Figure 2. Overexposure to NRG3 during the neonatal period induces an anxiety-like phenotype in adulthood, but has no impact on locomotor activity or temporal order recency discrimination.

(A) Total distance travelled in 5 minute intervals over a 1 hr exposure to the open field arena did not differ between NRG3-EGF or Vehicle treated mice (n = 12–14/treatment group). (B)Time spent in the center of the open field over a 1 hr period was significantly reduced in mice treated with NRG3-EGF as neonates compared to control treated mice (n = 12–14/treatment group). (C) Representative track plots of exploration in the open field of vehicle (left panel) and NRG3-EGF (right panel) overexposed mice. Inner area designated by white dashed line designates the center arena. (D) Adult mice treated with NRG3-EGF or vehicle during PND 2–10 performed successfully in the temporal order object recognition task of recency discrimination as adults (Discrimination ratio >0, n = 11–14/treatment group). (E) After a 10 minute period of habituation to the open field (indicated by dashed vertical line), mice neonatally overexposed to NRG3-EGF or vehicle were given a single i.p. injection of saline or 3 mg/kg amphetamine. No effect of treatment (NRG3-EGF) was observed on total distance travelled in 5 minute intervals of the subsequent 75 minutes in the context of amphetamine at a dose of 3 mg/kg (n = 6–7/group). Data represents mean ± s.e.m., *p<0.05 compared to vehicle treated mice.