Fig. 3

Differential phenotypes of netrin-G1 KO and netrin-G2 KO mice in the emotional domain. a and b Open field test: a Distance traveled by netrin-G1 KO and netrin-G2 KO mice was equivalent to that of WT mice (netrin-G1 KO, 3 mo-old; netrin-G2 KO, 3 mo-old; two-way mixed ANOVA for genotype, ns for interaction). b Place preference to the center over the periphery was not affected in netrin-G1 KO mice, while netrin-G2 KO mice spent more time in the center area (Student’s t-test). c Elevated plus maze test: WT mice preferred to stay in the closed arms. Netrin-G1 KO mice showed no arm preference and remained in the center area for a shorter time (6–7 mo-old, 2-way ANOVA for genotype and place, significant interaction; post hoc t-test, * P < 0.05, *** P < 0.001, **** P < 0.0001; ns, not significant). Netrin-G2 KO mice spent significantly more time in the open arms and did not differ from WT mice in the time spent in the center area (6–7 mo-old, 2-way ANOVA for genotype and place, significant interaction; post hoc t-test, * P < 0.05, *** P < 0.001). d Social recognition test: All genotypes interacted with juvenile mice for a significantly shorter time than WT mice when they encountered the same mouse on the second day. Netrin-G1 KO mice had a longer contact duration with unfamiliar but not familiar mice (3 mo-old, 2-way mixed ANOVA for genotype and familiarity, significant interaction, * < 0.05 post hoc t-test). Netrin-G2 KO mice had a longer contact duration with both unfamiliar and familiar mice (3 mo-old, 2-way ANOVA for genotype and familiarity, ns for interaction, ** < 0.01 post-hoc t-test). e Fear conditioning test: The freezing response was markedly reduced in netrin-G1 KO mice during conditioning (8 mo-old; 2-way mixed ANOVA for genotype and bin, ns for interaction, post-hoc t-test, * P < 0.05, *** P < 0.001). Netrin-G1 KO mice also showed a decreased freezing ratio in the contextual memory test (2-way mixed ANOVA for genotype, ns for interaction) and cued memory test (2-way mixed ANOVA for genotype, ns for interaction; post-hoc t-test, * P < 0.05, ** P < 0.01, *** P < 0.001). Netrin-G2 KO mice were not different from WT mice in any session (9–10 mo-old). Data are presented as mean ± SEM