Citation

Yamashita KM, de Nogueira TO, Senise LV, Cirillo MC, Gonçalves LR, Sano-Martins IS, Giorgi R, Santoro ML. J. Thromb. Haemost. 2011; 9(10): 2057-2066.

Affiliation

Laboratory of Pathophysiology, Institute Butantan, São Paulo Department of Clinical Medicine, School of Medicine, University of São Paulo, Brazil.

Copyright

(Copyright © 2011, John Wiley and Sons)

DOI

10.1111/j.1538-7836.2011.04449.x

PMID

21794075

Abstract

Background: The role of platelets in hemostasis is well known, but few papers have reported their role in pain and edema induced by inflammatory agents. Objective: To evaluate the role of circulating platelets in the local injury induced by two diverse inflammatory agents, Bothrops jararaca venom (Bjv) and carrageenan. Methods: Rats were (1) rendered thrombocytopenic by administration of polyclonal anti-rat platelet IgG (ARPI) or busulfan, or (2) treated with platelet inhibitors (aspirin or clopidogrel). Edema formation, local hemorrhage, and pain threshold were assessed following intraplantar injection of Bjv or carrageenan in rat hind paws. Additionally, whole platelets or platelet releasate were tested whether they directly induced hyperalgesia. Results: Platelet counts were markedly diminished in rats administered with either ARPI (± 88%) or busulfan (± 96%). Previous treatment with ARPI or busulfan slightly reduced edema induced by Bjv or carrageenan. Injection of Bjv, but not of carrageenan, induced a statistically significance increase in hemorrhage in hind paws of thrombocytopenic rats. Remarkably, hyperalgesia evoked by Bjv or carrageenan was completely blocked in animals treated with ARPI or busulfan, or pre-treated with aspirin or clopidogrel. On the other hand, intraplantar administration of whole platelets or platelet releasate evoked hyperalgesia, which was inhibited by pre-incubation with alkaline phosphatase. Conclusions: Thrombocytopenia or inhibition of platelet function drastically reduced hyperalgesia induced by injection of carrageenan or Bjv; moreover, platelets per se secrete phosphorylated compounds involved in pain mediation. Thus, blood platelets are crucial cells involved in pain genesis, and their role therein has been underestimated.

Language: en