Strain-dependent differential behavioral responses of zebrafish larvae to acute MK-801 treatment

The zebrafish is a relatively new model organism and has become a valuable tool in genetic, developmental, and pharmacological researches. Zebrafish larvae, compared with adult, are particularly suitable for high-throughput screening of drug effects. AB and TU are well established in-bred zebrafish strains. The behavioral responses to acute MK-801 treatments (0, 5, 20, 100, and 200 μM) under illumination at 50 lx were studied using zebrafish larvae of both AB and TU strains at 7 dpf with ZebraLab software. Two behavioral parameters, traveling distance and activity counts, were analyzed. “Traveling distance” represents locomotor activity, whereas “activity count” is any activity including small, non-ambulatory movements. Zebrafish larvae of TU strain demonstrated inhibitory effects in both behavioral parameters in response to MK-801 treatment. Zebrafish larvae of AB strain showed lack of responses to MK-801 treatments in traveling distance, and showed increases in activity counts. Therefore, zebrafish larvae of AB and TU strains demonstrated opposite responses in activity counts towards MK-801 treatment. Differences in the level of neurotransmitters and their respective metabolites (NE and MHPG, DA and DOPAC, 5-HT and 5-HIAA) between AB and TU strain zebrafish larvae were discovered by HPLC analysis, which was related to the strain-dependent differential behavioral responses to MK-801 treatment. Conclusion: Under the influences of MK-801, in contrast with TU strain, AB strain zebrafish larvae demonstrated activity changes similar to previous studies on rodents. AB strain larvae are better model organisms than TU strain larvae in MK-801 related behavioral studies.