Scopolamine-Induced Amnesia in Zebrafish: Behavioral Characterization and Pharmacological Reversal

The main objective of this study was to assess whether donepezil or haloperidol, after a 10-day training period, could inhibit inhibitory avoidance and alter learned behavior. To assess memory impairment, zebrafish were trained in a light/dark tank over a 20-day period: 10 days without mechanical stimulation and 10 days with mechanical stimulation. Three behavioral parameters were recorded, i.e., latency to enter the dark compartment, time spent in the dark zone, and the number of entries into the dark area. Following the training phase, scopolamine was administered to induce amnesia. Donepezil and haloperidol were used as reference compounds for comparison. Subsequently, zebrafish were placed in a cylindrical tank, and spontaneous exploratory behavior was evaluated by measuring the amount of time spent in the upper region of the tank, an indicator of anxiety-related behavior. The behavioral data from the training phase were used to establish a baseline profile of zebrafish performance in the light/dark tank. Scopolamine administration significantly altered all of the measured behavioral parameters, including exploratory behavior in the cylindrical tank. Notably, donepezil or haloperidol prevented the memory-impairing effects of scopolamine, supporting the use of the light/dark tank paradigm to evaluate the efficacy of pharmacological agents in reversing scopolamine-induced amnesia in zebrafish.