Antipsychotics were developed to treat schizophrenia in adults; however they have been increasingly prescribed in children and adolescents. The NMDA and GABAA receptors are involved in neurodevelopment and the pathophysiology of various mental disorders in children and adolescents. Male and female juvenile rats were treated orally with risperidone (0.3 mg/kg, 3 times/day), aripiprazole (1 mg/kg), olanzapine (1 mg/kg) or vehicle (control), starting from postnatal day (PD) 23 (±1 day) for 3 weeks (corresponding to the childhood-adolescent period in humans). Quantitative autoradiography was used to detect the binding density of [3H]MK-801 (an NMDA receptor antagonist) and [3H]muscimol (a selective GABAA receptor agonist). Aripiprazole elevated the [3H]MK801 binding levels in the NAcC of male rats, and the NAcS and CPu of female rats. Risperidone increased [3H]MK801 levels in the CPu of female rats, and the NAcS of male rats. Aripiprazole upregulated [3H]muscimol binding levels in the CPu and NAcC of male rats, while it elevated the [3H]muscimol levels in the PFC of female rats, compared to controls. These results suggest that early treatment with these antipsychotics modulates NMDA and GABAA neurotransmission in juveniles, which may play a role in their clinical efficacy in the control of mental disorders in children and adolescents.