القاي هايپواينسولينميا و تاثير آن بر ترشح لپتين، متابوليت هاي خون و ادرار، الگوي تغذيه اي و شاخص اندام هاي داخلي در گوسفند

Effects of hypoinsulinemia on leptin secretion, blood and urine metabolites, feeding pattern and internal organs indices in sheep

Introduction: The role of insulin and its importance in ruminants are different form monogastrics. In this study, permanent hypoinsulinemia with different severities was induced by low, intermediate and high doses of streptozotocin in sheep (25, 50 and 75 mg/kg body weight, respectively). Methods: Twenty male lambs were divided into 4 treatment groups and were maintained individually. Three intravenous injections of streptozotocin were given. The whole experiment lasted 8 weeks, and injections were administered by the end of the third week. Blood samples were collected weekly by venipuncture at fasting state and 2.5 h post-prandial. Food and water intake, as well as weight changes were measured weekly. After slaughter, internal organs were weighed and urine samples were collected from the bladder. Results: Animals receiving the high dose of streptozotocin could not continue the experiment because of abnormalities. The intermediate dose caused significant decrease in fasted and post-prandial insulin concentrations as well as fasted leptin levels compared to control (P<0.05). This dose also induced a significant increase in blood glucose, triglycerides, cholesterol, total protein, blood urea nitrogen and keton bodies compared to control (P<0.05). These animals also showed diabetic hyperphagia and enhanced water intake in weeks after injection in comparison with the control group (P<0.05) but in spite of increased food intake, they could not gain more weight than controls. Urine sugar and protein levels were increased dose-dependently but these changes did not reach significance (P>0.05). Weights and indices of internal organs showed no difference among groups, but only carcass weight in the group of intermediate dose was significantly higher than other groups. Conclusion: Our results suggest a pivotal regulatory role for insulin in energy metabolism of ruminants by exerting two opposing effects; central catabolic and peripheral anabolic. These data are consistent with the findings in monogastric animals. j