Transglutaminase-synthesized spermine derivative of substance P recognizes rat portal vein neurokinin-3 receptors.
The effects of the transglutaminase-synthesized polyamine derivatives of Substance P (SP) have been further characterized by their ability to contract in vitro the rat portal vein strip (RPV), a pharmacological preparation particularly rich in NK-3 receptors. The effects of selective agonists of NK-1, NK-2 and NK-3 receptors [Sar9,Met(O(2))11]SP, beta-Ala8 NKA(4-10), and senktide respectively, were also evaluated by measuring RPV concentration-response curves. Peptide [GR-82334 (NK-1) and MEN-10,376 (NK-2)] and nonpeptide [WIN 51,708 (NK-1) and SR 142801 (NK-3)] NK receptor antagonists were used to confirm the participation of the different NK receptors to contractile response. Our results demonstrated that the spermine derivative of SP (Spm-SP), previously shown to be unable to recognize NK-1 and NK-2 receptors in some bioassays, contracts RPV (EC50 = 588 nM) better than the native neuropeptide (EC50 = 1120 nM). A pretreatment with thiorphan, an inhibitor of neutral endopeptidases, significantly reduced such a difference. While this inhibitor shifts the SP concentration-response curves to the left (EC50 = 720 nM) the action of Spm-SP and [Sar9,Met(O(2))11]SP were completely thiorphan-resistant. In the absence of thiorphan we found the following rank order of potency: senktide > > beta-Ala8 NKA(4-10) > [Sar9,Met(O(2))11]SP = Spm-SP > SP. Among the mentioned NK receptor antagonists, only the selective NK-3 receptor antagonist, SR 142801, shifted to the right Spm-SP and [Sar9,Met(O(2))11]SP concentration-response curve, showing pKB values of 5.84 and 5.88, respectively. Therefore, the reported results suggest that the introduction of a Spm moiety into the SP alters the parent peptide molecule by increasing its affinity for NK-3 receptors and/or by preventing its degradation by some proteolytic enzymes.
Filippelli
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A
Institute of Pharmacology and Toxicology, Faculty of Medicine, 2nd University of Naples, Italy.
Esposito
C
C
Falciani
M
M
Costa
C
C
Cozzolino
A
A
Rossi
F
F
Porta
R
R
D000731:Androstanes / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D015288:Neurokinin A / Q000031:analogs & derivatives / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010803:Physalaemin / Q000031:analogs & derivatives / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018042:Receptors, Neurokinin-3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013373:Substance P / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D015244:Thiorphan / Q000494:pharmacology; D011503:Transglutaminases / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects
D000731:Androstanes; D001562:Benzimidazoles; D010446:Peptide Fragments; D010880:Piperidines; D018042:Receptors, Neurokinin-3; C086111:WIN 51708; C054724:senktide; C079014:GR 82334; C069192:neurokinin A(4-10), Tyr(5)-Trp(6,8,9)-Lys(10)-; C075389:substance P, N-spermine-Gln(5)-; D010803:Physalaemin; D013373:Substance P; D015288:Neurokinin A; D015244:Thiorphan; D011503:Transglutaminases; C091554:SR 142801