Autoradiographic comparison of neuronal and glial protein metabolism in rat hippocampus after food-motivated or footshock-motivated conditioning.

Quantitative autoradiography has shown that initial food-motivated conditioning results in an increase in 3H-phenylalanine incorporation into cytoplasmic proteins of rat hippocampal neurons. After 3 daily conditioning trials, the incorporation returned to an active control (pseudoconditioning) level while after 6 daily trials, the incorporation was decreased. No changes were revealed in the cells of hippocampal perineuronal glia. Four hours after a footshock-motivated passive avoidance trial, incorporation of 3H-phenylalanine was increased both in the neurons and in their perineuronal glia of rat hippocampus. By the time of a consolidation of this conditioning, such increase still remained perineuronal glia. An importance of the emotional background is outlined for a participation of glial cells in learning-induced metabolic changes in the nervous system.