Effect of intraportal and continuous intrajugular administration of insulin on feeding in sheep
Deetz, L.E.; Wangsness, P.J.; Kavanaugh, J.F.; Griel, L.C.
Journal of Nutrition 110(10): 1983-1991
1980
ISSN/ISBN: 0022-3166 PMID: 6999135 Document Number: 163280
The effect of intraportal and intrajugular administration of insulin on feed intake and on glucose and insulin of jugular blood was studied. Voluntary intake of 4 wethers was measured and jugular blood was sampled at various times after intraportal administration of the compounds and meal initiation. The compounds injected in the first experiment were saline and insulin 2, 4 and 6 mU/kg bodyweight (BW), and in a second experiment were saline and insulin 2, 6 and 12 mU/kg BW min infused for 15-min. Feed intake was depressed only by 15-min intraportal infusion of the 2 and 6 mU doses. Plasma insulin was increased at 5 min after injection of 4 and 6 mU doses, and increased at 5 and 15 min after 15-min infusion of all 3 treatments; plasma glucose was not affected. Two additional experiments used 4 wethers in which jugular blood was sampled during a 24-h intrajugular infusion of insulin. The combined treatments were saline and insulin 0.02, 0.2, 2 and 6 mU/kg BW min. The 6 mU dose stimulated feed intake, 2 mU increased plasma insulin and both 2 and 6 mU depressed plasma glucose. Thus, the site, timing and amount of exogeneous insulin administration may cause varying feed intake responses. The results are discussed with respect to a possible role of insulin in appetite control in sheep.