Figure 1

Oxytocin receptors affect the development, intensity and maintenance of social preference. (a) The behavioral chamber for social preference tests was composed of one test area and two stimulus areas, divided by transparent walls. After a habituation period, two stimulus fish were added to one stimulus area and the half next to the stimulus fish was defined as “social ROI” during analysis. (b) Social preference developed faster in both the oxtr^−/− and oxtrl^−/− fish and in oxtr^−/− fish the maintenance of social preference was impaired. Values are reported as mean ± standard error of the mean (s.e.m.). Asterisks represent the statistical comparison of age in the different genotypes. n(social wildtype, 2 wpf) = 15, n(social wildtype, 3 wpf) = 15, n(social wildtype, 4 wpf) = 16, n(social wildtype, 8 wpf) = 13, n(social oxtr^−/−, 2 wpf) = 15, n(social oxtr^−/−, 3 wpf) = 18, n(social oxtr^−/−, 4 wpf) = 12, n(social oxtr^−/−, 8 wpf) = 16, n(social oxtrl^−/−, 2 wpf) = 18, n(social oxtrl^−/−, 3 wpf) = 18, n(social oxtrl^−/−, 4 wpf) = 15, n(social oxtrl^−/−, 8 wpf) = 11. Kruskal–Wallis-Test: p(social wildtype) = 9.31 × 10⁻¹, p(social oxtr^−/−) = 1.65 × 10⁻², p(social oxtrl^−/−) = 4.09 × 10⁻⁵. Post-hoc Wilcoxon rank-sum test for socially reared oxtr^−/−: p(2wpf⇔3wpf) = 3.66 × 10⁻², p(2wpf⇔4wpf) = 6.11 × 10⁻¹, p(2wpf⇔8wpf) = 6.42 × 10⁻¹, p(3wpf⇔4wpf) = 7.40 × 10⁻², p(3wpf⇔8wpf) = 4.95 × 10⁻², p(4wpf⇔8wpf) = 6.42 × 10⁻¹. Post-hoc Wilcoxon rank-sum test for socially reared oxtrl^−/−: p(2wpf⇔3wpf) = 2.09 × 10⁻⁴, p(2wpf⇔4wpf) = 3.54 × 10⁻⁴, p(2wpf⇔8wpf) = 7.20 × 10⁻³, p(3wpf⇔4wpf) = 9.86 × 10⁻¹, p(3wpf⇔8wpf) = 9.86 × 10⁻¹, p(4wpf⇔8wpf) = 9.86 × 10⁻¹. (c) At 3 and 4 wpf, the level of social preference was increased in the oxtrl^−/− fish. Fish of the oxtr^−/− line also showed enhanced social preference at 3 wpf, but did not maintain this high level at 4 wpf. Each dot represents one experimental fish. Asterisks represent the statistical comparison of genotype in two age groups. n(social wildtype, 3 wpf) = 15, n(social oxtr^−/−, 3 wpf) = 18, n(social oxtrl^−/−, 3 wpf) = 18, n(social wildtype, 4 wpf) = 16, n(social oxtr^−/−, 4 wpf) = 12, n(social oxtrl^−/−, 4 wpf) = 15. Kruskal–Wallis-Test: p(social 2 wpf) = 2.25 × 10⁻¹, p(social 3 wpf) = 2.35 × 10⁻², p(social 4 wpf) = 3.61 × 10⁻², p(social 8 wpf) = 2.87 × 10⁻¹. Post-hoc Wilcoxon rank-sum test for socially reared 3 wpf: p(wt⇔oxtr^−/−) = 2.93 × 10⁻², p(wt⇔oxtrl^−/−) = 2.93 × 10⁻², p(oxtr^−/−⇔oxtrl^−/−) = 7.00 × 10⁻¹. Post-hoc Wilcoxon rank-sum test for socially reared 4 wpf: p(wt⇔oxtr^−/−) = 9.26 × 10⁻¹, p(wt⇔oxtrl^−/−) = 5.34 × 10⁻², p(oxtr^−/−⇔oxtrl^−/−) = 5.34 × 10⁻². Number of replicates (n) and excluded n can be found in Supplementary Table S1, significance values in Supplementary Table S2. Significance is reported as *p < 0.05, **p < 0.01, ***p < 0.001.