IDIORRHYTHMIC DOSE-RATE VARIABILITY IN DIETARY ZINC INTAKE GENERATES A DIFFERENT RESPONSE PATTERN OF ZINC-METABOLISM THAN CONVENTIONAL DOSE-RESPONSE FEEDING

We compared the effects of idiorrhythmic dose-rate feeding and convent ional dose-response on the induction of intestinal metallothionein (iM T), expression of aortal heat-shock protein mRNA (HSP70mRNA) induced b y restraint stress, and accumulation of Zn in the femur and incisor of young growing male rats, An idiorrhythmic approach requires that the average dietary Zn concentration (module, M) over the whole experiment (epoch, E) is kept constant across different groups, This is done by adjusting the Zn concentration of the supplemented diet supplied to co mpensate for the reduction in the number of days on which Zn-supplemen ted diet is fed, the latter being spread evenly over the experiment, I diorrhythms involve offering the diet with n times the overall Zn conc entration (M) only every nth day with Zn-deficient diet offered on oth er days, Idiorrythmic Zn dose-rate feeding changed Zn accumulation in the femur and incisor in a complex bi-modal fashion, indicating that m etabolic efficiency of dietary Zn is not constant but depends on Zn do se-rate, In contrast to feeding Zn in the conventional dose-response s cheme, iMT and HSP70mRNA were not affected by idiorrhythmic dose-rate feeding, Idiorrhythmic cycling in dietary Zn load posed no risk of a b iochemical overload nor caused the animals to be stressed, Idiorrhythm ic dose-rate feeding brings the dimension of time to the conventional dose-response model.