title: Cyclic food restriction alters substrate utilization and abolishes protection from mammary carcinogenesis female rats.
abstract: We tested the hypothesis that cyclic food restriction abolishes protection against mammary carcinogenesis. Virgin female Sprague Dawley rats (n = 159) were injected intraperitoneally with 25 mg/kg n-methyl-n-nitrosourea at 50 d of age. Eleven days later, rats were given free access to a 24.6 g fat/100 g AIN-76A diet (ad lib-c), fed in two meals (me-c), or fed in two meals restricted in weight by 33% for 1 wk followed by 3 wk of compensatory refeeding (me-r) for 18 wk or 4.5 restriction cycles. Energy and substrate utilization of 15 rats from each group was measured by indirect calorimetry. The me-r rats ate and weighed less (P < 0.0001), had a greater efficiency of food utilization (P < 0.01), and had a 12% higher incidence of mammary cancer (P < 0.0001) than ad lib-c rats after adjusting for the effect of final body weight. Resting metabolic rate was not different among groups, but me-r rats used less glucose during restriction and more glucose and less lipid for energy during body weight recovery than me-c rats (P < 0.0001). Increased energy efficiency and the shift in utilization of glucose and fatty acids followed closely the effects of cyclic food restriction and meal feeding on mammary carcinogenesis.
authors.affiliation: Department of Animal and Nutritional Sciences, University of New Hampshire, Durham, 03824, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Tagliaferro
authors.forename: A M
authors.initials: AM
authors.lastname: Ronan
authors.forename: L D
authors.initials: LD
authors.lastname: Meeker
authors.forename: H J
authors.initials: HJ
authors.lastname: Thompson
authors.forename: A L
authors.initials: AL
authors.lastname: Scott
authors.forename: D
authors.initials: D
authors.lastname: Sinha
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002153:Calorimetry, Indirect; D002273:Carcinogens / Q000633:toxicity; D004032:Diet / Q000592:standards*; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D015994:Incidence; D050356:Lipid Metabolism; D008325:Mammary Neoplasms, Experimental / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D008770:Methylnitrosourea / Q000633:toxicity; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D002273:Carcinogens; D005227:Fatty Acids; D008770:Methylnitrosourea; D005947:Glucose