Adaptation to a high protein, carbohydrate-free diet induces a marked reduction of fatty acid synthesis and lipogenic enzymes in rat adipose tissue that is rapidly reverted by a balanced diet

Authors: Brito, S M.R.C.; Moura, M A.F.; Kawashita, N H.; Festuccia, W T.L.; Garófalo, M A.R.; Kettelhut, I C.; Migliorini, R H.

Source: Canadian Journal of Physiology and Pharmacology, Volume 83, Number 6, June 2005 , pp. 477-482(6)

Publisher: NRC Research Press

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Abstract:

We have previously shown that in vivo lipogenesis is markedly reduced in liver, carcass, and in 4 different depots of adipose tissue of rats adapted to a high protein, carbohydrate-free (HP) diet. In the present work, we investigate the activity of enzymes involved in lipogenesis in the epididymal adipose tissue (EPI) of rats adapted to an HP diet before and 12 h after a balanced diet was introduced. Rats fed an HP diet for 15 days showed a 60% reduction of EPI fatty acid synthesis in vivo that was accompanied by 45%–55% decreases in the activities of pyruvate dehydrogenase complex, ATP-citrate lyase, acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase, and malic enzyme. Reversion to a balanced diet for 12 h resulted in a normalization of in vivo EPI lipogenesis, and in a restoration of acetyl-CoA carboxylase activity to levels that did not differ significantly from control values. The activities of ATP-citrate lyase and pyruvate dehydrogenase complex increased to about 75%–86% of control values, but the activities of glucose-6-phosphate dehydrogenase and malic enzyme remained unchanged 12 h after diet reversion. The data indicate that in rats, the adjustment of adipose tissue lipogenic activity is an important component of the metabolic adaptation to different nutritional conditions.Key words: lipogenesis, lipogenic enzymes, high protein diet, diet reversion.

Nous avons déjà montré que la lipogénèse in vivo est réduite de façon marquée dans le foie, la carcasse et quatre sites de tissu adipeux de rats adaptés à une diète sans glucide, à haute teneur en protéine (HP). Dans le présent travail, nous examinons dans le tissu adipeux épididymaire (ÉPI), l'activité des enzymes impliquées dans la lipogénèse de rats adaptés à une diète HP, avant et après substitution par une diète équilibrée pendant 12 h. Après 15 jours, la diète HP a provoqué une réduction de 60 % de la synthèse des acides gras de l'ÉPI in vivo, qui a été accompagnée par des diminutions de 45 % – 55 % des activités du complexe de la pyruvate déshydrogénase, ATP-citrate lyase, acétyl-CoA carboxylase, glucose-6-phosphate déshydrogénase et enzyme malique. La substitution par la diète équilibrée pendant 12 h a induit une normalisation de la lipogénèse de l'ÉPI in vivo et un rétablissement de l'activité de l'acétyl-CoA carboxylase à des taux proches des valeurs témoins. Les activités de l'ATP-citrate lyase et de la pyruvate déshydrogénase ont augmenté à environ 75 % – 86 % des valeurs témoins, mais les activités de la glucose-6-phosphate déshydrogénase et de l'enzyme malique sont demeurées inchangées 12 h après la substitution de la diète. Les résultats indiquent que, chez les rats, l'ajustement de l'activité lipogène du tissu adipeux est une composante importante de l'adaptation métabolique à diverses conditions nutritionnelles.Mots clés : lipogenèse, enzymes lipogènes, diète à haute teneur en protéine, substitution de la diète.[Traduit par la Rédaction]

Document Type: Research article

Publication date: 2005-06-01

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Adaptation to a high protein, carbohydrate-free diet induces a marked reduction of fatty acid synthesis and lipogenic enzymes in rat adipose tissue that is rapidly reverted by a balanced diet

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