Effect Of Cysteamine On Fatty Acid Composition In Rat Tissues And Its Mechanism

Cysteamine can deplete of somatostatin and promote the secretion of growth hormone to achieve the growth-promoting role. At the same time cysteamine can also affect fat metabolism and improve carcass quality. However, the best supplementation way and the appropriate amount of cysteamine are also not conclusive. Stearoyl-CoA desaturase (SCD) is a key enzyme involved in the biosynthesis of unsaturated fatty acids, which has significant impact on the fatty acid composition of tissues.In the present study,20male SD rats of about180g were selected to investigate the effect of dietary cysteamine on body weight, serum metabolites and tissue fatty acid composition, meanwhile the possible mechanism was discussed.1. Effect of cysteamine on body weight and serum metabolites.20SD rats were randomly divided into two groups, one group was fed with standard basal diet, another group was fed with standard basal diet and cysteamine, the adding amount of cysteamine was210mg/kgBW. The experiment lasted for four weeks. Body weight and feed intake were recorded weekly. At the end of the experiment, blood samples were taken from the eye venous plexus and serums were separated for analysis. Experimental results showed that the body weight of cysteamine-treated rats were slightly increased at the end of the first week, but at the third and fourth weeks, it decreased significantly (P<0.05); serum level of triglyceride decreased significantly (p=0.005), serum levels of cholesterol and glucose remained unaffected.2. Effect of cysteamine on Stearoyl-CoA Desaturase mRNA expression in rats’livers.In this study, rat liver tissue samples were taken in experiment one, relative quantitative RT-PCR method was used to determine the expression of SCD-1mRNA in control and cysteamine-treated rats’ livers. The results showed that cysteamine supplementation increased SCD-1mRNA expression in liver, but not significantly.3. Effect of cysteamine on fatty acid composition in rat tissues.In this experiment, liver, abdominal adipose tissue, dorsal muscle and semitendinosus muscle samples in experiment one were taken. Fat content in tissue was measured by Soxhlet method, and fatty acids content was analysed by gas chromatography. The results suggestted that cysteamine could improve the fat content of long dorsal muscle (p=0.001). At the same time cysteamine also had an impact on the fatty acid composition of tissues.The relative content of saturated fatty acids in livers of cysteamine-treated rats increased, such as C14:0, and so the relative content of unsaturated fatty acids, for example C18:1, C18:2, C18:3. The relative content of C16:0and C18:0decreased, but the differences were not significant.Cysteamine could improve the relative content of C18:1in the long dorsal muscles (p=0.009), the relative content of C14:0decreased significantly (p=0.011), the relative content of C16:0, C18:0also decreased, but the difference was not significant. Compared with the control group rats, the relative content of C14:0in semitendinosus of cysteamine-treated rats was higher (p=0.001). The relative contents of C16:0, C18:0, C18:1and C18:3had a downward trend, C18:2increased significantly (p=0.031) Cysteamine could significantly improve the relative content of C14:0in rat adipose tissue (p=0.009), while decrease the relative content C16:0and C18:1(p=0.003, p=0.038).