Dataset Information

Protective effect of glutathione S-transferase enzyme activity against aflatoxin B₁ in poultry species: relationship between glutathione S-transferase enzyme kinetic parameters, and resistance to aflatoxin B₁.

ABSTRACT: Comparative studies designed to investigate the role of glutathione S-transferase (GST) activity on the enzyme catalyzed trapping of aflatoxin B₁-8,9-epoxide (AFBO) with glutathione, and the relationship with aflatoxin B₁ (AFB₁) resistance have not been conducted in poultry. Hepatic cytosolic fractions of chickens, quail, turkeys and ducks were used to measure in vitro the enzymatic parameters maximal velocity (V_max), Michaelis-Menten constant (K_m) and intrinsic clearance (CL_int) for GST activity. AFB₁ used ranged from 2.0 to 157.5 µM and the AFB₁-GSH produced was identified and quantitated by HPLC. Significant differences were found in GST V_max values, being the highest in chickens, followed by quail, ducks and turkeys. The K_m values were also significantly different, with chickens < ducks < turkeys < quail. Chickens had the higher CL_int value in contrast to ducks. Differences by sex showed that duck females had a higher CL_int value than the turkey and quail, whereas duck males had a CL_int close to that of turkey. The ratio "AFBO production /AFB₁-GSH production" follows the order duck>turkey>quail>chicken, in agreement with the known poultry sensitivity. The extremely high "AFB₁ epoxidation activity/ GST activity" ratio observed in ducks might be the explanation for the development of hepatocellular carcinoma in this species.

SUBMITTER: Murcia HW

PROVIDER: S-EPMC8258694 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Ingestion of aflatoxin B1 (AFB1) represents a major risk factor in the aetiology of human hepatocellular carcinoma. In the rat, the harmful effects of AFB1 can be prevented by the administration of certain drugs which induce hepatic detoxification enzymes. We have previously shown that treatment of rats with the chemoprotector ethoxyquin (EQ) results in a marked increase in expression of the Alpha-class glutathione S-transferase (GST) Yc2 subunit which has high activity towards AFB1-8,9-epoxide [Hayes, Judah, McLellan, Kerr, Peacock and Neal (1991) Biochem. J. 279, 385-398]. To allow an assessment of whether the increased expression of GST Yc2 represents a general adaptive resistance mechanism to chemical stress, that is invoked by both chemoprotectors and carcinogens, we have examined the effects of EQ, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), phenobarbital (PB), AFB1, 3-methylcholanthrene (3-MC) and clofibrate on the AFB1-glutathione-conjugating activity and the GST subunit levels in rat liver. In addition, the effect of these drugs on the hepatic levels of an aldehyde reductase (AFB1-AR) that metabolizes the cytotoxic dialdehydic form of AFB1 has been studied as this enzyme also appears to be important in chemoprotection. Administration of the antioxidants EQ, BHA or BHT, as well as PB, led to a marked increase in levels of the GST Yc2 subunit in rat liver, and this increase coincided with a substantial rise in the GST activity towards AFB1-8,9-epoxide; neither AFB1, 3-MC nor clofibrate caused induction of Yc2 or any of the GST subunits examined. Among the xenobiotics studied, EQ was found to be the most effective inducing agent for the Yc2 subunit as well as Yc1, Yb1 and Yf. However, PB was equally as effective as EQ in increasing levels of the Ya-type subunits, although it was not found to be as potent an inducer of the other GST subunits, including Yc2. In addition to induction of GST, EQ caused a substantial increase in the hepatic content of AFB1-AR. Both BHA and BHT were also able to induce this enzyme but, by contrast, PB was found to be a poor inducer of AFB1-AR. AFB1, 3-MC and clofibrate were unable to serve as inducers of this reductase. The presence of Alpha-class GST, including the Yc2 subunit, was examined in various rat tissues. Constitutive expression of Yc2 was found in the epididymis at levels comparable with that observed in the liver from EQ-treated rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Dataset Information

Protective effect of glutathione S-transferase enzyme activity against aflatoxin B₁ in poultry species: relationship between glutathione S-transferase enzyme kinetic parameters, and resistance to aflatoxin B₁.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Protective effect of glutathione S-transferase enzyme activity against aflatoxin B1 in poultry species: relationship between glutathione S-transferase enzyme kinetic parameters, and resistance to aflatoxin B1.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Protective effect of glutathione S-transferase enzyme activity against aflatoxin B₁ in poultry species: relationship between glutathione S-transferase enzyme kinetic parameters, and resistance to aflatoxin B₁.