Cognitive, emotional and neurochemical effects of repeated maternal separation in adolescent rats

• MS reduced PPI in adolescent rats.
• MS increased anxiety-related behaviors in adolescent rats.
• MS decreased DRD2 expression in the NAc and hippocampus.
• MS decreased 5-HT1A expression in the mPFC and hippocampus.
• This study advances the use of MS as an animal model of mental disease.

As an adverse early life experience, maternal separation (MS) induces profound neurochemical, cognitive and emotional dysfunction. Previous studies have reported that MS affected prepulse inhibition (PPI), anxiety-related behaviors, dopaminergic and serotonergic activity in adult rats, and in the present study, we investigated the effects of repeated (4 h/day) maternal separation during postnatal days 1–21 on PPI and anxiety-related behaviors in an elevated plus maze, as well as dopamine D2 receptor (DRD2) and 5-HT1A receptor expression in the medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and hippocampus in adolescent rats. Our findings show that repeated MS results in reduced PPI, increased anxiety-related behaviors, decreased DRD2 protein expression in the NAc and hippocampus, and decreased 5-HT1A protein expression in the mPFC and hippocampus in adolescent rats. These data further demonstrate that MS can be used as an animal model of neuropsychiatric disease.