title: Magnesium deficiency differentially affects the retina and visual cortex of intact rats.
abstract: To determine the influence of magnesium (Mg) on the visual system, electroretinograms (ERG) and visual evoked potentials (VEP) were recorded under dark-(DA) and light-adapted (LA) conditions in intact rats. Weanling rats were fed either a Mg-deficient (Mg-D) or a control diet for 17 d before the tests, and ERG, VEP and immunohistopathological analyses of retinae and cortices were made. In the Mg-D rats, ear congestion, hair loss and loss of body weight were observed, and serum Mg concentration was approximately 25% of that in the control rats (P < 0.01). The amplitudes of the DA a-wave and the second positive peak of the oscillatory potentials (OP2) of the ERG, and the negative component of the VEP (N1) in Mg-D rats were significantly greater than those of control rats. However, the amplitudes of the DA b-wave, LA 2 Hz b-wave, the 20 Hz flicker responses and the implicit times of all response components did not differ between the two groups. The immunohistopathologic results also were not altered in the Mg-D rats. We suggest that the functional abnormalities induced by Mg deficiency may depend not only on the hyperactivity of the N-methyl-D-aspartate (NMDA) receptor, but also on the behavior of the Ca(2+) and Mg(2+) ions in the intact eye.
authors.affiliation: Department of Clinical Neurophysiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. ygoto@neurophy.med.kyushu-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Goto
authors.forename: A
authors.initials: A
authors.lastname: Furuta
authors.forename: S
authors.initials: S
authors.lastname: Tobimatsu
mesh_terms: D000818:Animals; D004596:Electroretinography; D005074:Evoked Potentials, Visual; D008275:Magnesium Deficiency / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000503:physiopathology*; D014793:Visual Cortex / Q000503:physiopathology*