Hypoinsulinemia induction and its effects on leptin secretion, blood and urine metabolites, feeding pattern and internal organs indices in sheep

Introduction: Insulin role and importance are different from that of monogastric. In this study, permanent hypoinsulinemia with various severities was induced using doses 0, 25, 50 and 75 mg/kg BW of streptozotocin (STZ) in sheep. Materials and methods: Twenty male lambs were divided into four treatment groups and maintained individually. Treatments were single, intravenous injection of doses of STZ. The duration of the experiment was eight consecutive weeks, and injection was performed at the end of third week. Blood samples were collected weekly via venipuncture at fasting and 2.5 h post-prandial times and analyzed. Feed and water intakes and also animals' weight changes were measured weekly. After slaughter, internal organs were weighed and urine samples were collected from bladder. Results: Animals receiving dose 75 could not continue the experiment because of abnormalities. Results showed the occurrence of hypoinsulinemia with injection of dose 50 with significant decrease in fasted and post-prandial insulin concentrations and also fasted leptin concentrations vs dose 0 as control (P<0.05). Dose 50 caused significant increase in blood glucose, triglycerides, cholesterol, total protein, blood urea nitrogen and keton bodies levels vs control (P<0.05). Animals receiving dose 50 showed diabetic hyperphagia and enhanced water intake in weeks after injection as compared to control (P0.05). Weights and indices of internal organs showed no differences between groups, but only carcass weight in group of dose 50 was significantly greater than others. Conclusion: Results suggested the pivotal regulatory role of insulin in energy metabolism of ruminants by exerting two opposing effects central catabolic and peripheral anabolic that was consistent with findings in monogastric animals.