Fig. 1

Adolescent SI induces social behavioral changes in male mice. A Schematic diagram illustrating the experimental pipeline. After weaning (P21), male mice were housed in groups of the same sex until P27 and housed either in groups or alone between P28 and P34. A series of behavioral tests consisting of the free interaction test, object exploration, 3-chamber test, and habituation test were conducted between P35 and P38. B Top, schematic representation of the free interaction test. Bottom, bar graphs with dots showing the time spent by the male subject mouse in social interaction with a novel mouse. SI mice spend more time interacting with novel mice compared with GH mice [mouse number: GH: n = 10; SI: n = 11; two-tailed unpaired Student’s t-test; t₍₁₉₎ = 14.53, P < 0.0001, 95% CI (99.32–132.7)]. C Top, schematic representation of the object exploration test. Bottom, bar graphs with dots showing the time spent by the subject mouse exploring the novel object. SI mice spend more time exploring the novel object compared with GH mice [mouse number: GH: n = 10; SI: n = 11; two-tailed unpaired Student’s t-test; t₍₁₉₎ = 2.94, P = 0.0083, 95% CI (3.77–22.31)]. D Top, schematic representation of the habituation test. Bottom, scatterplots showing the time spent by the subject mouse in social interaction with the same stimulus mouse for 4 consecutive 5-min trials with an inter-trial interval of 10 min. SI mice exhibited a significant habituation deficit compared with GH mice [mouse number: GH: n = 10; SI: n = 11; two-way RM ANOVA, trial: F_{(2.612,49.63)} = 14.13, P < 0.0001; housing condition: F_(1,19) = 9.47, P = 0.0062; trial × housing condition interaction: F_(3,57) = 6.09, P = 0.0011]. E Left, schematic representation of the 3-chamber sociability test. Middle, bar graphs with dots showing the time spent by the male subject mouse in sniffing directed at a wire cage containing the juvenile stimulus mouse (S) or an empty wire cage (E). Both SI and GH subject mice spent significantly more time interacting with the wire cage containing the juvenile stimulus mouse than the empty wire cage. Right, the discrimination index (stimulus minus empty) was similar between SI and GH subject mice in the sociability test [mouse number: GH: n = 10; SI: n = 11; two-tailed unpaired Student’s t-test; t₍₁₉₎ = 1.10, P = 0.28, 95% CI (−0.21 to 0.07)]. F Left, schematic representation of the 3-chamber social novelty preference test. Middle, bar graphs with dots showing the time spent by the male subject mouse in sniffing directed at the wire cage containing a familiar mouse (F) or a novel mouse (N1) 10 min after the sociability test. Both SI and GH subject mice spent significantly more time sniffing the cage containing the novel mouse than the familiar mouse. Right, the discrimination index (novel 1 minus familiar) of SI subject mice was significantly less than that of GH subject mice in the social novelty preference test [mouse number: GH: n = 10; SI: n = 11; two-tailed unpaired Student’s t-test; t₍₁₉₎ = 2.11, P = 0.0485, 95% CI (−0.48 to −0.002)]. G Left, schematic representation of the 3-chamber SRM test. Middle, bar graphs with dots showing the time spent by the male subject mouse in sniffing directed at the wire cage containing a familiar mouse (N1) or a novel 2 mouse (N2), 1 day after the initial interaction. GH, but not SI, subject mice spent significantly more time sniffing the cage containing the novel mouse than the familiar mouse (mouse number: GH: n = 10; SI: n = 11; paired Student’s t-test; t₍₁₀₎ = 0.29, P = 0.78, 95% CI (−7.30 to 9.52). Right, the discrimination index (novel 2 minus familiar) of SI subject mice was significantly less than that of GH subject mice in the SRM test [mouse number: GH: n = 10; SI: n = 11; two-tailed unpaired Student’s t-test; t₍₁₉₎ = 2.81, P = 0.011, 95% CI (−0.60 to −0.09)]. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01 and ***P < 0.001. Panels B–G were created with BioRender.com