Effect of centrally administered atropine and pirenzepine on radial arm maze performance in the rat.
The effect of two anticholinergic drugs administered intracerebroventricularly on acquisition of an 8-arm radial maze task was examined in the rat. Increasing doses of atropine (1, 4.5, 22.5, 45 micrograms/rat) and pirenzepine (4.5, 15, 60, 90 micrograms/rat) significantly impaired performance in the working-memory components of the task. For both drugs this impairment was linearly related to the log of the administered doses and log-dose-response relationship were parallel. The regression lines calculated for each parameter for both drugs were parallel to each other, thus allowing us to calculate the potency of atropine versus pirenzepine: atropine was 5.4 times more potent than pirenzepine for correct arm entries, 10 times more potent for the number of errors and 4 times more potent for the total time taken to complete the task. The relevance of M1 and M2 subtype central acetylcholine receptors in cognitive processes is discussed.
Sala
M
M
Institute of Pharmacology, Faculty of Mathematical, Physical and Natural Sciences, University of Milan, Italy.
Braida
D
D
Calcaterra
P
P
Leone
M P
MP
Comotti
F A
FA
Gianola
S
S
Gori
E
E
D000818:Animals; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D010890:Pirenzepine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012044:Regression Analysis
D010890:Pirenzepine; D001285:Atropine