[Electrophysiological study of 5,6-dihydroxytryptamine effect on defensive reflex conditioning in the snail].

: The role of serotonin in expression of membrane properties of identified neurons was studied during defensive reflex conditioning using the neurotoxic analogue of serotonin 5,6-dihydroxytryptamine (5,6-DHT). The defensive reflex conditioning in snails was destroyed on the second day after second injection of 5,6-DHT. Through the 1st weeks after second injection of 5,6-DHT the snails were learned but worse than snails after injection of saline solution. This result shows the recovery of snail's learning ability within 2 weeks after the second injection of 5,6-DHT. It was found that injection of 5,6-DHT prevented the decrease of membrane and threshold potentials of command neurons during defensive reflex conditioning as compared with the snails injected with 5,6-DHT without learning.