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Ultrastructure of the optic nerve in magnesium-deficient rats
Huaqing Gong1, Yumiko Takami, Tsugio Amemiya
1Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
Purpose:
The ultrastructure of the optic nerves in magnesium (Mg)-deficient rats was studied to elucidate the function of Mg.
Methods:
After delivery, mother Wistar Kyoto rats were fed a low-Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The optic nerves were examined by electron microscopy at 6 weeks of age.
Results:
In the Mg-deficient rats, serum Mg levels were significantly lower and calcium levels higher than in the control rats. Ultrastructural findings were: significantly fewer myelinated axons and significantly thinner myelin sheaths in the Mg-deficient rats than in the control and pair-fed controls, and more numerous unmyelinated axons. There were multifocal areas of destruction and necrosis in the optic nerve of Mg-deficient rats.
Conclusions:
This study suggests that the optic nerve needs Mg for the development and maintenance of its cell structure.