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GENDER SPECIFIC ALTERATION OF GLUCURONIDATION IN BROOK TROUT DURING THE ANNUAL REPRODUCTIVE CYCLE
Citation:
Solem, L. E., R C. Kolanczyk, P. K. Schmieder, AND J M. McKim. GENDER SPECIFIC ALTERATION OF GLUCURONIDATION IN BROOK TROUT DURING THE ANNUAL REPRODUCTIVE CYCLE. Presented at Society of Toxicology Annual Meeting, Philadelphia, PA, March 19-23, 2000.
Description:
There is limited information on the effect of physiological and biochemical changes associated with the annual reproductive cycle on hepatic phase ll biotransformation rates in fish. The purpose of this study was to provide insight regarding metabolic deactivation of xenobiotics and to provide data for the prediction of altered hepatic boitransformation rates and pathways during the reproductive cycle. In vitro phase II biotransformation of phenol was assessed using hepatic microsomes isolated from three male and three female brook trout (Salvelinus fontinalis) every four weeks from June through December. Glucuronidation of phenol over a range of substrate concentrations (1 to 60 mM) was quantified for the determination of Mivhaelis-Menton constants (km, Vmax) by HPLC with UV DAD. Initially there were no significant differences in clucuronide rate of formation (pmol/min/mg protein) or total capacity (pmol/min/liver) between immature adult females and males. At the peak of maturation, the maximum rate of glucuronide formation was 4-fold less in females, however, the total capacity was approximately equal between the seces, due to the increases in the hepatic and gonadal somatic indices and with changes in plsma hormone concentrations. These data provide valuable insight for resolving uncertainties which are central to fish predictive toxicity, namely, the role of biotransformation and maturation in chemical disposition.