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Riboflavin deficiency, metabolic rate and brown adipose tissue function in sucking and weanling rats
1MRC Dunn Nutritional Laboratory, Cambridge.
Insights
Riboflavin deficiency impacts rat growth and energy metabolism differently across age groups. Weanling rats showed increased oxygen consumption, suggesting better adaptation to deficiency through enhanced thermogenesis.
Area of Science:
- Biochemistry
- Nutritional Science
- Physiology
Background:
- Riboflavin (Vitamin B2) is crucial for cellular energy metabolism.
- Deficiency can impair growth and energy utilization.
- Brown adipose tissue plays a key role in thermoregulation.
Purpose of the Study:
- To investigate the effects of riboflavin deficiency on growth, oxygen consumption, and brown adipose tissue function in rats.
- To compare the impact of deficiency across different life stages: sucking pups, weanling rats, and dams.
Main Methods:
- Experimental induction of riboflavin deficiency in three groups of rats.
- Measurement of growth rate, whole-body oxygen consumption, erythrocyte glutathione reductase activity, and brown adipose tissue GDP-binding capacity.
- Comparison with weight-matched, pair-fed, and ad libitum-fed control groups.
Main Results:
- Riboflavin deficiency reduced growth rate and increased erythrocyte glutathione reductase activation coefficient in all groups.
- Sucking pups exhibited reduced O2 consumption, while weanling rats showed increased O2 consumption, particularly after noradrenaline stimulation.
- Brown adipose tissue cytochrome c oxidase activity was unaffected, but GDP-binding increased in deficient weanling rats.
Conclusions:
- Weanling rats demonstrated a greater ability to cope with riboflavin deficiency, potentially due to increased non-shivering thermogenesis.
- The findings suggest adaptive mechanisms in weanling rats that may counteract the negative effects of nutrient imbalance.
- The study discusses implications for thermoregulation in riboflavin-deficient children.
Abstract:
1. The effects of riboflavin deficiency on growth, whole-body oxygen consumption, cytochrome c oxidase (EC 1.9.3.1) activity and GDP-binding capacity of brown adipose tissue were measured in three groups of rats: sucking pups, weanling rats, and dams. Control groups were weight-matched, pair-fed or fed ad lib. 2. Riboflavin deficiency reduced growth rate and increased the activation coefficient of erythrocyte glutathione reductase (NAD(P)H) (EC 1.6.4.2), as predicted. In sucking pups it also reduced whole-body O2 consumption per unit body-weight, especially after noradrenaline stimulation. In weanling rats, however, it increased O2 consumption both before and after noradrenaline stimulation. 3. Cytochrome c oxidase (EC 1.9.9.1) activity of brown adipose tissue was not consistently affected by riboflavin deficiency. Binding of [3H]GDP to the mitochondria was increased in the deficient weanling rats. 4. Weanling rats therefore, seemed better able to withstand the effects of severe depletion. Their reduced growth and increased non-shivering thermogenesis helped to counteract the unfavourable ratio of riboflavin:other tissue-building materials. The relevance for thermoregulation in riboflavin-deficient children is discussed.