UC Irvine

Rates of protein and ribonucleic acid (RNA) synthesis in brain regions have been examined following suturing of the eyelids of one eye immediately after hatching. Although capable of receiving diffuse light, this eye could not be used effectively. Tritiated precursors were injected subcutaneously, and the extent of incorporation of radioactivity into macromolecules derived from symmetrically paired cerebral hemispheres and optic lobes was determined. One day after suture both the lobe and the hemisphere contralateral to the occluded eye manifested a reduced rate of RNA synthesis relative to the corresponding ipsilateral region. This effect persisted for over 17 days. Parallel long-term differences in protein synthetic rates or concentrations were not observed. This suggests that the major effect of varying RNA production was to modify the type of proteins synthesized rather than their amounts. The use of paired internal controls removed the possibility that asymmetric effects were due to non-experimentally controlled variables such as differences in systemic hormone levels. The results indicate that modification of the information content of visual input to the brain can result in widespread cerebral metabolic differences. © 1970.