Corticosterone facilitates long-term memory formation via enhanced glycoprotein synthesis.
Long-term memory formation for a passive avoidance task in one-day-old chicks requires a late phase of synaptic glycoprotein synthesis (including the neural cell adhesion molecule), commencing 5.5 h post-training. This phase occurred in chicks trained with a strong, but not a weak aversant, which only retained this memory for a few hours (< 10). In addition, previous work has shown that a corticosteroid action through central corticosteroid receptors is also required for long-term passive avoidance memory. Here, we tested the hypothesis that the corticosteroid action on memory formation might be exerted via modulation of the late phase of neural glycoprotein synthesis. One-day-old chicks were used as experimental subjects. Incorporation of the radiolabelled glycoprotein precursor [3H]fucose into synaptic membranes of the chick forebrain was used as an index of glycoprotein fucosylation. Bilateral intracerebral injections of a corticosterone dose (0.5 micrograms/hemisphere) that facilitates long-term retention of weak learning were able to induce the late phase of glycoprotein synthesis in undisturbed chicks. A further experiment examined the effect of antibodies against the neural cell adhesion molecule on the facilitatory action of corticosterone on long-term memory for the weak passive avoidance training. Chicks trained on a weak aversant were injected with corticosterone (0.5 micrograms/hemisphere) 30 min post-training and testing occurred 24 h post-training. Administration of the neural cell adhesion molecule antibodies during the late phase (5.5 h post-training) blocked the facilitatory action of corticosterone on long-term memory. These findings further support the view that corticosteroids have a role in memory consolidation. In addition to previously proposed effects on gene transcription, these data suggest a post-translational glycosylation mechanism for the modulatory effect of corticosteroids on long-term memory formation.
Sandi
C
C
Psychobiology Research Group, Cajal Institute, CSIC, Madrid, Spain.
Rose
S P
SP
Mileusnic
R
R
Lancashire
C
C
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D002645:Chickens; D003345:Corticosterone / Q000494:pharmacology*; D005260:Female; D006023:Glycoproteins / Q000096:biosynthesis*; D008297:Male; D008568:Memory / Q000187:drug effects*; D013997:Time Factors
D006023:Glycoproteins; D003345:Corticosterone