Date of Award
Doctor of Philosophy
John T. Smith
Frances A. Schofield, Lura M. Odland, Ada Marie Campbell
When animals are fed a low-sulfate diet from two weeks of age and transferred to a diet low in sulfate and without cod-liver oil developed a gross malformation of the hind limbs during the period of most active growth, as study of the effect of this procedure upon the metabolism of sulfate by the animal was planned. An interaction between inorganic sulfur and cod-liver oil in the normal metabolism of the albino rat was proposed.
The basic diet contained 0.0002 per cent of inorganic sulfur and adequate levels of organic sulfur as sulfur amino acids; four variations, with and without cod-liver oil and with and without vitamin E, were used. Cod-liver oil fractions and 0.10 per cent of sulfate as calcium sulfate were included in the diets for some of the experiments. Effects upon the growth, feed utilization, and over-all appearance were observed in the intact animals. Sulfate-S35 was injected subcutaneously; the specific activity of sulfomucopolysacchride from costal cartilage was determined, and autoradiograms of section from the proximal tibial epiphysis were prepared. Adjacent sections were stained with a variety of dyes. The animals used were of both sexes and of two strains of laboratory stock white rats. They were fed the diet from weaning for periods of three to twenty-one weeks in the various experiments. Female animals raised on the experimental diets and mated with stock colony males produced normal litters of young.
The addition of cod-liver oil to the diet resulted in an increased uptake of an injected dose of sulfate-S35 into the costal cartilage mucopolysacchharide. The cartilage of the epiphyseal plate had more uniform distribution of radiation 24 hr. after S35 injection. the animals without cod-liver oil had a greater accumulation of activity in their chondrocytes. The cartilage plates of animals after three or four weeks of consuming the diet without cod-liver oil were decreased in width; this was not seen in older animals. In general, the addition of cod-liver oil to the diet improved the growth and the efficiency of feed utilization and decreased the incidence of abnormal symptoms. There was an influence due to sex and to strain of the animal. The Tennessee males demonstrated a sensitivity to dietary regime by growth differences; the females, by changes in the sulfate content of their cartilage. The Dublin males were more sensitive to vitamin E deficiency. The Dublin females also demonstrated the decreased sulfomucopolysacchride-S35 uptake when cod-liver oil was omitted from an otherwise adequate diet.
Many of the possible causes of abnormal sulfation could be eliminated since the animals used for tissue and autoradiographic analysis grew and functioned normally. The changes were not the result of abnormally high or low vitamin A or D intakes. Vitamin E influenced the results probably through its role in the oxidation of sulfur amino acids to sulfate. The "prepping" procedure exerted an influence upon the reaction of the animal, possibly through decreasing the stores of sulfate and vitamin E present at weaning.
It was concluded that the cod-liver oil contained a factor which enhanced normal production of sulfated mucopolysacchrides, without which under the appropriate stress conditions the animals exhibited the gross lesion initially observed. Whether the factor was specifically a sulfolipid fraction of the oil is not known. It was concluded that the site of action was the cell membrane where increased permeability, resulting from the incorporation of long-chain, highly unsaturated fatty acids of the oil into the structural lipid of the chondrocyte membrane, facilitated the passage of the sulfomucopolysacchride from the cell. The low-sulfate content of the diet placed a stress on the production of sulfomucopolysaccharides and made this effect apparent. It was suggested that similar stresses upon the sulfate supply in protien deficiency are responsible for other lesions now attributed to the lack of protein alone.
Button, Grace Marcia, "The Influence of Cod-liver Oil upon the Metabolism of Sulfur in the Albino Rat. " PhD diss., University of Tennessee, 1965.