Muscarine receptors regulating electrically evoked release of acetylcholine in hippocampus are linked to pertussis toxin-sensitive G proteins but not to adenylate cyclase.
[3H]Acetylcholine release elicited with 360 pulses/3 Hz from slices of rabbit hippocampus is facilitated in the presence of the muscarine (M) receptor antagonist atropine (indicating the existence of autoinhibition) and diminished by the M receptor agonists carbachol and oxotremorine. N-Ethylmaleimide (30 microM) and pertussis toxin (8 micrograms/ml) counteracted antagonist-induced facilitation and agonist-induced inhibition of release, suggesting that a pertussis toxin-sensitive GTP-binding protein is involved in the chain of events mediating activation of M receptors to inhibition of release. Neither 8-bromo-cyclic AMP (300 microM), a membrane analogue of cyclic AMP, nor rolipram (10 microM), a phosphodiesterase inhibitor, affected electrically evoked release of [3H]acetylcholine. They also did not influence the oxotremorine-induced inhibition of transmitter release. In conclusion, no evidence was found for the assumption that activation of M autoreceptors is linked to inhibition of adenylate cyclase.
Allgaier
C
C
Institute of Pharmacology and Toxicology, University of Freiburg, F.R.G.
Choi
B K
BK
Hertting
G
G
D000109:Acetylcholine / Q000378:metabolism*; D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000502:physiology*; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D037342:Pertussis Toxin; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D037361:Adenylate Cyclase Toxin; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D015240:Phorbol 12,13-Dibutyrate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D000109:Acetylcholine; D005033:Ethylmaleimide