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Type: Thesis
Title: The impact of maternal overnutrition during the periconceptional period on the development of postnatal obesity in the sheep.
Author: Rattanatray, Leewen
Issue Date: 2010
School/Discipline: School of Molecular and Biomedical Science
Abstract: Women who enter pregnancy with an increased body weight have an increased risk of developing gestational diabetes later in pregnancy and of having a baby with a high birth weight and fat mass who is also at an increased risk of becoming overweight or obese in childhood or later adult life. It is not known, however, whether exposure of the oocyte and embryo during the periconceptional period alone to maternal obesity is associated with an increased risk of obesity in the offspring, and if so, whether the impact of maternal obesity can be ameliorated by maternal weight loss immediately before conception. The present study has investigated in sheep, whether, a high plane of maternal nutrition before and immediately after conception leads to the programming of an increased expression of adipogenic and lipogenic genes and fat mass in the offspring and whether a period of dietary restriction in overnourished mothers reverses these changes. Non pregnant ewes (n=23) were randomly assigned to one of four treatment groups, either control-control (CC) maintained at 100% maintenance energy requirements (MER) for at least 5 months prior to conception, control-restricted (CR) maintained at 100% MER for the first 4 months, then 1 month before conception were placed on a dietary restriction to 70% MER, high-high (HH) maintained ad libitum (170-190% MER) for 5 months prior to conception or high-restricted (HR) maintained at ad libitum for 4 months, and then 1 month before conception were placed on an energy-restricted diet (70% MER). To determine the effect of overnutrition in the periconceptional period only, single embryos were then transferred to recipient ewes which were maintained on a control diet (100% MER) for the remainder of pregnancy. All ewes were allowed to give birth naturally. At 4 months of age, lamb fat depots were weighed and samples collected for the measurement of mRNA expression for genes regulating adipogenesis and lipogenesis by quantitative real-time PCR. The studies in this thesis have shown that periconceptional overnutrition increased total fat mass in female lambs at 4 months of age. This change was not associated with an increase in peroxisome proliferator-activated receptor γ, leptin or adiponectin expression in the perirenal, omental and subcutaneous fat depots. The period of dietary restriction in overnourished ewes ablated this effect. These findings suggest that the effects of periconceptional overnutrition on the oocyte or early embryo alters the subsequent development of adipose tissue, and that the impact of periconceptional overnutrition may be reduced by a period of dietary restriction prior to entering pregnancy.
Advisor: McMillen, Isabella Caroline
Schwartz, Jeffrey
Dissertation Note: Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2010
Keywords: periconception; overnutrition; obesity; sheep
Provenance: Copyright material removed from digital thesis. See print copy in University of Adelaide Library for full text.
Appears in Collections:Research Theses

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