Dopamine D-1-deficient mutant mice do not express the late phase of hippocampal long-term potentiation

THE possible involvement of the dopamine D-1 receptor subtype in mechanisms of long-term potentiation (LTP) of the Schaffer collateral-commissural input of CA1 neurones was investigated using D-1-deficient mutant mice. In transversal hippocampus slices from mice lacking the D-1 receptor a normal post-tetanic and shortterm potentiation could be induced after applying a triple 100 Hz tetanization. However, the potentiated fEPSP in the mutant mice declined to control value about 140 min following tetanization, whereas in the wild type mice a normal, non-decremental LTP was observed. These data support the idea that besides the glutamatergic system, the synergistic activation of dopaminergic synapses is necessary for LTP maintenance.