LAUSR

It was shown that the application of methiothepin, the antagonist of serotonin (5-HT) receptors, caused a decrease in the membrane potential of the high-threshold premotor interneurons LPa3 and RPa3 of the intact snails and its increase to the previous level after the subsequent application of 5-HT in vitro. The application of methiothepin also led to a decrease in the membrane potential of these neurons, but the subsequent application of 5-HT did not lead to the return of the membrane potential to the previous level in animals trained in defensive reflex. It can be assumed that conditioning of the defensive reflex causes a state change of the 5-HT receptor system of premotor interneurons of defensive behavior.