Fig 1.
OXTRAvil WT (fxOxtrfx/fx; Avil-Cre-) and OXTRAvil KO (fxOxtrfx/fx; Avil-Cre+) males (top) and females (bottom) were isolated for 1 hour prior to sociability testing in the three chambered apparatus. The social novelty test took place directly after the sociability test and both tests were 10 minutes each. Directly after the social novelty test, males were single housed for at least 2 weeks and then tested for aggression in the resident intruder test which lasted for 15 minutes. All behavioral tests were video recorded.
Fig 2.
Sociability is present but significantly blunted in male and female OXTRAvil KO mice compared to WT.
Sociability—the preference for a holding tower containing a same-sex stimulus mouse (stimulus tower; gray markers) over an empty tower (empty tower; white markers)—is evident across groups by a decreased latency to approach the stimulus tower (A; F1, 60 = 4.934, p < .05; d = 0.57) and increased approach frequencies (B; F1, 60 = 57.774, p < .001; d = 1.98), sniffing durations (C; F1, 60 = 148.166, p < .001; d = 3.14), and chamber durations (D; F1, 60 = 94.729, p < .001; d = 2.51) of the stimulus tower compared to the empty tower. OXTRAvil KO females had increased latencies to approach the towers compared to OXTRAvil WT females (A; F1, 60 = 13.643, p < 0.001). OXTRAvil KO males and females had reduced approach frequencies (B; F1, 60 = 6.336, p < .05; d = 0.65), investigation (sniffing) durations (C; F1, 60 = 4.896, p < .05; d = 0.57), and chamber durations (D; F1, 60 = 4.067, p < .05; d = 0.52) between the conspecific containing tower/chamber and empty tower/chamber compared to OXTRAvil WT males and females. Data are graphed as individual data points and group averages. Difference scores (inset graphs) were calculated by subtracting approach frequency and sniffing/chamber duration of the empty side from the side containing the stimulus mouse. *in A = between-subject genotype by sex interaction, adjusted p < 0.05; * in B-D = within-subject genotype by tower type interaction, p < 0.05. See also S2 Fig in S1 File, S1 Table in S1 File.
Fig 3.
Preference for social novelty behaviors were similar in OXTRAvil WT and KO males and females.
OXTRAvil mice displayed a preference for social novelty—a preference for a tower holding a novel stranger mouse (stranger tower; gray markers) over a tower holding a familiar mouse (familiar tower; white markers)—as evident by increased approach frequencies (B; F1, 60 = 51.23, p < .001; d = 1.85) to the stranger tower, increased sniffing (C; F1, 60 = 52.208, p < .001; d = 1.864), and chamber durations (D; F1, 60 = 17.855, p < .001; d = 1.09). Social novelty preference was not impacted in OXTRAvil KO mice (no significant genotype x tower type interaction). Data are graphed as individual data points and group averages. Difference scores were calculated by subtracting approach frequency and sniffing/chamber duration towards the familiar conspecific from the stranger conspecific. ns = not significant. See also S3 Fig in S1 File, S1 Table in S1 File.
Fig 4.
Increased aggression in OXTRAvil KO males compared to OXTRAvil WT males in the resident intruder test (RIT).
A higher percentage of OXTRAvil KO males (black bar) displayed aggression in the RIT compared to OXTRAvil WT males (white bar, A). OXTRAvil KO males (gray markers) also had reduced latencies to fight (B; F1, 27 = 11.862, p < .01; d = 1.27) and increased frequencies of attack (C; F1, 27 = 4.719, p < .05; d = 0.83) compared to OXTRAvil WT males (white markers). Duration of fighting was not significantly different between OXTRAvil WT and KO males (D). Frequency and duration are graphed as individual data points and group averages ± standard error of the mean. A latency of 900 seconds was assigned to subjects that did not attack during the 15-minute-long test. See also S4 Fig in S1 File, S1 Table in S1 File.