Scopolamine and methylscopolamine differentially affect fixed-consecutive-number performance of male and female Wistar rats.
Male and female Wistar rats were trained on a fixed-consecutive-number schedule in which a response on a food lever was followed by the presentation of reinforcement when at least three, but not more than seven responses had been completed on a work lever. Subjects were treated with different doses of the centrally acting cholinergic antagonist scopolamine hydrobromide or the more peripherally active cholinergic antagonist scopolamine methylbromide (0.08, 0.16 or 0.32 mg/ml/kg) once behavior had stabilized. Scopolamine hydrobromide and scopolamine methylbromide dose-dependently decreased response rates in males and females. Scopolamine methylbromide decreased response rates more than equivalent doses of scopolamine hydrobromide and the rate-suppressant effects of both drugs were more marked in males than in females. Scopolamine hydrobromide dose-dependently decreased response accuracy, but differences between males and females were not observed. Response accuracy also decreased after scopolamine methylbromide, but did not vary as a function of the dose of the drug. The decrease in response accuracy induced by both drugs was attributable to an increase in the percentage of trials with a premature switch from the work lever to the food lever. Both scopolamine hydrobromide and scopolamine methylbromide dose-dependently increased the number of premature switches. Differences between males and females were not observed. Administration of scopolamine hydrobromide and scopolamine methylbromide also decreased the number of obtained reinforcers in a dose-dependent manner. Females obtained significantly fewer reinforcers than males, while scopolamine methylbromide affected the number of obtained reinforcers to a larger extent than scopolamine hydrobromide.
van Haaren
F
F
Netherlands Institute for Brain Research, Amsterdam.
van Hest
A
A
van Hattum
T
T
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004192:Discrimination, Psychological / Q000187:drug effects*; D005260:Female; D008297:Male; D019832:N-Methylscopolamine; D010276:Parasympatholytics / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule; D012601:Scopolamine / Q000494:pharmacology*; D012602:Scopolamine Derivatives / Q000494:pharmacology*; D012737:Sex Factors
D010276:Parasympatholytics; D012602:Scopolamine Derivatives; D012601:Scopolamine; D019832:N-Methylscopolamine