Toxicological Sciences 62, 54-60 (2001)
Copyright © 2001 by the Society of Toxicology
ENVIRONMENTAL TOXICOLOGY |
Induction of Glutathione S-transferase Activity and Protein Expression in Brown Bullhead (Ameiurus nebulosus) Liver by Ethoxyquin
Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida
The inducibility of hepatic cytosolic glutathione S-transferases (GSTs) was examined in brown bullheads, a freshwater fish that is highly susceptible to hepatic neoplasia following exposure to carcinogen-contaminated sediments. Juvenile bullheads were fed a semi-purified antioxidant-free diet supplemented with ethoxyquin (0.5% w/w dissolved in 3% corn oil), a prototypical rodent GST-inducing agent, twice daily for 14 days. Control bullheads received the antioxidant-free diet supplemented with corn oil (3% w/w). A significant increase (1.6-fold, p 
0.01) in hepatic cytosolic GST activity toward 1-chloro-2,4-dinitrobenzene (CDNB) was observed in the ethoxyquin-treated bullheads relative to control fish. A trend toward increased GST-NBC activity was observed in the ethoxyquin-treated fish (1.2-fold, p = 0.06), whereas no treatment-related effects were observed on GST activities toward ethacrynic acid (ECA). In contrast, GST activity toward (±)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide (BPDE) was repressed in affinity-purified cytosolic fractions prepared from ethoxyquin-treated bullheads relative to control bullheads. Silver staining and densitometric analysis of isoelectric-focused, affinity-purified GST proteins revealed increased expression of two basic GST-like isoforms in ethoxyquin-treated fish. In summary, exposure to ethoxyquin increases brown bullhead GST-CDNB catalytic activity and hepatic cationic GST protein expression. However, the increase in overall GST-CDNB activity by ethoxyquin is associated with repression of GST-BPDE activity, suggesting differential effects on hepatic bullhead GST isoforms by ethoxyquin. The potential repression of bullhead GST isoforms that conjugate the carcinogenic metabolites of PAH metabolism under conditions of environmental chemical exposure could be a contributing factor in the sensitivity of bullheads to pollutant-associated neoplasia.
Key Words: glutathione S-transferase; liver; enzyme induction; brown bullheads; ethoxyquin; isoelectric focusing..
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  V. J. Berdikova Bohne, K. Hamre, and A. Arukwe Hepatic Biotransformation and Metabolite Profile during a 2-Week Depuration Period in Atlantic Salmon Fed Graded Levels of the Synthetic Antioxidant, Ethoxyquin Toxicol. Sci., September 1, 2006; 93(1): 11 - 21. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. L. Henson and E. P. Gallagher Glutathione S-Transferase Expression in Pollution-Associated Hepatic Lesions of Brown Bullheads (Ameiurus nebulosus) from the Cuyahoga River, Cleveland, Ohio Toxicol. Sci., July 1, 2004; 80(1): 26 - 33. [Abstract] [Full Text] [PDF]
|
|