Scratching Behavior and Fos Expression in Superficial Dorsal Horn Elicited by Protease-Activated Receptor Agonists and Other Itch Mediators in Mice
AUTOR(ES)
Akiyama, Tasuku
FONTE
American Society for Pharmacology and Experimental Therapeutics
RESUMO
Protease-activated receptor (PAR)-2 and PAR-4 are implicated in nonhistaminergic itch. We investigated dose dependence, tachyphylaxis, and cross-tachyphylaxis of itch-associated scratching elicited by intradermal injections of PAR-2 and PAR-4 agonists, serotonin (5-hydroxytryptamine, 5-HT), and histamine in ICR mice, as well as μ-opioid modulation of PAR-2 agonist-evoked scratching. Each agent elicited dose-related increases in scratch bouts. Scratching elicited by the PAR-4 agonist and histamine both exhibited significant tachyphylaxis but no cross-tachyphylaxis with each other. Scratching evoked by 5-HT did not exhibit significant tachyphylaxis but did exhibit significant cross-tachyphylaxis to scratching evoked by the PAR-2 and PAR-4 agonists and histamine. Naltrexone and high-dose morphine (10 mg/kg) attenuated PAR-2 agonist-evoked scratching, whereas lower dose morphine (1 mg/kg) had no effect. High-dose morphine also significantly increased circling behavior, which may have interfered with scratching. The PAR-2 agonist and 5-HT produced overlapping distributions of Fos-like immunoreactivity in the superficial dorsal horn. These results indicate that PAR-2 and PAR-4 agonists, histamine, and 5-HT elicit itch-related scratching and activate superficial dorsal horn neurons that may participate in scratch reflex and ascending itch signaling pathways.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2683773Documentos Relacionados
- Cloning and characterization of human protease-activated receptor 4
- Protease‐activated receptor‐2 protects against pancreatitis by stimulating exocrine secretion
- Protease-activated receptors and inflammatory hyperalgesia
- Role of mast cells and protease-activated receptor-2 in cyclooxygenase-2 expression in urothelial cells
- Pancreatic protease‐activated receptors: friend and foe