Application of 1 μM N-methyl-d-aspartate (NMDA) either immediately before or following tetanic stimulation inhibits the induction of CA1 hippocampal long-term potentiation (LTP). We have examined the effect of trans-amino-1,3-cyclopentanedicarboxylic acid (ACPD), norepinephrine and acetylcholine on this NMDA-mediated LTP inhibition using extracellular recordings from in vitro rat hippocampal slices. When NMDA is accompanied by 100 μM ACPD or 10 μM norepinephrine, the block of LTP is overcome. The norepinephrine effect is mimicked by phenylephrine and methoxamine and is blocked by phentolamine and prazosin suggesting the involvement of α1-adrenergic receptors.
- Long-term potentiation
- Metabotropic receptor