Glycogen metabolism in rat ependymal primary cultures: Regulation by serotonin

Ependymal primary cultures are a model for studying ependymal energy metabolism. Intracellular glycogen is built up in the cultures dependent on culture age and the presence of glucose and glutamate. This energy store is mobilized upon glucose withdrawal, stimulation with isoproterenol, forskolin or...

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Bibliographic Details
Published in:Brain research 2005-10, Vol.1060 (1), p.89-99
Main Authors: Verleysdonk, Stephan, Kistner, Steffen, Pfeiffer-Guglielmi, Brigitte, Wellard, John, Lupescu, Adrian, Laske, Julia, Lang, Florian, Rapp, Mirna, Hamprecht, Bernd
Format: Article
Language:English
Subjects:
5-HT
Animals
Biochemistry and metabolism
Biological and medical sciences
Calcium - metabolism
Cells, Cultured
Central nervous system
Cyclic AMP - metabolism
Energy metabolism
Ependyma - metabolism
Fundamental and applied biological sciences. Psychology
Glutamic Acid - metabolism
Glycogen - metabolism
Glycogen phosphorylase
Glycogen Phosphorylase, Brain Form - metabolism
Glycogen Phosphorylase, Muscle Form - metabolism
Immunohistochemistry
Kinocilia
Rats
Receptors, Serotonin - metabolism
Reverse Transcriptase Polymerase Chain Reaction
RNA, Messenger - analysis
Serotonin - metabolism
Time Factors
Vertebrates: nervous system and sense organs
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Summary:Ependymal primary cultures are a model for studying ependymal energy metabolism. Intracellular glycogen is built up in the cultures dependent on culture age and the presence of glucose and glutamate. This energy store is mobilized upon glucose withdrawal, stimulation with isoproterenol, forskolin or serotonin and after uncoupling of oxidative phosphorylation from ATP production. Serotonin regulates ependymal glycogen metabolism predominantly via 5-HT receptor (5-HTR) 7, which elicits an increase in the level of ependymal cyclic AMP. Although the most abundant mRNAs for serotonin receptors are those of 5-HTR 2B and 5-HTR 3A, ependymal cells in primary culture do not respond to serotonin with an increase in their concentration of cytosolic calcium ions. The mRNAs of 5-HTRs 1A, 6, 1B, 5B, 7, 1/2C and 5A are also detectable in order of decreasing abundance. The mRNAs for 5-HTRs 1D, 1F, 3B and 4 are absent from the cultured cells. The ability of serotonin to mobilize ependymal glycogen depends on the culture age and the time allowed for glycogen buildup. During glycogen buildup time, glutamate is consumed by the cells. An increased ability of 5-HT to mobilize ependymal glycogen stores is noticed after the depletion of glutamate from the glycogen buildup medium. In ependymal primary cultures, cilia are colocalized with glycogen phosphorylase isozyme BB, while the MM isoform is not expressed. It is known from the literature that an increase in the concentration of cytosolic cAMP in ependymal cells leads to a decrease in ciliary beat frequency. Therefore, the present data point towards a function for ependymal glycogen other than supplying energy for the movement of cilia.
ISSN:0006-8993
1872-6240
DOI:10.1016/j.brainres.2005.08.045