Effects of pCPA treatment from postnatal day 1 through 7 on (A) marble-burying behavior and (B) spontaneous alternations in a T-maze of MAO A KO mice. pCPA, an inhibitor of trypophan hydroxylase that reduces 5-HT level, was injected (30 mg/kg/day, IP) daily from P1 to P7. Values represent mean ±SEM; *P<0.05, ***P<0.001 compared to untreated wild-type mice; #P<0.05, ###P<0.001 compared to untreated MAO A deficient mice; †P<0.05, ††P<0.01 compared to untreated saline-treated MAO A KO mice; δδP<0.01, δP<0.05 compared to saline treated wild-type mice. (Adapted from Bortolato et al., 2013b)