O 24 : Impact of ethanol administration on insulin sensitivity in wethers

Abstract 258

Background

Chronic alcohol intake enhances insulin resistance in human. The relationship between alcohol intake and insulin sensitivity in ruminants is unclear. Silage alcohols may induce insulin resistance. And, changes in insulin sensitivity induced by silage feeding during periods of fluctuating energy balance are unclear in ruminants. Therefore, insulin responsiveness to ethanol administration was investigated in sheep.

Materials and methods

Four mature wethers (84.0±2.6 kg BW) fitted with a rumen-cannula were assigned to either high energy (HE:1.7 ME of maintenance) or low energy (LE:0.5 ME of maintenance) diet with intraruminal infusion of either 240 ml water (control) or 96 g ethanol (equivalent to 5% of energy fed in HE) in a cross-over design for 14 d for HE and 7 d for LE. Diets and infusates amounts were divided into two equal portions and offered simultaneously twice daily (0900 and 2100 h). Hyperinsulinemic-euglycemic clamp (EGC) was performed on 13th and 14th d of HE and on 6th and 7th d of LE. Preliminary blood samples were collected 1 h before the morning feeding to determine basic blood glucose level. Afterward, insulin infusion (1 mµ/kg.BW/min) started at 0815 h and continued for 2 h. Glucose infusion (20% glucose) continued for 2 h to maintain the basic blood glucose level. Blood samples were collected at 5- and 15-min intervals to monitor blood glucose and insulin concentration, respectively. The amount of glucose infused was recorded at 10 min intervals and glucose infusion rate (GIR) was calculated (mg/kg.BW/min).

Results and conclusions

Plasma insulin concentration was greater in the control (88.9 ng/ml) than ethanol (68.4 ng/ml) in LE (P=0.012), but the reverse was observed in the HE where ethanol group showed higher insulin (77.9 ng/ml) than the control (51.0 ng/ml) (P=0.002). Plasma glucose concentration did not differ between control and ethanol in either energy plan, but the GIR showed the same trend of plasma insulin where GIR was greater in the control (1.78) than ethanol (1.04) in LE (P=0.004) but was higher in ethanol (1.448) than in control (1.11) in HE (p=0.008). Plasma ethanol was higher in LE (53.5 mg/dl) than in HE (40.9 mg/dl) (P<0.05). In conclusion, ethanol turnover and insulin responsiveness associated with ethanol administration are enhanced in HE and decreased in LE. Also, ethanol absorption may alter systemic insulin action which might result from changes in insulin sensitivity in the whole body.