Locomotion and Behavioral Toxicity in Larval Zebrafish: Background, Methods, and Data - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 153

Figure 12.4 Effect of acute D -amphetamine on locomotor activity. Larvae were exposed to 10% Hanks'
buffer solution (control, n¼48) or a concentration of drug (0.24-20 mM, n¼22-24/concentration) for 30min
before recording began. Effects of each drug dose are plotted as meanSEM distance moved in 2min. Ten
minutes of light was followed by 20min of dark for two cycles (denoted by the bar in the lower portion of the
figure). At the lower doses, D -amphetamine increased activity in dark; however, at the higher doses activity
was decreased. Changes in activity due to drug were considerably muted during the light periods.

the drugs would be produced in the larvae. D -Amphetamine, for example, is a
psychomotor stimulant that produces a characteristic biphasic effect onmotor activity
in both rats and mice; low doses increase activity while higher doses decrease it
(Campbell et al., 1969; Porrino et al., 1984; Antoniou et al., 1998; Niculescu et al.,
2005; Badanich et al., 2008).
In this study, rearingwas carried out as previously described until the afternoon of
testing. The larvae were exposed to either 10%Hanks' solution (control) or a range of
D -amphetamine concentrations (0.24-20.0

M), which were evenly distributed (di-
agonally) throughout the plate. The plate was then placed on the platform, and
recording of activity began 30 min later. Testing included two cycles of 10min of light
and 20min of dark. Figure 12.4 shows the effect of acute D -amphetamine exposure.
The lowest dose produced no effect on activity, while the next higher dose increased
activity. Further increases in dose produced decreases in activity. This biphasic drug
effect was especially clear for dark activity; the pattern is the same for activity in light,
although themagnitude is considerably less. These results are similar to those found in
numerous studies on the effects of D -amphetamine on the activity of rats and mice.
Moreover, the rapid change in activity with lighting conditions, at all doses, indicates
that the drug primarily affected locomotion rather than sensory (visual) function.
Additional work in our laboratory (Irons et al., 2010; MacPhail et al., 2009)
determined the acute effects of cocaine and ethanol. These drugs also produced
effects that resembled those reported for rats and mice. The effects of ethanol were
especially intriguing in that locomotionwas increased considerably at an intermediate
dose in both light and dark periods, indicating an almost complete loss of visual

m