Effect of three galanin antagonists on the pressor response to galanin in the Cane toad, Bufo marinus.
Galanin is a neuropeptide that causes a marked pressor response in several non-mammalian vertebrate species, and some marsupials. In this study, the effect of three galanin antagonists were tested on the pressor response to an intravenous dose (6.3 nmol/kg) of porcine galanin in anaesthetised Cane toads, Bufo marinus. Antagonists were injected at either 20 or 50 times the molar dose (x MD) of galanin. The antagonist, C7 (Galanin 1-13-spantide) reduced the pressor effect of galanin by 32.2 +/- 6.0% when delivered at 20 x MD (n = 4) and by 42.9 +/- 15.7% when delivered at 50 x MD (n = 4) of galanin, the response recovering within 30 min. A second antagonist, M32a (Galanin 1-13-NPY 24-36) had no effect on the pressor response to galanin at 20 x MD (n = 4), but significantly reduced the pressor effect by 54.8 +/- 6.4% at 50 x MD (n = 5), which also recovered within 30 min. Administration of a third antagonist, galantide or M15 (Galanin 1-13-Substance P5-11), resulted in a profound drop in blood pressure, and did not affect the response to galanin at either dose. In conclusion, C7 and M32a are effective, short-term antagonists of the blood pressure effects of galanin in the toad.
Mahns
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DA
School of Physiology and Pharmacology, University of New South Wales, Sydney, Australia.
Courtice
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GP
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002024:Bufo marinus / Q000378:metabolism*; D019004:Galanin / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D009478:Neuropeptide Y / Q000031:analogs & derivatives / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011993:Recombinant Fusion Proteins; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D013552:Swine; D014662:Vasoconstrictor Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D009478:Neuropeptide Y; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D014662:Vasoconstrictor Agents; C082566:galanin-NPY chimeric peptide M32; C074975:galantide; C079788:galanin (1-13)-spantide amide; D013373:Substance P; D019004:Galanin