Methods for Assessing Neurotoxicity in Zebrafish - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 115

Figure 10.1 Effects of ethanol on zebrafish embryos. Motor neuron examination (a and b):
48hpf zebrafish were stained with Znp-1, a motor neuron-specific antibody. In untreated controls, the
motor neurons are highly organized along the somites (arrows). However, after treatment with 2.5%
ethanol, motor neuron loss was observed. Assessment of neuron proliferation (c and d): neuron
proliferation was examined by immunostaining with an anti-PCNA antibody (white area). The pattern
of proliferating neuronal cells in the brain was different and proliferation zone was smaller in ethanol-
treated embryos.

10.3.2 Compound Effects on Dopaminergic Neurons

Dopaminergic neurons of the midbrain are the main source of dopamine (DA) in the
mammalian central nervous system and loss of DA is associated with Parkinson's
disease (PD), one of the most prominent human neurological disorders. Dopami-
nergic neurons, which are present in low numbers, are found in a “harsh” region of the
brain, the substantia nigra pars compacta, which is DA-rich and contains both redox
available neuromelanin and high iron content. Dopaminergic neurons play an
important role in the control of multiple brain functions including voluntary move-
ment and a broad array of behavioral processes such as mood, reward, addiction, and
stress. To assess compound effects on dopaminergic neurons, 2dpf zebrafish were
treated with 250 M 6-OHDA, a neurotoxin that destroys catecholaminergic terminals,

for 3 days and then processed for immunostaining using an anti-tyrosine hydroxylase
(TH) antibody. Although this antibody stains catecholaminergic neurons, it has been
demonstrated that all tyrosine hydroxylase positive neurons in zebrafish diencephalon
(hypothalamus, posterior tuberculum, ventral thalamus, and pretectum) areDAneurons

m