seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide and Chronic-Disease

Pruritus is a common symptom of skin diseases, and is associated with impaired sleep quality and a considerable reduction in the patient's quality of life. Recently, it was reported that there are sex-specific differences in scratching behavior in chronic pruritus patients. Namely, female chronic pruritus patients scratch more and have significantly more scratch lesions than male patients. However, few animal studies have examined sex-related differences in scratching behavior. Thus, the present work investigated sex-related differences in animal pruritus using pruritogens, which are often used to create experimental animal models of itching.. Acute pruritus was induced in ICR mice by a single intradermal injection of histamine, 4-methylhistamine, serotonin, compound 48/80, substance P (SP), or the proteinase-activated receptor-2 (PAR-2)-activating peptide SLIGRL-NH2. Chronic pruritus was induced by 5 weeks of the repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) to BALB/c mice.. Female mice showed significantly higher scratching counts in SLIGRL-NH2-induced pruritus than male mice. Conversely, there was no obvious sex-related difference in scratching behavior for the other pruritogens examined.. These results indicate that sex-related differences may exist in the pruritogen-responsive neurons that transmit the itch signal induced by SLIGRL-NH2, but not by histamine or 5-HT.

Topics: Acute Disease; Animals; Behavior, Animal; Chronic Disease; Disease Models, Animal; Female; Histamine; Male; Mice; Mice, Inbred BALB C; Mice, Inbred ICR; Oligopeptides; Pruritus; Serotonin; Sex Factors

This study investigated the involvement of tryptase and proteinase-activated receptor (PAR) subtypes in spontaneous scratching, an itch-associated behavior, in NC mice. This strain of mice showed chronic atopy-like dermatitis and severe spontaneous scratching, when kept a long time in a conventional environment. The trypsin-like serine proteinase inhibitor nafamostat mesilate (1 - 10 mg/kg) dose-dependently inhibited spontaneous scratching in mice with dermatitis. The activity of tryptase was increased in the lesional skin, which was inhibited by nafamostat at a dose inhibiting spontaneous scratching. Enzyme histochemistry revealed the marked increase of toluidine blue-stained cells, probably mast cells, with tryptase activity in the dermis of the lesional skin. Intravenous injection of anti-PAR(2) antibody suppressed spontaneous scratching of mice with dermatitis. Intradermal injection of the PAR(2)-activating peptide SLIGRL-NH(2), but not PAR(1), (3), (4)-activating peptides, elicited scratching at doses of 10 - 100 nmol/site in healthy mice. PAR(2)-immunoreactivity was observed in the epidermal keratinocytes in healthy and dermatitis mice. These results suggest that PAR(2) and serine proteinase(s), mainly tryptase, are involved in the itch of chronic dermatitis.

Topics: Animals; Benzamidines; Chronic Disease; Dermatitis, Atopic; Disease Models, Animal; Dose-Response Relationship, Drug; Epidermal Cells; Epidermis; Guanidines; Keratinocytes; Male; Mast Cells; Mice; Oligopeptides; Protease Inhibitors; Receptor, PAR-2; Tryptases

Protease-activated receptor-2 (PAR-2) can be activated after proteolysis of the amino terminal of the receptor by trypsin or by synthetic peptides with a sequence corresponding to the endogenous tethered ligand exposed by trypsin (eg, SLIGRL-NH(2)). PAR-2 mediates nitric oxide (NO)-dependent dilatation in cerebral arteries, but it is unknown whether PAR-2 function is altered in cardiovascular diseases. Since hypertension selectively impairs NO-mediated cerebral vasodilatation in response to acetylcholine and bradykinin, we sought to determine whether PAR-2-mediated vasodilatation is similarly adversely affected by this disease state.. We studied basilar artery responses in Wistar-Kyoto rats (WKY) (normotensive) and spontaneously hypertensive rats (SHR) in vivo (cranial window preparation) and in vitro (isolated arterial rings). The vasodilator effects of acetylcholine, sodium nitroprusside, and activators of PAR-2 and protease-activated receptor-1 (PAR-1) were compared in WKY versus SHR. Immunohistochemical localization of PAR-2 was also assessed in the basilar artery.. Increases in basilar artery diameter in response to acetylcholine were 65% to 85% smaller in SHR versus WKY, whereas responses to sodium nitroprusside were not different. In contrast to acetylcholine, vasodilatation in vivo to SLIGRL-NH(2) was largely preserved in SHR, and SLIGRL-NH(2) was approximately 3-fold more potent in causing vasorelaxation in SHR versus WKY in vitro. In both strains, responses to SLIGRL-NH(2) were abolished by N(G)-nitro-L-arginine, an inhibitor of NO synthesis. Activators of PAR-1 had little or no effect on the rat basilar artery. PAR-2-like immunoreactivity was observed in both the endothelial and smooth muscle cells of the basilar artery in both strains of rat.. These data indicate that NO-mediated vasodilatation to PAR-2 activation is selectively preserved or augmented in SHR and may suggest protective roles for PAR-2 in the cerebral circulation during chronic hypertension.

Topics: Acetylcholine; Animals; Cerebral Arteries; Chronic Disease; Enzyme Inhibitors; Hypertension; Male; Nitroarginine; Nitroprusside; Oligopeptides; Peptide Fragments; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, PAR-1; Receptor, PAR-2; Receptors, Thrombin; Vasodilation