Fig. 3.

Reduced dense-core vesicle secretion in Vti1a/b-deficient neurons. a Representative examples of single DIV-14 neurons expressing NPY-pHluorin, before, during HFS (16 trans, 50APs at 50 Hz) and after NH₄⁺ superfusion. Scale bar = 5 µm. Images show maximum projections of time-lapse recordings. b DCV fusion is reduced in DKO neurons (DHZ: 123.6 ± 26.4; DKO: 18.9 ± 4.5; DKO + Vti1a: 108.5 ± 20.7; DKO + Vti1b: 119.8 ± 22.1 fusion events/neuron; Kruskal–Wallis). c Reduced DCV pool, calculated upon NH₄⁺ superfusion, in DKO neurons (DHZ: 3259.9 ± 395.8; DKO: 1865.0 ± 182.3; DKO + Vti1a: 2997.6 ± 314.7; DKO + Vti1b: 2697.0 ± 294.4 DCVs/neuron; Kruskal–Wallis). d Decreased DCV fusion probability in DKO neurons (DHZ: 3.29 ± 0.51; DKO: 0.96 ± 0.17; DKO + Vti1a: 3.60 ± 0.43; DKO + Vti1b: 4.59 ± 0.67%; Kruskal–Wallis). e, f Histogram and cumulative plots of the total (top) and fraction (bottom) of DCV fusion events per stimulation train (gray bars). Bars show mean ± SEM. Bullets and columns represent individual observations and independent litters, respectively. Gray bars represent 16 × 50 AP at 50 Hz stimulation. N = 25, 29, 28, 27 for DHZ, DKO, DKO + Vti1a and DKO + Vti1b, respectively. *p < 0.05, ***p < 0.001