Altered morphology of motor cortex neurons in the VPA rat model of autism.

Autism occurs in 1 in 1,000 children and incidence may be increasing. Investigating brain development and developmental injury in humans is difficult. As such, many studies rely on animal models of disorders. We chose to investigate the valproic acid-exposed rat, as this model shares many similarities with autism. Pregnant Long-Evans rats were administered either valproic acid (VPA) or saline during fetal neural tube development. Morphological analyses of cells in layer II of the golgi impregnated motor cortex were done to determine dendritic length, volume, and complexity in both groups. No differences were found in length or volume of cortical dendrites, but dendritic arborization was more complex in apical dendrites of pyramidal cells in VPA-exposed animals than controls. The implication of this finding is that pruning in the VPA-exposed rat is not occurring, which is consistent with theories related to abnormal human brain development in autism.