Full text
| |
| Author(s): |
Thiago de Oliveira Nogueira
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) |
| Defense date: | 2011-03-25 |
| Examining board members: |
Renata Giorgi;
Frederico Azevedo da Costa Pinto;
Sandra Coccuzzo Sampaio Vessoni
|
| Advisor: | Renata Giorgi |
| Abstract | |
Neutrophilic peritonitis induced by glycogen causes antinociception in mice subjected to the writhing test, which is médiated by a calcium-binding protein with a molecular mass of 14 kDa, named S100A9. The purpose of this study was to deepen the study on the involvement of neutrophils in glycogen-induced antinociception in rats subjected to the paw pressure test and evaluate the expression of S100A9 protein in time periods when this effect was detected. Glycogen induces antinociception in rats between 2 and 12 hours after intraplantar injection. Pretreatment of animals with fucoidan, a selectin inhibitor, not only reversed the antinociceptive effect, but also induces hyperalgesia between 2 and 6 hours after glycogen injection. Eight hours after treatment with glycogen, fucoidan only inhibited the antinociception induced by the inflammatory agent. Histological analysis showed an increased migration of polymorphonuclear cells between 2 and 8 hours after glycogen administration, which was inhibited by pretreatment with fucoidan. Both intraplantar and subcutaneous injection of naloxone, a nonspecific inhibitor of opioid receptors, did not affect the antinociceptive effect induced by glycogen at all evaluated times. In relation to the expression of S100A9 analyzed by Western blotting, it was observed that the samples obtained from the footpad injected with glycogen, between 2 and 12 hours, had a band with a molecular weight of 14 kDa, which is similar to molecular weight of S100A9. Relative quantification of the bands marked with anti-S100A9 in the time periods between 2 and 12 hours showed a significant increase in protein expression in samples obtained from animals treated with glycogen, compared with those treated with saline. Intraperitoneal injection of glycogen induced a significant increase in the total number of cells in the abdominal cavity of animals between 2 and 12 hours after treatment, represented by increased numbers of migrated polymorphonuclear cells. The supernatants obtained from peritoneal exudate between 2 and 12 hours after injection of glycogen, administered intraplantarly, not only reversed the hyperalgesia induced by carrageenan (Cg) but also induced antinociceptive effect. Already, the supernatant obtained 24 hours after injection of glycogen only partially reversed the hyperalgesic effect induced by Cg. The treatment of the supernatant obtained 4 hours after injection of glycogen with anti-S100A9 abolished the antinociceptive effect observed with the supernatant on hyperalgesia induced by Cg. These data suggest that antinociception entailed by glycogen in rats submitted to the paw pressure is dependent on neutrophil migration. Moreover, this effect is not related to the release of opioid peptides but possibly to the S100A9 protein secretion by these cells. In addition, the results obtained with the supernatants of peritoneal exudate after glycogen injection show that during neutrophilic peritonitis a molecule able to inhibit carrageenan-induced hyperalgesia is secreted and induce antinociception entailed by glycogen, which is possibly the S100A9 protein. (AU) | |
| FAPESP's process: | 08/07762-5 - Participation of S100A9 protein in antinociception caused by the supernatants obtained from the peritoneal exudate induced by glycogen or by the intraplantar injection of this inflammatory agent in rats submitted to the paw pressure test. |
| Grantee: | Thiago de Oliveira Nogueira |
| Support Opportunities: | Scholarships in Brazil - Master |