The cyanobacterial toxin, MC-LR, is predominantly presented during toxic cyanobacterial blooms and is consumed by phytoplanktivorous fish and zooplanktivorous fish directly. Detoxification of MC-LR in liver was believed to begin with conjugate formation with GSH, catalyzed by
GSTs. MC-LR GSH conjugates display increased solubility and are subjected to accelerated biliary excretion. In this study, we showed that the
mRNA transcriptions of GSTA, GPX and UCP2 were increased within 8h following MC-LR exposure in isolated hepatocytes of Nile tilapia, confirming the roles of phase II
enzymes, especially
GSTs, in MC-LR detoxification in tilapia. The widely used
food-additive, synthetic
antioxidant,
tert-butylhydroquinone (
tBHQ) has been shown to induce phase II
enzymes including
GSTs, via the
antioxidant responsive elements (ARE) locate in the regulatory regions of these genes. Our results also showed that the transcription of various
GSTs, including GSTA, GSTR2 and GSTT were significantly induced by
tBHQ in Nile tilapia. In consistence, fish fed on
tBHQ-containing diet (0.01 percent
tBHQ) showed significantly reduced MC-LR accumulation in liver tissues 48 h after an
oral administration of a single dose of 250 μg MC-LR/kg
body weight (bwt). The findings in this research suggested that
tBHQ could reduce MC-LR accumulations in liver, likely through the induction of phase II metabolizing
enzymes such as
GSTs. Subacute effects of
tBHQ and its potential applications in fishery need to be further investigated.