Protective Effect of Taurine on Tri ortho cresyl Phosphate (TOCP)-Induced Cytotoxicity in C6 Glioma Cells - Advances in Experimental Medicine and Biology - page 216

22.1 Introduction

TOCP, one of organophosphorus compounds (OPs), has been widely used as a plas-
ticizer, a flame-retardant, and a gasoline additive in industry (Craig and Barth 1999 ;
Winder and Balouet 2002 ). It has been known that TOCP induced neurotoxicity in
humans and animal species (Barrett and Oehme 1994 ; Zhang et al. 2007 ) . Studies
on TOCP neurotoxicity also focused mainly on neurons, which are considered to be
the primary target for neurotoxicity. Recent studies show that astrocytes are also an
important target for many OPs neurotoxicity. However, there have no reports of
TOCP induced astrocyte toxicity. Thus, one major question concerning the neuro-
toxicity of TOCP is whether TOCP exerts astrocyte toxicity.
As the most abundant glial cell types in the brain, astrocytes have a number of
roles in modulation of synaptic transmission and plasticity, secretion of growth fac-
tors, uptake of neurotransmitters, and regulation of extracellular ion concentrations
and metabolic support of neurons (Hertz and Zielke 2004 ; Nedergaard et al. 2003 ;
Newman 2003 ). In addition, they have high concentrations of antioxidants and anti-
oxidant enzymes, for example, GSH and GPx, and play prominent role in the brain's
antioxidant defense (Desagher et al. 1996 ; Dringen et al. 2000 ) . Garcia et al. ( 2001 )
reported that chlorpyrifos enhanced reactive oxygen species (ROS) formation in C6
glioma cells. Qiao et al. ( 2005 ) also reported that oxidative mechanisms contribute
to the developmental neurotoxicity of chlorpyrifos. Thus, does the neurotoxicity of
TOCP involve in disruption the antioxidant defense of astrocyte?
Taurine, 2-aminoethanesulfonic acid is a simple aminosulfonic acid which pres-
ents in large amounts in most cell types and tissues as a free amino acid. Taurine has
a function as neuromodulator or neurotransmitter in CNS which could maintain the
structural integrity of the membrane, regulate calcium binding and transport
(Wu et al. 2005 ; Wu and Prentice 2010 ), and exhibit a protective effect in a variety
of detrimental situations, often acting as antioxidant (Schaffer et al. 2009 ) . However,
there are no reports about the protective effects of taurine on TOCP-induced
neurotoxicity.
In the present study, we investigated the effects of TOCP exposure and taurine
pretreatment on cell viability, LDH leakage, morphological changes, and the activ-
ity of GPx and the content of GSH in C6 glioma cells, in order to evaluate the
potential role of taurine on TOCP-induced cytotoxicity.

22.2 Methods

22.2.1 Cell Culture

Rat C6 glioma cells were maintained in DMEM supplemented with 10% fetal
bovine serum (FBS), 100 U/ml penicillin, and 100 mg/ml streptomycin, in an incu-
bator aerated with 5% CO 2 at 37°C.