Original Research Effects of non-surgical periodontal treatment on the L-arginine- nitric oxide pathway and oxidative status in platelets Mariana Alves de Sa ´ Siqueira 1 , Ricardo Guimara ˜ es Fischer 1 , Nata ´ lia Rodrigues Pereira 2 , Marcela Anjos Martins 2 , Monique Bandeira Moss 2 , Anto ˆ nio Cla ´ udio Mendes-Ribeiro 2 , Carlos Marcelo da Silva Figueredo 1 and Tatiana Marlowe Cunha Brunini 2 1 Department of Periodontology, Faculty of Odontology, Rio de Janeiro State University, Rio de Janeiro, CEP: 20551-030, Brazil; 2 Department of Pharmacology and Psychobiology, Rio de Janeiro State University, Rio de Janeiro, CEP: 20551-030, Brazil Correponding author: Tatiana Marlowe Cunha Brunini. Email: tbrunini@pq.cnpq.br Abstract Several studies have suggested an increase of cardiovascular disease (CVD) risk on periodontitis patients. An enhancement has been demonstrated on both platelet activation and oxidative stress on periodontitis patients, which may contribute for this association. Therefore, the aim of this study was to evaluate the effects of non-surgical periodontal treatment on the L-argi- nine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway and oxidative status in platelets. A total of eight peri- odontitis patients and eight controls were included in this study. Clinical, laboratory and experimental evaluations were performed on baseline and 90 days after periodontal treatment (except for western blot analysis). The clinical periodontal evaluation included measurements of probing pocket depth (PPD), clinical attachment loss (CAL), % of sites with plaque and % of sites with bleeding on probing. We evaluated: L-[ 3 H]arginine influx; nitric oxide synthase (NOS) and arginase enzymes activity and expression; expression of guanylate cyclase and phosphodiesterase-5 enzymes; cGMP levels; platelet aggregation; oxidative status through superoxide dismutase (SOD) and catalase activities, and measurement of reactive oxygen species (ROS) levels and C-reactive protein (CRP) levels. The initial results showed an activation of both L-arginine influx and via system y þ L associated with reduced intraplatelet cGMP levels in periodontitis patients and increased systemic levels of CRP. After periodontal treatment, there was a significant reduction of the % of sites with PPD 4–5mm, % of sites with CAL 4–5 mm, and an enhancement in cGMP levels and SOD activity. Moreover, CRP levels were reduced after treatment. Therefore, alterations in the intraplatelet L-arginine-NO-cGMP pathway and oxidant–antioxidant balance associated with a systemic inflammatory response may lead to platelet dysfunction, which may contribute to a higher risk of CVD in periodontitis. Keywords: L-arginine-NO-cGMP pathway, platelets, periodontitis, oxidative status Experimental Biology and Medicine 2013; 238: 713–722. DOI: 10.1177/1535370213480690 Introduction Cardiovascular diseases (CVDs) are the leading causes of death in the world, being responsible for more than 17 mil- lion deaths in 2008. A large proportion of CVDs result from atherosclerosis, a complex pathological process in the walls of blood vessels characterized for deposition of fatty mater- ials and cholesterol inside the lumen of medium- and large- sized blood vessels. The rupture of this plaque triggers the formation of a blood clot, which can cause a heart attack or a stroke if it blocks the coronary artery or a blood vessel in the brain, respectively. 1 Since the traditional risk factors for ath- erosclerosis were not sufficient to account for the aetiology of this multifactorial process, several novel risk factors have been identified, such as microbial pathogens, fibrinogen, and C-reactive protein (CRP). 2 In this context, over the last two decades, the relationship between periodontitis and CVDs has been investigated. However, the physiopathological mechanisms involved in this association are still not fully understood. 3–7 Periodontitis is stated as a chronic inflammatory process, mainly associated with Gram negative bacteria, character- ized by the loss of connective tissue attachment and bone around the teeth, whose prevalence in the adult population is about 40–50%. 8 Since only a small proportion of the popu- lation develops periodontitis in severe forms, it is possible that the initiation and progression of the disease are the result of activation of the host’s immune-inflammatory ISSN: 1535-3702 Experimental Biology and Medicine 2013; 238: 713–722 Copyright ß 2013 by the Society for Experimental Biology and Medicine by guest on April 16, 2016 ebm.sagepub.com Downloaded from