Characterization of the locomotor activities of zebrafish larvae under the influence of various neuroactive drugs.

BACKGROUND

Behavioral changes in animals reflect functional changes in their central nervous system. Neuroactive drugs that act on different neural pathways can induce specific behavioral responses; therefore, it is possible to infer the activities of neuroactive drugs by studying the behavioral changes induced by drugs of interest in animals.

METHODS

In this study, AB strain zebrafish larvae at 7 days post fertilization (dpf) were treated with different concentrations of drugs that act on different neural pathways. Changes in the swimming distances of zebrafish larvae under different illumination conditions and the differences in locomotor activities between light and dark conditions (lighting motor index) were analyzed.

RESULTS

Among the drugs studied, different concentrations of sulpiride had no effect on larval locomotor activity either under light or dark conditions. Progressively decreased spontaneous movements were observed in zebrafish larvae treated with increasing doses of MK-801 and valproic acid. With increasing concentrations of pentylenetetrazole and yohimbine, the spontaneous movement of larval zebrafish presented a bell-shaped response. When the illumination changed from light to dark, zebrafish larvae not treated with drugs demonstrated increased locomotor activities. However, high levels of yohimbine, pentylenetetrazole decreased the degree of change in the lighting motor index.

CONCLUSIONS

In conclusion, drugs that affect different neural pathways exert different influences on the locomotor activities of zebrafish larvae. This study presents an initial effort to establish a framework that correlates the drug activities and the behavioral responses of zebrafish larvae under drug treatments, which may provide a potential identification of the pathways of novel drugs with neurological activities through their behavioral influences.