Oxygen-induced retinopathy in newborn rats: orthograde axonal transport changes in optic pathways.

The aim of this study was to evaluate axonal transport along the optic pathways of neonatal rats in which oxygen-induced retinopathy had been experimentally produced. One group of 116 rats was exposed to an FiO2 of 80% for the first 5 days of life and then kept under room-air conditions for the following 10 days. A second group of 108 rats was maintained under room-air conditions for the first 15 days of life. On the 16th day of life, 1.5 microliter of [35S]taurine was injected into the vitreous of the right eye of each animal and radioactivity was measured, at various intervals from the injection, in the right optic nerve, the chiasma and the left optic tract. Statistically significant reductions in axonal transport were observed in all three segments of the optic pathways of the oxygen-supplemented animals compared with the control group. The authors discuss various explanations for their findings and hypothesize that the alterations observed in this study may have significant and more or less long-term effects on the normal maturation of the visual system.