Hepatomegaly Induced by Trans-10,cis-12 Conjugated Linoleic Acid in Adult Hamsters Fed an Atherogenic Diet Is Not Associated with Steatosis

Abstract

Objective: To study the effects of trans-10,cis-12 conjugated linoleic acid (CLA) on liver size and composition, as well as on hepatic lipogenesis and fatty acid oxidation, in adult hamsters.

Methods: Sixteen male Syrian Golden hamsters (8-month-old; initial body weight 167 ± 5 g) were divided into two groups and fed on atherogenic diets supplemented either with 0.5% linoleic acid or trans-10,cis-12 CLA, for 6 weeks. Liver lipids, fatty acid profile, protein, water and DNA contents were analysed. The activity and expression of several enzymes involved in liver fatty oxidation and lipogenesis were assessed, as was the expression of transcriptional factors controlling these enzymes.

Results: The addition of CLA to the diet led to significantly greater liver weight due to hyperplasia. No changes were observed in liver composition. CLA did not modify the expression or the activity of analysed oxidative enzymes. With regard to lipogenic enzymes, an increase in the expression and the activity of acetyl-CoA carboxylase was found.

Conclusions: These results show that the expected body fat-lowering effect of trans-10,cis-12 CLA, observed in young rodents, is not found in adult hamsters. The lack of increase in liver fatty acid oxidation, help to explain why that effect was not found in these animals. Further, the CLA treatment-induced hepatomegaly is a consequence of hyperplasia.

• conjugated linoleic acid
• fatty acid oxidation
• lipogenesis
• liver
• steatosis

• CLA = conjugated linoleic acid
• PPAR = peroxisome proliferator-activated receptor
• SREBP = sterol regulatory element binding protein
• ACC = acetyl-CoA carboxylase
• FAS = fatty acid synthase
• G6PDH = glucose-6-phosphate dehydrogenase
• ME = malic enzyme
• CPT-Ia = carnitine palmitoyltransferase-Ia
• ACO = acyl-coenzyme A oxidase I

This study was supported by grants from the Ministerio de Educación y Ciencia (AGL2005-02494), Gobierno Vasco (IT-265-07; CTP R05/01), University of País Vasco (GIU06/82) and CYTED (Programa Iberoamericano de Ciencia y Tecnología para el desarrollo). J. Miranda is a recipient of a doctoral fellowship from the Ministerio de Educación y Ciencia.

Palm oil was a generous gift from Agra-Unilever Foods España S.A. (Leioa, Spain).

Notes

Conflict of interest: None of the authors had any conflict of interest.