2‐Furoyl‐LIGRL‐NH₂, a potent agonist for proteinase‐activated receptor‐2, as a gastric mucosal cytoprotective agent in mice

Abstract

1 Proteinase-activated receptor-2 (PAR 2 ), expressed in capsaicin-sensitive sensory neurons, plays a protective role in gastric mucosa. The present study evaluated gastric mucosal cytoprotective effect of 2-furoyl-LIGRL-NH 2 , a novel highly potent PAR 2 agonist, in ddY mice and in wild-type and PAR 2 -knockout mice of C57BL/6 background. 2 Gastric mucosal injury was created by oral administration of HCl/ethanol solution in the mice. The native PAR 2 -activating peptide SLIGRL-NH 2 , administered intraperitoneally (i.p.) at 0.3-1 mmol kg À1 in combination with amastatin, an aminopeptidase inhibitor, but not alone, revealed gastric mucosal protection in ddY mice, which was abolished by ablation of capsaicin-sensitive sensory neurons. 3 I.p. administration of 2-furoyl-LIGRL-NH 2 at 0.1 mmol kg À1 , without combined treatment with amastatin, exhibited gastric mucosal cytoprotective activity in ddY mice, the potency being much greater than SLIGRL-NH 2 in combination with amastatin. This effect was also inhibited by capsaicin pretreatment. 4 Oral administration of 2-furoyl-LIGRL-NH 2 at 0.003-0.03 mmol kg À1 also protected against gastric mucosal lesion in a capsaicin-reversible manner in ddY mice. 5 I.p. 2-furoyl-LIGRL-NH 2 at 0.1-0.3 mmol kg À1 caused prompt salivation in anesthetized mice, whereas its oral administration at 0.003-1 mmol kg À1 was incapable of eliciting salivation. 6 In wild-type, but not PAR 2 -knockout, mice of C57BL/6 background, i.p. administration of 2-furoyl-LIGRL-NH 2 caused gastric mucosal protection. 7 Thus, 2-furoyl-LIGRL-NH 2 is considered a potent and orally available gastric mucosal protective agent. Our data also substantiate a role for PAR 2 in gastric mucosal protection and the selective nature of 2-furoyl-LIGRL-NH 2 .

Identification and Characterization of Novel Small-Molecule Protease-Activated Receptor 2 Agonists

“…Ample evidence indicates PAR2 receptors mediate prono- ciceptive and proinflammatory effects through a neurogenic mechanism of action (Ricciardolo et al, 2000;Steinhoff et al, 2000;Fiorucci et al, 2001;Vergnolle et al, 2001;Nguyen et al, 2003;Kawabata et al, 2005;Su et al, 2005). Treatment with PAR2 APs or trypsin can stimulate the release of CGRP and substance P from both central and peripheral terminals of primary afferent nociceptive neurons, which in turn may mediate states of pain and inflammation .…”

“…Similarly, single high doses of PAR2 agonists inhibit infiltration of inflammatory cells into the lungs and reduce airway resistance of lipopolysaccharide-challenged mice and ovalbumin sensitized mice (Moffatt et al, 2002;De Campo and Henry, 2005;Morello et al, 2005), whereas administration of multiple doses of SLIGRL-NH 2 or genetic overexpres- at ASPET Journals on May 9, 2018 jpet.aspetjournals.org Downloaded from ulcer PAR2 agonists prevent/limit tissue damage to the stomach lining by inducing mucus secretion, possibly through a neurogenic mechanism (Kawabata et al, 2005). Likewise, cerulein-induced pancreatitis and associated abdominal hyperalgesia/allodynia were exacerbated in PAR2 knockout mice and suppressed by 2-furoyl-LIGRLO-NH 2 in WT, but not PAR2, knockout mice (Kawabata et al, 2006).…”

“…PAR2 receptors are found on primary spinal afferent neurons coexpressed with substance P, calcitonin gene-related peptide (CGRP), and transient receptor potential vanilloid receptor (TRPV) 1 Amadesi et al, 2004;Dai et al, 2004). Convincing evidence has been reported showing that PAR2 receptors mediate many of their actions through a neurogenic mechanism (Ricciardolo et al, 2000;Steinhoff et al, 2000;Fiorucci et al, 2001;Vergnolle et al, 2001;Nguyen et al, 2003;Amadesi et al, 2004;Kawabata et al, 2005;Su et al, 2005;Cenac et al, 2007). Given these physiological roles for PAR2 receptors, PAR2 agonists would be expected to exacerbate most nociceptive and inflammatory processes; however, PAR2 also exerts a protective effect in many settings (Cocks et al, 1999;Cicala et al, 2001;Fiorucci et al, 2001;Kawabata et al, 2004bKawabata et al, , 2006De Campo and Henry, 2005;Morello et al, 2005;D'Agostino et al, 2007), especially in models of asthma and pulmonary inflammation; thus, there may be therapeutic roles for PAR2 agonists (De Campo and Henry, 2006;Henry, 2006).…”

Proteinase-activated receptors in the gastrointestinal system: a functional linkage to prostanoids

“…PAR1 and PAR2 play multiple roles in the gastric mucosa in rats and/or mice, being primarily protective (Kawabata et al, 2001a;Kawabata et al, 2004c). However, the underlying mechanisms for the gastric mucosal protection caused by PAR1 and PAR2 activation are largely different; i. e. the protective effect of PAR1 agonists is dependent on PGs formation (Kawabata et al, 2004c), whereas PAR2 agonists elicit gastric mucus secretion and mucosal protection by activating sensory neuron, an effect being independent of PGs (Kawabata et al, 2001a;Kawabata et al, 2005). COX-1-derived PGs appear to predominantly mediate the PAR1-triggered gastric mucosal protection, since a COX-1 inhibitor, SC-560, but not a COX-2 inhibitor, NS-398, abolished the protective effect (Kawabata et al, 2004c).…”

Thrombin receptor agonist peptide immobilized in microspheres stimulates reparative processes in rats with gastric ulcer

“…Experiments on rat model of ethanol ulcer showed that PAR1-AP injected intravenously with amastatin (aminopeptidase inhibitor) protected the gastric mucosa in mild injuries [4]. Moreover, the protective effect of PAR2 agonist peptide (2-furoyl-LIGRL) was demonstrated on the model of gastric mucosa injury induced by ethanol and HCl [5].…”