Influence of muscarinic ligands on the amplitudes of the evoked surface potential's late components in the optic tectum of the urodele Plethodon jordani.
Recordings of field potentials from the tectal surface of an urodele amphibian were obtained in an in vitro preparation under influence of various muscarinic drugs. Bath applied acetylcholine (ACh) led to no change in the amplitudes or the shape of the evoked potentials. If the ACh-esterase blocker (-)-physostigmine was applied synchronously, the late components of the surface potential increased in amplitude. The non-selective cholinergic agonist carbachol showed a similar effect which was partially diminished by the nicotinic antagonist d-tubocurarine chloride (d-TC) and the muscarinic antagonist atropine sulfate. The application of the non-selective muscarinic agonist (+)-pilocarpine hydrochloride led to an increase of the late oligo- and polysynaptic events. This effect was reduced by the M(1)-antagonist pirenzepine dihydrochloride. The presented findings suggest that muscarinic receptors play a more important role in tectal processing than assumed in previous studies which emphasized the role of nicotinic receptors.
Kahl
H
H
Brain Research Institute, University of Bremen, Germany. kahl@zfn.uni-bremen.de
Wiggers
W
W
D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000378:metabolism / Q000494:pharmacology; D005074:Evoked Potentials, Visual / Q000187:drug effects; D008024:Ligands; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018721:Muscarinic Agonists / Q000378:metabolism / Q000494:pharmacology; D010830:Physostigmine / Q000378:metabolism / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000502:physiology*; D013477:Superior Colliculi / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D014403:Tubocurarine / Q000378:metabolism / Q000494:pharmacology; D014562:Caudata
D008024:Ligands; D018721:Muscarinic Agonists; D011976:Receptors, Muscarinic; D002217:Carbachol; D010830:Physostigmine; D000109:Acetylcholine; D014403:Tubocurarine