Drugs online research references
Psychopharmacology (Berl). 1992;106(2):175-8.
Oxiracetam antagonizes the disruptive effects of scopolamine on memory in the radial maze.
Magnani M, Pozzi O, Biagetti R, Banfi S, Dorigotti L.
ISF Laboratories for Biomedical Research, Milano, Italy.
The effects exerted by oxiracetam on the disruption of performance induced by scopolamine in the radial arm maze were investigated in overtrained rats. Scopolamine induced a dose-related decrease in the efficiency of responding and an increase of running time. The effect of the SC injection of 0.2 mg/kg scopolamine on the efficiency of responding was antagonized by the IP administration of 30 mg/kg oxiracetam, while the effect on running time induced by the same dose of scopolamine was not. Physostigmine (0.3 mg/kg SC) antagonized both effects of 0.2 mg/kg scopolamine. Methylscopolamine, at the dose of 0.2 mg/kg SC, was devoid of any effect on both parameters. Increasing the dose of methylscopolamine to 0.63 mg/kg did cause serious peripheral effects which eventually prevented some animals from completing the task. Similar peripheral effects were observed after administration of 0.63 mg/kg scopolamine. The effects of this dose of scopolamine on efficiency and running time were not antagonized by pretreatment with 100 mg/kg oxiracetam. Oxiracetam alone (30 or 100 mg/kg IP) did not modify the performance of previously trained rats. The present results suggest that oxiracetam selectively restores cholinergic mechanisms which are involved in learning and memory.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1549645&dopt=Abstract
Pharmacol Biochem Behav. 1992 Feb;41(2):377-84.
Behavioral effects of some diphenyl-substituted antimuscarinics: comparison with cocaine and atropine.
Witkin JM, Genovese RF, Witkin KM, Chiang PK.
Psychobiology Laboratory, NIDA Addiction Research Center, Baltimore, MD 21224.
To more fully characterize the behavioral excitatory effects observed with certain diphenyl-substituted antimuscarinics, various behavioral effects of benactyzine, a prototype excitatory antimuscarinic, was evaluated in rats. These effects were compared to those of cocaine, atropine, and azaprophen, a muscarinic antagonist that contains both the diphenyl substituents of benactyzine and a ring isomeric with the tropane ring of atropine. Under a fixed-interval 5-min schedule of food presentation, cocaine and benactyzine increased response rates. Atropine and azaprophen only decreased responding. The muscarinic agonist oxotremorine attenuated the rate-increasing effects but did not alter the disruptions in the temporal patterning produced by benactyzine or shift the dose-effect function to the right. In rats discriminating 10 mg/kg cocaine from saline, benactyzine partially substituted for cocaine, producing a maximum of 50% cocaine-appropriate responses. Benactyzine fully substituted for scopolamine in rats discriminating 0.056 mg/kg scopolamine from saline. All antimuscarinics increased locomotor activity when activity levels were low in control animals, but the increases were less than those produced by cocaine. Cocaine increased both locomotor activity and fixed-interval responding at comparable doses, whereas 10-fold higher doses of benactyzine were required to increase locomotor activity. These results support the following conclusions: 1) In addition to its classical antimuscarinic behavioral profile, benactyzine has behavioral excitatory actions similar in some respects to those of cocaine; 2) the behavioral excitatory effects of benactyzine do not appear to be due solely to antagonism of muscarinic receptors; and 3) the alkyl-ester may be an important structural feature of diphenyl-substituted antimuscarinics for the induction of behavioral stimulation.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1574528&dopt=Abstract
Pharmacol Biochem Behav. 1990 Apr;35(4):903-9.
Scopolamine differentially disrupts the behavior of male and female Wistar rats in a delayed nonmatching to position procedure.
van Hest A, Stroet J, van Haaren F, Feenstra M.
Netherlands Institute for Brain Research, Amsterdam.
Evidence is available that pharmacological interference with the cholinergic system may disrupt behavior in experimental procedures designed to investigate learning and memory processes. Recently it has been suggested that the cholinergic system may be sexually dimorphic. The present experiment was designed to investigate whether or not manipulation of the cholinergic system differentially affected memory processes in both sexes. Male and female Wistar rats were exposed to a delayed nonmatching to position procedure and were challenged with increasing doses of scopolamine hydrobromide (a central and peripheral muscarinic receptor blocker) and scopolamine methyl bromide (which does not pass the blood-brain barrier). Response accuracy decreased in both sexes as the delay interval duration increased. Behavioral differences between saline-treated males and females were not observed. Response accuracy decreased dose-dependently after subjects were injected with scopolamine hydrobromide. Response accuracy also decreased after treatment with scopolamine methyl bromide, but to a smaller extent. Males showed less accurate responding after treatment with either drug than females. These results provide behavioral evidence for the hypothesis that cholinergic functioning may differ between the sexes.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2345764&dopt=Abstract
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