Methoctramine moderately improves memory but pirenzepine disrupts performance in delayed non-matching to position test.
The present study was designed to investigate the effect of i.c.v. administration of various muscarinic receptor antagonists in rats on memory performance in delayed non-matching to position test. The drugs chosen were the non-selective antagonist scopolamine (3 and 10 micrograms), the muscarinic M1 receptor-selective antagonist pirenzepine (10 and 30 micrograms) and the muscarinic M2 receptor-selective antagonist methoctramine (2, 5 and 20 micrograms). Scopolamine delay-independently decreased % correct choices and reduced motor activity. Pirenzepine also delay-independently decreased % correct choices. In contrast, methoctramine 2 micrograms, but not at 5 or 20 micrograms, improved slightly, but significantly, % correct performance delay-dependently. The present data suggests that the decrease in activation of inhibitory muscarinic M2 autoreceptors induced by methoctramine produces a specific improvement of short-term memory at long forgetting delays.
Aura
J
J
Department of Neuroscience and Neurology, University of Kuopio, Finland. aura@jalus.uku.fi
Sirviö
J
J
Riekkinen
P
P
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology; D003959:Diamines / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D008568:Memory / Q000187:drug effects*; D009043:Motor Activity / Q000187:drug effects*; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D010276:Parasympatholytics / Q000494:pharmacology*; D010890:Pirenzepine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic / Q000187:drug effects; D012601:Scopolamine / Q000494:pharmacology
D003959:Diamines; D018727:Muscarinic Antagonists; D010276:Parasympatholytics; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D012601:Scopolamine; C054938:methoctramine