Early effects of sodium iodate injection on ERG in mice

The electroretinogram (ERG) was recorded in 15 ICR albino mice before and 2, 4 and 24 h after injection of 40 mg/kg of NaIO3 and the results were compared with the corresponding ultrastructural findings. Both a- and b-wave amplitudes decreased at 2 h after injection and increased at 4 h to the levels before injection and further increased at 24 h after injection. The b-wave threshold intensity increased by 2.1 log units at 2 h after injection. Thereafter, it decreased once at 4 h and significantly increased at 24 h by 3.4 log units. Electron microscopic examination showed swollen cytoplasmic organelles of the retinal pigment epithelial cells at 4 h after injection. It was thus demonstrated that an early effect of NaIO3 on the electrical response of the mouse retina was more conspicuous than histopathological changes.