Transcriptional regulation of lipid metabolism in transition dairy goats by fish oil and stearate

To better understand the interaction between saturated or unsaturated fatty acids and genes involved in lipid metabolism in liver and subcutaneous adipose tissue, a nutritional study involving twenty three second parity alpine dairy goats fed either a non fat-supplemented basal diet (C; n=8), or a basal diet supplemented with stearic acid (ST; n=7) or a basal diet supplemented with fish oil (FO; n=8) was set up. 30 g/head/d extra fatty acids during the dry period and 50 g/head/d during lactation were supplemented starting one week before parturition up to 21 days in milk. Liver and subcutaneous adipose tissue samples were harvested at day 7, 7 and 21 relative to kidding and immediately snap frozen in liquid nitrogen. mRNA levels of CPT1A, MSMO1 and SLC27A2 in liver and ACACA, FASN, PLIN2, LEP and IL6 in adipose were measured by quantitative real-time RT-PCR. Data obtained were analyzed using the MIXED procedure of SAS. Milk production, milk composition, body weight and body condition score did not differ between treatments. CPT1A had a similar pattern between treatments and was up regulated at day 7 and down regulated at day 21. No differences were observed for MSMO1 expression. Long-Chain-Fatty-Acid-CoA Ligase (SLC27A2), was down regulated before kidding and, at day 7, reached the highest up regulation in all treatments. At day 21, was then down regulated in C and ST but still up regulated in FO (P<0.05). The enzyme encoded by this gene plays a key role in lipid biosynthesis and fatty acid degradation and could be linked to the delayed fat mobilization in FO subcutaneous adipose tissue observed at day 21. These results support the idea that dietary unsaturated and saturated fatty acids are able to differentially regulate lipid metabolism in liver and adipose tissue.