Cholinergic drug effects on a delayed conditional discrimination task in the rat.
The centrally acting cholinergic antagonist scopolamine (0.025-0.10 mg/kg ip) and the peripherally acting cholinergic antagonist methyl-scopolamine (0.01-0.10 mg/kg) dose dependently impaired discriminability independent of delay in a delayed conditional discrimination task that precludes use of mediating behavior. This indicates that scopolamine does not specifically affect working memory. Drugs that enhance cholinergic transmission neither improved discriminability nor attenuated scopolamine-induced impairments. In a post hoc analysis scopolamine was found to impair discriminability in a delay-dependent manner in rats that performed at a high level in pretest sessions. Methyl-scopolamine impaired performance independently of delay in these rats. The authors suggest that a ceiling effect at short delays produced this Drug x Delay interaction of scopolamine in the best performing rats.
Herremans
A H
AH
Department of Psychopharmacology, Faculty of Pharmacy, Rudolf Magnus Institute of Neuroscience, Utrecht University, The Netherlands.
Hijzen
T H
TH
Olivier
B
B
Slangen
J L
JL
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D001115:Arecoline / Q000494:pharmacology; D001921:Brain / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects*; D004193:Discrimination Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D008297:Male; D011939:Mental Recall / Q000187:drug effects*; D019832:N-Methylscopolamine; D010095:Oxotremorine / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011950:Receptors, Cholinergic / Q000187:drug effects*; D012153:Retention, Psychology / Q000187:drug effects; D012601:Scopolamine / Q000494:pharmacology*; D012602:Scopolamine Derivatives / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects; D013619:Tacrine / Q000494:pharmacology
D010276:Parasympatholytics; D011950:Receptors, Cholinergic; D012602:Scopolamine Derivatives; D001115:Arecoline; D013619:Tacrine; D010095:Oxotremorine; D010830:Physostigmine; D012601:Scopolamine; D019832:N-Methylscopolamine