Dietary vitamin B12, sulfur amino acids, and odd-chain fatty acids affect the response of rats to nickel deprivation
1993
Nielsen, Forrest H. | Uthus, Eric O. | Poellot, Rhonda A. | Shuler, Terrence R.
An experiment was performed to ascertain whether changing the dietary intake of two substances, cystine and margaric acid (heptadecanoic acid), that affect the flux through pathways involving the two vitamin B-12-dependent enzymes, methionine synthase and methylmalonyl-CoA mutase, would affect the interaction between nickel and vitamin B-12. Rats were assigned to treatment groups of six in a fully crossed, four-factorial arrangement. The independent variables, or factors were: per kg of fresh diet, nickel analyzed at 25 and 850 mu-g; vitamin B-12 supplements of 0 and 50 mu-g; margaric acid supplements of 0 and 5 g; and L-cystine supplements of 0 and 12 g. The diet without cystine was marginally deficient in sulfur amino acids. Nickel affected growth, liver wt/body wt ratio (LB/BW), and a number of variables associated with iron, calcium, zinc, copper, and magnesium metabolism. Most of the effects of nickel were modified by the vitamin B-12 status of the rat. In numerous cases, the interaction between nickel and vitamin B-12 was dependent on, or altered by, the cystine or margaric acid content of the diet. Thus, the findings showed that the extent and the direction of changes in numerous variables in response to nickel deprivation varied greatly with changes in diet composition. These variables include those previously reported to be affected by nickel deprivation, including growth and the distribution or functioning of iron, calcium, zinc, copper, and magnesium. The findings also support the hypothesis that nickel has a biological function in a metabolic pathway in which vitamin B-12 is important.
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