Duration of dietary restriction: an important determinant for the incidence and age of onset of leukemia in male F344 rats.
The effect of duration and age of initiation of dietary restriction (DR) on the spontaneous occurrence of leukemia was studied in male F344 rats. Four nutritional paradigms were employed: Group 1, ad libitum fed; Group 2, dietary restricted starting at 6 weeks of age; Group 3, dietary restricted from 6 weeks to 6 months of age; Group 4, dietary restricted starting at 6 months of age. The relative incidence (relative onset rate) of leukemia was highest in the rats of Groups 1 and 3 and lowest in the rats of Group 2. The age of onset was earliest in Group 1 followed by Groups 3, 4, and 2 in that order. The progression (duration from onset to death) did not differ significantly between the groups. These results indicate that the duration of DR correlates with the incidence and age of onset of leukemia but not with its progression. The age of initiation of DR is not as important a determinant as the duration of DR in regard to incidence and age of onset. The incidence and the age of onset of leukemia appear to relate to the total cumulative energy intake of the rat (i.e., age multiplied by mean daily energy intake).
Higami
Y
Y
First Department of Pathology, Nagasaki University School of Medicine, Japan.
Yu
B P
BP
Shimokawa
I
I
Masoro
E J
EJ
Ikeda
T
T
D017668:Age of Onset; D000818:Animals; D004032:Diet; D007942:Leukemia, Experimental / Q000209:etiology*; D008297:Male; D011379:Prognosis; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors