Double Bond Position Plays an Important Role in Delta-9 Desaturation and Lipogenic Properties of Trans 18:1 Isomers in Mouse Adipocytes.

ABSTRACT

The objective of this research was to study the delta-9 desaturation of individual trans (t) fatty acids that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on lipogenic gene expression in adipocytes. It was hypothesized that delta-9 desaturation and lipogenic properties of t-181 isomers depend on the position of double bond. Differentiated 3T3-L1 adipocytes were treated with 200 µM of t6-181, t9-181, t11-181, t13-181 or t16-181, cis (c)-9 181 or bovine serum albumin (BSA) vehicle control for 48 h. Cells were then harvested for fatty acid and gene expression analyses using gas chromatography and quantitative PCR respectively. Among t-181 isomers, t13-181 and t11-81 had the greatest percent delta-9 desaturation (44 and 41 % respectively) followed by t16-181 and t6-181 (32 and 17 % respectively), while c9-181 and t9-181 did not undergo delta-9 desaturation. Trans9-181 up-regulated (P < 0.05) the expression of lipogenic genes including fatty acid synthase and stearoyl-CoA desaturase-1 (P < 0.05), whereas the expression of these genes were not affected with other t-181 isomers (P > 0.05). Consistent with gene expression results, t9-181 increased the de novo lipogenic index (160/182n-6) compared with control cells and increased delta-9 desaturation index (c9-161/180) compared to other t-181 isomers (P < 0.05). The current study provides further evidence that the predominant trans fatty acid in PHVO (t9-181) has isomer specific lipogenic properties.