Effects of Azaprophen, Scopolamine and Trihexyphenidyl on Schedule-Controlled Behavior, Before and After Chronic Physostigmine
WALTER REED ARMY INST OF RESEARCH WASHINGTON DC DIV OF NEUROPSYCHIATRY
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The effect of the muscarinic acetylcholine receptor antagonists, azaprophen 0.3-10.0 mgkg, scopolamine 0.0-30 mgkg and trihexyphenidyl 0. 3-10.0 mgkg were examined in rats using a VI 18 s schedule of food reinforcement, before and after chronic physostigmine administration. All three compounds produced dose-dependent increases in the rate of responding. Scopolomine was more potent than trihexphenidyl which was equipotent to azaprophen. All three compounds antagonized the response rate-decreasing effects of physostigmine in dose-dependent fashion. Following 43 consecutive daily administrations of physostigmine 0.4 mgkg, partial tolerance developed to its response rate-decreasing effects. When the three antagonists were again examined alone and in combination with physostigmine, their effects were generally unchanged. These results further characterize the behavioral effects of azaprophen, scopolamine and trihexphenidyl.
- Medicine and Medical Research