Glycogen autophagy in the liver and heart of newborn rats. The effects of glucagon, adrenalin or rapamycin
D.J. Kondomerkos1, S.A. Kalamidas1, O.B. Kotoulas1 and A.C. Hann2
1Department of Anatomy, Histology and Embryology, Medical School, University of Ioannina, Ioannina, Greece and 2Electron Microscopy Unit, Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
Offprint requests to: Dr. Stefanos A. Kalamidas, Department of Anatomy, Histology and Embryology, Medical School, University of Ioannina, 45110 Ioannina, Greece. e-mail: skalamid@cc.uoi.gr
Summary. The effects of glucagon, adrenalin or rapamycin on glycogen autophagy in the liver and heart of newborn rats were studied using biochemical determinations and electron microscopy. Glucagon or adrenalin increased autophagic activity in the hepatocytes and myocardiocytes, glycogen-hydrolyzing acid glucosidase activity in the liver and heart and degradation of glycogen inside the autophagic vacuoles. Glucagon or adrenalin also increased the maltose-hydrolyzing acid glucosidase activity in the liver, but not in the heart. Similar effects were produced in the newborn heart by rapamycin.
These observations support previous studies suggesting that the cellular machinery which controls glycogen autophagy in the liver and heart of newborn animals, is regulated by the cyclic AMP and the mTOR pathways. Histol. HIstopathol. 20, 689-696 (2005)
Key words: Glycogen autophagy, Glucagon, Adrenalin, Rapamycin
DOI: 10.14670/HH-20.689