title: Difference in response of hepatic glutathione S-transferase activities to protein-free diet between young and old C57/BL male mice.
abstract: Responses of hepatic glutathione S-transferase (GST) activities to protein-free diet (PFD) and normal diet (ND) refeeding were compared for young (6-month-old) and old (22-month-old) C57/BL male mice. Enzyme activities toward 1-chloro-2,4-dinitrobenzene (CDNB) were not significantly different between young and old rat livers in the basal condition without diet manipulation. When animals were fed PFD for 1 week, GST activities toward CDNB significantly declined in both age groups in comparison to respective basal values, but there was no significant difference in activities between the two age groups after a 7-day PFD. When they were refed with ND for 2 days (on day 2 of ND), the activities in young mice rose to a level significantly higher than the corresponding basal value. In contrast, in old animal livers, the activity slightly but further tended to decline on day 2 of ND. Activities in old rat livers returned to the basal level on day 5 of ND, while activities in young animal livers that increased to levels higher than basal levels due to the overshoot returned to the basal level on day 7 of ND. Enzyme activities toward 1,2-dichloro-4-nitrobenzene (DCNB) were significantly higher in young rat livers than in old ones at the basal period. However, enzyme activities also overshot the basal level on day 2 of ND after 7-day PFD in young mouse livers, while in old mouse livers the activities were lowest on this day. Activities returned to the basal level on day 7 of ND in both age groups. Thus, the greatest difference in enzyme activities between young and old mouse livers for both substrates was observed on day 2 of ND after 7-day PFD, rather than at either the basal period or immediately after 7-day PFD. The results essentially agree with our previous findings on female C57/BL mice as well as female Fischer-344 rats, suggesting that the age-induced changes in the GST system become clearly manifest after diet manipulation of PFD followed by ND refeeding, rather than in values during a basal period without diet manipulation, regardless of sex or species of animal.
authors.affiliation: Department of Clinical Physiology, Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: M C
authors.initials: MC
authors.lastname: Carrillo
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Kanai
authors.forename: M
authors.initials: M
authors.lastname: Nokubo
authors.forename: K
authors.initials: K
authors.lastname: Kitani
mesh_terms: D000375:Aging; D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D004044:Dietary Proteins; D005982:Glutathione Transferase