Benzodiazepine inhibits anxiogenic-like response in cocaine or ethanol withdrawn planarians

Planarians spend less time in light versus dark environments. We hypothesized that planarians withdrawn from cocaine or ethanol would spend even less time in the light than drug-naive planarians and that a benzodiazepine would inhibit this response. Planarians pretreated in cocaine or ethanol were placed at the midline of a Petri dish containing spring water that was split evenly into dark and light compartments. Planarians withdrawn from cocaine (1, 10, 100 μmol/l) or ethanol (0.01%) spent less time in the light compartment than water controls; however, this withdrawal response to cocaine (100 μmol/l) or ethanol (0.01%) was abolished by clorazepate (0-100 μmol/l). These data suggest that planarians, similar to rodents, show benzodiazepine-sensitive, anxiogenic-like responses during cocaine or alcohol withdrawal.