REDUCTION OF HIPPOCAMPAL LONG-TERM POTENTIATION IN TRANSGENIC MICE ECTOPICALLY EXPRESSING THE NEURAL CELL-ADHESION MOLECULE L1 IN ASTROCYTES

The influence of the neural cell adhesion molecule L1 on hippocampal l ong-term potentiation (LTP) was investigated using transgenic mice ect opically expressing L1 in astrocytes (GFAP-L1), L1 is a member of the immunoglobulin superfamily of hemophilic adhesion molecules predominan tly expressed in neurones, Previously, it has been demonstrated that l ocal application of L1 antibodies and recombinant L1 fragments impair the expression of LTP, Here, we show that LTP induced by theta-burst s timulation or by pairing presynaptic stimulation with postsynaptic dep olarisation was strongly reduced in GFAP-L1 mice, whereas basal synapt ic transmission, post-tetanic potentiation, and paired-pulse facilitat ion were not modified, These results further support the idea that L1 is involved in synaptic plasticity and suggest that adhesion molecule- dependent changes in synaptic morphology contribute to the expression of LTP. (C) 1996 Wiley-Liss, Inc.