IMPACT OF AGE AND VITAMIN A SUPPLEMENTATION ON THERMOGENIC FACTORS IN A RAT MODEL OF CHILDHOOD OBESITY RISK

Open Access
Author:
Weaver, Alexis L
Area of Honors:
Nutritional Sciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. A. Catharine Ross, Thesis Supervisor
  • Alison Diane Gernand, Honors Advisor
Keywords:
  • Vitamin A
  • Childhood Obesity
  • Thermogenesis
  • Rat Model
  • Nutrition
Abstract:
Childhood obesity is major global health issue, affecting both developed and developing countries throughout the world. Despite the efforts of many health professionals, the percentage of children suffering from obesity has not been reduced over the last 15 years. Vitamin A (VA) deficiency is another troubling global health problem that affects many people, causing disorders like xerophthalmia or even early death. Recent studies have found that early postnatal supplementation of VA can increase expression of uncoupling protein 1 (UCP1), found in the brown adipose tissue of small mammals. Additional studies have found that a mixture of VA and retinoic acid (VARA) can ‘carry over’ some modifications in gene expression into later adolescence when compared to VA alone. This study aimed to determine if early postnatal VA supplementation will increase the expression of UCP1, and will therefore increase energy expenditure and promote weight loss in rats that are at a marginal VA status and on a high fat diet. Moreover, the study aimed to test if VARA could maintain a level of increased UCP1 expression in later adolescence compared to VA supplementation. Three treatment groups were created to test this hypothesis - VA, VARA, and placebo - and all groups were dosed and euthanized at a set schedule in order to mimic life stages of the human neonate and adolescent. Retinol content was measured using UPLC and genetic expression of UCP1 was determined by (q)RT-PCR. UPLC results indicated that VA and VARA supplementation increased tissue concentration of VA by more than 2 fold immediately after dosing, but returned to normal after several days. Furthermore, no significant change was found between the three groups with regard to UCP1 expression. In conclusion, while retinol was able to enter the BAT, neither VA nor VARA supplementation increased UCP1 mRNA expression, thus refuting our hypothesis.