title: Longevity, body weight, and neoplasia in ad libitum-fed and diet-restricted C57BL6 mice fed NIH-31 open formula diet.
abstract: Groups of C57BL6 mice of each sex were assigned to one of 2 dietary regimens, ad libitum (AL) or dietary restriction (DR), to study effects of food restriction on body weight, survival, and neoplasia. The AL and DR groups were subdivided into a scheduled sacrifice group for examination at 6-mo intervals, and a lifetime group to provide longevity data. Necropsies and microscopic examinations were conducted on 911 animals. In the lifetime group food consumption averaged 33.6 and 34.4 g per week by AL males and AL females, respectively; the DR counterparts were given 40% less. The diet contained 4.35 kcal/g. The average lifetime body weights were 34.8, 26.8, 22.6, and 21.6 g for AL males, AL females, DR males, and DR females, respectively, and their age at 50% survival was 27.5, 26.9, 31.7, and 33.5 mo. Maximal lifespan was increased 18% in DR males and females. Lifetime incidence of tumor-bearing mice was 89% and 86% for AL males and females, versus 64% for each sex of DR mice. Dramatic reduction occurred in female DR mice in lymphoma (9% vs 29%), pituitary neoplasms (1% vs 37%), and thyroid neoplasms (0.4% vs 8%). In males, hepatocellular tumors were reduced to 1% from 10% by DR. In contrast, the incidence of histiocytic sarcoma was increased in DR females and unaffected in DR males. Tumor onset was delayed in DR animals; 87% of all neoplasms in males and 95% in females had occurred in the AL mice by 24 mo, whereas the DR animals had only 52% and 39% of their lifetime incidence, respectively, by that age. This study provided comparative AL and DR data from C57BL6 mice examined randomly at 6-mo intervals (cross-sectional group) in parallel with data from animals in similar cohort that was unsampled and allowed to succumb naturally (longevity group). Dietary restriction reduced the lifetime percentage of tumor-bearing animals and the number of tumors per animal, and delayed the age at onset of most neoplasms.
authors.affiliation: Pathology Associates, Inc., Jefferson, Arkansas 72079, USA.
authors.forename: B N
authors.initials: BN
authors.lastname: Blackwell
authors.forename: T J
authors.initials: TJ
authors.lastname: Bucci
authors.forename: R W
authors.initials: RW
authors.lastname: Hart
authors.forename: A
authors.initials: A
authors.lastname: Turturro
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology*; D002423:Cause of Death; D004032:Diet; D004435:Eating / Q000502:physiology*; D005260:Female; D005526:Food, Formulated; D008136:Longevity / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000453:epidemiology* / Q000401:mortality