Meeting Abstract
P3.144 Thursday, Jan. 6 Changes in expression and phosphorylation of AMPK and ACC in the hibernating Golden-mantled ground squirrel (C. lateralis) GEARHART, C.G.*; HEALY, J.E.; FLORANT, G.L.; CO St. Univ. myotis.velifer@gmail.com
C. lateralis (a hibernator) undergoes multi-day torpor bouts (when body temperature (Tb) approaches ambient temperature (Ta)) punctuated by short periods of euthermia (normal Tb). Metabolism is severely reduced during torpor, and animals are aphagic during the hibernation season, relying primarily on fat reserves. AMP-activated protein kinase (AMPK) acts as an energy sensor within the cell, and is activated (pAMPK) when AMP:ATP ratios are high, down-regulating ATP use, and up-regulating ATP production. Acetyl-CoA carboxylase (ACC) is deactivated (pACC) by pAMPK, allowing fatty acid oxidation. We examined changes in expression and phosphorylation of AMPK and ACC between two groups: winter euthermic and torpid squirrels. We expected animals in torpor (Tb=7°C) to have lower total AMPK and ACC than euthermic animals due to reduced metabolic rate, and euthermic animals to have higher pACC. In winter, we euthanized 6 torpid and 4 euthermic squirrels. We performed Western blots on liver, white adipose tissue (WAT), and brown adipose tissue (BAT), and probed for total and phosphorylated AMPK and ACC. We found no significant changes in liver between the two groups. WAT had significantly higher total AMPK and pAMPK in the torpid state over the euthermic state, but the pAMPK:AMPK ratio did not significantly differ between the two, and no significant changes were seen in ACC in WAT. BAT had significantly higher total ACC and pACC in torpid squirrels than in euthermic squirrels, with a higher ratio of pACC:ACC in the torpid state. We saw no significant changes in AMPK in BAT. WAT and BAT showed significant changes between the two states that countered our hypotheses, and no other changes were seen. Investigating AMPK and ACC during other stages of the torpor cycle may clarify our results.
