Reprod. Nutr. Dev. 45 (2005) 441-451
DOI: 10.1051/rnd:2005039

In vitro metabolism of rumenic acid in bovine liver slices

Anne De La Torre^a, Dominique Gruffat^a, Jean-Michel Chardigny^b, Jean-Louis Sebedio^b, Denys Durand^a, Olivier Loreau^c and Dominique Bauchart<sup>a

a</sup>  INRA, Research Unit on Herbivores, Nutrients and Metabolisms Group, 63122 Saint-Genès-Champanelle, France
^b  INRA, Lipid Nutrition Unit, 21065 Dijon, France
^c  CEA Saclay, 91191 Gif/Yvette Cedex, France

(Received 21 December 2004; accepted 22 March 2005)

Abstract - Ruminant products are the major source of CLA for humans. However, during periods of fat mobilization, the liver might play an important role in CLA metabolism which would limit the availability of the latter for muscles and milk. In this context, rumenic acid (cis-9, trans-11 CLA) metabolism in the bovine liver (n = 5) was compared to that of oleic acid (n = 3) by using the in vitro liver slice method. Liver slices were incubated for 17 h in a medium containing 0.75 mM of FA mixture and 55 M of either [1-¹⁴C] rumenic acid or [1-¹⁴C] oleic acid at 37 °C under an atmosphere of 95% O₂-5% CO₂. Rumenic acid uptake by liver slices was twice (P = 0.009) that of oleic acid. Hepatic oxidation of both FA (> 50% of incorporated FA) led essentially to the production of acid-soluble products and to a lower extent to CO₂ production. Rumenic acid was partly converted (> 12% of incorporated rumenic acid) into conjugated C18:3. CLA and its conjugated derivatives were mainly esterified into polar lipids (71.7%), whereas oleic acid was preferentially esterified into neutral lipids (59.8%). Rumenic acid secretion as part of VLDL particles was very low and was one-fourth lower than that of oleic acid. In conclusion, rumenic acid was highly metabolized by bovine hepatocytes, especially by the oxidation pathway and by its conversion into conjugated C18:3 for which the biological properties need to be elucidated.

Key words: rumenic acid / oleic acid / metabolism / liver / bovine

Corresponding author: Dominique Gruffat gruffat@sancy.clermont.inra.fr

© INRA, EDP Sciences 2005