Meeting Abstract

15.2  Monday, Jan. 4  Effects of peripheral ghrelin injections on food intake and behavior of golden-mantled ground squirrels (Spermophilus lateralis) HEALY, J.E.*; OSTROM, C.E.; GEARHART, C.N.; FLORANT, G.L.; Colorado State University jehealy@rams.colostate.edu

Mammals that hibernate (hibernators) undergo a circannual cycle of body mass gain and loss mediated primarily by food intake, but the pathways controlling food intake in hibernators have not been fully elucidated. Ghrelin is an orexigenic hormone that is known to increase food intake and adiposity in all mammals studied so far, but no published studies exist on the effect of ghrelin in hibernators. In order to determine the effects of ghrelin injection on food intake, body mass, and activity levels in hibernators, we peripherally injected ghrelin (intraperitoneally) into eight S. lateralis at various times of the year and at different stages of their hibernation season. We measured food intake and changes in body mass for the six hour period following injections, and remotely monitored behavior with the aid of a direct-streaming video recorder. We found that food intake increased with ghrelin injections; even some animals injected while hibernating at low tissue temperature aroused from torpor and ate, which is unusual for S. lateralis. There was also an increase in activity levels in all animals injected with ghrelin, especially in behaviors involving feeding and thermoregulation (such as food seeking behaviors and nesting). This study is the first to show an effect of injected ghrelin on a hibernator. We believe that ghrelin is involved in control of food intake in summer-active S. lateralis, and may be implicated in the behavioral changes that occur in these animals prior to the hibernation season. This research supported by a Sigma Xi Grant-in-Aid of Research to JEH and by an NIH grant to GLF R25DK067017.