Altered Colchicine-Binding Capacity in Chick Brain Regions: Relationship to Intensity or Information Content of Visual Input

The binding of [3H]colchicine to postmitochondrial supernatant fractions of chick brain has been studied, absorbing colchicine-bearing proteins on DEAE-cellulose filter discs. This was assayed at several times after unilateral enucleation of day-old chicks. Binding was unaltered in optic lobes or anterior dorsal forebrain regions contralateral to the removed eye, relative to the corresponding regions contralateral to and thus directly or secondarily innervated by the intact eye. Colchicine binding was also assayed after training chicks to suppress pecking at a metallic bead coated with aversive-tasting methylanthranilate. At 4 but not 24 h after the one-trial training, binding was selectively elevated in the anterior dorsal forebrain roof. Results are taken to imply that alterations in tubulin content of chick brain may reflect stress-related changes, possibly mediated by systemic endocrine flux, rather than a more localized learning experience.