The effects of VIP on cyclic AMP and glycogen levels in vertebrate retina

The effects of VIP and related-peptides (PHI, secretin, glucagon) on cyclic AMP formation were investigated in intact pieces of rabbit retina. VIP and PHI increased cyclic AMP levels with EC 50 of 160 nM and 300 nM respectively. At 5 μM the peptides increased cyclic AMP 46 fold (VIP) and 38 fold (PH...

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Published inPeptides (New York, N.Y. : 1980) Vol. 5; no. 2; pp. 295 - 298
Main Authors Schorderet, M., Hof, P., Magistretti, P.J.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 01.01.1984
Subjects
Animals
Colforsin
Cyclic AMP
Cyclic AMP - metabolism
Diterpenes - pharmacology
Dopamine - pharmacology
Gastrointestinal Hormones - pharmacology
Glucagon - pharmacology
Glycogen - metabolism
Glycogenolysis
In Vitro Techniques
Neuropeptides
Peptide PHI
Peptides - pharmacology
Potassium - pharmacology
Rabbits
Retina
Retina - drug effects
Retina - metabolism
Secretin - pharmacology
Vasoactive Intestinal Peptide - pharmacology
VIP
Cyclic AMP
Retina
Neuropeptides
Glycogenolysis
VIP
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Summary:The effects of VIP and related-peptides (PHI, secretin, glucagon) on cyclic AMP formation were investigated in intact pieces of rabbit retina. VIP and PHI increased cyclic AMP levels with EC 50 of 160 nM and 300 nM respectively. At 5 μM the peptides increased cyclic AMP 46 fold (VIP) and 38 fold (PHI). Secretin was much less potent and glucagon was totally inactive. VIP was also tested for its effects on glycogen levels under similar experimental conditions. In contrast to its pronounced glycogenolytic action in mouse cerebral cortical slices, VIP at 1 μM decreased only moderately (38.3%) 3H-glycogen newly synthesized from 3H-glucose by pieces of rabbit retina. Furthermore a discrepancy between the efficacy of VIP in increasing cyclic AMP and in promoting glycogenolysis appears to exist. A similar dissociation between these two cellular events was also observed with other neuroactive substances. Thus the pronounced increase in cyclic AMP induced by dopamine and forskolin was accompanied by only a moderate decrease in 3H-glycogen levels. Conversely 50 mM potassium induced a 79.9% decrease in 3H-glycogen levels without any significant increase in cyclic AMP.
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ISSN:0196-9781
1873-5169
DOI:10.1016/0196-9781(84)90222-5