Figure 3.

Inhibition of LTP produced by exogenous application of colominic acid and recombinant PSA-NCAM. (A) Graph showing the LTP obtained in control hippocampal slices (○) and slices treated for 30 min before stimulation with 0.5 mg/ml of colominic acid (●), a mixture of α2–8-linked PSAs of various lengths. Data are mean ± SEM of seven experiments. (B) Graph showing a similar blockade of LTP produced by exogenous application for 30 min before stimulation of a recombinant PSA-NCAM-Fc chimera (20–25 μg/ml; ●), obtained by transfection of a tumoral cell line. The control LTP (○) was obtained in slices treated with the conditioned medium of transfected, nonsecreting cells. Data are mean ± SEM of five experiments.