Octopamine boosts snail locomotion: behavioural and cellular analysis.
We measured the reduction in locomotion of unrestrained pond snails, Lymnaea stagnalis, subsequent to transdermal application of two selective octopamine antagonists, epinastine and phentolamine. After 3 h in fresh standard snail water following treatment with 4 mM epinastine or 3.5 mM phentolamine, the snails' speed was reduced to 25 and 56% of the controls (P < 0.001 and P = 0.02, respectively). The snails' speed decreased as the drug concentration increased. In the isolated CNS, 0.5 mM octopamine increased the firing rate of the pedal A cluster motoneurons, which innervate the cilia of the foot. In normal saline the increase was 26% and in a high magnesium/low calcium saline 22% (P < 0.05 and 0.01, respectively). We conclude that octopamine is likely to modulate snail locomotion, partially through effects on pedal motoneurons.
Ormshaw
Jennifer C
JC
Department of Biology, University of York, P.O. Box 373, York , YO10 5YW, UK.
Elliott
Christopher J H
CJ
D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003984:Dibenzazepines / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000378:metabolism*; D009655:Octopamine / Q000378:metabolism*; D010646:Phentolamine / Q000494:pharmacology; D012908:Snails / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D003984:Dibenzazepines; D006634:Histamine H1 Antagonists; D007093:Imidazoles; D009655:Octopamine; C053090:epinastine; D010646:Phentolamine