Striatal volume changes in a rat model of childhood attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common childhood neuropsychiatric disorders. Based on neuroimaging studies, the striatum is reported to be abnormal in size, but it is still not clear how they change during developmental stages. Spontaneously hypertensive rats (SHRs) are the commonly used animal model for ADHD. We investigated volume differences of the striatum at various ages before puberty in SHRs versus a control strain, Wistar-Kyoto rats (WKYs). Volumes of the bilateral striatum were measured using micrographs of Nissl-stained serial sections in both strains of rats at the ages of 4, 5, 6, 7, 8, 9, and 10weeks (n=4, each strain at each age). The results demonstrated that the age of a significant striatal volume difference between SHRs and WKYs was 5weeks; however, there was no significant difference for the corresponding total brain volume at each matched age. It suggested that the timing for striatal abnormalities in ADHD occurs during an early stage of childhood.