Abstract
BackgroundMicrosomal stearoyl-CoA desaturase1 (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFAs); palmitoleic (16:1) and oleic (18:1) acid from their respective substrates palmitic (16:0) and stearic (18:0) acids. The ratio of 18:1 to 18:0 has been implicated in the regulation membrane fluidity and function. SCD1 is abundantly expressed in obese humans as well as rodent models. However, no studies have correlated the fatty acid desaturation index (16:1/16:0 and 18:1/18:0), an indicator of SCD1 activity with the markers of obesity in terms of body mass index (BMI) and adiposity index (AI). Therefore, here, we attempted to relate the fatty acid desaturation index with BMI and AI in Wistar NIN-obese mutant rat strains namely, WNIN/Ob and WNIN/GR-Ob (with impaired glucose tolerance).MethodsFor this purpose, 200 days old male 6 lean and 6 obese rats of both strains were taken. Fatty acid composition was analyzed in plasma, various tissues such as liver, white adipose tissues (retroperitoneal, epididymal, omental, and subcutaneous) and brown adipose tissue.ResultsFatty acid composition data showed significant increase in palmitoleic (16:1) and oleic (18:1) acid levels, which were reflected in increased desaturation index (16:1/16:0 and 18:1/18:0) in plasma and all the tissues of obese rats of both strains, when compared with their respective age and sex-matched lean rats. Further, we found a strong positive correlation between desaturation index, BMI and AI in plasma and most of the tissues analyzed.ConclusionSo far, plasma Δ9 desaturation index has been well correlated with hypertriglyceridemia and we, by employing two models of obesity namely, WNIN/Ob and WNIN/GR-Ob, have shown Δ9 desaturation index of plasma correlated with physical markers of obesity such as BMI and AI. In conclusion, Δ9 desaturation index may serve as a potential sensitive biochemical marker to assess the degree of obesity and impact of therapeutic/nutritional interventions to combat obesity, along with other indicators.
Highlights
Microsomal stearoyl-CoA desaturase1 (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFAs); palmitoleic (16:1) and oleic (18:1) acid from their respective substrates palmitic (16:0) and stearic (18:0) acids
Microsomal stearoyl-CoA desaturase1 (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFA); palmitoleoyl and oleoyl-CoAs from their respective substrates palmitoyl and stearoyl-CoAs by Δ9-cis desaturation
Desaturation Index of plasma and various tissues Plasma, various white adipose tissues (RPWAT, EWAT, SWAT and OWAT) and brown adipose tissue (BAT) of obese rats of both strains showed higher Δ9 desaturation index as evidenced by elevated 16:1 to 16:0 and 18:1 to 18:0 ratios compared to their age and sex-matched lean rats (Figures 1a &1b and 2a &2b)
Summary
Microsomal stearoyl-CoA desaturase (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFAs); palmitoleic (16:1) and oleic (18:1) acid from their respective substrates palmitic (16:0) and stearic (18:0) acids. Microsomal stearoyl-CoA desaturase (SCD1) is the rate limiting enzyme involved in the biosynthesis of monounsaturated fatty acids (MUFA); palmitoleoyl and oleoyl-CoAs from their respective substrates palmitoyl and stearoyl-CoAs by Δ9-cis desaturation. These MUFAs are major substrates for the synthesis of various lipids such as phospholipids (PL), triglycerides (TG), cholesteryl and wax esters. It appears that the SCD1 activity may be one of the crucial factors that play a major role in the development of obesity and its associated disorders
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