Ultrastructural evidence against in vivo disaggregation of brain polyribosomes after administration of L-dopa or phenylalanine

Abstract

SummaryL-dopa or phenylalanine was injected intraperitoneally into immature rats. Brain samples fixed and embedded by conventional methods were sectioned for electron microscopic study. In contrast to chemical evidence in the literature for disaggregation of brain polysomes in fractions of whole brain from animals so treated, we found no ultrastructural evidence of disaggregation in either neurons or glial cells. The fact that we and others have observed polysome disaggregation in electron micrographs of sections from other types of animal experiments suggests that our observation of stable polysomes in the present work is not the result of technical artifact, and that the disaggregation observed in brain fractions by others had probably not occurred in their intact animals. It is unlikely that the behavioral and physiological changes occurring in patients treated with L-dopa can be correlated with the state of aggregation of brain polyribosomes.