Meeting Abstract
P2.37 Friday, Jan. 4 To Eat or Not to Eat: Food Intake Regulation in Hibernators FENN, A.M.*; HEALY, J.E.; RICHTER, M.M.; WILKERSON, G.; FLORANT, G.L.; Colorado State University; Colorado State University; Colorado State University; Colorado State University; Colorado State University amfenn@simla.colostate.edu
Mammals that hibernate typically do not feed during the winter. For example, the yellow-bellied marmot (Marmota flaviventris) does not feed for roughly seven months after nearly doubling its body mass in the autumn. AMP-activated protein kinase (AMPK) acts as a sensor of peripheral energy balance within the hypothalamic arcuate nucleus (HARC) and is postulated to play a role in the regulation of food intake in mammals. AMPK is activated when cellular energy is low, specifically when the AMP/ATP ratio is high. 5�-aminoimidazole-4-carboxamide ribonucleosicle (AICAR) is a known specific agonist of AMPK as it mimics the effects of high AMP on AMPK activation. We hypothesized that infusing AICAR near to the HARC of fasting marmots would activate AMPK in the HARC leading to an increase in food intake during the fasting period. Cannulae were stereotaxically implanted into the ventricles near the HARC of five marmots. Five cannulae were connected to seven-day Alzet mini-pumps filled with AICAR (50�g/�L; n=4) and one saline control. The AICAR and saline were infused at a rate of 25�g/hr. During the seven days, the four marmots infused with AICAR failed to undergo torpor and significantly increased their food intake from 0.00g/day to an average of 12.2 g/day (p<.01). The control animal returned to torpor and did not increase food intake. These results suggest that AICAR activated AMPK, disrupted torpor patterns, and significantly increased food intake over the period the animals were infused. After AICAR infusion was complete, all but one animal re-entered hibernation and refused to eat, even though food was readily available. These results support our hypothesis that AMPK may be involved in the pathway(s) that regulates food intake in marmots. Supported by NIH grant (R25 DK067017) to GLF.
