Lipofuscin accumulation in extraocular muscle of rats deficient in vitamins E and A

The influences of vitamin E and A deficiencies on the formation of lipofuscin in two different muscle fiber types of the extraocular muscle were tested. Weanling female albino rats (Sprague-Dawley) were divided into three groups and fed purified diets that were adequate or deficient in vitamin E and A: +E, +A; -E, +A; and -E, -A. After 35 weeks on this diet, the animals were killed for analysis of extraocular muscle. When examined by fluorescence microscopy, the extraocular muscle of the (-E, +A) rats showed more lipofuscin-specific fluorescence than the (+E, +A) and (-E, -A) rats. Lipofuscin was then further analyzed by electron microscopy (EM), using morphometric analysis. By this high-resolution technique, the increased lipofuscin of the (-E, +A) extraocular muscle was seen to be confined mostly to the type I fibers. The type II fibers were quite insensitive to vitamin E deficiency: in type II fibers, the (-E, +A) and (-E, -A) muscle showed very small amounts of lipofuscin, and the (+E, +A) showed none at all. Vitamin A has an influence on vitamin E-deficiency and appears to be involved in the formation of lipofuscin in type I muscle fibers of the extraocular muscle.