Effects of synthetic ergot derivatives on the two identifiable giant neurons, sensitive to dopamine, of Achatina fulica Ferussac.

On the two dopamine (DA)-sensitive giant neurones, PON (periodically oscillating neuron, excited by DA) and TAN (tonically autoactive neuron, inhibited by DA), of an African giant snail (Achatina fulica Férussac), effects of synthetic ergot derivatives, including lisuride and pergolide, which are considered to be dopamine agonists, were examined. Of the substances examined, three of the ergot derivatives related to pergolide, D-8,9-didehydro-6-propylergoline-8-methanol (LY149174), D-6-methyl-8 beta-(2-(methylsulfinyl)ethyl)ergoline (LY116470) and D-2-chloro-6-methyl-8 beta-(2-(methylsulfinyl)ethyl)ergoline (LY127817), showed excitatory effects on PON, while pergolide (D-8 beta-( (methylthio)methyl)-6-propylergoline, LY127809) and lisuride (N-D-6-methyl-8-isoergolenyl-N',N'-diethylcarbamide) had no effect. On the other hand, only D-6-methyl-8 beta-(2-(methylsulfinyl)ethyl)ergoline (LY116470) had any excitatory effects on TAN.