INTRAVENTRICULAR INFUSIONS OF ANTINEURAL CELL-ADHESION MOLECULES IN A DISCRETE POSTTRAINING PERIOD IMPAIR CONSOLIDATION OF A PASSIVE-AVOIDANCE RESPONSE IN THE RAT

Intraventricular infusions of anti-neural cell adhesion molecule (anti-NCAM) are demonstrated to inhibit consolidation of a passive avoidance response when administered in the 6-8-h posttraining period. Anti-NCAM was ineffective when administered during training or at any other time up to 10 h thereafter, and no amnesic effects were observed with absorbed anti-NCAM or anti-neurofilament protein. Amnesia was observed only at the 48-h recall time, and this could not be attributed to poor antibody penetration or a prolonged residence time, as studies with I-125-labelled anti-NCAM in trained animals demonstrated a rapid accumulation into all brain regions, and this was marked in the olfactory bulb and hippocampus, areas showing an inherent and paradigm-specific increase in NCAM sialylation state, respectively. The lack of an amnesic action at the 24-h recall time is attributed to anti-NCAM-impaired synapse structuring becoming apparent following the paradigm-specific increases in NCAM sialylation state.