CHANGES IN FATTY-ACID COMPOSITION IN RAT ADIPOSE-TISSUE INDUCED BY DIETARY OBESITY

The aim of the study was to evaluate the effects of cafeteria feeding on the composition of fatty acids in retroperitoneal fat pad and also to determine what happens to fatty acids when rats previously fed the cafeteria diet are returned to regular rat chow. The study of the pose -cafeteria rats enabled us to determine the effects of dietary induced excess weight in the absence of artefactual interferences from the di et because these rats, unlike the cafeteria obese rats, ate the same d iet as controls. In response to cafeteria feeding there were increases in the majority of adipose tissue fatty acids. However, significant d ecreases were observed in the relative proportions of 18:2n-6 and in t wo related n-6 polyunsaturated fatty acids (18:3n-6 and 20:3n-6), as w ell as in 16:1. In the post-cafeteria obesity model the previous dieta ry influence on fatty acid composition was still evident. The maintena nce of both the high levels and proportions of 18:1 and the decrease o f 16:1 percentage in the post-cafeteria rats argues in favour of an al teration in the activity of the elongation metabolic pathway Certain c hanges affecting polyunsaturated fatty acid adipose depot composition of obese tars, mainly the decreased levels of 18:2n-6, are long lastin g and could be related to the maintenance of the obese status. On the whole, although the fatty acid composition of adipose tissue is influe nced by the composition of the diet, there are some differences in bot h the maintenance of the effects and also in the selectivity of adipos e tissue for the different fatty acids of obese and lean rats.