Lithium rescues the deficit of social interaction in neonatal isolation rats. Both male (A) and female (B) rats subjected to maternal separation for 1 h/day from PND 1–9 exhibit remarkably more time in object’s compartment and less time in stranger rat’s compartment during social interaction test compared to normal reared controls. Lithium injection immediately after daily isolation recovers the impairment of social interaction behavior in both male (A) and female (B). Two-way ANOVA analysis was used in this experiment. For isolated male rats in stranger rat’s compartment: treatment × drug, F(1, 76) = 5.588, P < 0.05; treatment, F(1, 76) = 5.515, P < 0.05; drug, F(1, 76) = 1.403, P > 0.05. For isolated female rats in stranger rat’s compartment: treatment × drug, F(1, 76) = 5.111, P < 0.05; treatment, F(1, 76) = 5.179, P < 0.05; drug, F(1, 76) = 2.236, P > 0.05. For isolated male rats in object’s compartment: treatment × drug, F(1, 76) = 4.374, P < 0.05; treatment, F(1, 76) = 4.218, P < 0.05; drug, F(1, 76) = 0.307, P > 0.05. For isolated female rats in object’s compartment: treatment × drug, F(1, 76) = 3.984, P < 0.05; treatment, F(1, 76) = 5.161, P < 0.05; drug, F(1, 76) = 3.473, P > 0.05. Data show mean ± SEM (*p < 0.05; **p < 0.01).