An analysis of the effects of early ketamine exposure on the learning and memory of adult zebrafish using the Noldus visual tracking system

Objective To analyze the effects of early ketamine exposure on the learning and memory of adult zebrafish using the Noldus visual tracking system combined with T maze. Methods Zebrafish were randomly divided into five groups: a control group (using E3 solution) and ketamine (Ket) exposure groups (at the doses of 0.2, 0.4, 0.8 and 1.6 g/L Ket). The 4 hpf (hours post fertilization) zebrafish embryos in Ket exposure groups were exposed to different concentrations of ketamine for 14 h. When the embryos grew up to adult zebrafish, their trace was recorded, while their learning and memory was evaluated using the Noldus video tracking system combined with T maze. The maze was equipped with an enriched chamber (EC) on the left arm. The behavior of zebrafish was examined once per day for a total of five times. The swimming trace and the latency to enter into EC of each group were recorded. Results The zebrafish were trained for five times. Compared with their behavior on the first time, the control group showed remarkably reduced latency to enter into EC on the fifth time (P<0.05), while no marked decreases in the latency was found in the Ket exposure groups. Conclusions The Noldus visual tracking system combined with T maze is a reliable system to evaluate the learning and memory of adult zebrafish. Embryonic exposure to ketamine can lead to impaired learning and memory of zebrafish in adulthood.