The role of kinin B1 and B2 receptors in the scratching behaviour induced by proteinase-activated receptor-2 agonists in mice

Abstract

Background and purpose: Activation of the proteinase-activated receptor-2 (PAR-2) induces scratching behaviour in mice. Here, we have investigated the role of kinin B(1) and B(2) receptors in the pruritogenic response elicited by activators of PAR-2.

Experimental approach: Scratching was induced by an intradermal (i.d.) injection of trypsin or the selective PAR-2 activating peptide SLIGRL-NH(2) at the back of the mouse neck. The animals were observed for 40 min and their scratching response was quantified.

Key results: I.d. injection of trypsin or SLIGRL-NH(2) evoked a scratching behaviour, dependent on PAR-2 activation. Mice genetically deficient in kinin B(1) or B(2) receptors exhibited reduced scratching behaviour after i.d. injection of trypsin or SLIGRL-NH(2). Treatment (i.p.) with the non-peptide B(1) or B(2)receptor antagonists SSR240612 and FR173657, respectively, prevented the scratching behaviour caused by trypsin or SLIGRL-NH(2). Nonetheless, only treatment i.p. with the peptide B(2)receptor antagonist, Hoe 140, but not the B(1)receptor antagonist (DALBK), inhibited the pruritogenic response to trypsin. Hoe 140 was also effective against SLIGRL-NH(2)-induced scratching behaviour when injected by i.d. or intrathecal (i.t.) routes. Also, the response to SLIGRL-NH(2) was inhibited by i.t. (but not by i.d.) treatment with DALBK. Conversely, neither Hoe 140 nor DALBK were able to inhibit SLIGRL-NH(2)-induced scratching behaviour when given intracerebroventricularly (i.c.v.).

Conclusions and implications: The present results demonstrated that kinins acting on both B(1) and B(2) receptors played a crucial role in controlling the pruriceptive signalling triggered by PAR-2 activation in mice.

Figure 1

(A) Scratching behaviour induced by the selective PAR-2 activating peptide SLIGRL-NH₂ (25 to 200 µg·site⁻¹, i.d.), the inactive control peptide LRGILS-NH₂ (100 µg·site⁻¹, i.d.) or compound 48/80 (C48/80; 10 µg·site⁻¹, i.d.) in Swiss mice. (B) Effect of the treatment with the selective peptide PAR-2 antagonist FSLLRY-NH₂ (100 µg·site⁻¹, co-injection) on the SLIGRL-NH₂ (100 µg·site⁻¹)-induced scratching behaviour in Swiss mice. (C, D) Effect of the treatment with the corticoid dexamethasone (0.5 mg·kg⁻¹, s.c., 4h) or the selective histamine H₁ receptor antagonist pyrilamine (10 mg·kg⁻¹, s.c., 30 min) on the (C) SLIGRL-NH₂ (100 µg·site⁻¹)- or (D) trypsin (200 µg·site⁻¹)-induced scratching behaviour in Swiss mice. Each column represents the mean of six to 10 animals and the vertical bars represent the SEM. Significantly different when compared with saline group (*P < 0.05) and SLIGRL-NH₂- or trypsin-treated group (^#P < 0.05). PAR-2, proteinase-activated receptor-2.

Figure 2

(A, B) Scratching behaviour induced by trypsin (200 µg·site⁻¹, i.d.) in kinin (A) B₁ (B₁R^−/−) or (B) B₂ (B₂R^−/−) receptor deficient mice. (C, D) Scratching behaviour induced by SLIGRL-NH₂ (100 µg·site⁻¹, i.d.) in (C) B₁R^−/− or (D) B₂R^−/− mice. (E, F) Overt nociception (licking) induced by trypsin (300 µg·site⁻¹, i.pl.) in (E) B₁R^−/− or (F) B₂R^−/− mice. Each column represents the mean of six to 10 animals and the vertical bars represent the SEM. Significantly different when compared with wild-type (WT) saline group (*P < 0.05) and WT SLIGRL-NH₂- or trypsin-treated group (^#P < 0.05).

Figure 3

Scratching behaviour induced by (A) deoxycholate (100 µg·site⁻¹, i.d.), (B) chloroquine (200 µg·site⁻¹, i.d.) or (C) compound 48/80 (C48/80; 10 µg·site⁻¹, i.d.) in kinin B₁ (B₁R^−/−) or B₂ (B₂R^−/−) receptor deficient mice. Each column represents the mean of six to 10 animals and the vertical bars represent the SEM. Significantly different when compared with wild-type (WT) saline group (*P < 0.05) and WT deoxycholate-, chloroquine- or compound 48/80-treated group (^#P < 0.05).

Figure 4

(A, B) Effect of the treatment with the selective kinin B₁ receptor antagonists des-Arg⁹-Leu⁸-bradykinin (DALBK; 150 nmol·kg⁻¹, i.p., 30 min) or SSR240612 (1 mg·kg⁻¹, i.p., 30 min) on the scratching behaviour induced by (A) trypsin (200 µg·site⁻¹) or (B) SLIGRL-NH₂ (100 µg·site⁻¹) in Swiss mice. (C, D) Effect of the treatment with the selective kinin B₂ receptor antagonists Hoe 140 (50 nmol·kg⁻¹, i.p., 30 min) or FR173657 (30 mg·kg⁻¹, i.p., 30 min) on the scratching behaviour induced by (C) trypsin (200 µg·site⁻¹) or (D) SLIGRL-NH₂ (100 µg·site⁻¹) in Swiss mice. Each column represents the mean of six to 10 animals and the vertical bars represent the SEM. Significantly different when compared with saline group (*P < 0.05) and SLIGRL-NH₂- or trypsin-treated group (^#P < 0.05).

Figure 5

(A, B, C) Effect of (A) intradermal (0.3 nmol·site⁻¹, i.d.), (B) intrathecal (25 pmol·site⁻¹, i.t.) or (C) intracerebroventricular (25 pmol·site⁻¹, i.c.v.) treatment with the selective kinin B₁ receptor antagonist DALBK on the scratching behaviour induced SLIGRL-NH₂ (100 µg·site⁻¹) in Swiss mice. (D, E, F) Effect of (D) intradermal (3 nmol·site⁻¹, i.d.), (E) intrathecal (100 pmol·site⁻¹, i.t.) or (F) intracerebroventricular (100 pmol·site⁻¹, i.c.v.) treatment with the selective kinin B₂ receptor antagonist Hoe 140 on the scratching behaviour induced SLIGRL-NH₂ (100 µg·site⁻¹) in Swiss mice. Each column represents the mean of six to 10 animals and the vertical bars represent the SEM. Significantly different when compared with saline group (*P < 0.05) and SLIGRL-NH₂-treated group (^#P < 0.05).