LONG-TERM ENHANCEMENT OF SYNAPTIC TRANSMISSION BY SYNTHETIC MAST-CELL DEGRANULATING PEPTIDE AND ITS LOCALIZATION OF BINDING-SITES IN HIPPOCAMPUS

A bee venom, mast-cell-degranulating (MCD) peptide, was synthesized by stepwise formation of the two disulfide bridges. This synthetic MCD peptide induced long-term potentiation (LTP) in the CA1 region of a hippocampus slice at concentrations ranging from 10-7 to 10-5 M. The potentiating effect of MCD was not lost by biotinylation of its N-terminus, and thus it became possible to investigate localization of its binding site at a cellular level in the hippocampus slice at a LTP-inducible concentration (1 μM). We found that even after brief application of N-biotinyl-MCD (1 μM) to perfusate, its presence was observed in pyramidal cell bodies in the CA1 and CA3 regions, but not in granule cells in the dentate gyrus of the hippocampus slice. This observation does not coincide with the localization of its high-affinity binding sites revealed by 125I-MCD binding, suggesting that another type(s) of MCD binding site, such as low-affinity binding sites, are present in the hippocampus. © 1990.