Transglutaminase-synthesized gamma-(glutamyl5) spermidine derivative of substance P is a selective tool for neurokinin-2 receptors characterization.
The ability of transglutaminase-synthesized 1,3-diaminopropane, spermidine (Spd), spermine (Spm), and monodansylcadaverine gamma-(glutamyl5)derivatives of substance P (SP) to produce bronchoconstriction was investigated. In urethane-anaesthetized guinea pigs, intravenous injections of SP derivatives contracted differently bronchial smooth muscle and caused hypotension. The most effective bronchoconstrictor among SP analogs was the gamma-(glutamyl5)Spd derivative of SP (Spd-SP; EC50 = 5.3 nmol/kg), which was more potent than the native peptide (EC50 = 26.5 nmol/kg). In contrast, the gamma-(glutamyl5)Spm derivative of SP (Spm-SP) was found completely unable to cause bronchoconstriction and was significantly less effective than SP in determining hypotension. The contractile effect of Spd-SP and Spm-SP was investigated in vitro on rat isolated colon, a well-characterized preparation rich in NK2 receptors. In addition, Spd-SP was tested on the endothelium-denuded rabbit pulmonary artery (RPA) and the hamster isolated trachea (HT), both tissue preparations containing only a single functional receptor subtype (NK2A and NK2B, respectively). The results obtained showed that Spd-SP recognizes NK2 receptors occurring on rat isolated colon more effectively (EC50 = 11 nM) than the native peptide (EC50 = 45 nM). Conversely, Spm-SP evokes a contractile response less effective than that elicited by SP (EC50 = 312 nM). Furthermore, Spd-SP (0.1-10 microg kg(-1)) produced a concentration-dependent contraction of both HT and RPA, exhibiting a potency respectively 12 and 30 times higher than SP in contracting HT and RPA. Our results indicate that the introduction of a Spd moiety at the level of glutamine-5 of SP gives rise to an analog that possesses a different capability to recognize NK2 receptors than the parent peptide. Moreover, since Spd-SP seems to contract more effectively RPA than HT, we conclude that it preferentially recognizes the NK2A receptor subtype.
Mancuso
F
F
Department of Experimental Pharmacology, University of Naples Federico II, Italy.
Costa
C
C
Calignano
A
A
Mariniello
L
L
Rossi
F
F
Porta
R
R
Esposito
C
C
D000818:Animals; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D003106:Colon / Q000098:blood supply / Q000187:drug effects; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008297:Male; D011651:Pulmonary Artery / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D018041:Receptors, Neurokinin-2 / Q000819:agonists*; D018039:Receptors, Tachykinin / Q000145:classification*; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology*; D014132:Trachea / Q000098:blood supply / Q000187:drug effects; D011503:Transglutaminases / Q000378:metabolism
D016085:Bronchoconstrictor Agents; D018041:Receptors, Neurokinin-2; D018039:Receptors, Tachykinin; D013096:Spermine; D013373:Substance P; D011503:Transglutaminases