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Additional file 1: Supplementary Figure 1. Drinking amount of saccharine solution and water during retrieval test in mice used for c-fos analysis. (A-C) Data showing the mean quantity of saccharine solution (orange columns) and water (blue columns) consumed during the retrieval test in M3 into IC (A), M3 into BLA (B) and M3 into IC and BLA groups (C), the results of which corresponds to Figs. 1f-g, 2f-g and 5e-f, respectively. Left and right panels showing saline- and CNO-infused group, respectively (M3 into IC, N = 7 animals in each group; M3 into BLA, saline group, N = 7, CNO group, N = 8 animals; M3 into IC and BLA, saline group, N = 5, CNO group, N = 6 animals). Data are represented as mean ± SEM; *p

Figure S1. General health and motor function in Scn2a KO mice. Figure S2. Scn2aKO/+ mice show hyperactivity and low anxiety during the first 60 min of exploration in a new environment. Figure S3. Exploratory activity is not significantly affected in the elevated plus maze task in Emx1- and Vgat-Cre conditional Scn2a knockout mice. Figure S4. Treatment by AMPA receptor modulator CX516 shows a maximal effect at 40 mg/kg for spontaneous exploratory behavior assessment. Figure S5. Treatment with the AMPA receptor modulator CX516 did not affect the decrease in anxiety-related behavior of Scn2aKO/+ in the elevated-plus maze. Figure S6. CX516 injection does not affect significantly locomotor coordination performance. Figure S7. Habituation and activity in the 3-chambers task were comparable between Scn2aKO/+ and WT mice. Figure S8. Isolation-induced ultrasonic vocalizations are conserved in Scn2aKO/+ pups at P6. Figure S9. Scn2aKO/+ mice display despair behavior in the forced-swim task but conserved startle and pre-pulse inhibition response. Figure S10. Freezing behavior is increased in Scn2aKO/+ mice three days post-conditioning. Figure S11. Fear memory induced freezing remains abnormally elevated in Scn2aKO/+ mice 48 h after conditioning. (PDF 4068 kb)

Although the dorsal raphe nucleus (DRN) has long been linked to neural control of aggression little is known about the regulatory influences of the DRN when an animal engages in either adaptive species typical aggressive behavior or escalated aggression. Therefore it is important to explore which neurotransmitter inputs into the DRN determine the escalation of aggression in male mice. Previously we observed that microinjection of the GABAB receptor agonist baclofen into the DRN escalates aggressive behavior in male mice. Here we used a serotonin (5 HT) neuron specific GABAB receptor knock out mouse to demonstrate that baclofen acts on nonserotonergic neurons to escalate aggression. Intra DRN baclofen administration increased glutamate release but did not alter GABA release within the DRN. Microinjection of l glutamate into the DRN escalated dose dependently attack bites toward an intruder. In vivo microdialysis showed that glutamate release increased in the DRN during an aggressive encounter and the level of glutamate was further increased when the animal was engaged in escalated aggressive behavior after social instigation. Finally 5 HT release was increased within the DRN and also in the medial prefrontal cortex when animals were provoked by social instigation and during escalated aggression after social instigation but this increase in 5 HT release was not observed when animals were engaged in species typical aggression. In summary glutamate input into the DRN is enhanced during escalated aggression which causes a phasic increase of 5 HT release from the DRN 5 HT neurons.

Additional material and methods for experiments displayed in the Additional file 2. Includes protocols for ultrasonic vocalizations, motor and sensory functions, forced-swim and tail suspension tests, and startle response and prepulse inhibition. (DOCX 16 kb)

Additional material and methods for experiments displayed in the Additional file 2. Includes protocols for ultrasonic vocalizations, motor and sensory functions, forced-swim and tail suspension tests, and startle response and prepulse inhibition. (DOCX 16 kb)