[Atropine suppresses associative potentiation in the hippocampus].

The effect of the muscarinic antagonist atropine on associative long-term potentiation of the CA1 population EPSPs was studied in rat hippocampal slices. Local application of atropine (10(-4) M) significantly suppressed associative long-term potentiation (40-60 min after the tetanization) in a <<weak>> input (str. Radiatum 128 +/- 10% vs 168 +/- 9% in control, p < 0.03). Long term potentiation in the <<strong>> input itself was not suppressed and even tended to be enhanced by atropine (str. Oriens 158 +/- 4% vs 137 +/- 13 during control). The results suggest that synaptically released endogenous acethylcholine supports induction of long-term potentiation in the synapses with a low level of activation.