The use of aminoguanidine, a selective inducible nitric oxide synthase inhibitor, to evaluate the role of nitric oxide on periapical healing

Abstract

Background:Nitric oxide (NO) is one of the many chemical mediators involved in inflammatory processes. In addition to periapical inflammation, NO can have a role in periapical healing. The purpose of this study was to evaluate the effect of aminoguanidine (AG) as a selective inhibitor of inducible nitric oxide synthase (iNOS) on the degree of healing response of periapical lesions of the canine teeth of cats.Methods:In this interventional experimental study, the root canals of 48 cat canine teeth were infected with cat dental plaque and sealed. After induction of periapical lesions, root canal therapy (RCT) was performed. On the day of RCT phase, the cats were administered either AG (experimental group) or normal saline (control group), which was continued on a daily basis until the day of sacrifice. Four canine teeth in one cat served as negative and positive controls. The animals were sacrificed 6 weeks after RCT. The healing response of the periapical zones was analyzed histologically. The mean scores of healing for the two groups were compared using Mann–Whitney U test.Results:The mean scores of healing for the AG group (2.45±0.508) were significantly higher than those of the control group (2±0.510) (P<0.05).Conclusion:The use of an iNOS selective inhibitor such as AG can accelerate the healing process in periapical lesions.

Selective nitric oxide synthase inhibitor promotes bone healing

“…The results of the afore-mentioned two studies. [ 14 15 ] were in accordance with our findings. This indicates that the local application of AG may have the same desired effects as systemic administration of iNOS inhibitors without the unwanted systemic side effects.…”

“…In another study, Farhad et al . [ 15 ] assessed the effect of systemic administration of AG on healing rate of periapical tissues and showed that selective NO inhibitor enhanced the healing of periapical lesions. The first phase of healing is based on an inflammatory process.…”

“…Moreover, Farhad et al . [ 15 ] reported that systemic administration of AG significantly increased the healing score of induced periapical lesions in canine teeth in a cat model.…”

Radiation and Diabetic Retinopathy: A Dark Synergy

“…Intriguingly, the amacrine cell loss in this study was reversed by treatment with aminoguanidine (AG), a benefit the authors attributed solely to inhibition of advanced glycation end-products (AGEs) [169]. However, if iNOS had been induced as a secondary effect of nNOS-related nitrositive stress, the AG treatment could have exerted additional benefit in its role as a selective inhibitor of iNOS [170,171]. Clearly, RNS injury in amacrine cells during diabetes and following exposure to IR requires further work in animal models.…”

Participação da atividade redox e das armadilhas extracelulares de neutrófilos na gênese e desenvolvimento da lesão periapical induzida experimentalmente em camundongos

“…Camundongos knockout para a enzima iNOS apresentaram lesões periapicais maiores, maior recrutamento de células inflamatórias, formação de abscessos periapicais (Fukada et al, 2008), além de níveis mais elevados de IL-1β, TNF-α, RANK e RANKL, podendo o NO regular negativamente a formação de osteoclastos (Silva et al, 2012). No entanto, o uso de um inibidor seletivo do iNOS durante o tratamento endodôntico de dentes com lesões periapicais induzidas experimentalmente em gatos acelerou a cicatrização periapical, mostrando um papel prejudicial do NO no processo de reparo periapical (Farhad et al, 2011). Já Wang e colaboradores (2020), mostraram que o uso de metformina suprimiu a expressão de iNOS e reduziu a reabsorção óssea na periodontite apical induzida experimentalmente em ratos.…”