A new hypotensive polyunsaturated fatty acid dietary combination regulates oleic acid accumulation by suppression of stearoyl CoA desaturase 1 gene expression in the SHR model of genetic hypertension

Polyunsaturated fatty acids (PUFA) are known to repress SCD-1 gene expression, key enzyme of monounsaturated fatty acid biosynthesis. Alterations of the monounsaturated/saturated fatty acids ratio have been implicated in various diseases related to the metabolic syndrome, including hypertension. We previously evidenced that lipogenesis end-products accumulated in spontaneously hypertensive rats (SHR), and that a dietary combination of n-6/n-3 PUFA had hypotensive effects. Our present objective was to test the hypothesis that these SHR liver lipid disorders might be modulated, in response to this hypotensive combination, by changes in SCD-1 expression and activity. So we studied, in hepatocytes, SCD-1 transcription by Northern blotting, as well as plasma and liver fatty acid composition by gas-liquid chromatography. Liver SCD-1 gene expression was suppressed by 50%, and in different lipid classes, relative abundance of stearic and oleic acids decreased. Consequently, the Delta9 desaturation index, calculated from the ratio of oleic vs. stearic acids, decreased. In addition, the level of circulating saturated fatty acids decreased when one of oleic acids increased. These data provided evidence that the tested hypotensive PUFA combination reverses the high monounsaturated/saturated fatty acids ratio associated to hypertension in SHR, via a regulation monounsaturated fatty acid relative abundance by repression of SCD-1 gene.