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Acute effects of ethanol or d-amphetamine on the locomotor activity of larval zebrafish in a microtiter plate format.
Citation:
Irons, T. D., R. C. MACPHAIL, D. L. HUNTER, B. K. PADNOS, AND S. J. PADILLA. Acute effects of ethanol or d-amphetamine on the locomotor activity of larval zebrafish in a microtiter plate format. Presented at Fourth Aquatic Animal Models of Human Disease Conference, Durham, NC, January 31 - February 03, 2008.
Impact/Purpose:
To support criteria for MYP
Description:
As part of an effort to develop a rapid in vivo screen for EPA’s prioritization of toxic chemicals, we have begun to characterize the locomotor activity of zebrafish (Danio rerio) larvae. We are assessing the acute effects of prototypic drugs that are known to act on the central nervous system. Initially, we chose ethanol and d-amphetamine. When administered acutely to mammals, both are known to increase behavior at low doses and decrease behavior at high doses. Our goal was to determine if immature zebrafish showed a similar response. Zebrafish larvae (6 days post-fertilization) were individually maintained in 96-well microtiter plates at 26°C and under a 14:10 light:dark cycle with lights on at 0830 hr. Non-lethal concentrations of ethanol (1.0 – 4.0% v/v) or d-amphetamine SO4 (0.08 – 20.00 μM) were administered to the larvae by immersion. Each drug was screened on an individual plate, with all doses and controls represented. A total of 12 – 32 larvae were exposed to each concentration. Locomotor activity was assessed beginning 20 minutes into exposure using a Noldus video activity monitor and Ethovision 3.1 software to track each animal under either visual light or dark (infrared) conditions for up to 90 minutes post-dosing. Acute ethanol exposure increased activity in the dark in the 1% (2X of control) and 2% (3X of control) exposure groups; however, in the light, only the 2% (7X of control) group showed increased activity. The animals exposed to 4% ethanol remained immobile under both lighting conditions. d-Amphetamine exposure increased activity in the dark to a maximum of 50% at 0.73 μM, then decreased activity by 33% at the highest dose (20 μM). In general the pattern of response was similar for both compounds: low concentrations increased activity while higher concentrations decreased activity--similar to the patterns obtained in rodent tests of motor activity. These results indicate that very young zebrafish are sensitive to centrally-active drugs, and that drug challenges may be conducted in a convenient, microtiter plate format. T.D. Irons is supported by the NIH NIGMS Initiative for Maximizing Student Diversity. This is an abstract of a proposed presentation; the information does not necessarily reflect Agency policy.