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'Lipogenic Enzymes' in keywords Facet   Publication Year 1996  [X]
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1996[X]
1Author    M. Einrad Boll3, LutzW D W Eberb, Andreas StampflbRequires cookie*
 Title    Nutritional Regulation of the Activities of Lipogenic Enzymes of Rat Liver and Brown Adipose Tissue  
 Abstract    Nutrition-induced effects on the activity of enzymes of lipogenesis, fatty acid synthase (FAS; EC 2.3.1.85). ATP citrate lyase (ACL; EC 4.1.3.8), malic enzyme (ME; EC 1.1.1.40), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehy­ drogenase (PGDH; EC 1.1.1.44) were investigated in liver and interscapular brown adipose tissue (BAT) of rats. The lipogenic enzymes could be grouped into two categories according to their response to dietary manipulations; FAS and ACL. both key enzymes of lipogenesis, responded fast and strongly to dietary manipulations. ME, G6PD H and PG D H , enzymes which also contribute to metabolic pathways other than lipogenesis, responded in a more sustained and less pronounced fashion. Feed deprivation caused the specific activities of lipogenic enzymes to decline several-fold. R efeeding of previously fasted (up to 3 days) animals increased the activities dramatically (10-to 25-fold) to far above pre-fasting levels ("overshoot"). Repetition of the fasting/refeed­ ing regimen increasingly impaired the ability of both tissues to synthesize overshooting en­ zyme activities in the subsequent refeeding period. The fasting-induced decline of the activi­ ties was prevented when sugars were provided to the animals via drinking water. The sugars displayed different effectivities; sucrose= glucose> fructose> m a lto s e » lactose. Sugars as the sole nutrient after fasting were also able to induce overshooting enzyme activities. Again, activities of FAS and ACL responded in a more pronounced fashion than the other three enzymes. Transition from feeding one diet to feeding a new diet of different composition led to adapta­ tion of the lipogenic enzym e activities to levels characteristic for the new diet. Replacing a low-carbohydrate with a high-carbohydrate diet proceeded with major alterations o f enzyme activities. TTiis process of attaining a new level took up to 20 days and involved pronounced oscillations of the specific activities. In contrast, when a high-carbohydrate diet was replaced with another diet, particular one high in fat, transition to new enzyme activities was com ­ pleted within 2 -3 days and proceeded without oscillations. All dietary manipulations caused more pronounced responses in young (35d-old) than in adult (180d-old) animals. 
  Reference    Z. Naturforsch. 51c, 859 (1996); Received August 8 1996 
  Published    1996 
  Keywords    Lipogenic Enzymes, D iet Composition, Starvation/Refeeding, Sugars, Enzyme Regulation Oscillation 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0859.pdf 
 Identifier    ZNC-1996-51c-0859 
 Volume    51