Distribution of omega-6 and omega-3 polyunsaturated fatty acids in the whole rat body and 25 compartments.

ABSTRACT

The steady state compositions of omega-6 and omega-3 polyunsaturated fatty acids (PUFA) throughout the various viscera and tissues within the whole body of rats have not previously been described in a comprehensive manner. Dams consumed diets containing 10wt% fat (15% linoleate and 3% α-linolenate). Male offspring (n=9) at 7-week of age were euthanized and dissected into 25 compartments. Total lipid fatty acids for each compartment were quantified by GC/FID and summed for the rat whole body; total n-6 PUFA was 12wt% and total n-3 PUFA was 2.1% of total fatty acids. 182n-6 accounted for 84% of the total n-6 PUFA, 204n-6 was 12%, 183n-3 was 59% of the total n-3 PUFA, 205n-3 was 2.1%, and 226n-3 was 32%. The white adipose tissue contained the greatest amounts of 182n-6 (1.5g) and 183n-3 (0.2g). 204n-6 was highest in muscle (60mg) and liver (57mg), while 226n-3 was greatest in muscle (46mg), followed by liver (27mg) and carcass (20mg). In terms of fatty acid composition expressed as a percentage, 182n-6 was the highest in the heart (13wt%), while 183n-3 was about 1.3wt% for skin, white adipose tissue and fur. 204n-6 was highest (21-25wt%) in the circulation, kidney, and spleen, while 226n-3 was highest in the brain (12wt%), followed by the heart (7.9wt%), liver (5.9wt%), and spinal cord (5.1wt%). Selectivity was greatest when comparing 226n-3 in brain (12%) to white adipose (0.08%) (68-fold) and 225n-6 in testes (15.6%) compared to white adipose (0.02%), 780-fold.