Retinal changes in magnesium-deficient rats

The purpose of the present study is to investigate the retina in magnesium (Mg) deficiency and elucidate the local functions of trace elements. After delivery, mother Wistar Kyoto rats were fed a low Mg diet containing 0.1 mg Mg per 100 g diet with all other nutrients and distilled and deionized wat er. Infant rats were suckled by their mother rats for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pel lets containing 24 mg Mg per 100 g diet and all other nutrients. The retina s were examined by electron microscopy and secondary ion mass spectrometry (SIMS) microscopy at 6 weeks of age. In the Mg-deficient rats serum Mg leve ls were significantly lower and calcium (Ca) levels higher than in the cont rol rats. The retinas of Mg-deficient rats showed multifocal necrosis in th e pigment epithelial cells; photoreceptor cell outer segments were deformed near the necrotic cells, and some pigment epithelial cells contained many lamellar bodies. Many photoreceptor cell nuclei showed pyknotic (apoptosis- like) changes. SIMS images showed lower Mg concentration throughout the ret ina of the Mg-deficient rats, and the ratio of Ca to Mg concentration was s ignificantly higher than in the control rats. Mg deficiency induces multifo cal necrosis in the retinal pigment epithelial cells and pyknotic (apoptosi s-like) changes in the photoreceptor cell nuclei. The changes in Mg-deficie nt retinas may be due to an imbalance in the distribution of Mg and Ca trac e elements. (C) 2000 Academic Press.