The stimulation of glycogenolysis in isolated hepatocytes by opioid peptides

The opioid peptides [Leu]enkephalin and dynorphin-(1-13) were shown to enhance glycogen breakdown when added directly to hepatocytes. This was the result of a concerted effect on the enzymes of glycogen metabolism, with a stimulation of glycogen phosphorylase activity and a simultaneous decrease in...

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Bibliographic Details
Published inBiochemical journal Vol. 238; no. 2; pp. 531 - 535
Main Authors Leach, R P, Titheradge, M A
Format Journal Article
LanguageEnglish
Published England 01.09.1986
Subjects
Animals
Calcium - pharmacology
Cyclic AMP - metabolism
Dynorphins - pharmacology
Enkephalin, Leucine - pharmacology
Glycogen Synthase - metabolism
In Vitro Techniques
Liver - drug effects
Liver - enzymology
Liver Glycogen - metabolism
Male
Phosphorylase a - metabolism
Protein Kinases - metabolism
Rats
Rats, Inbred Strains
Stimulation, Chemical
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Summary:The opioid peptides [Leu]enkephalin and dynorphin-(1-13) were shown to enhance glycogen breakdown when added directly to hepatocytes. This was the result of a concerted effect on the enzymes of glycogen metabolism, with a stimulation of glycogen phosphorylase activity and a simultaneous decrease in glycogen synthase I activity. The latter only became significant when the enzyme was activated by incubating the cells in presence of 20 mM- or 40 mM-glucose. The effect of the opioid peptides was independent of an increase in cyclic AMP or any change in the activity ratio of the cyclic AMP-dependent protein kinase and was abolished by depleting the cells of Ca2+. Both [Leu]enkephalin and dynorphin-(1-13) produced a significant decrease in cyclic AMP formation, suggesting that in liver, as in neuronal tissue, they may act by inhibiting adenylate cyclase activity.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2380531