Effect of sucrose feeding on glucose tolerance and their relationship with lipid metabolism in maternal and fetal livers in rat

Differential effects of habitual chow-based and semi-purified diets on lipid metabolism in lactating rats and their offspring

Diet during pregnancy and lactation is a critical factor in relation to the health of dams and their offspring. Currently, control diets used in metabolic imprinting studies differ in composition and type, i.e. semi-purified diets (SD) or chow-based diets (ND). The aim of the present study was to determine whether two widely used control diets, a SD and a ND, that mainly differ in fat content (5·08 and 3·26 %, respectively) and its sources (soyabean oil for the SD and cereals and fish for the ND), fibre (6 and 15 %, respectively), and cholesterol (26 and 69 mg/kg diet, respectively) can influence the lipid metabolism of dams and their offspring. Wistar rats were fed either the SD or the ND during pregnancy and lactation. At weaning, SD-fed dams presented severe hepatic steatosis and increased levels of circulating TAG, NEFA and insulin. Importantly, the offspring presented an altered plasma lipid profile. In contrast, the ND allowed for a normal gestation and lactation process, and did not affect the metabolism of offspring. In parallel, virgin rats fed the SD showed no metabolic alterations. A higher intake of SFA and MUFA and a lower consumption of PUFA observed in SD-fed dams during the lactation period could contribute to explaining the observed effects. In conclusion, two different control diets produced very different outcomes in the lipid metabolism of lactating rats and their offspring. The present results highlight the importance of the assessment of the metabolic state of dams when interpreting the results of metabolic programming studies.

Maternal chocolate and sucrose soft drink intake induces hepatic steatosis in rat offspring associated with altered lipid gene expression profile

AIM

According to the World Diabetes Foundation, there is an urgent need to investigate the impact of maternal health and nutrition during pregnancy to understand the background for the accelerating incidence of obesity and type 2 diabetes. In this study, we specifically concentrated on the role of overfeeding during different developmental periods.

METHODS

Sprague-Dawley rats were offered chow or high-fat/high-sucrose diet (chow plus chocolate and soft drink) during gestation and lactation. At birth, offspring were randomly cross-fostered within each dietary group into small and normal litter sizes until weaning, giving four dietary groups.

RESULTS

At postnatal day 1, offspring from high-fat/high-sucrose-fed dams were heavier and had increased hepatic triglycerides (TG), hepatic glycogen, blood glucose and plasma insulin compared with offspring from chow-fed dams. Hepatic genes involved in lipid oxidation, VLDL transport and insulin receptor were down-regulated, whereas FGF21 expression was up-regulated. Independent of postnatal litter size, offspring from high-fat/high-sucrose-fed dams aged 21 days had still increased hepatic TG and up-regulated FGF21 expression, while plasma insulin started to decrease. Litter size reduction in offspring from high-fat/high-sucrose-fed dams further increased body weight and adiposity, and up-regulated genes involved in hepatic mitochondrial lipid oxidation and VLDL transport compared with all other groups. Litter size reduction did not have any impact on body weight gain and adiposity in offspring born to chow-fed dams.

CONCLUSION

Our results suggest that supplementation of chocolate and soft drink during gestation and lactation contributes to early onset of hepatic steatosis associated with changes in hepatic gene expression and lipid handling.

Sucrose feeding effects inhibition of gamma-glutamyltranspeptidase in the liver of the rat: possible mediation by thyroid hormone

The effect of sucrose on Fischer 344 rat liver gamma-glutamyltranspeptidase (gammaGT) was studied: in adults fed sucrose for 3 weeks; and rats exposed to sucrose from the 18th day of gestation to the 40th day after birth. Rats fed regular rodent chow served as controls. Sucrose caused mild lipemia; and in the liver an increase in size and fat build-up without damage. In adult sucrose-fed rats, compared to controls, plasma glucose levels were increased: 1.12-, 1.40- and 1.13-fold after 24, 48h and 3 week consumption of sucrose, respectively. Insulin levels were unaltered for the first week of sucrose consumption but increased from control levels: 16% at 1 week, and 2.0-fold at 3 weeks. The T3 levels were comparable to control levels 24h after the sucrose was started and were increased: 1.22-, 1.13- and 1.12-fold at 48h, 1 and 3 weeks, respectively. The T4 levels were comparable at all time points between sucrose-fed and control rats. Liver gammaGT activity exhibited a steady decrease from control levels: after 24, 48h, 1 and 3 weeks of sucrose feeding the decrease was 5, 8, 21 and 37%, respectively in homogenates; and 10, 17, 24 and 41%, respectively in plasma membranes. Perinatal sucrose exposure effected in 40-day-old rats, compared controls: a 1.09-fold increase in plasma glucose; no change in plasma insulin; an increase of 1.15- and 1.39-fold in plasma levels of total and free T3, respectively; a decrease of 20 and 14% in plasma levels of total and free T4, respectively. gammaGT activity was decreased in liver plasma membranes isolated from sucrose-exposed rats relative to those of control: 80% in the male; 82% in the female. Relative specific activities of gammaGT were the same in both males: 15.4 and 16.1 in control and sucrose-exposed male rats, respectively; and females: 14.1 and 15.4 in control and sucrose-exposed female rats, respectively. gammaGT was 2-fold higher in the livers of female relative to male rats in sucrose-exposed and control groups. Kidney gammaGT activities were the same in control and sucrose-exposed rats. The involvement of T3 in the sucrose-induced decrease in liver gammaGT is discussed.