5-HT release in nucleus accumbens rescues social deficits in mouse autism model

Abstract

Dysfunction in prosocial interactions is a core symptom of autism spectrum disorder. However, the neural mechanisms that underlie sociability are poorly understood, limiting the rational development of therapies to treat social deficits. Here we show in mice that bidirectional modulation of the release of serotonin (5-HT) from dorsal raphe neurons in the nucleus accumbens bidirectionally modifies sociability. In a mouse model of a common genetic cause of autism spectrum disorder-a copy number variation on chromosome 16p11.2-genetic deletion of the syntenic region from 5-HT neurons induces deficits in social behaviour and decreases dorsal raphe 5-HT neuronal activity. These sociability deficits can be rescued by optogenetic activation of dorsal raphe 5-HT neurons, an effect requiring and mimicked by activation of 5-HT1b receptors in the nucleus accumbens. These results demonstrate an unexpected role for 5-HT action in the nucleus accumbens in social behaviours, and suggest that targeting this mechanism may prove therapeutically beneficial.

Extended Data Fig. 1 |. Activation of DR neurons or their NAc projections increases sociability, and bidirectional modulation of DR 5-HT neuron activity bidirectionally modifies sociability.

a, b, Quantification of chamber time (a: eYFP, F_6,45 = 0.6823, P = 0.6647, n = 6; ChR2, F_6,72 = 17.21, P < 0.01; n = 9) and proximity time (b: eYFP, F_3,30 = 0.7517, P = 0.5300, n = 6; ChR2, F_3,48 = 32.96, P < 0.01, n = 9) in the three-chamber assay. c, Quantification of centre time in the locomotion assay (c: F_5,65 = 1.263, P = 0.2908, n = 6–9). d, e, Quantification of chamber time (d: eYFP, F_6,54 = 0.2602, P = 0.9529, n = 7; ChR2, F_6,72 = 19.36, P < 0.01, n = 9) and proximity time (e: eYFP, F_3,36 = 0.3456, P = 0.7925, n = 7; ChR2, F_3,48 = 26.44, P < 0.01, n = 9) in the three-chamber assay. f, Quantification of centre time in the locomotion assay (F_5,40 = 0.7786, P = 0.5710, n = 5). g, h, Quantification of chamber time (g: eYFP, F_6,54 = 0.7293, P = 0.6280, n = 7; ChR2, F_6,72 = 3.812, P < 0.05, n = 9) and proximity time (h: eYFP, F_3,36 = 0.9256, P = 0.4383, n = 7; ChR2, F_3,48 = 4.844, P < 0.05, n = 9) in the three-chamber assay. i, j, Quantification of chamber time (i: eYFP, F_6,54 = 1.058, P = 0.3989, n = 7; NpHR, F_6,81 = 13.04, P < 0.01, n = 10) and proximity time (j: eYFP, F_3,36 = 1.661, P = 0.1926, n = 7; NpHR, F_3,54 = 16.29, P < 0.01, n = 10) in the three-chamber assay. k, l, Quantification of novel object interaction assay (k: F_1,52 = 0.01018, P = 0.9200, n = 13–15), locomotion assay (l: F_1,52 = 0.7626, P = 0.3865, n = 13–15), and centre time (m: F_5,130 = 0.766, P = 0.5759, n = 13–15) in Sert-cre mice expressing DIO-eYFP or DIO-ChR2 in DR receiving soma stimulation. n–p, Quantification of novel object interaction assay (n: F_1,30 = 0.04112, P = 0.8407, n = 7–10), locomotion assay (o: F_1,30 = 0.3837, P = 0.5403, n = 7–10), and centre time (p: F_5,80 = 1.195, P = 0.3190, n = 8–10) in Sert-cre mice expressing DIO-eYFP or DIO-NpHR in DR receiving soma stimulation. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 2 |. Bidirectional modulation of DR-to-NAc 5-HT terminals modifies sociability, but not control behaviours.

a, b, Quantification of chamber time (a: eYFP, F_6,63 = 1.383, P = 0.2352, n = 8; ChR2, F_6,72 = 4.891, P < 0.05, n = 9) and proximity time (b: eYFP, F_3,42 = 0.9652, P = 0.4181, n = 8; ChR2, F_3,48 = 7.565, P < 0.05, n = 9) in the three-chamber assay. c, d, Quantification of chamber time (c: eYFP, F_6,81 = 1.626, P = 0.1506, n = 10; NpHR, F_6,81 = 6.253, P < 0.05, n = 10) and proximity time (d: eYFP, F_3,54 = 2.304, P = 0.0872, n = 10; NpHR, F_3,54 = 7.821, P < 0.05, n = 10) in the three-chamber assay. e–g, Quantification of novel object interaction assay (e: F_1,30 = 0.00206, P = 0.9641, n = 8–9), locomotion assay (f: F_1,30 = 0.03023, P = 0.8631, n = 8–9), and centre time (g: F_5,75 = 1.205, P = 0.3151, n = 8–9) in Sert-cre mice expressing DIO-eYFP or DIO-ChR2 in DR receiving DR-to-NAc terminal stimulation. h–j, Quantification of novel object interaction assay (h: F_1,38 = 0.213, P = 0.6471, n = 10–11), locomotion assay (i: F_1,34 = 1.077, P = 0.3066, n = 9–10), and centre time (j: F_5,90 = 0.1646, P = 0.9749, n = 9–10) in Sert-cre mice expressing DIO-eYFP or DIO-NpHR in DR receiving DR-to-NAc terminal stimulation. Data are mean ± s.e.m. *P < 0.05, **P < 0.01; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 3 |. 16p11.2 deletion decreases sociability, but not an anxiety-related behaviour.

a, b, Quantification of chamber time (a: control, F_2,45 = 39.5, P < 0.001, n = 16; heterozygous, F_2,21 = 23.39, P < 0.001, n = 8; homozygous, F_2,21 = 31.54, P < 0.001, n = 8) and proximity time (b: control, F_1,30 = 14.61, P < 0.001, n = 16; heterozygous, F_1,14 = 10.14, P < 0.01, n = 8; homozygous, F_1,14 = 11.88, P < 0.01, n = 8) in the three-chamber assay. c, Quantification of centre time (c: F_10,135 = 1.03, P = 0.4215, n = 7–15) in control, heterozygous 16p11.2^flx:Nes-creER and homozygous 16p11.2^flx:Nes-creER mice. d, e, Quantification of chamber time in the three-chamber assay (d: 16p11.2^flx:Δcre, F_2,24 = 121.2, P < 0.001, n = 9; 16p11.2^flx:cre, F_2,24 = 27.86, P < 0.001, n = 9; Sert-cre:16p11.2^flx, F_2,21 = 84.95, P < 0.001, n = 8) and proximity time (e: 16p11.2^flx:Δcre, F_1,16 = 26.13, P < 0.001, n = 9; 16p11.2^flx:cre, F_1,16 = 6.885, P < 0.05, n = 9; Sert-cre:16p11.2^flx, F_1,14 = 44.00, P < 0.001, n = 8). f, Quantification of centre time in (c: F_2,22 = 0.6019, P = 0.5565, n = 8–9) 16p11.2^flx:Δcre, 16p11.2^flx:cre and Sert-cre:16p11.2^flx mice. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 4 |. Optogenetic activation of DR neurons reverses social deficits induced by 16p11.2 deletion, but does not alter control behaviours.

a, Schematic of AAV-DJ-Cre and DIO-ChR2 injected into and optic fibre implanted above the DR in 16p11.2^flx mice. b, Timeline of behavioural experiments. c, d, Quantification of sociability during juvenile interaction (c: F_1,36 = 62.43, P < 0.001, n = 10) and the three-chamber sociability assay (d: F_1,34 = 2.298, P < 0.05, n = 9–10) in 16p11.2^flx mice expressing DIO-eYFP or DIO-ChR2 and AAV-DJ-Cre in DR receiving soma stimulation. e, f, Quantification of chamber and proximity time in the three-chamber assay (e: eYFP, F_2,24 = 92.48, P < 0.001, n = 9 (left); F_1,16 = 17.53, P < 0.05, n = 9 (right); f: ChR2, F_6,81 = 3.085, P < 0.05, n = 10 (left); F_3,54 = 3.493, P < 0.05, n = 10 (right)). g–i, Quantification of novel object interaction assay (g: F_1,36 = 0.956, P = 0.3424, n = 10), locomotion assay (h: F_1,36 = 1.962, P = 0.1698, n = 10), and centre time (i: F_5,90 = 0.7668, P = 0.5761, n = 10) in 16p11.2^flx mice. Data are mean ± s.e.m. *P < 0.05, ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Extended Data Fig. 5 |. Optogenetic activation of DR 5-HT neurons or DR-to-NAc 5-HT terminals rescues social deficits induced by 16p11.2 deletion, but does not alter control behaviours.

a, b, Quantification of chamber and proximity time in the three-chamber assay (a: eYFP, F_2,21 = 84.95, P < 0.001, n = 8 (left); F_1,14 = 44.00, P < 0.001, n = 8 (right); b: ChR2, F_6,81 = 9.26, P < 0.001, n = 10 (left); F_3,54 = 11.54, P < 0.001, n = 10 (right)). c–e, Quantification of the novel object interaction assay (c: F_1,32 = 0.03819, P = 0.8463, n = 9), locomotion assay (d: F_1,32 = 0.141, P = 0.7097, n = 8–10), and centre time (e: F_5,80 = 0.195, P = 0.9636, n = 8–10) in Sert-cre:16p11.2^flx mice expressing DIO-eYFP or DIO-ChR2 in DR receiving soma stimulation. f, g, Quantification of chamber and proximity time in the three-chamber assay (f: eYFP, F_2,27 = 73.89, P < 0.001, n = 10 (left); F_1,18 = 63.38, P < 0.001, n = 10 (right); g: ChR2, F_6,81 = 11.33, P < 0.001, n = 10 (left); F_3,54 = 14.55, P < 0.001, n = 10 (right)). h–j, Quantification of novel object interaction assay (h: F_1,36 = 0.01038, P = 0.9194, n = 10), locomotion assay (i: F_1,32 = 0.3655, P = 0.5497, n = 9), and centre time (j: F_5,90 = 0.9092, P = 0.4788, n = 10) in Sert-cre:16p11.2^flx mice expressing DIO-eYFP or DIO-ChR2 in DR receiving DR-to-NAc 5-HT terminal stimulation. Data are mean ± s.e.m. ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 6 |. 5-HT release in the NAc is not acutely reinforcing.

a, b, Quantification of chamber time in the real-time CPP assay for 0 Hz (a) and 20 Hz (b) stimulation for initial (left) and reversal (right) stimulations (a: 0 Hz initial F_2,16 = 10.22, P < 0.05, n = 9; 0 Hz reversal F_2,16 = 29.01, P < 0.001, n = 9; b: 20 Hz initial F_2,16 = 19.37, P < 0.001, n = 9; 20 Hz reversal F_2,16 = 7.53, P < 0.01, n = 9) in Sert-cre mice receiving DR-to-NAc terminal stimulation. c, d, Quantification of chamber time in the real-time CPP assay for 0 Hz (c) and 20 Hz (d) stimulation for initial (left) and reversal (right) stimulations (c: 0 Hz initial F_2,16 = 12.44, P < 0.001, n = 9; 0 Hz reversal F_2,16 = 19.92, P < 0.001, n = 9; d: 20 Hz initial F_2,16 = 8.56, P < 0.01, n = 9; 20 Hz reversal F_2,16 = 9.517, P < 0.001, n = 9) in Sert-cre:16p11.2^flx mice receiving DR-to-NAc terminal stimulation. e, Quantification of nosepokes for active and inactive ports for Sert-cre and Sert-cre:16p11.2^flx mice (Sert-cre F_2,32 = 1.9, P = 0.1655, n = 9; Sert-cre:16p11.2^flx F_2,32 = 0.25, P = 0.7821, n = 9). f, g, Quantification of chamber time (left) and proximity time (right) in high-fat food three-chamber assay for Sert-cre mice (F_6,72 = 0.6713, P = 0.6731, n = 9; F_3,48 = 1.495, P = 0.2279, n = 10) and Sert-cre:16p11.2^flx mice (F_6,72 = 0.4006, P = 0.8763, n = 10; F_3,48 = 0.4157, P = 0.7425, n = 10) (g). Post-hoc analysis showed no significant difference between stimulated and non-stimulated chambers. *P < 0.05, **P < 0.01, ***P < 0.001; repeated measures, one-way (a–d) or two-way (f, g) ANOVA with Tukey’s multiple comparison post hoc test, or one-way ANOVA with Sidak’s multiple comparison post hoc test comparing active to inactive nosepokes (e). Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 7 |. Activation of DR 5-HT terminals in the dorsal striatum does not enhance sociability nor rescue social deficits induced by 16p11.2 deletion.

a, Schematic of DIO-ChR2-eYFP injected into the DR and optic fibre implanted above the dorsal striatum (DS) in Sert-cre or Sert-cre:16p11.2^flx mice. b, Timeline of behavioural experiments. c, d, Quantification of sociability during the juvenile interaction assay (c: F_1,14 = 0.5429, P = 0.4734, n = 4–5) and sociability in the three-chamber assay (d: F_1,14 = 0.055, P = 0.8177, n = 4–5) in Sert-cre or Sert-cre:16p11.2^flx mice expressing DIO-eYFP or DIO-ChR2 with terminal stimulation of DR 5-HT neurons in the dorsal striatum. e, f, Quantification of the three-chamber assay showing chamber (left) and proximity (right) time (e: Sert-cre, F_6,36 = 1.078, P = 0.3939, n = 5 (left); F_3,24 = 2.009, P = 0.1395, n = 5 (right); f: Sert-cre:16p11.2^flx, F_2,9 = 16.44, P < 0.001, n = 4 (left); F_1,6 = 11.2, P < 0.01, n = 4 (right)). g–i, Quantification of novel object interaction assay (g: F_1,14 = 0.058, P = 0.8125, n = 4–5), locomotion assay (h: F_1,14 = 0.6195, P = 0.4444, n = 4–5), and centre time (i: F_1,7 = 8.292, P < 0.05, n = 4–5) in Sert-cre or Sert-cre:16p11.2^flx mice. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and considered were not significant. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Extended Data Fig. 8 |. Activation of DR-to-NAc 5-HT terminals does not elicit long-lasting effects on sociability.

a–j, Quantification of sociability during juvenile interaction assay on day 1 of stimulation (a: F_1,16 = 10.65, P < 0.001, n = 9), day 2 (b: F_1,16 = 16.71, P < 0.01, n = 9), day 3 session 1 (c: F_1,16 = 17.7, P < 0.01, n = 9), session 2 (d: F_1,16 = 27.05, P < 0.05, n = 9), session 3 (e: F_1,16 = 13.35, P < 0.01, n = 9), session 4 (f: F_1,16 = 25.03, P < 0.05, n = 9) and day 4 session 1 (g: F_1,16 = 17.41, P < 0.001, n = 9), session 2 (h: F_1,16 = 39.76, P < 0.01, n = 9), session 3 (i: F_1,16 = 35.49, P < 0.001, n = 9), and session 4 (j: F_1,16 = 8.295, P < 0.01, n = 9) in Sert-cre or Sert-cre:16p11.2^flx mice expressing DIO-ChR2 with DR-to-NAc 5-HT terminal stimulation. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test.

Extended Data Fig. 9 |. 5-HT1b receptor antagonist infusion into NAc blocks enhanced sociability due to DR 5-HT neuron stimulation.

a, Quantification of chamber and proximity time in the three-chamber assay (a: ChR2 + vehicle, F_6,54 = 15.15, P < 0.001, n = 7 (left); F_3,36 = 18.00, P < 0.001, n = 7 (right); b: ChR2 + NAS-181, F_6,45 = 1.479, P = 0.2069, n = 6 (left); F_3,30 = 1.926, P = 0.1467, n = 6 (right)) in Sert-cre mice expressing DIO-ChR2 in DR with either vehicle (red) or NAS-181 (pink) infused into the NAc before analysis of behaviour. c, d, Quantification of sociability during the juvenile interaction assay (c: F_1,24 = 0.004638, P = 0.9463, n = 7) and the three-chamber assay (d: F_1,22 = 0.1686, P = 0.1686, n = 6–7) in Sert-cre mice expressing DIO-eYFP in DR with either vehicle (black) or NAS-181 (grey) infused into NAc before behaviour. e, f, Quantification of the three-chamber assay showing chamber and proximity time (e: eYFP + vehicle, F_6,54 = 12.36, P < 0.001, n = 7 (left); F_3,36 = 15.98, P < 0.01, n = 7 (right); f: eYFP + NAS-181, F_6,45 = 0.4512, P = 0.8403, n = 6 (left); F_3,30 = 0.7365, P = 0.7365, n = 6 (right)) in Sert-cre mice expressing DIO-eYFP in DR with either vehicle (grey) or NAS-181 (blue) infused into the NAc before analysis of behaviour. g–i, Quantification of the novel object interaction assay (g: F_1,24 = 0.0791, P = 0.7809, n = 7), locomotion assay (h: F_1,24 = 0.8954, P = 0.3535, n = 7), and centre time (i: F_5,60 = 0.6042, P = 0.6969, n = 7) in Sert-cre mice expressing DIO-eYFP in DR with either vehicle (grey) or NAS-181 (blue) infused into the NAc before behaviour. Data are mean ± s.e.m. ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 10 |. 5-HT1b receptor antagonist infusion into the NAc does not alter control behaviours and blocks rescue of 16p11.2 deletion social deficits by DR 5-HT neuron stimulation.

a–c, Quantification of the novel object interaction assay (a: F_1,24 = 0.0579, P = 0.8120, n = 7), locomotion assay (b: F_1,24 = 0.4764, P = 0.4967, n = 7), and centre time (c: F_5,60 = 0.3936, P = 0.8513, n = 7) in Sert-cre mice expressing DIO-ChR2 in DR with either vehicle (red) or NAS-181 (pink) infused into the NAc before behaviour. d, e, Quantification of chamber and proximity time in the three-chamber assay (d: ChR2 + vehicle, F_6,90 = 9.03, P < 0.05, n = 11 (left); F_3,60 = 13.04, P < 0.05, n = 11 (right); e: ChR2 + NAS-181, F_6,90 = 1.226, P = 0.3004, n = 11 (left); F_3,60 = 1.69, P = 0.1786, n = 11 (right)) in Sert-cre:16p11.2^flx mice expressing DIO-ChR2 in DR with either vehicle (red) or NAS-181 (aqua) infused into the NAc before behaviour assays during optogenetic stimulation. f–h, Quantification of novel object interaction assay (f: F_1,18 = 01.263, P = 0.2758, n = 5–6), locomotion assay (g: F_1,18 = 0.0344, P = 0.8549, n = 5–6), and centre time (h: F_5,45 = 1.22, P = 0.3155, n = 5–6) in Sert-cre:16p11.2^flx mice expressing DIO-ChR2 in DR with either vehicle (black) or NAS-181 (blue) infused into the NAc before behaviour assays. Data are mean ± s.e.m. *P < 0.05; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant.

Extended Data Fig. 11 |. Infusion of 5-HT1b receptor agonist into the NAc increases sociability, but does not alter control behaviours.

a, Schematic of 5-HT1b receptor agonist (CP93129) infusion into the NAc in Sert-cre or Sert-cre:16p11.2^flx mice. b, Timeline of behavioural experiments. c, d, Quantification of chamber and proximity time in the three-chamber assay (c: vehicle, F_2,15 = 45.82, P < 0.001 (left); F_3,30 = 4.453, P < 0.05 (right), n = 6; d: CP93129, F_2,15 = 63.11, P < 0.001 (left); F_1,10 = 17.23, P < 0.05, (right), n = 6) in Sert-cre mice with either vehicle (red) or CP93129 (aqua) infused into the NAc before analysis of behaviour. e, f, Quantification of chamber and proximity time in the three-chamber assay (e: vehicle, F_2,12 = 67.49, P < 0.001(left); F_1,8 = 41.03, P < 0.001 (right), n = 5; f: CP93129, F_2,12 = 29.73, P < 0.001 (left); F_1,8 = 17.17, P < 0.01 (right), n = 5) in Sert-cre:16p11.2^flx mice with either vehicle (blue) or CP93129 (pink) infused into the NAc before analysis of behaviour. g–i, Quantification of the novel object interaction assay (g: F_1,18 = 1.612, P = 0.2204, n = 5–6), locomotion assay (h: F_1,18 = 0.0149, P = 0.9041, n = 5–6), and centre time (i: F_5,50 = 1.492, P = 0.2093; F_5,40 = 0.4561, P = 0.8063, n = 5–6) in Sert-cre and Sert-cre:16p11.2^flx mice with either vehicle or NAS-181 infused into the NAc before behaviour. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; repeated measures, two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Fig. 1 |. Activation of DR neurons or their NAc projections increases sociability.

a, Schematic of optogenetic manipulation. b, Timeline of experiments. c, d, Quantification of juvenile interaction assay (c: F_1,44 = 6.262, P < 0.05; n = 10–14) and three-chamber sociability assay (d: F_1,26 = 4.327, P < 0.05; n = 6–9) in wild-type mice (blue signifies optical activation). In this and all subsequent figures, the left panels illustrate individual subjects; right panels display mean ± s.e.m. e, f, DR neuron stimulation did not alter the novel object interaction assay (e: F_1,52 = 0.8324, P = 0.3658, n = 14) or the locomotion assay (f: F_1,44 = 0.00053, P = 0.9817; n = 10–14). g, Schematic of optogenetic manipulation. h, Timeline of experiments. i, j, Quantification of juvenile interaction (i: F_1,50 = 8.999, P < 0.01; n = 11–16) and three-chamber sociability (j: F_1,28 = 4.320, P < 0.05; n = 7–9) assays in wild-type mice. k, l, Stimulation of DR-to-NAc terminals does not alter the novel object interaction assay (k: F_1,24 = 0.4047, P = 0.5307, n = 7) or the locomotion assay (l: F_1,16 = 0.6484, P = 0.4325, n = 5). *P < 0.05, **P < 0.01; two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Fig. 2 |. Bidirectional modulation of DR 5-HT neuron activity modifies sociability.

a, Schematic of optogenetic manipulation. b, Timeline of experiments. c, d, Quantification of juvenile interaction (c: F_1,56 = 10.85, P < 0.01; n = 14–16) and three-chamber sociability (d: F_1,28 = 4.597, P < 0.05; n = 7–9) assays in Sert-cre mice expressing ChR2 or eYFP. e, f, Quantification of juvenile interaction (e: F_1,30 = 12.77, P < 0.01; n = 7–10) and three-chamber sociability (f: F_1,30 = 11.98, P < 0.001; n = 7–10) assays in Sert-cre mice expressing NpHR or eYFP. g, Schematic of optogenetic manipulation. h, Timeline of experiments. i, j, Quantification of juvenile interaction (i: F_1,30 = 15.78, P < 0.01; n = 8–9) and three-chamber sociability (j: F_1,30 = 6.413, P < 0.05; n = 8–9) in Sert-cre mice expressing ChR2 or eYFP. k, l, Quantification of juvenile interaction (k: F_1,38 = 16.29, P < 0.001; n = 10–11) and three-chamber sociability (l: F_1,36 = 5.66, P < 0.01; n = 10) assays in Sert-cre mice expressing NpHR or eYFP. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; two-way ANOVA with Tukey’s multiple comparison post hoc test. Comparisons with no asterisk had P > 0.05 and were considered not significant. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Fig. 3 |. 16p11.2 deletion in DR and 5-HT neurons decreases sociability.

a, Schematic of human chromosome 16p11.2 and deletion of syntenic region of mouse chromosome 7F3. b, Genetic crosses used to delete 16p11.2 from whole brain. PND, postnatal day. c, Timeline of experiments. d, e, Quantification of juvenile interaction (d: F_2,30 = 26.98, P < 0.01; n = 8–17) and three-chamber sociability (e: F_2,29 = 10.03, P < 0.001; n = 8–16) in control, heterozygous and homozygous mice with deletion of 16p11.2. f, g, Deletion of 16p11.2 does not alter the novel object interaction assay (f: F_2,31 = 0.6613, P = 0.5233; n = 8–18), but homozygous 16p11.2 deletion increases locomotor activity (g: F_2,27 = 6.341, P < 0.01; n = 7–16). h, Schematic of 16p11.2 deletion in DR. i, Genetic crosses to delete 16p11.2 from 5-HT neurons. j, Timeline of experiments. k, l, Quantification of juvenile interaction (k: F_2,37 = 26.72, P < 0.001; n = 9–16) and three-chamber sociability (l: F_2,23 = 21.45, P < 0.001; n = 8–9) assays in 16p11.2^flx mice expressing ΔCre or Cre in DR and Sert-cre:16p11.2^flx mice. m, n, Deletion of 16p11.2 did not alter the novel object interaction assay (m: F_2,23 = 0.138, P = 0.8718, n = 8–9) or the locomotion assay (n: F_2,22 = 2.371, P = 0.1168, n = 8–9). Data are mean ± s.e.m. **P < 0.01; ***P < 0.001; one-way ANOVA with Tukey’s multiple comparison post hoc test. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Fig. 4 |. 16p11.2 deletion in DR 5-HT neurons decreases their activity.

a, Schematic of experimental set-up. b, Left, time course of average GCaMP6f transient z-scores event-locked to social interaction. Right, quantification of average peak z-score during social interaction (t₁₁ = 2.321, P < 0.05). c, Representative heat map of z-score changes over all trials from single mice. d, Sample traces of spiking in 5-HT DR neurons. e, Quantification of spiking (F_7,56 = 2.305, P < 0.05). f, Summary of cumulative probability of spontaneous excitatory postsynaptic current (sEPSC) amplitudes. g, Mean sEPSC amplitude changes (t₁₉ = 0.069, P < 0.001, n = 10–11). h, Summary of cumulative probability of sEPSC frequency. i, Mean sEPSC frequency changes. *P < 0.05, **P < 0.01, ***P < 0.001; unpaired t-test (b, g, i), repeated measures two-way ANOVA with Sidak’s multiple comparison post hoc test (d), or Kolmogorov–Smirnov test (f, h). The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.

Fig. 5 |. Rescue of social deficits in 16p11.2 deletion mice by 5-HT activity in the NAc.

a, b, Quantification of juvenile interaction (a: F_1,32 = 25.15, P < 0.001; n = 9) and three-chamber sociability (b: F_1,32 = 16.63, P < 0.001; n = 8–10) assays in Sert-cre:16p11.2^flx mice expressing ChR2 or eYFP receiving soma stimulation. c, d, Quantification of juvenile interaction (c: F_1,36 = 69.84, P < 0.001; n = 10) and three-chamber sociability (d: F_1,36 = 16.46, P < 0.001; n = 10) assays in Sert-cre:16p11.2^flx mice expressing ChR2 or eYFP receiving DR-to-NAc terminal stimulation. e, Schematic of experimental set-up. f, Timeline of experiments. g, h, Quantification of juvenile interaction (g: F_1,24 = 12.6, P < 0.01; n = 7) and three-chamber sociability (h: F_1,22 = 4.322, P < 0.05; n = 7) in Sert-cre mice expressing ChR2 in DR with either vehicle or NAS-181 infused into NAc. i, j, Quantification of juvenile interaction (i: F_1,40 = 29.24, P < 0.001; n = 11) and three-chamber sociability (j: F_1,38 = 29.06, P < 0.001; n = 10–11) in Sert-cre:16p11.2^flx mice expressing ChR2 in DR with either vehicle or NAS-181 infused into NAc. k, l, Quantification of juvenile interaction (k: F_1,9 = 19.03, P < 0.001; n = 10–11) and three-chamber sociability (l: F_1,9 = 18.4, P < 0.01; n = 5–6) in Sert-cre and Sert-cre:16p11.2^flx mice with either vehicle or CP93129 infused into NAc. Data are mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001; two-way ANOVA with Sidak’s multiple comparison post hoc test. The schematic of the mouse brain in this figure has been adapted with permission from Franklin & Paxinos.