Double KO of Syt4 and Syt7 strongly reduces STD DA release. (a) Average [DA]o peaks (µM) obtained in the dorsal striatum, ventral striatum and VTA of Syt4 constitutive KO mice bred from heterozygous crosses. (b) Same for the constitutive Syt7 KO mice. (c) Same for double Syt4/Syt7 KO mice (Syt4−/−; Syt7−/−) and heterozygotes control animals (Syt4−/−; Syt7+/− and Syt7−/−; Syt4+/−). Each recording from the VTA was obtained in aCSF+5 μM nomifensine/sulpiride with two recording sites per slice, two slices per animal and pulse-train stimulation (30 pulses, 10 Hz, 400 µA). Each recording from the striatum was obtained in normal aCSF from six recording sites per slice, two slices per animal, for the dorsal striatum and four for the ventral striatum (nucleus accumbens core and shell), using single-pulse stimulation (1 ms, 400 µA). Error bars represent ± s.e.m. The statistical analysis was carried out by one-way ANOVA followed by a Tukey test (ns, non-significant; ***p < 0.001; #p < 0.0001). Numbers above bars represent the number of slices recorded (in bold) followed by number of animals used.