Fetal growth restriction rat model induced by low protein diet during pregnancy

Abstract

Objective To explore the impacts of 75％ low-protein diet intake during gestation on fetal growth restriction (FGR) rat model establishment.Methods Thirty-eight pregnant Sprague-Dawley rats were included into the study.At first,five pregnant rats were fed with sufficient normal diet with protein content of 22％.Their daily food consumption was recorded and taken as the basis to determine daily feed consumption of 75％ low-protein group (protein content 9.2％).In order to ensure that each group finally had at least ten pregnant rats to deliver,there were 11 rats assigned to the control group (pregnant rats fed with sufficient normal diet,protein content was 22％),13 to the low-protein group (pregnant rats fed with low protein diet,protein content was 9.2％,but the food consumption was the same as control group) and 14 to the 75％ lowprotein group (pregnant rats fed with low-protein diet,protein content was 9.2％,the food consumption was 75％ of the control group).All female rats were fed with sufficient normal diet after delivery.The body weight,overall weight gain during gestation,the mortality rate and the non-delivery rate of pregnant rats were compared.The third day's newborn weight after birth,FGR incidence and the mortality rate within three days after birth of newborns were also compared.One way analysis of variance,LSD-t test,independent sample t-test and Chisquare test were used as statistical methods.Results (1) The body weight of pregnant rats:There was no significant difference in body weight among the three groups at gestational day 0,3 and 6.On day 9,body weight of 75％ low-protein group [(271.9±8.4) g] and low-protein group [(274.1 ±7.8) g] were significantly lower than that of the control group [(287.2± 18.7) g] (t=2.514 and 2.170,both P＜0.05),but there was no significant difference between the former two groups.On Day 12,body weight of 75％ low-protein group [(275.7 ± 10.7) g] and low protein group [(285.1 ± 12.5) g] were significantly lower than that of the control group [(306.4±29.7) g] (t=3.262 and 2.218,both P＜0.05),and the difference between the former two groups was also statistically significant (t=2.098,P＜0.05).Before delivery,body weight of 75％ low-protein group,low protein group and control group were (300.4±14.1) g,(317.0±16.3) g and (372.9±19.1) g,respectively with statisticall significance (F=64.219,P＜0.05).The overall weight gain during pregnancy for 75％low-protein group,low-protein group and control group was (61.6± 19.8) g,(81.8±21.6) g and (139.3± 12.0) g,respectively.The difference among the three groups was statistically significant (F=55.863,P＜0.05).(2) The mortality rates of pregnant rats for 75％ low-protein group,low-protein group and control group were 3/14,2/13 and 1/11 respectively without significant difference (P＞0.05).Neither was the non-delivery rate within 30 days (embryonic resorption) for the three groups (1/14,1/13,0/11,P＞0.05).(3) The numbers of pups were 101 in 75％ low-protein group,104 in low-protein group and 107 in control group.The newborn mortality rate within three days after birth was 28.7％ (29/101) in 75％ tow-protein group and 23.0％ (24/104)in low-protein group,with were significantly higher than that of the control group (7.5％,8/107) (x2=16.022and 9.976,both P＜0.05),but there was no significant difference between groups.The third day's newborn weight after birth for 75％ low-protein group,low-protein group and control group were (6.3 ±0.8) g,(6.9±0.9) g and (8.1 ±0.9) g,the difference was statistically significant (F=90.602,P＜0.05).FGR incidence for 75％ low-protein group was 55.6％ (40/72),which was significantly higher than that of the low-protein group (28.8％,23/80) and the control group (5.0％,5/99) (x2=11.220,54.834 and 18.833 all P＜0.05).Conclusion 75％ low-protein diet feeding during pregnancy is an ideal method to induce FGR rat model with high FGR incidence,whereas and low mortality rates of pregnant rats,the fetuses and newborns. Key words: Diet, protein-restricted; Fetal growth retardation; Disease models, animal