(RS)-alpha-methyl-4-carboxyphenylglycine (MCPG) does not block theta burst-induced long-term potentiation in area CA1 of rat hippocampal slices.
We have used the selective metabotropic glutamate receptor antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG) to investigate in the CA1 hippocampal subregion in vitro whether coactivation of N-methyl-D-aspartate (NMDA) and metabotropic glutamate receptors is necessary for the induction of long-term potentiation (LTP) when LTP is induced by theta burst stimulation (TBS). When MCPG (500 microM) was bath applied 14-30 min prior to a triple high-frequency tetanization (100 Hz, 1 s) and washed out immediately afterwards the potentiation of the extracellularly recorded field potentials decayed gradually to baseline (P < 0.05) over 2-3 h. However, when MCPG was applied in the same manner before a triple TBS (10 bursts at 5 Hz, 100 Hz within the bursts) the resulting potentiation remained stable for at least 4 h. MCPG had no effect on baseline synaptic transmission or post-tetanic potentiation. These results demonstrate a clear difference in the mechanisms underlying these two different forms of LTP.
Brown
R E
RE
Department of Neurophysiology, Institute for Neurobiology, Magdeburg, FRG.
Rabe
H
H
Reymann
K G
KG
D000818:Animals; D001565:Benzoates / Q000494:pharmacology*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors*; D013826:Theta Rhythm / Q000187:drug effects*
D001565:Benzoates; D018094:Receptors, Metabotropic Glutamate; C079694:alpha-methyl-4-carboxyphenylglycine; D005998:Glycine