Comparison of growth and fatty acid metabolism in rats fed diets containing equal levels of gamma-linolenic acid from high gamma-linolenic acid canola oil or borage oil

We have utilized transgenic technology to develop a new source of gamma-lin olenic acid (GLA) using the canola plant as a host. The aim of the present study was to compare the growth and fatty acid metabolism in rats fed equal amounts of GLA obtained from the transgenic canola plant relative to CCA f rom the borage plant. Young male Sprague-Dawley rats (n = 10/group) were ra ndomized and fed a purified AlN93G diet (10% lipid by weight) containing ei ther a mixture of high GLA canola oil (HGCO) and corn oil or a control diet containing borage oil (BO) for 6 wk. CLA accounted For 23% of the triglyce ride fatty acids in both diets. Growth and diet consumption were monitored every 2-3 d throughout the study. At study termination, the fatty acid comp osition of the liver and plasma phospholipids was analyzed by gas chromatog raphy. The growth and diet consumption of the HGCO group were similar to th e BO group. There were no adverse effects of either diet on the general hea lth or appearance of the rats, or on the morphology of the major organs. Th ere was no significant difference between the diet groups for total percent age of n-6 polyunsaturated fatty acids present in either the total or indiv idual phospholipid fractions of liver or plasma. The relative percentage of CLA and its main metabolite, arachidonic acid, in each phospholipid fracti on of liver or plasma were also similar between groups. The percentage of 1 8:2n-6 in liver phosphatidylethanolamine and phosphatidylinositol/serine wa s higher(P < 0.05) and 22:5n-6 was lower in the HGCO group than the BO grou p. This finding could be attributed to the higher 18:3n-3 content in the HG CO diet than the 80 diet. Results from this long-term feeding study of rats show for the first time that a diet containing transgenically modified can ola oil was well-tolerated, and had similar biological effects, i.e., growt h characteristics and hepatic metabolism of n-6 fatty acids, as a diet cont aining borage oil.