Guanine nucleotides regulate the effect of substance P on striatal adenylate cyclase of the rat.
Substance P was incubated in an adenylate cyclase assay of a particulate fraction of caudate-putamen tissue of the rat in order to examine the effect of the peptide on D-1 receptor coupled adenylate cyclase in vitro. Substance P did not influence basal adenylate cyclase activity or the stimulation of the enzyme by dopamine. No influence of substance P was seen on the effects of calcium and magnesium chloride as a cofactor of adenylate cyclase. Also the inhibition of adenylate cyclase activity by the dopamine antagonist fluphenazine was not influenced by substance P. However, substance P was able to enhance cyclic AMP formation in the presence of guanosine-imidodiphosphate (Gpp(NH)p), whereas the stimulatory effect of guanosine-triphosphate (GTP) was inhibited by substance P. In our study we suggest that substance P interacts with the guanine nucleotide regulatory subunit without directly affecting D-1 dopamine receptors in the caudate-putamen of the rat.
Moser
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Dept. of Neurology, Med. University, Lübeck, F.R.G.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002421:Caudate Nucleus / Q000187:drug effects / Q000201:enzymology; D003342:Corpus Striatum / Q000187:drug effects / Q000201:enzymology*; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D005476:Fluphenazine / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D015636:Magnesium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000494:pharmacology*
D006150:Guanine Nucleotides; D015636:Magnesium Chloride; D013373:Substance P; D006160:Guanosine Triphosphate; D000262:Adenylyl Cyclases; D005476:Fluphenazine; D002118:Calcium; D004298:Dopamine