Cardiac Lipid Changes in Rats Fed Oils Containing Long-Chain Fatty Acids

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Abstract

Fat accumulation occurred in the myocardium of young rats fed docosenoic acid provided by liquid or partially hydrogen-ated rapeseed oil or partially hydrogenated herring oil. The composition of the cardiac fatty acids and the histopathology in rats receiving oil as 40% of calories were studied after 3, 7, 14 and 28 days. In those fed liquid rapeseed oil, a peak accumulation was reached at 7 days and thereafter decreased, and the concentration of docosenoic acid was higher than in those fed the hydrogenated oils.

A zero-effect level of abnormal fat deposition from liquid rapeseed oil was found to be 5% by weight of the diet or 10% of calories. Further increases in the level of dietary rapeseed oil enhanced the cardiac fat droplets and the accumulation of dietary fatty acids, particularly docosenoic acid.

Canbra oil had no effect on lipid accumulation in the heart.

Résumé

Une accumulation de lipide s'est produite dans le myocardium de jeunes rats nourris d'acide docosenoique dans de l'huile de colza liquide ou partiellement hydrogénée ou de l'huile d'hareng partiellement hydrogénée. La composition des acides gras des tissus du coeur et de l'histoipathologie du tissu de rats absorbant de l'huile comme source de 40% de calories furent analysées à la suite de 3, 7, 14 et 28 jours. Chez les rats nourris à l'huile de colza liquide, une accumulation maximale fut obtenue au 7ème jour suivi d'un décroisement; la concentration d'acide docosenoique était plus considérable que chez les rats nourris avec les huiles hydrogénées.

Il a été observé, que le niveau auquel il ne se trouvait pas de déposition abnormal e de lipide était de 5% du poids de la diète ou 10% de calories. Un accroissement du niveau d'huile de colza dans la diète augmente les goûtelettes de lipide dans les tissus du coeur ainsi que l'accumulation des acides gras diététique, plus particulièrement, l'acide docosenoique.

L'huile de canbra n'a pas causé d'accumulation de lipide dans le coeur.

Introduction

Histopathological changes were observed in the heart muscle of rats fed rapeseed oil containing appreciable quantities of erucic acid (Roine et al., 1960; Rocquelin and Cluzan, 1968; Thomasson et al., 1970; Abdellatif and Vies, 1970). During the first few days of the dietary treatment, an accumulation of lipid appeared in the myocardium, and then regressed during the ensuing weeks as necrotic foci developed (Abdellatif and Vles, 1970).

To investigate the extent of fat deposition and the fatty acid constituents of the heart, rats were fed long-chain fatty acids from different sources for varying periods of time. In addition, graduated amounts of liquid rapeseed oil were fed to determine a no-effect level of enhanced fatty deposits in the young rat.

Section snippets

Methods

Charles River rats, specific pathogen free, were obtained at weaning and divided into similar groups on the basis of sex and body weight. They were maintained in individual cages and fed ad libitum a basal diet containing, by weight, 20% casein, 20% sucrose, 30% cornstarch, 1% vitamin mixture (Beare et al, 1963b), 4% salt mixture, U.S.P. XIV, 5% alphacel and 20% test oil or fat.

In the first experiment, 320 rats, half of each sex, were fed: 1) a 3:1 mixture of lard and corn oil, 2) liquid

Results

From the composition of the dietary oils fed in the first experiment (Table 1), it is seen that the control mixture of lard and corn oil contained mostly C16 and C18 fatty acids and that the other oils had appreciable quantities of C20 and C22 fatty acids. Upon partial hydrogenation, the rapeseed and herring oils contained elevated levels of saturated fatty acids, but the C22 fraction was still mostly in the monoenoic form.

The amount of food consumed and the weight gained by the rats were

Discussion

Thornasson (1955) suggested that fatty acids with twenty or more carbon atoms exerted an unfavorable influence on the growth of young animals. In this regard, the effect of erucic acid in rapeseed oil is well known, and appears to be similar to that of its positional isomers, particularly cetoleic acid found in herring oil.

The early accumulation of lipid globules in the myocardium of rats fed liquid rapeseed oil was first reported by Thomasson et al. (1970) and described in detail by Abdellatif

Acknowledgements

Liquid rapeseed oil, partially hydrogenated rape-seed oil and partially hydrogenated herring oil were kindly supplied by Canada Packers Kesearch and Development Laboratories.

The competent technical assistance of Leona M. Gray, M. Anne Moore, Kudy H. Hollywood, Claude Desloges and Nicholas Ben-Tchartchavadze is gratefully acknowledged.

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