Fig. 3
PVN oxytocin projections to VTA dopamine neurons mediate SI-induced craving for social interaction. A Schematic representation of the experimental design. AAVDJ-hSyn-DIO-hM4D(Gi)-mCherry was bilaterally injected into the PVN of male Oxytocin-Ires-Cre mice. One week after viral infection, mice were housed either in groups or alone, treated with CNO or vehicle in their drinking water for 1 week, and then subjected to the free interaction test, object exploration, and habituation test. B Representative images showing the co-expression of hM4D(Gi)-mCherry and oxytocin immunoreactivity in the PVN (left). Scale bar, 100 μm. Right, magnification of the boxed area; scale bar, 20 μm. C Behavioral performance of mice in the free interaction test. There were no significant differences among male vehicle-treated GH, CNO-treated SI, and CNO-treated GH mice in the time spent interacting with a novel mouse [mouse number: GH/vehicle: n = 7; SI/vehicle: n = 7; GH/CNO: n = 9; SI/CNO: n = 8; two-way ANOVA, group: F(1,27) = 6.183, P = 0.0194; treatment: F(1,27) = 5.12, P = 0.0319; group × treatment interaction: F(1,27) = 4.33, P = 0.047]. D Behavioral performance of mice in the object exploration test. There was a significant difference between male vehicle-treated SI and CNO-treated SI mice while exploring the novel object [mouse number: GH/vehicle: n = 7; SI/vehicle: n = 7; GH/CNO: n = 9; SI/CNO: n = 8; two-way ANOVA, group: F(1,27) = 7.80, P = 0.0095; treatment: F(1,27) = 4.72, P = 0.0387; group × treatment interaction: F(1,27) = 7.45, P = 0.011]. E Behavioral performance of mice in the habituation test. There was a significant difference between male vehicle-treated SI and CNO-treated SI mice in behavioral habituation to repeated social stimulation [mouse number: GH/vehicle: n = 7; SI/vehicle: n = 7; GH/CNO: n = 9; SI/CNO: n = 8; two-way RM ANOVA, trial: F(2.65,71.55) = 63.85, P < 0.0001; treatment: F(3,27) = 8.56, P = 0.0004; trial × treatment interaction: F(9,81) = 4.39, P = 0.0001; Tukey’s post hoc multiple comparisons test, PGH/Vehicle vs. SI/Vehicle < 0.0001, PGH/Vehicle vs. SI/CNO = 0.0309, PSI/Vehicle vs. GH/CNO = 0.0002, PSI/Vehicle vs. SI/CNO = 0.0386]. F Schematic representation of the experimental design. AAVDJ-hSyn-DIO-hM3D(Gq)-mCherry was bilaterally injected into the PVN of male Oxytocin-Ires-Cre mice. One week after viral infection, mice were housed in groups, treated with vehicle or CNO in their drinking water for 1 week, and then subjected to the free interaction test, object exploration, and habituation test. G Representative images showing the co-expression of hM3D(Gq)-mCherry and oxytocin immunoreactivity in the PVN (left). Scale bar, 100 μm. Right, magnification of the boxed area; scale bar, 20 μm. H Behavioral performance of mice in the free interaction test. CNO-treated GH mice spend more time interacting with the novel mice compared with vehicle-treated GH mice [mouse number: GH/vehicle: n = 8; SI/vehicle: n = 7; GH/CNO: n = 8; SI/CNO: n = 9; two-way ANOVA, group: F(1,28) = 0.91, P = 0.3475; treatment: F(1,28) = 0.53, P = 0.4734; group × treatment interaction: F(1,28) = 10.92, P = 0.0026]. I Behavioral performance of mice in the object exploration test. CNO-treated GH mice spend more time exploring the novel object compared with vehicle-treated GH mice [mouse number: GH/vehicle: n = 8; SI/vehicle: n = 7; GH/CNO: n = 8; SI/CNO: n = 9; two-way ANOVA, group: F(1,28) = 4.22, P = 0.0494; treatment: F(1,28) = 3.25, P = 0.0823; group × treatment interaction: F(1,28) = 5.36, P = 0.0281]. J Behavioral performance of mice in the habituation test. CNO-treated GH mice exhibited a significant habituation deficit compared with vehicle-treated GH mice [mouse number: GH/vehicle: n = 8; SI/vehicle: n = 7; GH/CNO: n = 8; SI/CNO: n = 9; two-way RM ANOVA, trial: F(2.746,79.62) = 32.64, P < 0.0001; treatment: F(3,29) = 4.87, P = 0.0073; trial × treatment interaction: F(9,87) = 3.45, P = 0.0011; Tukey’s post hoc multiple comparisons test, PGH/Vehicle vs. SI/Vehicle = 0.0007, PGH/Vehicle vs. GH/CNO = 0.0107, PGH/Vehicle vs. SI/CNO = 0.0099]. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01 and ***P < 0.001. Panels A and F were created with BioRender.com