Rat Models Of Intrauterine Growth Restriction Established By Maternal Food Restriction And The Effects On Main Organs In Newborn Rats

Objectives To compare the different methods of maternal food restriction during pregnancy in modelling intrauterine growth restriction (IUGR) rats,and to compare the effects of different maternal rats food restriction on main organs in the newborn rats small for gestational age(SGA).Methods Pregnant rats were randomly assigned to four groups: three food restriction groups and one control group. The food restriction groups were given middling food restriction throughout pregnancy, severe food restriction from pregnant day 14, and severe food restriction from pregnant day 7,respectively. Compare the effects of maternal rats food restriction on newborn rats in growth, main organs' weights,and the rate of SGA occurrence. And the histiocyte morphology of cerebra and stomachs were observed.Results SGA risk was the highest (62.2 % ) in middling food restriction throughout pregnancy group. The weights, heights, tail lengths, and weights of cerebra, hearts, lungs, livers, stomachs, spleens, and kidneys of newborn rats from food restriction groups were significantly different to those from control group (P＜0.05) . Histiocyte morphology changes were visible in cerebra and stomach mucous membrane in SGA rats. method to establish IUGR model. Food restriction during pregnany will result in histiocyte morphology changes with cerebra and stomach in newborn rats. Objectives To explore the changes of Ghrelin mRNA and protein expression in fundus of stomach of rats born small for gestational age (SGA) and to analyze the relationship with the catch-up growth of postnatal rats with SGA.Methods The intrauterine growth restriction(IUGR) models were respectively established by middling food restriction throughout pregnancy, severe food restriction from pregnant day 14, and severe food restriction from pregnant day 7. The newborn rats were acquired after delivery, among which 10 rats were selected randomized from each group at postnatal day 0,day 20 and day 40, and their weights,lenghts of bodies and tails were measured and recorded before being executed. The fundus of stomach were taken to determine Ghrelin mRNA and protein expression, in which real-time fluorescence quantitive PeR (real-time FQ-PCR) and immunohistochemistry (IHC) were used respectively. Both Ghrelin mRNA and protein expression were compared among SGA rats from food restriction groups,AGA rats from food restriction groups and AGA rats from control group at postnatal day 0, and also were compared among SGA non-catching-up rats, SGA catching-up rats and normal AGA rats at postnatal day 20 and day 40. Results At postnatal day 0 , stomach fundus Gherlin mRNA expression is higher in SGA rats from food restriction groups than those in AGA rats from food restriction or control groups (p＜0.05). At postnatal day 20 and day 40, there is no significant difference in stomach fundus Gherlin mRNA expression among SGA non-catching-up rats, SGA catching-up rats and normal AGA rats (p＞0.05) . At postnatal day 0, stomach fundus Gherlin IOD in SGA rats from food restriction groups is higher than AGA rats from food restriction and control groups (p＜0.05). Ghrelin IOD in SGA catching-up rats is higher than SGA non-catching-up rats and normal AGA rats (p＜0.05) at postnatal day 20, and there is no significant difference among them at postnatal day 40 (p＞0.05) .Conclusion The increase of Ghrelin mRNA expression in stomach fundus of SGA rats of postnatal day 0 suggests that Ghrelin might be involved in the physiological regulation or pathological process of IUGR, and intrauterine nutritional status or endocrine circumstances may have effects on the cells of gastric fundus of the fetuses, which results in the up-regulation of Ghrelin expression. The changes of endogastric Ghrelin expression in postnatal day 20 catching-up SGA rats suggests that Ghrelin might be involved in the regulation of SGA catch-up growth in early life, which still need to be determined. Objectives To explore the changes of Growth hormone secretagogue receptor(GHSR) mRNA and protein experssion in hypothalamus of rats born small for gestational age(SGA), and to analyze the relationship with the catch-up growth of postnatal rats with SGA.Methods The intrauterine growth restriction(IUGR) models were respectively established by middling food restriction throughout pregnancy,severe food restriction from pregnant day 14, and severe food restriction from pregnant day 7. And the newborn rats were acquired after delivery. 10 rats were selected randomized from each group at postnatal day 0, day 20 and day 40, and their weights, lenghts of bodies and tails were measured and recorded before being executed. The hypothalamus were taken to determine GHSR mRNA and protein expression, in which real-time fluorescence quantitive PCR (real-time FQ-PCR) and immunohistochemistry (IHC) were used respectively.Both GHSR mRNA and protein expression were compared among SGA rats from food restriction groups, AGA rats from food restriction groups and AGA rats from control group at postnatal day 0, and also were compared among SGA non-catching-up rats, SGA catching-up rats and normal AGA rats at postnatal day 20 and postnatal day 40. Results At postnatal day 0, hypothalamus GHSR mRNA expression is lower in SGA rats from food restriction groups than those in AGA rats from food restriction or control groups (p＜0.05). At postnatal day 20, hypothalamus GHSR mRNA expression is higher in SGA catching-up rats than those in SGA non-catching-up rats from food restriction groups or AGA rats from control group (p＜0.05). And at postnatal day 40, there is no significant difference in GHSR mRNA expression among SGA non-catching-up rats, SGA catching-up rats and normal AGA rats (p＞0.05) . At postnatal day 0, there is no significant difference in hypothalamus GHSR IOD among SGA rats from food restriction groups, AGA rats from food restriction groups and AGA rats from control group (p＞0.05). Hypothalamus GHSR IOD in SGA catching-up rats is higher than SGA non-catching-up rats and normal AGA rats at postnatal day 20 (p＜0.05) , and there is no significant difference among them at postnatal day 40 (p＞0.05).Conclusion Maternal food restriction and energy deficiency during pregnancy may impair GHSR cells in hypothalamus of fetal rats, which may lead to a decrease of GHSR mRNA expression in newborn SGA rats. GHSR expression in hypothalamus may be recovered after a period of postnatal time in some SGA rats, and may be involved in their catch-up-growth. The Ghrelin-GHSR system may play an important role in SGA rats' catch-up growth regulation before puberty.