Potentiation of capsaicin-induced neurogenic inflammation by 5-HT7 receptors in the rat hind paw: involvement of calcitonin gen-related peptide

Publication date: Available online 3 May 2018 Source:Peptides Author(s): Luis D. Arreola-Peralta, Frida Altamirano-Reyna, Deni M. Galindo-González, Jessica G. Solis-Anguiano, Enza Lacivita, Marcello Leopoldo, José A. Terrón A decrease in the activation threshold of primary sensory neurons to transient receptor potential V1 (TRPV1) stimulation by serotonin 5-HT7 receptors has been reported but no confirmation if this might translate into facilitation of neurogenic inflammation has been provided. We analysed the modulation of capsaicin (CAP)-induced neurogenic inflammation in the rat hind paw by the selective 5-HT7 receptor agonist, LP-44, and the involvement of calcitonin gen-related peptide (CGRP) in this effect. Animals received intra-plantar injections (30 μl) of vehicle, CAP (0.05%, 0.1% and 0.2%), LP-44 (7.5 and 15 nmol) and the combination of LP–44 + CAP; then, the time course of the inflammatory responses was measured. The effect of the 5-HT7 receptor antagonist, SB-269970 (3 mg/kg, s.c.), on responses produced by LP-44 alone and combined with CAP was tested. As expected, CAP produced concentration- and time-dependent inflammatory responses in the hind paw. Interestingly, LP-44 by itself also produced inflammation in a concentration- and time-dependent manner, and magnified CAP-induced responses. Systemic pre-treatment with SB-269970 significantly blunted LP-44 (15 nmol)-induced inflammation as well as magnified inflammatory responses produc...
Source: Peptides - Category: Biochemistry Source Type: research