Systemic injection of pirenzepine induces a deficit in passive avoidance learning in rats.
When injected IP, the M1 muscarinic receptor antagonist pirenzepine dose-dependently induced a deficit in passive avoidance learning in rats. This activity was optimal at 75 mg/kg injected 1 h before the acquisition session. The deficit induced by pirenzepine was antagonized by oxotremorine (0.03-0.3 mg/kg SC) and physostigmine (0.1 mg/kg SC), but not neostigmine. By comparison, under the same experimental conditions, physostigmine and oxotremorine also antagonized the deficit induced by an equipotent dose of scopolamine (0.5 mg/kg IP), although the activity of physostigmine appeared stronger against scopolamine than against pirenzepine. These results suggest that pirenzepine could produce a centrally-mediated behavioural disruption when injected systemically.
Worms
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P
Sanofi Recherche, Neurobiology Department, Montpellier, France.
Gueudet
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C
Pério
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A
Soubrié
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P
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D007279:Injections, Subcutaneous; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009388:Neostigmine / Q000494:pharmacology; D010095:Oxotremorine / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D010890:Pirenzepine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D009388:Neostigmine; D010890:Pirenzepine; D010095:Oxotremorine; D010830:Physostigmine