Developmental changes of selected minerals in Zucker rats

Effects of obesity and age on copper, iron, zinc, sodium, potassium, and protein were compared in liver, kidney, brain, and muscle of obese (fa/fa) and nonobese (non-fa/fa) male Zucker rats. Blood plasma cerulopasmin, copper, zinc, sodium, and potassium were also determined. Mean brain weight of fa/fa rats was less than that of non-fa/fa rats at 12 weeks of age; mean brain protein concentration was greater in fa/fa than in non-fa/fa at 5 and 12 weeks of age. At 18-19 days of age, mean sodium concentration (mg/g protein) in liver of fa/fa was less than that of non-fa/fa. At 5 weeks of age, mean copper concentration (microgram/g protein) in kidney was greater in fa/fa. Mean total copper, iron, zinc, sodium, and potassium in liver and kidney were greater in fa/fa than in non-fa/fa at 5 weeks because of the larger livers and kidneys of fa/fa. Mean concentrations of copper, zinc, sodium, and potassium per gram of brain protein were slightly (6-10%) less in fa/fa than in non-fa/fa at 5 weeks. By 12 weeks, mean concentrations of copper in liver, kidney, (tibialis) muscle, and blood plasma, ceruloplasmin in blood plasma, zinc in liver and muscle, iron in muscle, and sodium in liver were greater in fa/fa than in non-fa/fa. However, total amount of each mineral in muscle at 12 weeks was less in fa/fa than in non-fa/fa because of the smaller mean muscle weight of fa/fa. Mean concentrations of copper and zinc in brain and of iron in liver and brain were less in fa/fa than in non-fa/fa at 12 weeks. The major age-related changes in fa/fa that were not observed in non-fa/fa were large increases in liver and kidney copper between 5 and 12 weeks of age. It seems that the abnormal mineral metabolism is a consequence of the obesity, but the mechanisms are not identified.