Age-dependent hepatic lipogenic enzyme activities in starved-refed rats.
Food intake, plasma glucose, insulin (I) and triiodothyronine (T3) and liver glucose 6-phosphate dehydrogenase (G6P-DH), malic enzyme (ME). ATP-citrate lyase, acetyl-CoA carboxylase (AcCoACx) and fatty acid synthase (FAS) activities were measured in 2 and 22 months old rats before, after 3 d starvation and 2,4,6. 24 and 48 h refeeding a high carbohydrate (74% w/w) diet. Expressed per 100 g of body weight, the carbohydrate intake of old rats was 55% lower than that of young rats. Plasma insulin was higher in old than in young rats and decreased (-40%) after starvation and returned to control values 4 h after refeeding. In young rats plasma insulin fell after starvation (-85%) and returned to normal values 2 h after refeeding. No significant differences were observed in plasma [T3] between the two groups. During the first 6 h of refeeding, plasma glucose increased 2-fold and returned to control values after 24 h in young rats. In old rats, plasma glucose returned to its control value after 2 h. Compared to the starved level, 48 h after refeeding, G6P-DH, ME, ATP-citrate lyase, AcCoACx and FAS activities increased 5- to 6-fold in young rats, while in old rats the increase was much smaller and represented 35% of that observed in young rats. These results suggest, that the age-related reduction in inducibility of hepatic lipogenic enzymes of rats refed a high carbohydrate diet after starvation may be due to a spontaneous decrease in the carbohydrate intake and to a decrease effectiveness of insulin (insulin resistance).
Bois-Joyeux
B
B
Centre de Recherche sur la Nutrition du CNRS, Meudon-Bellevue, France.
Chanez
M
M
Aranda-Haro
F
F
Peret
J
J
D001275:ATP Citrate (pro-S)-Lyase / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000378:metabolism; D005502:Food; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000201:enzymology*; D008291:Malate Dehydrogenase / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000201:enzymology*; D014284:Triiodothyronine / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D014284:Triiodothyronine; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D064429:Fatty Acid Synthases; D001275:ATP Citrate (pro-S)-Lyase; D000103:Acetyl-CoA Carboxylase