CHANGES IN THE ACTIVITIES OF HEPATIC XENOBIOTIC-METABOLIZING ENZYMES AFTER THE ADMINISTRATION OF CLENBUTEROL TO FEMALE BROILERS

Clenbuterol is a beta(2)-agonist drug which in some countries is used illegally to enhance the productivity of various food-producing specie s, including poultry. This work investigated whether the prolonged exp osure of female broilers to clenbuterol modified the activity of hepat ic microsomal or cytosolic enzyme systems concerned with the metabolis m of drugs, pesticides, carcinogens and endogenous substrates such as sexual steroids. Clenbuterol was added to the birds' diet at concentra tions of 1 or 25 ppm for 21 days. There was a dose-related decrease in the concentration of cytochrome P-450, and in the activities of the p olycyclic aromatic hydrocarbon-inducible monooxygenases ethoxyresorufi n O-de-ethylase and aryl hydrocarbon hydroxylase. The activities of gl utathione S-transferase, N-acetyltransferase and uridinediphosphoglucu ronyltransferase were not affected by the treatment.