Effects of Estrogen, Nitric Oxide, and Dopamine on Behavioral Locomotor Activities in the Embryonic Zebrafish: A Pharmacological Study

Mitochondria as targets for toxicity and metabolism research using zebrafish

BACKGROUND

The study of mitochondrial functions in zebrafish was initiated before the 1990s and has effectively supported many of the recent scientific advances in the functional studies of mitochondria.

SCOPE OF REVIEW

This work elaborates various peculiarities and general advances in the study of mitochondria using this animal model.

MAJOR CONCLUSIONS

The inclusion of zebrafish models in scientific research was initiated with structural studies of mitochondria. Then, toxicological studies involving chemical compounds were undertaken. Currently, there is a decisive tendency to use zebrafish to understand how chemicals impair mitochondrial bioenergetics. Zebrafish modeling has been fruitful for the analysis of ion homeostasis, especially for Ca²⁺ transport, since zebrafish and mammals have the same set of Ca²⁺ transporters and mitochondrial membrane microdomains. Based on zebrafish embryo studies, our understanding of ROS generation has also led to new insights.

GENERAL SIGNIFICANCE

For the study of mitochondria, a new era was begun with the inclusion of zebrafish in bioenergetics research.

The role of neuronal nitric oxide and its pathways in the protection and recovery from neurotoxin-induced de novo hypokinetic motor behaviors in the embryonic zebrafish (Danio rerio)

Neuronal nitric oxide (nNO) has been shown to affect motor function in the brain. Specifically, nNO acts in part through regulation of dopamine (DA) release, transporter function, and the elicitation of neuroprotection/neurodegeneration of neurons in conditions such as Parkinson's disease (PD). Recently, the zebrafish has been proposed to be a new model for the study of PD since neurotoxin damage to their nigrostriatal-like neurons exhibit PD-like motor dysfunctions similar to those of mammalian models and human patients. Results from this study demonstrate that treatment of 5 days post fertilization (dpf) fish with a nNO synthase inhibitor as a co-treatment with 6-OHDA facilitates long-term survival and accelerates the recovery from 6-OHDA-induced hypokinesia-like symptoms. These findings are unique in that under conditions of neurotoxin-induced stress, the inhibition of the NO-related S-nitrosylation indirect pathway dramatically facilitates recovery from 6-OHDA treatment but inhibition of the NO-sGC-cGMP direct pathway is essential for survival in 5 dpf treated fish. In conclusion, these results indicate that nNOS and the inhibition of the NO-linked S-nitrosylation pathway plays an important role in antagonizing the protection and recovery of fish from neurotoxin treatment. These data begin to help in the understanding of the role of NO as a neuroprotectant in dopaminergic pathways, particularly those that influence motor dysfunctions.