Abstract
Diseases associated with insulin resistance, e.g. overweight/obesity, type 2 diabetes mellitus, cardiovascular diseases and some cancers, are characterized by the decrease of the tissue content of long-chain polunsaturated fatty acids and concomitantly increased accumulation of non-essential - saturated fatty acids (SFA) and monounsaturated fatty acids (MFA) in the adipose tissue and other organs (liver, pankreas, cardiac and skeletal muscle). Here, fatty acids (FA) with 16 or 18 carbons - palmitic acid (PA, 16:0), stearic acid (SA, 18:0), palmitoleic acid (POA, 16:1 n-7), vaccenic (VA, 18:1n-7) and oleic acid (OA, 18:1n-9).These FA represent about 75 % of the FA pool in triacylglycerols (TAG) in abovementioned tissues.
Accumulation of SFA and MFA is caused by a high dietary fat intake and as a result of the stimulated de novo lipogenesis (DNL) from the non-lipid compounds, mostly from carbohydrates. The DNL pathway utilize several enzymes.
Fatty acid synthase (FAS), catalyzes synthesis of PA from acetyl-CoA. Long-chain fatty acid elongase, Elovl6 catalyzes the elongation of PA to SA and POA to VA.
Stearoyl-CoA desaturase-1 (SCD-1) brings the double bond to the9 position of the FA molecule. SCD-1 catalyzes the synthesis of POA from PA and OA from SA.
SCD-1 activity is regulated by genetic, hormonal and nutritional factors on one hand and by plethora of environmental factors and pathological states. The changes of the SCD-1 activity were described in numerous diseases, such as metabolic ones (obesity, metabolic syndrome, type 2 diabetes mellitus, atherogenic dyslipidemia), cardiovascular diseases (arterial hypertension, coronary artery disease), chronic subclinical inflammation, osteoporosis and some cancers.