Effect of dietary polyunsaturated fatty acids on Stearoyl CoA-Desaturase gene expression in intramuscular lipids of lamb

The effect of replacement of dietary sun- flower oil (SO) with linseed oil (LO) on Stearoyl CoA desaturase (SCD) gene expres- sion was investigated. Thirty-six lambs were randomly assigned to four groups and fed with one of the experimental diets, consisting of lucerne pellets with oil (60 g/Kg). The diets varied in the percentage of the oil supplemented and were: 100% SO; 66.6% SO plus 33.3% LO; 33.3% SO plus 66.6% LO and 100% LO. The trial period was of 7 weeks. Longissimus dorsi was removed from each carcass and stored at -80°C until the analysis. Total fatty acids composition was determined by gas-chromatograph, while SCD gene expression was assessed by Real- Time Reverse-Transcription PCR. Replacement of SO with LO decreases significantly the SCD mRNA content with a concomitant increment of polyunsatured fatty acids (PUFA) n-3. These results are related to the higher level of PUFA n-3 present in linseed than sunflower. Although, there were differences on mRNA level, there was not a simultaneously changes on SCD activity. In conclusion, PUFA n-3 act on the regulation of mRNA SCD level without affecting the activity of the relative enzyme