In male castrated albino rats the incorporation of C14 from acetate-1-C14 into the cholesterol of the liver, the adrenals, and the heart is significantly increased as compared to the incorporation found in the same tissues of control animals. The metabolic C14O2 originating from the injected acetate is not affected by castration, nor is the total activity of the urine. There is, incidentally, a significant increase in adrenal weight following castration.
A large increase in the ascorbic acid content has been shown to occur in the tissues of the white rat (able to synthesize that vitamin) after prolonged exposure and adaptation to cold (+ 4° to − 4 °C.). The increase in ascorbic acid is much smaller if the rats exposed to low temperatures receive daily supplements of that vitamin. On the other hand, a decrease in ascorbic acid content of the tissues has been found in rats unable to adjust themselves to cold environment. From the above results obtained with the white rat, it seems that the acclimatization to low temperatures—and not only maintenance of life at the same temperatures—requires large quantities of ascorbic acid.That conclusion was confirmed by experiments with guinea-pigs (animals that do not synthesize ascorbic acid); the results obtained show that resistance and adaptation of the guinea-pig to cold environment depend on the amount of ascorbic acid received daily; besides, during the process of acclimatization to cold, more ascorbic acid is retained in the tissues of the guinea-pigs exposed to low temperatures than in the same tissues of control animals kept at room temperature; finally, a direct relation has been observed between adaptability to cold environment and the content of ascorbic acid in the adrenals.
The purpose of this research was to investigate the relative value of different diets for conferring on animals resistance to extremes of temperature. These diets were equicaloric and equivitaminic and differed only in the relative proportions of fats, proteins, and carbohydrates. The self-selection method of feeding was used, with rats exposed to low and to high temperatures. The results obtained with this method have been verified on large groups of animals adapted and not adapted to extreme temperatures. It has been found that a diet rich in fats is decidedly superior to one rich in carbohydrates (both diets being equicaloric and equivitaminic) for adaptation and resistance to cold on the part of the animals, and that a diet rich in carbohydrates and poor in fats is much more favourable than one rich in fats for conferring resistance to heat.
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