Refinement of anesthetic choice in procedures preceding psychopharmacological studies

Abstract

RationalePrevious studies indicated that some general anesthetics induce long-term antidepressant and/or anxiolytic-like effects. This raises the concern about the use of anesthesia in surgeries that precede psycopharmacological tests, since it may be a potential bias on results depending on the experimental design used.\n\nObjectivesTo evaluate whether commonly used general anesthetics in surgeries preceding psychopharmacological tests would affect rat behavior in tests predictive of antidepressant or anxiolytic-like effects. We also evaluated whether prior anesthesia would interfere in the detection of the antidepressant-like effect of imipramine or the anxiolytic-like effect of diazepam.\n\nMethodsWe tested if a single exposure to subanesthetic or anesthetic doses of 2,2,2-tribromoethanol, chloral hydrate, thiopental or isoflurane would change rats behavior in the forced swimming test (FST) or in the elevated plus-maze (EPM) test, at 2 hours or 7 days after administration.\n\nResultsPrevious anesthesia with the aforementioned anesthetics did not change rat behavior in FST per se nor it changed the antidepressant-like effect induced by imipramine treatment. Rats previously anesthetized with tribromoethanol or chloral hydrate exhibited, respectively, anxiogenic-like or anxiolytic-like behavior in the EPM. Prior anesthesia with thiopental or isoflurane did not produce any per se effect in rat behavior in the EPM nor disturbed the anxiolytic-like effect of diazepam.\n\nConclusionOur results suggest that, in our experimental conditions, tribromoethanol and chloral hydrate are improper anesthetics for surgeries that precede behavioral tests related to anxiety. Isoflurane or thiopental may be suitable for anesthesia before evaluation in animal models predictive of antidepressant or anxiolytic-like effect.