[Experimental studies on microphthalmos formation in neonatal rats treated with monosodium-L-glutamate]

Changes in the eyeball size were investigated in rats treated with monosodium glutamate (MSG) during the neonatal period. Correlations among ocular size and degenerative changes of the retina and optic nerve were also studied ophthalmoscopically and histologically. Rats received MSG 5 times, 2 times or once. In rats which received MSG 5 times, the administration was made at 1, 3, 5, 7 and 9 days of birth. In rats, which received MSG 2 times, the administration was made on 2 subsequent days (1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10, 12 and 13 or 15 and 16 postnatal days). In the group of rats, which received MSG once, the administration was made on each from the 1st to the 15th postnatal day. Microphthalmos formation was clearly observed only in rats with 5 times and 2 times (9 and 10 days) injection of MSG. In these rats, narrowing of retinal vessels, paleness and excavation of optic disks were observed ophthalmoscopically. Total liquefaction of the vitreous body were seen in the same groups. Histological examinations also revealed degeneration of the inner layers of the retina. These findings indicated that the administration of MSG at critical stages during postnatal development induces disturbances of eyeball growth. It was also suggested that the growth of the eyeball is closely associated with the postnatal development of the retina.