Meeting Abstract

P2.38  Friday, Jan. 4  Plasma ghrelin levels in golden-mantled ground squirrels (Spermophilus lateralis) HEALY, Jessica E*; CRAVEN, Heather; FLORANT, Gregory L; Colorado State University; Colorado State University; Colorado State University jehealy@simla.colostate.edu

Ghrelin is a recently discovered hormone which has profound effects on food intake and lipogenesis in mammals. The release of ghrelin from the stomach occurs in a pulsatile manner and its circulating levels are dependent on feeding condition. In rodents, plasma ghrelin levels are increased before a meal and decrease immediately following a meal. In all diurnal mammals studied thus far, ghrelin levels are highest during nocturnal fasting. S. lateralis is a diurnal mammal that hibernates and has a robust annual cycle of mass gain and loss which is primarily due to food intake. We hypothesized that, in the summer, ghrelin levels in S. lateralis would be highest at night, and would increase over a short term fast (1-5 days). We measured plasma ghrelin levels in S. lateralis over a 24 hour period and found a diurnal pattern with the highest levels at night and lower levels during the day (with peaks corresponding to times when squirrels were eating). We also determined ghrelin levels over a short term fast, and found that levels steadily increased through day 3, but dropped slightly by day 5. This is the first report of ghrelin levels in a mammalian hibernator. Furthermore, our results illustrate a 24 hour secretory profile for ghrelin in S. lateralis, and support the hypothesis that ghrelin levels increase with fasting in this mammal. We suggest that ghrelin may be important for the regulation of food intake and body mass cycles in mammals that hibernate. This work was supported by a Sigma Xi Grant-in-aid-of-research to JEH.