Vitamins are readily available in the modern diet due to liberalized fortification and supplementation policies. This research tested the hypothesis that high multi-vitamin intake by Wistar rats during pregnancy leads to the development of obesity and characteristics of the metabolic syndrome in the offspring. Pregnant Wistar rats were fed the AIN-93G diet containing either the recommended (RV) or 10-fold increase (HV) in vitamin content. Pups were weaned to the RV diet (Study 1), an obesogenic liquid diet (Ob, Study 2), low vitamin diets (1/3RV or 1/6RV, Study 3), or a nutrient selection paradigm (NSP) with 10% and 60% casein diets (Study 4). Body weight (BW), food intake (FI), glucose and insulin responses, appetite hormones, abdominal fat pad mass (FPM) and systolic blood pressure (SBP) was measured. Expressions of mRNA for hypothalamic serotonin (5-HT) receptors and proopiomelanocortin (POMC) were measured in Study 4. Males, but not females, born to HV dams had higher post-weaning BW and FI when weaned to the RV or 1/3RV diet, and exhibited components of metabolic syndrome, including higher FPM, hyperglycemia, insulin resistance and elevated SBP compared with those born to RV dams. The Ob diet led to exaggerated weight gain and expressions of components of metabolic syndrome in both sexes born to dams fed the HV diet. Female pups on the 1/6RV diet from HV dams had two-fold higher glucose response and lower insulin response, but no difference in post-weaning BW and daily FI compared to those from RV dams. In contrast to the pups born to HV dams and fed a single diet, those from the HV dams and on the NSP gained less weight and ate less, and had lower hypothalamic mRNA expressions of 5-HT receptors and POMC. In conclusion, high multi-vitamin intake during pregnancy may lead to obesity, and result in a higher risk of developing characteristics of metabolic syndrome in the offspring. However, sex, weaning diet composition, and the presence of diet choice alter the outcomes.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/29885 |
| Date | 31 August 2011 |
| Creators | Szeto, Ignatius Man Yau |
| Contributors | Anderson, G. Harvey |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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