Age effects on hepatic drug metabolism in Syrian hamsters

The influence of age on hepatic microsomal drug metabolism was determined in male and female Syrian hamsters fed purified diet or commercial ration. Data from hamsters are reported on hepatic contents of microsomal protein and cytochrome P450, as well as activities of arylhydrocarbon hydroxylase and aniline hydroxylase measured at 4, 10, 22, 34, and 64 weeks of age. Hepatic microsomal protein increased at 34 and 64 weeks in hamsters fed purified diet and at 64 weeks in those fed commercial diet. Cytochrome P450 liver content, based on microsomal protein, was highest at 10 weeks in hamsters given purified diets. Peak values were less with the commercial diet and did not differ between 10, 22, and 34 weeks. When expressed on a body weight basis, cytochrome P450 values increased between 4 and 10 weeks in all groups, except in males fed purified diet, in which values increased up to 34 weeks. Arylhydrocarbon hydroxylase activity increased between 4 and 10, 22 or 34 weeks and declined by 64 weeks in every group when based on microsomal protein content or body weight. Aniline hydroxylase activity, based on microsomal protein, increased between 4 and 10 or 22 weeks and then declined by 64 weeks in every group, except in females fed commercial diet, in which no increase occurred. Changes in aniline hydroxylase, based on body weight, were not consistent with these patterns. Maximum values occurred at 4 weeks for females and at 22 weeks for males fed purified diet, but at 10 weeks in males given commercial diet. Declines in drug metabolism between maturity and senescence were greater when data were expressed on the basis of microsomal protein content, when compared with data on a body weight basis.