Pregnant C57BL/6 mice (n=80 for control group and n=82 for
ELS group) were housed individually under controlled illumination (12-h light/dark cycle with lights off at 18:00h) and ambient
temperature (24±2
◦
C, 40% humidity), and had ad libitum access
to food and water. Pups were born on gestation days 19–21 and
the day of birth was termed postnatal day (P) 0. On P1, pups were
removed from the nests and five healthy pups that included both
genders (threemales andtwofemales)wererandomlyplacedback
witheachdam.Allbehavioraltestswereperformedduringthelight
cyclebetween9:00hand15:00h.Atthedayoftesting,experimental mice were transferred to the experiment room and allowed to
acclimate allowed to acclimate for approximately 3h before testing.Toavoidvariabilitycausedbyhormonal cycles infemales,only
male offspring were used in this study. To avoid litter effects, only
one offspring per dam was used in each experiment. In addition,
all mice were used only once for an individual behavioral task. If
any pup died during the lactation period, all other offspring were
sacrificed immediately and were not included in the study. All
experimental procedures were carried outin accordance with the
National Institutes of Health Guide for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care
and Use Committee of National Cheng Kung University