Effects Of Intrauterine Growth Restriction During Late Pregnancy On Fetal Thymus Cell Proliferation Of Mongolia Ovine And Underlying Mechanisms

This paper mainly investigated the effects of intrauterine growth restriction during late pregnancy on liver cell proliferation and gene expression involved in Mongolia ovine fetus. The techniques of synchronous estrus and artificial insemination were applied on 24 Mongolian ewes, which had similar live weight.6 ewes were slaughtered at 90 d of gestation and the remaining animals were allocated to three different groups:Restricted Group1 (RG1,0.175 MJME·BW-0.75·d-1, n=6), Restricted Group2 (RG2,0.33 MJME·BW-0.75·d-1, n=6) and Control Group (CG, ad libitum,0.67 MJME·BW-0.75·d-1, n=6). At 140 d of gestation,6 ewes in each group were slaughtered.(1) With the decreasing of the dietary energy density during late pregnancy, fetal weight(p<0.01), thymus weight(p<0.01), total DNA content(p<0.01),index of proliferation(p<0.05) and PCNA(p<0.01) were significantly lower in RGl,the percentages of G0-G1 phase cells in RG1 group(p<0.05) was significantly increase; the fetal weight(p<0.01), thymus weight(p<0.05), total DNA content(p<0.05) were lower in RG2 group, which is one of the important reasons for the limited cell proliferation.(2) The RG1 GHR (p<0.01), IGF-1R (p<0.01), IGF-2R (p<0.01),CyclinB (p<0.05),CyclinD (p<0.05),CDK1 (p<0.05),CDK2 (p<0.01),CDK4 (p<0.01), E2F1 (p<0.01),E2F4 (p<0.01),E2F5 (p<0.01) were significantly lower than CG group, The RG2 GHR (p<0.01),IGF-1R (p<0.05),CDK1 (p<0.05),CDK2 (p<0.01),CDK4 (p<0.01), E2F1 (p<0.05), E2F5 (p<0.01) were significantly lower than CG, IGF-2R, CyclinB, E2F4 were trend of decrease(p>0.05).(3) The RG1 group of growth hormone (p<0.01), insulin-like growth factor 1 (p<0.05), insulin-like growth factor 2 (p<0.01), GHR (p<0.05),IGF-1R (p<0.05),IGF-2R (p<0.05),CyclinA (p<0.05),CyclinB (p<0.05),CyclinD (p<0.05),CyclinE (p<0.05), E2F2 (p<0.05) were significantly lower than CG group; IGFBP-1 was significantly higher than CG (p<0.05), E2F1、E2F4、E2F5 were trend of increase(p>0.05), CDK1、CDK2、 CDK4 were trend of decrease(p>0.05); The RG2 IGFBP-2 (p<0.01), GHR (p<0.05) were significantly lower than CG, IGFBP-1 significantly higher than CG (p<0.05),The protein CyclinA, CyclinB, CyclinD, CyclinE, CDK1, CDK2, CDK4, E2F2 were trend of decrease(p>0.05), E2F1, E2F4, E2F5 were trend of increase(p>0.05).