Quality of rearing guides expression of behavioral and neural seizure phenotypes in EL mice

The present studies employed behavioral and neural markers of seizure-related plasticity to examine the relative contributions of genetic predisposition versus rearing environment in generating adult phenotypes in EL mice, a stress-induced animal model of epilepsy. Early environment was manipulated by cross-fostering pups of the EL strain to a seizure-resistant CD-1 control strain of mouse. The impact of changes in rearing quality on growth,exploratory and stress-reactivity phenotypes were examined, with a focus on the role of maternal care in shaping seizure susceptibility and neural cF os activation. Improvement in maternal care imposed by replacing biological EL dams with foster CD-1 mothers was sufficient to decrease pup mortality, to increase body weight gain (+0.1 g/day) and to delay the onset of seizure susceptibility in EL offspring beyond post-natal day 80–90. Moreover,hypoactivity in hippocampus and cortex among EL offspring cross-fostered to EL, but not CD-1 control, dams suggests that changes in rearing environment were accompanied by enduring changes in brain plasticity. Thus, neural and behavioral phenotypes of EL mice are dependent upon post-partum maternal care which if systematically enhanced can postpone seizure expression.