Fig. 4: Deletion of NCLX weakens synaptic release and the lowers the initial release probability.

a SypHy responses are weaker in NCLX-KO neurons. WT and NCLX-KO neurons expressing sypHy were stimulated at 20 Hz for 5 s in 2 mM Ca²⁺ saline. Shown are mean ± SEM sypHy traces. SypHy responses in the synapses of NCLX-KO neurons were lower. b Quantification of peak sypHy responses. Peak ∆F/F₀ fluorescence, as in (a) and sypHy responses in NCLX-KO neurons bathed in [Ca²⁺]_o = 4.5 mM shown in red, n = 19, 17 and 11, respectively, ~50 mitochondria each, p = 0.04 Kruskal-Wallis multiple comparison ANOVA (Chi-square = 6.42), post-hoc analysis using Mann–Whitney tests, **p = 0.01 (U = 243, Z = 2.57), ns p = 0.52 (U = 120, Z = 0.65), bars indicate medians and the error bars the 10–90 percentiles. c Progressive blockage of NMDARs by MK-801 used to assess P_r. The initial P_r of Schaffer collateral synapses onto CA1 neurons was assessed by bathing slices in magnesium-free saline containing MK-801, DNQX and bicuculline. Stimulation was delivered every 15 S and NMDAR-fEPSPs were recorded. Shown are representative traces recorded from a brain slice of a WT mouse in response to the 1st, 10th and 30th stimuli, illustrating the progressive blockage of NMDARs by MK-801. d The initial synaptic probability of release (Pr) is lower in NCLX-KO neurons. NMDAR response amplitudes as a function of stimulus number, illustrating the different rate of progressive blockage of NMDAR-fEPSPs in WT and NCLX-KO neurons. mean ± SEM, n = 9 and 6 recordings from 4 WT and 3 NCLX-KO mice, respectively. e Half-life of NMDAR response blockage in (d) (7.89 ± 0.92, 13.31 ± 1.74, mean ± SEM in terms of stimulus number), **p = 0.01, two-sided Student’s t test (t = −2.99, DF = 13).