Fig. 5

C3–C3R regulation of D1rs regulates male, but not female, social play behavior. To determine if disrupting C3–C3R interactions via NIF increases play in a D1r-dependent manner, we utilized siRNA against rat D1r (200 µM) or scRNA controls. a P30 males were co-injected with NIF + D1r siRNA in one hemisphere and NIF + scRNA in the contralateral hemisphere, and then D1r immunoreactivity was assessed at P38. b In the presence of NIF, D1r siRNA was capable of decreasing D1r levels relative to NIF + scRNA within-animal control hemispheres (~20%; Table 5A). c P22 females were injected with NIF + D1r siRNA in one hemisphere and NIF + scRNA in the contralateral hemisphere, and then D1r immunoreactivity was assessed at P30. d In the presence of NIF, D1r siRNA was capable of decreasing D1r levels relative to NIF + scRNA within-animal control hemispheres (~30%; Table 5B). Representative images precede histograms; scale bar equals 100 µm. n = 3/sex. e Experimental design: P30 males and P22 females were bilaterally microinjected into the NAc with either Vehicle + scRNA (Veh sc), Vehicle + D1r siRNA (Veh si), NIF + scRNA (NIF sc), or NIF + D1r siRNA (NIF si). At P37 and P22, animals were single-housed for 24 h, and then a novel age- and sex-matched conspecific was introduced into their home cage for 10 min social behavior tests (n = 9–10/sex/treatment). Males: f NIF + scRNA increased social play behavior in males, which was eliminated by D1r siRNA (NIF si; Table 5C). g No treatment changed social exploration behavior (Table 5D). Females: h NIF + scRNA increased social play behavior in females, which was not affected by D1r siRNA (NIF si; Table 5E). i No treatment changed social exploration behavior (Table 5F). Immunohistochemical data were calculated as in Fig. 2 and analyzed with two-tailed one-sample t-tests. Behavioral data were analyzed with one-way ANOVAs and Holm-Sidak’s post-hoc comparisons. Histograms portray the mean ± SEM with individual data points overlaid. Significant one-sample t-tests from 100 (b, d) and post-hoc Holm-Sidak t-tests (f–i) (p < 0.05) comparisons are delineated with an asterisk. All statistics are in Table 5