Seizure-prone EL mice exhibit deficits in pup nursing and retrieval assessed using a novel method of maternal...

The selectively bred EL mouse strain exhibits hyperreactivity to environmental disturbance reflected by handling-induced seizures and motor hyperactivity in an exploratory task relative to a non-seizure-prone control strain. One possible mechanism for the nongenomic transmission of an adult seizure-prone/hyperactive phenotype is the quality of parenting provided to immature offspring. In particular, the quality of maternal behavior has been implicated as an environmental determinant in rodent biochemical and behavioral development. A complication in testing this hypothesis is that human handling for husbandry and testing itself triggers seizures in seizure-prone EL mice. Thus, the present study evaluated potential EL versus control strain differences in maternal behavior using a novel apparatus for passive observation of undisturbed mice. Nonmaternal behaviors were also measured to control for any nonspecific differences in activity or exploration. EL dams were slower than DDY controls to initiate pup retrieval and spent less time nursing/crouching over pups than DDY mice. EL dams also exhibited a profile of sustained exploration and grooming over time relative to the profile of DDY controls. These results suggest that EL mothers exhibit an overabundance of motor activities that compete with crouching/nursing and retrieval behaviors required for viability of the litter.