Fig. 1. D2 heterozygous KO mice exposed to maternal separation stress exhibited autistic-like behaviors. (A, B) Experimental design for maternal separation stress, weaning, and subsequent behavioral tests (A). Diagram illustrating maternal separation of pups from their mothers for 3 hours a day and their return (B). Red arrow, time point for sacrifice. (C~E) Representative heatmaps showing exploratory activity in the three-chamber test of wildtype (WT) and D2+/− mice raised normally (CON) or after exposure to early-life stress (ELS) (C). The amount of time spent in the social target chamber (St) and empty chamber (E) for WT mice (D) and D2+/− mice (E). n= 10~16 animals (WT·CON, p<0.0001; WT·ELS, p=0.0014; D2+/−·CON, p=0.0009; D2+/− ·ELS, p=0.0543). (F) The amount of sniffing time with a social target for WT mice and D2+/− mice in the three-chamber test. n= 8~16 animals (ELS effect, F(1, 42)=9.518, p=0.0036; genotype effect, F(1, 42)=10.94, p=0.0019; ELS x genotype interaction, F(1, 42)=4.454, p=0.0408). (G) The amount of time spent in social interaction with facial and anogenital sniffing (G) of WT and D2+/− mice raised normally or after exposure to early-life stress. n= 8~16 animals (ELS effect, F(1, 43)=7.448, p=0.0092; genotype effect, F(1, 43)=7.947, p=0.0073; genotype x ELS interaction, F(1, 43)=7.301, p=0.0098). (H, I) Locomotion (H) and grooming behaviors (I) in the open field test of WT and D2+/−mice raised normally or after exposure to early-life stress. n= 6~16 animals. (Grooming: ELS effect, F(1, 35)=2.632, p=0.1137; genotype effect, F(1, 35)=3.995, p=0.0534; genotype x ELS interaction, F(1, 35) =6.035, p=0.0191). Data are presented as mean±SEM. * and ** denote differences between the indicated groups at p<0.05 and p<0.01, respectively (Student's t-test, two-way ANOVA and Holm-Sidak post hoc test).
