Liver glucose and glycogen content was assayed enzymatically as previously described (26 (link)). Frozen liver (≈20 mg) from fed mice was lysed in deionized water (500 μl) using metal beads in a Tissue Lyser (Qiagen) and the resulting lysates were centrifuged at 12,000 g for 20 minutes at 4°C. The supernatant (75 μl) was boiled for 3 minutes and, once cooled, mixed with an amyloglucosidase solution (Sigma-Aldrich 25 μl diluted 1:5 in KAc 0.1 M buffer pH 5,5) and left overnight at room temperature to hydrolyze glucose incorporated into glycogen. Samples were boiled for 3 minutes to stop the reaction and centrifuged for 3 minutes at 12.000 g and glucose was analyzed using the HK assay kit (Sigma-Aldrich) following manufactureŕs instructions. A reaction without amyloglucosidase provided the amount of free glucose (expressed as μg per mg of tissue). To obtain the amount of glucose derived from glycogen in each sample, free glucose value was subtracted from that of total glucose after amyloglucosidase digestion.