Changes in the incorporation of [ 14C] orotic acid into brain RNA of visually deprived rats following exposure to light

Abstract

Newly-weaned rats that had been kept in the dark from birth were injected intraventricularly with [ 14C]orotic acid. Experimental rats were exposed to light for 2 hr and dark controls were returned to a dark environment for 2 hr. It was found that the relative specific activity of the RNA in the visual cortex of the former was significantly higher than that in the visual cortex of the latter. No difference was seen in the frontal cortex. The RNA content of the visual cortex of the rat exposed to light was significantly lower than that of the dark controls. This was not the case in the frontal cortex. Adult rats deprived of light for periods of 4–10 days also exhibited an increased RNA relative specific activity in the visual cortex after being exposed to light although the RNA content did not alter significantly. No changes were seen in the frontal cortex. Blind rats (of the “Campbell” strain) showed no changes in RNA metabolism in the visual cortex on being transferred from a dark to a light environment.