Testing for dopamine in zebrafish?

Question

is there any way (dead or alive) to test for the preseance of dopamine in a zebrafish brain? can you take the brain, and add a sloution and see the dopamine neurons? please help

Answer 1

Zebrafish are vertebrate organisms that are of growing interest for preclinical

drug discovery applications. Zebrafish embryos develop most of the

major organ systems present in mammals, including the cardiovascular, nervous

and digestive systems, in < 1 week. Additional characteristics that make

them advantageous for compound screening are their small size, transparency

and ability to absorb compounds through the water. Furthermore, gene

function analysis with antisense technology is now routine procedure. Thus,

it is relatively simple to assess whether compounds or gene knockdowns

cause toxic effects in zebrafish. Assays are being developed to exploit the

unique characteristics of zebrafish for pharmacological toxicology. This

review discusses assays that may be used to assess in vivo toxicity and provides

examples of compounds known to be toxic to humans that have been

demonstrated to function similarly in zebrafish.

Keywords: cardiotoxicity, cytochrome P450, neurotoxicity, teratogenesis, zebrafish

Expert Opin. Drug Metab. Toxicol. (2006) 2(2):231-240

1. Introduction

Many drugs developed by the pharmaceutical industry fail in clinical trials because of

unanticipated toxic side effects. Toxicity may be caused by a compound interacting

with a molecular target that is distinct from the target selected for therapeutic benefit,

defined as an off-target effect. An example of this is the large number of compounds

that interfere with the cardiac potassium ion channel human ether a-go-go (hERG),

which can cause a fatal arrhythmia [1].

Alternatively, severe side effects may result from blockage of a molecular target

in a nontargeted tissue, defined as an on-target effect; for example, NSAIDS

derive therapeutic benefit from inhibiting COX-1 and/or -2. However, inhibition

of COX-1 in the gastrointestinal system has been shown to cause gastric ulcers

and more recently, specific inhibition of COX-2 has been potentially linked to

cardiovascular complications [2].

Drugs are usually tested for in vivo toxicity in mammalian models, such as mouse,

rat and dog. Toxicity testing is a time-consuming and expensive part of the modern

drug discovery process. In the last few years, many investigators have begun to

explore the use of zebrafish as an alternative model for toxicity testing of pharmaceuticals

in order to provide an in vivo assessment of compound effects at an earlier

stage in drug discovery. Because they are small, easy to care for, inexpensive to maintain,

and produce large numbers of transparent embryos that develop outside of the

mother, zebrafish have been used to study almost every aspect of vertebrate biology,

including the development and function of the cardiovascular system, the CNS and

the digestive system. The ability to culture large numbers of zebrafish embryos and

larvae in small volumes of media [3] facilitates rapid testing of compounds for toxicity,

while using a minimal amount of compound (nanograms or less per animal).

Compounds in the media are absorbed by the zebrafish through the skin and gills at

embryonic stages and through the digestive system during later larval stages. Embryonic,

larval and adult zebrafish have all been used for many years for environmental

toxicity testing [4]. Although this review focuses on assays that use the