Fig. 3
From: Regulation of density of functional presynaptic terminals by local energy supply
Presynaptic Ca2+ sensitivity determines functional terminal density to bursts. (a and b) At low (Ctrl 0.8) and high [Mg2+]o (1.2 4hr) conditions, colocalization of SYP, VGLUT1, VGAT and Bassoon positive fluorescent puncta with FM1-43 labeled releasable terminals to “maximal stimulation” (600 APs at 10 Hz) at the same dendrite (a). No significant changes were observed (n = 6 coverslips for each bar, p = 0.38-0.84) (b). Dotted line represents the total number of SYP(+) puncta of Ctrl 0.8. (c and d) Colocalization of FM(+) terminals following 5AP- and 600AP-stimulation at the same branches (c). 51.3 ± 9.8 % (n = 12 coverslips, totally 7542 5AP-induced puncta and 14701 600AP-induced puncta were analyzed) and 90.6 ± 2.9 % (n = 16 coverslips, totally 16926 5AP-induced puncta and 18601 600AP-induced puncta were analyzed) terminals were functional in response to 5AP bursts (d) at low and high [Mg2+]o conditions. (e and f) Acute change of [Ca2+]o/[Mg2+]o ratio led to the change of detectable functional terminals (e). Statistics of N 5AP at different [Ca2+]o/[Mg2+]o ratio (f) (n = 5–11 coverslips). Pseudo-color scale: fluorescent intensity. Two-tailed Student’s t-test comparing 5AP to 600AP as indicated (d), or comparing 1.2 4hr to Ctrl 0.8 at each [Ca2+]o/[Mg2+]o (f), ** p < 0.01, *** p < 0.001. For each bar or point in (b, d and f), the mean ± SEM of coverslips was presented