Glycogen phosphorylase isozymes and energy metabolism in the rat peripheral nervous system--an immunocytochemical study.
Glycogen represents the major brain energy reserve which is located mainly in astrocytes. Though the role of brain glycogen has drawn increasing attention, little is known about glycogen metabolism in the peripheral nervous system. In the present work, we have demonstrated immunocytochemically the ubiquitous presence of glycogen phosphorylase (GP), one of the major control sites in glycogen metabolism, in the axons of rat spinal and sciatic nerves, but not in Schwann cells. Application of isozyme-specific antibodies revealed the presence of the GP BB (brain) isoform, but not the MM (muscle) isoform. This is in accord with previous results demonstrating the presence of isoform BB, but not MM, in the few GP-containing brain and spinal cord neurons and in vagus nerve axons. In contrast, brain astrocytes express both isoforms. As GP BB is mainly regulated by the cellular AMP level, a special role of glycogen in the energization of the nerve axons is suggested. The cellular locations of hexokinase, pyruvate dehydrogenase and glucose transporters are discussed in respect to possible metabolic roles of glycogen in peripheral nerves.
Pfeiffer-Guglielmi
Brigitte
B
Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.
Francke
Mike
M
Reichenbach
Andreas
A
Hamprecht
Bernd
B
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D024981:Glycogen Phosphorylase / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D009414:Nerve Growth Factors / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism; D017933:Peripheral Nervous System / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism
D007527:Isoenzymes; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C051774:neurofilament protein H; D024981:Glycogen Phosphorylase