LONG-TERM POTENTIATION IN THE RAT HIPPOCAMPUS INDUCED BY THE MAST-CELL DEGRANULATING PEPTIDE - ANALYSIS OF THE RELEASE OF ENDOGENOUS EXCITATORY AMINO-ACIDS AND PROTEINS

Using a push-pull device, we have analysed, in vivo, the release of endogenous excitatory amino acids and proteins induced by the mast cell degranulating peptide in the CAI region of the hippocampus. Local application of the mast cell degranulating peptide (20 μM) for 5 or 10 min produced a long-term potentiation of the slope of the field excitatory postsynaptic potential (70 ± 40%, 3 h after the drug application). This long-term potentiation was associated with (i) a transient increase (10 min) in the release of endogenous glutamate and aspartate and (ii) a late transient enhanced release of proteins and newly secreted proteins. In cases in which the mast cell degranulating peptide induced recurrent interictal activity, there was a sustained enhanced release of glutamate. These observations suggest that mast cell degranulating peptide induced long-term potentiation is not associated with a sustained enhanced release of excitatory amino acids. © 1990.