Figure 2. Cohort 2. Amphetamine impaired sociability on chamber time in control B6 mice and increased social sniffing in BTBR.

Social approach was assayed in an automated photocell-equipped 3-chambered arena, along with observer scoring of direct sniffing interactions from videotapes of the social approach session. (A) The B6 control strain displayed normal sociability, defined as spending more time in the chamber with the novel mouse than in the chamber with the novel object, in the saline vehicle treated group. AMPH impaired B6 sociability on the chamber time parameter. (B) BTBR exhibited its characteristic lack of sociability, i.e. did not spend more time in the novel mouse chamber than in the novel object chamber, after treatment with either saline or AMPH. (C) B6 displayed normal sociability on the more sensitive parameter, time spent sniffing the novel mouse as compared to time spent sniffing the novel object, after treatment with both saline and AMPH 2.0 mg/kg. (D) BTBR exhibited its characteristic lack of sociability on the sniff time parameter following saline vehicle administration. However, BTBR treated with AMPH exhibited significant sociability on the more sensitive sniff time parameter. *p < 0.05, novel mouse versus novel object. (E) B6 and (F) BTBR displayed a greater number of entries into the side chambers after treatment with AMPH, indicating a general increase in exploratory locomotion during the social approach task. *p < 0.05 Amphetamine 2.0 mg/kg i.p. (AMPH) versus saline vehicle (SAL). N = 13–16 per dose for each strain in Cohort 2.