azaguanine and Starvation

The food intake, liver composition and hepatic activity of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6P-DH), malic enzyme (ME) and acetyl CoA carboxylase (AcCoA Cx) were studied in starved-refed rats. When rats were refed a mixed diet for 3 days, food intake significantly increased (by 33%) from day 1 to 3 and the glycogen accumulation was maximal after 24 hours, but decreased significantly by day 3 (by 34%). In contrast, liver triglycerides sharply increased (10-fold) from day 1 to 3. Furthermore, during refeeding a large increase of G6P-DH, ME and AcCoA Cx was reached on day 3 when the average activity was 5.5- to 6.5-fold higher than before fasting. When rats were refed under conditions of self-selection (carbohydrates, lipids and proteins) total food intake was the same each day, but lipid and carbohydrate intakes varied reciprocally: lipid intake decreased whereas carbohydrate consumption increased during the 3 day refeeding period. Liver glycogen level was unchanged and both the triglyceride accumulation and the overshoot of lipogenic enzymes were highly attenuated: on day 3, they reached 50% of values observed in mixed diet refed rats. Administration of 8-azaguanine during refeeding under self-selecting conditions lowered food intake but had no effect on the pattern of food intake on the first day. In the following days, lipid intake fell dramatically. Azaguanine does not alter liver glycogenesis, but prevents both liver triglyceride accumulation and the overshoot of lipogenic enzymes.

Topics: Animals; Azaguanine; Body Weight; Dietary Carbohydrates; Dietary Fats; Food Preferences; Liver; Male; Rats; Starvation

Intact and adrenalectomized (ADX) rats were starved for 48 hours and refed a 65% glucose diet for 48 hours. Isotonic saline or 8 azaguanine (8AZ) and/or glucocorticoid was administered to the animals during the refeeding period. The typical enzyme overshoot response to refeeding was observed in the intact rats and in the ADX rats given hormone replacement. No overshoot was observed in ADX rats without hormone replacement or in the intact or in hormone treated ADX rats injected with 8AZ. These results suggest that glucocorticoid is involved in the genesis of the enzyme overshoot response to starvation-refeeding, perhaps through an effect on de novo RNA synthesis.

Topics: Adrenalectomy; Animals; Azaguanine; Enzyme Induction; Glucose; Glucosephosphate Dehydrogenase; Hydrocortisone; Malate Dehydrogenase; Male; Rats; Starvation

Rat liver glucose 6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities were increased by starvation-refeeding to levels above those found in rats fed ad libitum. The increases in enzyme activities above ad libitum-fed levels were prevented by 8-azaguanine and 6-azauridine, but not by 2-azauridine. Blood insulin levels were not affected at the time studied. Two aza analogs, 8-azaadenine and 5-azacytidine, proved to be too toxic in this type of studies. Since 8-azahypoxanthine, 8-azaxanthine and 5-azauracil were neither effective in preventing the enzyme overshoot, nor toxic to the animals, it was concluded that the toxiciyty to the animals of 8-azaadenine and 5-azacytidine is due to the compounds themselves rather than to the breakdown products.

Topics: Adenine; Animals; Aza Compounds; Azacitidine; Azaguanine; Azauridine; Feeding Behavior; Glucosephosphate Dehydrogenase; Hypoxanthines; Liver; Malate Dehydrogenase; Male; Nucleotides; Rats; Starvation; Uracil; Xanthines

Topics: Animals; Azaguanine; Carbon Radioisotopes; Kinetics; Liver; Male; Orotic Acid; Rats; RNA; Specific Pathogen-Free Organisms; Starvation; Tritium

Topics: Aldehyde Oxidoreductases; Animals; Aza Compounds; Azaguanine; Hypoxanthines; Kinetics; Liver; Male; Purines; Rats; Starvation; Xanthines

Topics: Age Factors; Animals; Azaguanine; Caseins; Diet; Eating; Glucose; Glucosephosphate Dehydrogenase; Insulin; Lipid Metabolism; Liver; Malate Dehydrogenase; Male; Rats; Starvation

Topics: Animal Nutritional Physiological Phenomena; Animals; Azaguanine; Body Weight; Caseins; Diet; Dietary Carbohydrates; Dietary Proteins; Enzyme Induction; Glucose; Glucosephosphate Dehydrogenase; Liver; Male; Organ Size; Rats; RNA, Messenger; Starvation; Sucrose; Time Factors

Topics: Animals; Azaguanine; Dietary Proteins; Ketone Oxidoreductases; Liver; Male; Rats; Starvation; Time Factors; Xanthine Dehydrogenase; Xanthines

Topics: Animal Nutritional Physiological Phenomena; Animals; Azaguanine; Body Weight; Depression, Chemical; Germ-Free Life; Glucosephosphate Dehydrogenase; Lipid Metabolism; Liver; Malate Dehydrogenase; Male; NADP; Nutritional Physiological Phenomena; Obesity; Organ Size; Rats; Starvation; Time Factors

Topics: Animal Nutritional Physiological Phenomena; Animals; Azaguanine; Body Weight; Depression, Chemical; Diet; Dietary Carbohydrates; Germ-Free Life; Glucose; Glucosephosphate Dehydrogenase; Insulin; Insulin Antibodies; Liver; Malate Dehydrogenase; Male; Metabolism; NADP; Rats; RNA; Starvation; Stimulation, Chemical; Time Factors

Topics: Animal Nutritional Physiological Phenomena; Animals; Azaguanine; Body Weight; Depression, Chemical; Dietary Carbohydrates; Germ-Free Life; Glucosephosphate Dehydrogenase; Hyperinsulinism; Injections, Intraperitoneal; Insulin; Insulin Antibodies; Lipid Metabolism; Lipids; Liver; Malate Dehydrogenase; Male; Rats; RNA; Starvation; Time Factors

Topics: Animals; Azaguanine; Glucosephosphate Dehydrogenase; Liver; Malate Dehydrogenase; Male; Nutritional Physiological Phenomena; Rats; RNA; Starvation; Time Factors

Topics: Animals; Azaguanine; Body Weight; Diet; Glucokinase; Glucose-6-Phosphate Isomerase; Glucosephosphate Dehydrogenase; Glycerolphosphate Dehydrogenase; Hexokinase; Isomerases; Ketones; Liver; Liver Glycogen; Malate Dehydrogenase; Male; Phosphogluconate Dehydrogenase; Phosphotransferases; Proteins; Pyruvate Kinase; Rats; RNA; Starvation; Statistics as Topic; Time Factors