Ruling out postnatal origins to attention-deficit/hyperactivity disorder (ADHD)-like behaviors in a seizure-prone rat strain

Adult Fast (seizure-prone) and Slow (seizure-resistant) kindling rat strains exhibit divergent behaviors in paradigms relevant to attention-deficit/hyperactivity disorder (ADHD) in humans. Similar dissociations in rodent behavior have been linked to disparities in early life experience, suggesting that differential maternal care or postnatal interactions may underlie these behaviors. Consequently, the authors compared maternal behavior and preweaning pup weights in these 2 strains under control and cross-fostered conditions and examined its effects on subsequent adult offspring behavior. Ultimately, several distinct maternal behaviors were apparent between the 2 strains under control conditions, and some of those behaviors were then malleable by pup condition. Yet, in spite of the resultant complex maternal patterns across groups, all offspring showed behavioral phenotypes akin to their genetic strain. Thus, a specific postnatal environment is unlikely to underwrite ADHD-like behaviors in the seizure-prone Fast rats, which implicates a genetic or prenatal origin for the ADHD phenotype.