AMP -activated protein kinase (AMPK) plays a role in metabolic regulation under stress conditions, and inadequate AMPK signaling may be also involved in aging process. The aim was to find out whether AMPK α 2-subunit deletion affects heart function and ische mic tolerance of adult and aged mice. AMPK α 2 -/- (KO) and wild type (WT) female mice were compared at the age of 6 and 18 months. KO mice exhibited subtle myocardial AMPK α 2-subunit protein level, but no difference in AMPK α 1-subunit was detected between the strains. Both α 1- and α 2-subunits of AMPK and their phosphorylation decreased with advanced age. Left ventricular fractional shortening was lower in KO than in WT mice of both age groups and this difference was maintained after high-fat feeding. Infarct size induced by global ischemia/reperfusion of isolated hearts was similar in both strains at 6 months of age. Aged WT but not KO mice exhibited improved ischemic tolerance compared with the younger group. High-fat feeding for 6 months during aging abolished the infarct size-reduction in WT without affecting KO animals; nevertheless, the extent of injury remained larger in KO mice. The results demonstrate that adverse effects of AMPK α 2-subunit deletion and high-fat feeding on heart function and myocardia l ischemic tolerance in aged female mice are not additive., K. Slámová, F. Papoušek, P. Janovská, J. Kopecký, F. Kolář., and Obsahuje bibliografii
After 8 weeks of intermittent fasting, mice fed both a standard laboratory diet and a high-fat diet became hyperphagic and showed an increased amount of glycogen storage in the liver. An important effect of the adaptation to intermittent feeding with a high-fat diet seems to be an activation of the oxidation of lipids. Lipid oxidation prevails over lipogenesis so that the protein levels in the liver and skeletal muscle are preserved and maintained constant.
The simultaneous effect of intermittent starvation and a high-fat diet were investigated in mice after several weeks of experimental feeding. The animals adapted to intermittent fasting fed a high-fat diet showed a lower degree of hyperphagia than animals adapted to intermittent fasting fed a standard laboratory diet. The weight of both individual portions of the stomach was elevated in adapted animals fed both a standard laboratory diet and the high-fat diet. The weight of the small intestine was increased in adapted animals fed a high-fat diet. The length of the small intestine was not changed after 8 weeks of intermittent starvation in both adapted groups (standard laboratory diet, high-fat diet). A higher amount of body fat was found in both groups of animals adapted to intermittent fasting (standard laboratory diet, high-fat diet) but adapted animals fed a high-fat diet showed less body fat than adapted animals fed a standard laboratory diet. Lower levels of serum lipids were found in adapted animals fed a high-fat diet. These results suggest that both lipogenesis and lipid oxidation are accentuated by intermittent starvation and a high-fat diet act concomitantly.