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 200μM) under illumination at 50lx were studied using zebrafish larvae of both AB and TU strains at 7dpf 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.

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.