Octopamine boosts snail locomotion: behavioural and cellular analysis
- 176 Downloads
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.
KeywordsLymnaea Epinastine Phentolamine Pedal ganglion Movement
We are grateful to Agnes Vehovszky for reading a draft of the manuscript.
- Elliott CJH, Kemenes G (1992) Cholinergic interneurons in the feeding system of the pond snail Lymnaea stagnalis. II. N1 interneurons make cholinergic synapses with feeding motoneurons. Philos Trans R Soc Lond B 336:167–180Google Scholar
- Morton JE (1974) Molluscs. Hutchinson, LondonGoogle Scholar
- Syed NI, Harrison D, and Winlow W (1988) Locomotion in Lymnaea: role of serotonergic motoneurones controlling the pedal cilia. A-cluster neurones. Neurobiology of invertebrates, transmitters, modulators and receptors (36), 387–402. Symposia of the biological academy of Hungary. Salanki J and Rosza KS Ref type: serial (Book, Monograph)Google Scholar
- Whim MD, Evans PD (1991) The role of cyclic amp in the octopaminergic modulation of flight muscle in the locust. J Exp Biol 161:423–438Google Scholar