Efeitos do tratamento periodontal não-cirúrgico na via L-arginina-óxido nítrico e no estresse oxidativo em plaquetas

• Autor(a) principal: Medeiros, Mariana Siqueira de
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/13982
• topic: L-arginine-NO-cGMP pathway; Platelets; Periodontitis; Oxidative stress; Via L-arginina-NO-GMPc; Plaquetas; Periodontite; Estresse oxidativo; Periodontite - Tratamento; Periodontite - Fatores de risco; Plaquetas (Sangue) - Análise química; Stress oxidativo; Óxido nítrico; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA::PERIODONTIA

Studies published over the last two decades have suggested an increase of cardiovascular disease (CVD) risk on periodontitis patients, but the physiopathological mechanisms involved in this association are not yet clear. Since it has been demonstrated an enhancement on both platelet activation and oxidative stress on periodontitis patients, the aim of this study was to investigate the L-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway on platelets from periodontitis patients, and the effect of non-surgical periodontal treatment in these variables. A total of 10 patients without periodontitis (periodontal healthy controls or gingivitis patients) and 10 periodontitis patients were included in this study. The clinical, laboratorial, and experimental evaluations were performed at the beginning of the study and 90 days after the basic periodontal therapy (periodontitis group). The clinical periodontal evaluation included the measurements of probing pocket depth (PPD), clinical attachment level (CAL), plaque percentage, and percentage of bleeding on probing. The following experiments were performed: L-arginine influx; nitric oxide synthase and arginase enzymes activity and expression; expression of guanylate cyclase and phosphodiesterase-5 enzymes; measurement of intraplatelet cGMP levels; platelet aggregation; oxidative stress evaluation (total oxidant activity and activity of both antioxidant enzymes catalase and superoxide dismutase SOD); measurement of C reactive protein (CRP) and fibrinogen. The initial results demonstrated an activation of L-arginine influx in platelets from periodontitis patients via y+L system, reduced intraplatelet cGMP levels and increased CRP. After periodontal treatment, it was observed reduction on percentage of sites with PPD ≥ 6 mm, CAL 4-5 mm and CAL ≥ 6 mm, enhancement on cGMP levels, to levels comparables to patients without periodontitis, accompanied by a higher activity of both antioxidant enzymes SOD and catalase. The other evaluated parameters did not showed significant alterations before and after periodontal treatment. The present results suggested a decreased NO biodisponibility in platelets from periodontitis patients and that the non-surgical periodontal treatment was effective to revert this condition, due to an enhancement on antioxidant defence. Therefore, alterations on L-arginine-NO-cGMP pathway and oxidative stress may lead to platelet dysfunction, which could contribute to a higher risk of CVD in periodontitis patients.