ABSTRACT
INTRODUCTION: Transparency is a unique attribute of zebrafish that permits direct assessment of drug effects on the nervous system using whole mount antibody immunostaining and histochemistry. METHODS: To assess pharmacological effects of drugs on the optic nerves, motor neurons, and dopaminergic neurons, we performed whole mount immunostaining and visualized different neuronal cell types in vivo. In addition, we assessed neuronal apoptosis, proliferation, oxidation and the integrity of the myelin sheath using TUNEL staining, immunostaining and in situ hybridization. The number of dopaminergic neurons was examined and morphometric analysis was performed to quantify the staining signals for myelin basic protein and apoptosis. RESULTS: We showed that compounds that induce neurotoxicity in humans caused similar neurotoxicity in zebrafish. For example, ethanol induced defects in optic nerves and motor neurons and affected neuronal proliferation; 6-hydroxydopamine caused neuronal oxidation and dopaminergic neuron loss; acrylamide induced demyelination; taxol, neomycin, TCDD and retinoic acid induced neuronal apoptosis. DISCUSSION: Effects of drug treatment on different neurons can easily be visually assessed and quantified in intact animals. These results support the use of zebrafish as a predictive model for assessing neurotoxicity.
Subject(s)
Neurotoxins/toxicity , Toxicity Tests/methods , Acrylamide/toxicity , Animals , Anthracenes/toxicity , Apoptosis/drug effects , Cell Proliferation/drug effects , Embryo, Nonmammalian/drug effects , Ethanol/toxicity , Glutarates/toxicity , In Situ Hybridization , In Situ Nick-End Labeling , Motor Neurons/drug effects , Myelin Sheath/drug effects , Neomycin/toxicity , Neurons/cytology , Neurons/drug effects , Optic Nerve/drug effects , Oxidopamine/toxicity , Paclitaxel/toxicity , Polychlorinated Dibenzodioxins/toxicity , Tretinoin/toxicity , ZebrafishABSTRACT
In this study, we developed an in vivo method to determine drug effects on oxidation-induced apoptosis in the zebrafish brain caused by treatment with L-hydroxyglutaric acid (LGA). We confirmed that LGA-induced apoptosis was caused by oxidation by examining the presence of an oxidative product, nitrotyrosine. Next, we examined the effects of 14 characterized neuroprotectants on LGA-treated zebrafish, including: D-methionine (D-Met), Indole-3-carbinol, deferoxamine (DFO), dihydroxybenzoate (DHB), deprenyl, L-NAME (N(G)-nitro-L-arginine methyl ester), n-acetyl L-cysteine (L-NAC), 2-oxothiazolidine-4-carboxylate (OTC), lipoic acid, minocycline, isatin, cortisone, ascorbic acid and alpha-tocopherol. Eleven of 14 neuroprotectants and 7 of 7 synthetic anti-oxidants exhibit significant protection in zebrafish. Buthionine sulfoximine (BSO), used as a negative control, exhibited no significant protective effects. In addition, three blood-brain barrier (BBB) impermeable compounds exhibited no significant effects. Our results in zebrafish were similar to results reported in mammals supporting the utility of this in vivo method for identifying potential neuroprotective anti-oxidants.
