Effect of dietary calorie and fat restriction on mammary tumor growth and hepatic as well as tumor glutathione in rats.
Effect of dietary calorie restriction and fat reduction on growth of established mammary carcinoma in rats and on glutathione levels in liver and tumor tissue was investigated. Reduced (GSH) and oxidized (GSSG) glutathione were determined enzymatically. Female Sprague-Dawley rats were injected with 25 mg/kg methylnitrosourea (MNU) on day 50 of life for tumor induction, and subsequently fed a diet containing 50 kcal/day with 45% (energy %) fat. When tumors reached approximately 1 cm3, the diet was changed for 10 +/- 2 weeks. Four dietary groups were formed: two high calorie groups (50 kcal/day) with 45% or 25% fat and two calorie restricted groups (35 kcal/day) with 45% or 25% fat, respectively. Tumor growth was significantly inhibited by the 30% calorie restriction, and the inhibition was most effective in the calorie restricted group with low fat level. However, reduction of fat, alone, had no significant inhibitory effect. GSSG levels in both liver and tumor showed no differences among the groups. Hepatic GSH levels tended to be lower in the calorie-restricted groups, and showed no difference between isocaloric groups with different fat levels. In contrast, GSH in tumor tissue tended to be lower in the low fat groups, independently of calorie levels.
Zhu
P
P
Institute of Toxicology and Chemotherapy, German Cancer Research Center, Heidelberg.
Frei
E
E
Bunk
B
B
Berger
M R
MR
Schmähl
D
D
D000818:Animals; D001835:Body Weight; D004041:Dietary Fats / Q000008:administration & dosage*; D002149:Energy Intake; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008325:Mammary Neoplasms, Experimental / Q000178:diet therapy* / Q000378:metabolism / Q000473:pathology; D008770:Methylnitrosourea; D009929:Organ Size; D014176:Protein Biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains
D004041:Dietary Fats; D008770:Methylnitrosourea; D005978:Glutathione