Prenatal critical period for fetal growth restriction and the effect of FGR on learning and memorizing ability in rats' offsprigs

Abstract

Objective To investigate the characteristics of fetal growth restriction(FGR)induced by intraperitoneally injection of Actinomycin D to pregnant rats or passive smoking of pregnant rats,to explore the effect of FGR on learning and memorizing ability of the offsprings involved and to observe the weight gaining of FGR offsprings.Methods FGR animal models were successfully established by both methods.Morris Water Escape Task was used to evaluate the search behavior of FGR offsprings and their spatial rememberance at different stages.Results The incidences of induced FGR were 53.47%(Actinomycin D)and 35.53%(passive smoking)respectively,and both were apparently higher than that of the control(P＜0.05).The incidences of FGR were 26.2%,47.7%and 46.5% respectively when Actinomycin D wasinjected at early,mid and late trimester.No difference was found in the incidence of FGR between the mid and late trimester(P＞0.05),but higher incidence of FGR was shown in mid and late trimester compared with the early trimester(P＜0.05).For the passive smoking pregnant rats at early,mid and late trimester,the incidences of FGR were 20.9%,40% and 45.7%.Significant difference was shown between the mid andearly late trimester(P＜0.05).During the Morris test,the progenies in FGR group spent more times in finding the platfom than those of the control,and more occasionally did they get through the area in which the platform was placed.Progenies in FGR group grew more quickly than those of the control,however,thebody weight of FGR progenies had never outweighted that of the control.Conclusions FGR animal model can be successfully established at any trimester in pregnant rats by either of the methods.The mid and late trimesters are the critical time for inducing FGR.Learning and memorizing ability of FGR offsprings is impaired to some extent.There is a postnatal careh-up growth in FGR offsprings. Key words: Fetal growth retardation; Learning; Memory