Cholinergic interneurons in the feeding system of the pond snail Lymnaea stagnalis. III. Pharmacological dissection of the feeding rhythm.
The feeding activity of the pond snail Lymnaea stagnalis was stimulated by depolarization of a modulatory interneuron (SO) or of a N1 pattern-generating interneuron. The cholinergic antagonists phenyltrimethylammonium (PTMA), methylxylocholine (MeXCh), hexamethonium (HMT) and atropine (ATR) were applied at 0.5 mM in the bath and their effects on the rhythmic feeding pattern were monitored. Each of the antagonists slowed or blocked the feeding rhythm. The block was due to interference in the pattern generating network, not to disturbance of modulatory inputs. The experimental results favour a model in which the alternation of protraction (N1) and retraction (N2) phases occurs by recurrent inhibition. The results would be more difficult to explain on the reciprocal inhibition model. When all the N1 output was blocked, the N1 neurons fired rhythmic bursts endogenously.
Department of Biology, University of York, Heslington, U.K.
C J
CJ
Elliott
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology; D004064:Digestive System / Q000294:innervation; D004435:Eating / Q000502:physiology*; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D066298:In Vitro Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D008195:Lymnaea / Q000502:physiology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D006584:Hexamethonium Compounds; D000644:Quaternary Ammonium Compounds; D011950:Receptors, Cholinergic; C009571:phenyltrimethylammonium; C008515:methylxylocholine; D018738:Hexamethonium; D001285:Atropine; D002794:Choline