Zebrafish Swimming Behavior Research Articles

Persisting effects of a PBDE metabolite, 6-OH-BDE-47, on larval and juvenile zebrafish swimming behavior

Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants that are widely detected in the environment, biota, and humans. In mammals, PBDEs can be oxidatively metabolized to form hydroxylated polybrominated diphenyl ethers (OH-BDEs). While studies have examined behavioral deficits or alterations induced by exposure to PBDEs in both rodents and fish, no study to date has explored behavioral effects from exposure to OH-BDEs, which have been shown to have greater endocrine disrupting potential compared to PBDEs. In the present study, zebrafish (Danio rerio) were exposed during embryonic and larval development (0–6days post fertilization, dpf) to a PBDE metabolite, 6-hydroxy, 2,2′,4,4′ tetrabromodiphenyl ether (10–50nM) and then examined for short and long-term behavioral effects. Exposed zebrafish tested as larvae (6dpf) showed an altered swimming response to light–dark transitions, exhibiting hypoactivity in light periods compared to control fish. When fish exposed from 0–6dpf were tested as juveniles (45dpf), they showed an increased fear response and hyperactivity in response to tests of novel environment exploration and habituation learning. These results demonstrate that early life exposure to a PBDE metabolite can have immediate or later life (more than a month after exposure) effects on activity levels, habituation, and fear/anxiety.

Protective effect of rutin on impairment of cognitive functions of due to antiepileptic drugs on zebrafish model.

Aim:The severity of adverse reactions due to antiepileptics is observed during initiation and early treatment in which impairment of cognitive effects are common. Since long time, herbal medicine is a natural remedy to treat neural symptoms. Phytochemicals have been proven to be potent neuro-protective agents. Rutin, a bioflavonoid is established to be nootropic in many studies. In this study, we aimed to determine the protective effect of rutin in zebrafish against the side effects produced by AEDs.Materials and Methods:Seizures were induced in zebrafish by phenylenetetrazole. Rutin pretreatment (50 mg/kg, single injection, i.p.) was done before commencement of the study. Behavioral studies were performed as: latency to move high in the tank, locomotion effects, color effect, shoal cohesion, light/dark test on Zebrafish.Results:Treatment with rutin reverted the locomotor behavior to normal. Treatment with AEDs caused fishes to move in all regions while, in case of treatment with rutin, the response reverted to normal. Treatment with AEDs altered swimming behavior of zebrafish, however, rutin showed a positive effect over this behavior. Treatment with AEDs resulted in restricted movement of zebrafish to the dark zone. Treatment with rutin caused increased latency of zebrafish to move in the light compartment. Similarly, time spent in the light compartment by zebrafish treated with rutin was significantly (P < 0.01) higher as compared to zebrafish treated with AEDs.Conclusion:The results suggest a protective role of rutin on cognition impaired by AEDs.

The Spinning Task: A New Protocol to Easily Assess Motor Coordination and Resistance in Zebrafish

The increasing use of adult zebrafish in behavioral studies has created the need for new and improved protocols. Our investigation sought to evaluate the swimming behavior of zebrafish against a water current using the newly developed Spinning Task. Zebrafish were individually placed in a beaker containing a spinning magnetic stirrer and their latency to be swept into the whirlpool was recorded. We characterized that larger fish (>4 cm) and lower rpm decreased the swimming time in the Spinning Task. There was also a dose-related reduction in swimming after acute treatment with haloperidol, valproic acid, clonazepam, and ethanol, which alter coordination. Importantly, at doses that reduced swimming time in the Spinning Task, these drugs influenced absolute turn angle (ethanol increased and the other drugs decreased), but had no effect of distance travelled in a regular water tank. These results suggest that the Spinning Task is a useful protocol to add information to the assessment of zebrafish motor behavior.

Unexpected neuronal protection of SU5416 against 1-Methyl-4-phenylpyridinium ion-induced toxicity via inhibiting neuronal nitric oxide synthase.

SU5416 was originally designed as a potent and selective inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) for cancer therapy. In this study, we have found for the first time that SU5416 unexpectedly prevented 1-methyl-4-phenylpyridinium ion (MPP+)-induced neuronal apoptosis in cerebellar granule neurons, and decreased 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced loss of dopaminergic neurons and impairment of swimming behavior in zebrafish in a concentration-dependent manner. However, VEGFR-2 kinase inhibitor II, another specific VEGFR-2 inhibitor, failed to reverse neurotoxicity at the concentration exhibiting anti-angiogenic activity, strongly suggesting that the neuroprotective effect of SU5416 is independent from its anti-angiogenic action. SU5416 potently reversed MPP+-increased intracellular nitric oxide level with an efficacy similar to 7-nitroindazole, a specific neuronal nitric oxide synthase (nNOS) inhibitor. Western blotting analysis showed that SU5416 reduced the elevation of nNOS protein expression induced by MPP+. Furthermore, SU5416 directly inhibited the enzyme activity of rat cerebellum nNOS with an IC50 value of 22.7 µM. In addition, knock-down of nNOS expression using short hairpin RNA (shRNA) abolished the neuroprotective effects of SU5416 against MPP+-induced neuronal loss. Our results strongly demonstrate that SU5416 might exert its unexpected neuroprotective effects by concurrently reducing nNOS protein expression and directly inhibiting nNOS enzyme activity. In view of the capability of SU5416 to cross the blood-brain barrier and the safety for human use, our findings further indicate that SU5416 might be a novel drug candidate for neurodegenerative disorders, particularly those associated with NO-mediated neurotoxicity.

Effect of sodium hypochlorite on zebrafish swimming behavior estimated by fractal dimension analysis

The behavioral responses of zebrafish (Danio rerio) to sublethal concentrations of sodium hypochlorite (NaClO)-based household bleach were quantified in order to index toxicity of the solution. The swimming behavior of zebrafish was captured using nonplanar 3D stereocameras in combination with 3D coordinate computation with perspective correction (3DCCPC) to compute for actual 3D coordinates. Swimming trajectory and velocity were quantified by fractal dimension analysis. The results showed that, under incremental concentrations of NaClO-based aqueous solutions with the maximum of 0.005% v/v, the fractal dimension of swimming velocity trended to increase with the concentration. The fractal dimension of swimming trajectories trended to increase with pH. Hence, the results have proven that the system is a useful tool to indicate behavioral changes, which may be implemented in biomonitoring systems for acute toxicity bioassay.

Developmental chlorpyrifos effects on hatchling zebrafish swimming behavior

Chlorpyrifos (CPF), a widely used organophosphate insecticide and potent acetylcholinesterase inhibitor, interferes with neurobehavioral development. Rat models have been key in demonstrating that developmental CPF exposure causes learning deficits and locomotor activity alterations, which persist into adulthood. Complementary nonmammalian models can be useful in determining the neurodevelopmental mechanisms underlying these persisting behavioral effects. Zebrafish ( Danio rerio) with their clear chorion and extensive developmental information base provide an excellent model for assessment of molecular processes of toxicant-impacted neurodevelopment. We have developed methods for assessing spatial discrimination learning in adult zebrafish and have documented persisting effects of developmental CPF exposure on swimming activity and learning after low and high doses of CPF (10 and 100 ng/ml) administered to zebrafish embryos on Days 1–5 postfertilization (pf). In the current study, we developed methods for behavioral assessment of CPF exposure on swimming activity in newly hatched zebrafish. An equal area segmented annular grid (concentric circles divided into quadrants through the diameter) was made in a 16-mm diameter cylinder. The test area was placed on a heating device secured to an Olympus SZH10 dissecting scope stage. Zebrafish embryos were exposed to 10 ng/ml CPF, 100 ng/ml CPF, or vehicle control (25 μl/ml DMSO) ( n=8–10/treatment group). Each treatment group was kept in a total volume of 25 ml of egg water (60 mg/ml Instant Ocean) including DMSO with or without CPF mixed to above dilutions in an incubator set at 28.5°C. CPF dilutions or vehicle were changed daily with exposure ending on Day 5 pf. Testing of larval zebrafish was performed on Days 6 and 9 pf. The fish were placed in the test cylinder with 1.5 ml of egg H 2O (28.5°C). After a 2-min acclimation period, the swimming activity of the fish was measured for a 3-min testing session. The 100 ng/ml CPF dose caused significant slowing of swimming activity on Days 6 and 9 pf and had persisting effects of impairing spatial discrimination and decreasing response latency in adulthood. Developmental exposure to 10 ng/ml of CPF did not cause a significant change in locomotor activity during the period soon after hatching. CPF exposure during early development caused clear behavioral impairments detectable during the posthatching period. In a previous study, we found that early developmental CPF exposure caused behavioral alterations in zebrafish, which lasted throughout adulthood. The molecular mechanisms by which early developmental CPF exposure produces these behavioral impairments expressed in adulthood can now be studied in the zebrafish model.

Effects of atrazine on swimming behavior of zebrafish, Brachydanio rerio

Effects of atrazine (5–3125 μg l −1) on the swimming behavior of zebrafish, Brachydanio rerio, were studied by recording and quantifying the spontaneous locomotor activity. Exposure to atrazine significantly ( P < 0.0001) altered the behavior: the zebrafish preferred habitats with dark substratum of the aquaria. Since the different exposure concentrations did not reveal clearly different responses, we assume a threshold effect rather than a dose-effect relationship. Possible ecological consequences of these findings are outlined.