Characterisation of antibodies specific for chick brain neural cell adhesion molecules which cause amnesia for a passive avoidance task.

Antisera were prepared against six postsynaptic density glycoprotein fractions (150-180, 62-80, 50, 41, 33, and 28 kDa) that show enhanced fucosylation during memory formation after training day-old chicks in a one-trial passive avoidance task. Each antiserum was tested for its possible effect on memory retention. Bilateral intracranial injections of two of the antisera, R-1 and R-6, or their IgGs (IgG-1 and IgG-6), resulted in amnesia for the passive avoidance task when chicks were tested 24 h later, IgG-1 and IgG-6 antibodies were amnestic only when injected 5.5 h after training, and had no effect when injections were made 30 min before training, thus resembling an effect previously observed with polyclonal or monoclonal anti-N-CAM antibodies. IgG-1 and IgG-6 antibodies were found to be specific for protein epitopes of glycoproteins that contain a high amount of N-linked mannose and fucose, and a very low amount of polysialic acid and O-linked galactose. Absorption of IgG-6 antibodies with neural cell adhesion molecule (N-CAM) isolated from synaptic plasma membranes derived from day-old chick brain resulted in loss of amnestic effect.(ABSTRACT TRUNCATED AT 250 WORDS)