Relationship between the level of plasma insulin and lipid profile in Iranian fat-tailed sheep

Insulin is an important hormone in regulating lipid metabolism in a variety of animal tissues; it can both decrease lipolysis and cause an increase in triglyceride synthesis of adipose tissue in ruminants. In this study, variations in the plasma concentration of insulin and its correlation with the plasma cholesterol, triglyceride, high-density lipoprotein (HDL cholesterol), low-density lipoprotein (LDL cholesterol), and very-low-density lipoprotein (VLDL) concentrations were investigated. Blood samples were collected from the jugular vein of 96 clinically healthy, non-pregnant ewes (grouped according to their age 1–3, 3–6, 6–12, 12–24, 24–48, and >48 months) in the autumn months. The level of plasma insulin was determined by chemiluminescence and other parameters were measured by spectrophotometry using commercial kits. According to our data from Iranian fat-tailed sheep, increasing age results in significant decrease in the plasma concentration of insulin (p < 0.05, r = −0.278), cholesterol (p < 0.05, r = −0.249), and HDL (p < 0.01, r = −0.299), there was also a significant correlation between plasma insulin and LDL concentration (p < 0.05, r = 0.268). In addition, we found significant differences between age groups for cholesterol and HDL concentrations (p < 0.05).