Heat-induced escape behavior in zebrafish larvae

Abstract

Behavioral thermoregulation is critical for animals to survive in various ambient temperatures. However, cellular and molecular mechanisms of behavioral thermoregulation are not known. Zebrafish is a small tropical fish. Because body of zebrafish larvae is translucent, neurons of the brain are visible. If larvae exert behavioral thermoregulation, we can investigate cellular and molecular mechanisms of behavioral thermoregulation. In this study, we examined whether 3 dpf (day post-fertilization) larvae perform behavioral thermoregulation. When larvae, reared at 28 °C, were released to a pool of high temperature (32.5–40 °C), they exerted escape behavior. To investigate the involvement of brain in this behavior, decerebration was performed. Decerabrated larvae were alive and provoked tail-beating behavior in response to NMDA, but they did not exert heat-induced escape behavior. To identify a receptor mediating heat-induced escape behavior, we hypothesized that TRP (Transient Receptor Potential) V1 and TRPV4 are candidate receptors. Both TRPV1 and TRPV4 were detected by RT-PCR from 3 dpf larvae. We conclude that zebrafish larvae exert heat-induced escape behavior. [J Physiol Sci. 2007;57 Suppl:S180]