Increased GABAA receptor binding in amygdala after prenatal administration of valproic acid to rats

Objective Prenatal exposure to valproic acid (VPA) enhances the risk for later development of autism spectrum disorders (ASD). An altered gamma-aminobutyric acid (GABA) system may be a key factor in ASD. Here we investigated possible changes in the GABA system in rats exposed to a low dose of prenatal VPA. Method We performed autoradiography with [ 3 H]muscimol, (a GABA A receptor agonist), and [ 11 C]Ro15-4513 (a partial agonist of the GABA A α 1+5 receptor subtypes), in brain sections containing amygdala, thalamus and hippocampus of rats treated prenatally with 20 mg/kg VPA or saline from the 12th day of gestation. Result Prenatal VPA significantly increased [ 11 C]Ro15-4513 binding in the left amygdala compared with controls ( p 3 H]muscimol binding. Conclusion We observed an asymmetric increase in GABA A receptor binding. Disturbances in the GABA A receptor system have also been detected in human autism with [ 11 C]Ro15-4513.