeled synapses, respectively. Yellow and white arrows indicate synchronized and uncoupled synapses, respectively. The associated numbers correspond to the time (s) between the stimulus and the response. (B) Average number of active synapses in neurons pretreated with peptide antagonist (gray) or not (black). (C) Average SypHy fluorescence increase in response to electrical stimulation normalized to SypHy fluorescence upon NH₄Cl application in control and treated neurons. (D) Density dot plot illustrating the time point of activity and the percentage of synapses that were either synchronized to the stimulus or that responded before or after the stimulus. The time point of response of each unsynchronized synapse is indicated by individual symbols whereas all synchronized synapses are indicated by one orange circle. Orange dashes are the average time point of unsynchronized response ± SEM.