Supplementary Figure 9: Anxiety-like behavior, exploratory activity, and performance in the cued fear conditioned tests were similar in WT and Sphk2–/– mice.
(a-c) WT and SphK2-/- mice show similar responses in the marble-burying test and for exploratory behavior in a novel environment. (a) No genotype differences were found for the number of marbles buried (unpaired t-test: t(1,17) = 0.73; P = 0.48), as well as (b) for the distance traveled (unpaired t-test: t(1,17) = 0.19; P = 0.86) and (c) time spent thigmotaxic in a novel environment (unpaired t-test: t(1,17) = 1.73; P = 0.10). (d) WT and SphK2-/- mice were evaluated in the Light/Dark Box test to assess anxiety-like behavior. Both genotypes spent significantly more time in the dark compartment than the light compartment (paired Student's t test: WT: t(1,8) = 3.91; P < 0.01; SphK2-/-: t(1,8) = 5.69; P< 0.01), but did not differ between each other in the dark (unpaired t-test: t(1,16) = 1.43; P = 0.17) or light (unpaired Student's t test: t(1,16) = 1.43; P = 0.17) compartments. (e) WT and SphK2-/- mice displayed similar freezing behavior and extinction in tone-paired conditioning paradigm. WT and SphK2-/- mice had similar levels of freezing during the 3 min prior to tone-shock pairing (pre-shock), 60 s after tone-shock paring (post-shock), and during 200 s tone presentation without shock 24 h after conditioning (day 2) (two-way repeated measures ANOVA; interaction: F(2,34) = 2.03; P = 0.15; time: F(2,34) = 15.8; P < 0.0001; genotype: F(1,34) = 3.0; P = 0.10). *P < 0.001, vs. pre-shock (Bonferroni post hoc test). Both genotypes exhibited similar decreases in freezing across the six days of extinction training (two-way ANOVA; interaction: F(5,85) = 0.52; P = 0.76; genotype: F(1,85) = 1.52; P = 0.23; test day: F(5,85) = 13.8; P < 0.0001). P < 0.001 for days 6 and 7 as compared to day 2 (Bonferroni post hoc test). Tests in (a-d) were performed in the same cohort of mice. N = 9-10 mice/group. Data are expressed as mean ± s.e.m.
