Effect of Insulin on Fever in Endotoxic Sheep

Abstract

A study was conducted to determine the effect of intravenous (i.v.) administration of insulin on fever in sheep challenged with bacterial endotoxin, lipopolysaccharide (LPS). Six castrated male Suffolkcross wethers were randomly assigned to receive one of the following treatment combinations i.v: Saline control (SAL+SAL); SAL + LPS (0.06 μg kg-l BW) or various doses of insulin (I) (2, 6, 12 or 20 mU kg-l BW) + LPS (0.06 μg kg-1 BW). Serial blood samples were collected at hourly intervals for 10 h after the start of i.v injections. Glucose concentrations in the plasma were measured. Rectal temperature was monitored at the same time as for serial blood sampling. Temperatures for the saline control sheep (SAL+SAL) remained relatively constant throughout the study period ranging from 38.9 ± 0.1 to 39.1 ± 0.1^ºC. The SAL+LPS treated sheep had significantly (P<0.05) elevated temperatures compared to the saline controls from 1 to 8 h post LPS injection. The sheep injected with 12mUI +LPS had significantly (P<0.05) lower body temperature compared to the SAL +LPS treated sheep from 3 to 6 h post LPS injection. Within the insulin + LPS treatment combinations the 12mUI +LPS combination was found to significantly reduce (P<0.05) body temperature in sheep to levels similar to the saline controls from 5 to 8 h after LPS injection. Sheep on the SAL+LPS or I+LPS treatments had reduced (P<0.05) glucose levels than the saline control sheep from 5 to 8 h post LPS injection. This study demonstrates the ability of insulin to reduce fever in LPS challenged sheep.