Immune modulatory and antioxidant effects of melatonin in experimental periodontitis in rats

Effects of melatonin against experimentally induced apical periodontitis in rats

Apical periodontitis is an inflammatory condition resulting from microbial invasion in the root canal system, causing periapical tissue destruction and bone resorption. This study investigated melatonin's effects, known for its antioxidant and anti-inflammatory properties, on experimentally induced apical periodontitis in rats. Three groups of rats were studied: control, apical periodontitis and apical periodontitis with melatonin treatment. Proinflammatory cytokines and enzyme levels in blood serum were measured, and micro-CT analysis assessed bone resorption. Results showed significantly elevated cytokines and enzyme levels in the apical periodontitis group compared to the control. However, in the melatonin-treated group, these levels were significantly reduced (p < 0.01-0.001). Micro-CT analysis indicated decreased periapical resorption cavity volume and surface area with melatonin treatment. This suggests that systemic melatonin administration can mitigate inflammation and reduce bone resorption in experimentally induced apical periodontitis in rats, potentially holding promise for human endodontic disease treatment pending further research.

P2X7 receptor antagonist A-438079 alleviates oxidative stress of lung in LPS-induced septic rats

Sepsis is a deadly systemic inflammatory response of the body against infection resulting in immune response, cell differentiation and organ damage. Endotoxemia is one of the causes of sepsis-related acute respiratory distress and respiratory burst is an important generator of oxidants. Inflammation may be aggravated by overexpression of ATP-gated purinergic receptors (i.e., P2X7R) following cell damage. We aimed to evaluate the effects of P2X7R antagonist A-438079 on lung oxidative status and the receptor expression in endotoxemia of sepsis. Rats were subjected to sepsis by E. coli lipopolysaccharide (LPS) and treated with 15 mg/kg A-438079. The increase in circulatory IL-1β and IL-8 concentrations in LPS group confirmed the systemic inflammatory response to endotoxemia compared with Control groups (p < 0.001). Besides, there was an increase in P2X7R expression in lung tissue after LPS administration. Compared with Control groups, there were significant increases in the values of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) (p < 0.001), and myeloperoxidase (MPO) (p < 0.05) in lung tissue of LPS group. P2X7R expression in lung and IL-1β level in blood did not increase in LPS + A-438079 group. A-438079 decreased the lung levels of MDA, GSH, CAT and SOD (p < 0.001), and MPO (p < 0.01) in septic rats. As a result, administration of pathogen-associated LPS led to increased P2X7R expression into lung tissue and elevated lipid peroxidation product MDA with regard to oxidative damage. The P2X7R antagonist A-438079 alleviated the oxidative stress of lung with a balance of tissue oxidant/antioxidant factors in experimental sepsis in rats.

Blockade of P2X7 receptor-mediated purinergic signaling with A438079 protects against LPS-induced liver injury in rats

The study aimed to investigate the hepatoprotective effects of purinergic receptor (P2X7R) antagonism by A438079 in liver damage. An experimental model of inflammation was performed by intraperitoneal (i.p.) lipopolysaccharide (LPS) administration in the rat. The groups were Control, A438079, dimethyl sulfoxide (DMSO), LPS, LPS + DMSO, and LPS + A438079. Following LPS (8 mg/kg) injection, A438079 (15 mg/kg) and DMSO (0.1 mL) were administrated (i.p) in the study groups. The blood and the liver tissues were removed for histological, biochemical, and western blot analyses. In the biochemical analysis, serum aspartate transaminase (AST) and alanine transaminase (ALT) concentrations, the tissue glutathione (GSH) level, and superoxide dismutase (SOD) activity dramatically decreased and malondialdehyde (MDA) level increased in the LPS and LPS + DMSO groups compared to the LPS + A438079 group. In the histological analysis, severe sinusoidal dilatation, necrotic hepatocytes, and inflammatory cell infiltration were observed in the LPS and LPS + DMSO groups while these effects were lessened in the LPS + A438079 group. The relative protein expression levels of P2X7R, Nf-kB-p65, IL-6, and Caspase-3 were significantly higher in the LPS and the LPS + DMSO groups than in the LPS + A438079 group. On the other hand, these protein expressions were considerably lower in the Control, A438079, and DMSO groups compared to the LPS + A438079 group. In addition, Bcl-2 protein expression was significantly lower in the LPS and the LPS + DMSO groups and higher in the LPS + A438079 group compared to the other groups. The protective effect of A438079 against LPS-induced hepatic inflammation may be related to P2X7R antagonism, inflammatory mediators, and apoptotic cell death.

Melatonin decreases plasma TNF-α and improves nonenzymatic antioxidant defence and insulin sensitivity in rats with apical periodontitis fed a high-fat diet

AIM

To analyse the effects of melatonin (ME) treatment on oxidative stress and insulin resistance (IR) in rats with apical periodontitis (AP) fed a high-fat diet (HFD).

METHODOLOGY

Eighty 60-day-old rats were divided into eight groups: control (CN), AP, HFD with AP (HFDAP), control with ME (CNME), AP with ME (APME), HFD with ME (HFDME) and HFD with AP+ME (HFDAPME). The animals from the HFD groups were fed a HFD throughout the experimental period. On day 7, the animals from the AP groups were subjected to experimental AP, and after 70 days, the ME groups were treated for 30 days. Glycaemia, insulinaemia, homeostatic model assessment for IR index, tumour necrosis factor-α (TNF-α), and interleukin-6 were analysed in plasma using biochemical tests and enzyme-linked immunosorbent assay. Thiobarbituric acid-reactive substances (TBARS), carbonyl protein (CP), superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione (GSH) and total antioxidant capacity (ferric reducing antioxidant power [FRAP]) were analysed in the gastrocnemius muscle.

RESULTS

(1) Association of AP and HDF exacerbated IR, and ME treatment improved this alteration; (2) AP and HFD and their association showed increased TNF-α, and ME reversed it; (3) TBARS increased in the AP and HFDAP groups, and ME reversed only in the group with the association of disease and diet; (4) CP increased in all HFD groups and improved in the ME groups; (5) GSH activity decreased in all experimental groups, and ME increased this parameter only in the CN and AP groups; (6) FRAP did not change between the groups, but ME treatment increased its activity in the AP and HFD groups; (7) ME increased SOD in the CN and AP groups.

CONCLUSION

Apical periodontitis and HFD promoted IR, and the association of AP with diet promoted IR exacerbation; this resistance might have been caused by an increase in TNF-α. AP promoted more intense changes in lipid oxidative damage than in protein oxidative damage. In non-enzymatic antioxidant defence, it was observed that both AP and HFD and their association promoted a decrease in GSH levels. Overall, ME treatment reversed changes such as oxidative stress and IR.

Estimation of gingival crevicular fluid oxidative stress markers in school-aged children and teenagers with insufficient sleep

BACKGROUND

Sleep is crucial for survival. Sleep deprivation causes ROS accumulation and, consequently, oxidative stress. The goal of the study was to evaluate gingival crevicular fluid (GCF) levels of the oxidative stress status hydrogen peroxide (H₂O₂), superoxide glutathione (GSH), and cellular oxidative damage marker malondialdehyde (MDA) in school-aged children and teenagers with insufficient sleep.

METHODS

This study investigated sleep duration in 80 participants from two different developmental stages: school-aged children (6-13 years) and teenagers (14-17 years). GCF samples were obtained from all individuals, and samples were investigated to detect H₂O₂, GSH, and MDA levels using the micro method.

RESULTS

Results reveal that GCF MDA and H₂O₂ in school-age children and teenagers with insufficient sleep were significantly higher than in children with sufficient sleep. GCF GSH with insufficient sleep was insignificantly lower than in children with sufficient sleep. There was no significant difference between school-age and teenage populations.

CONCLUSION

Sleep deprivation causes increased levels of oxidative stress in gingival crevicular fluid, and adequate sleep is essential for maintaining redox balance.

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

Neural Regulations in Tooth Development and Tooth-Periodontium Complex Homeostasis: A Literature Review

The tooth-periodontium complex and its nerves have active reciprocal regulation during development and homeostasis. These effects are predominantly mediated by a range of molecules secreted from either the nervous system or the tooth-periodontium complex. Different strategies mimicking tooth development or physiological reparation have been applied to tooth regeneration studies, where the application of these nerve- or tooth-derived molecules has been proven effective. However, to date, basic studies in this field leave many vacancies to be filled. This literature review summarizes the recent advances in the basic studies on neural responses and regulation during tooth-periodontium development and homeostasis and points out some research gaps to instruct future studies. Deepening our understanding of the underlying mechanisms of tooth development and diseases will provide more clues for tooth regeneration.

Melatonin enhances osteogenic differentiation of dental pulp mesenchymal stem cells by regulating MAPK pathways and promotes the efficiency of bone regeneration in calvarial bone defects

Background

Mesenchymal stem cell (MSC)-based tissue engineering plays a major role in regenerative medicine. However, the efficiency of MSC transplantation and survival of engrafted stem cells remain challenging. Melatonin can regulate MSC biology. However, its function in the osteogenic differentiation of dental pulp-derived MSCs (DPSCs) remains unclear. We investigated the effects and mechanisms of melatonin on the osteogenic differentiation and bone regeneration capacities of DPSCs.

Methods

The biological effects and signaling mechanisms of melatonin with different concentrations on DPSCs were evaluated using a proliferation assay, the quantitative alkaline phosphatase (ALP) activity, Alizarin red staining, a real-time polymerase chain reaction, and a western blot in vitro cell culture model. The in vivo bone regeneration capacities were assessed among empty control, MBCP, MBCP + DPSCs, and MBCP + DPSCs + melatonin preconditioning in four-created calvarial bone defects by using micro-computed tomographic, histological, histomorphometric, and immunohistochemical analyses after 4 and 8 weeks of healing.

Results

In vitro experiments revealed that melatonin (1, 10, and 100 μM) significantly and concentration-dependently promoted proliferation, surface marker expression (CD 146), ALP activity and extracellular calcium deposition, and osteogenic gene expression of DPSCs (p < 0.05). Melatonin activated the protein expression of ALP, OCN, and RUNX-2 and inhibited COX-2/NF-κB expression. Furthermore, the phosphorylation of mitogen-activated protein kinase (MAPK) p38/ERK signaling was significantly increased in DPSCs treated with 100 μM melatonin, and their inhibitors significantly decreased osteogenic differentiation. In vivo experiments demonstrated that bone defects implanted with MBCP bone-grafting materials and melatonin-preconditioned DPSCs exhibited significantly greater bone volume fraction, trabecular bone structural modeling, new bone formation, and osteogenesis-related protein expression than the other three groups at 4 and 8 weeks postoperatively (p < 0.05).

Conclusions

These results suggest that melatonin promotes the proliferation and osteogenic differentiation of DPSCs by regulating COX-2/NF-κB and p38/ERK MAPK signaling pathways. Preconditioning DPSCs with melatonin before transplantation can efficiently enhance MSCs function and regenerative capacities.

Assessment of Stress Salivary Markers, Perceived Stress, and Shift Work in a Cohort of Fishermen: A Preliminary Work

Due to work-related stress, today, work itself represents a daily challenge that must be faced in many occupations. While, in the past, the scientific community has focused on the helping professions, since, an increasing number of professions have since been investigated. Therefore, different approaches exist in order to assess this disorder, representing a scientific field wherein biological and psychological dimensions both need to be evaluated. In this paper, we consider three biological salivary markers: interleukin 1 beta (IL-1β), cortisol, and melatonin. The choice derives from recent contributions to the literature in which the interplay between these markers has been verified. Briefly, such interplay could explain how the central nervous, endocrine, and immune systems communicate with each other, supporting a holistic concept of person. In 30 marine fishermen from the Apulia region of Italy, perceived stress was measured using the Professional Stress Scale (PSS) and sleep disturbances were assessed through the Pittsburgh Sleep Quality Index (PSQI). Salivary markers were collected at 8:00 a.m. and 2:00 p.m. Those subjects reporting sleep disturbance and having altered scores in two PSS subclasses, home-work conflict and self-esteem, presented inverted salivary melatonin and cortisol nictemeral rhythms (with regard to melatonin levels at 8:00 a.m., those workers reporting values higher than the median showed 64.1% versus 48.6% home-work conflict with respect to cortisol levels, subjects having an inverted circadian rhythm showed 69.9% versus 52.5% home-work conflict, and these values resulted 47.7% versus 25.3% when the self-esteem was considered). As regards melatonin, PSQI score is statistically different in the two groups of subjects as identified by median melatonin at 8:00 a.m.; specifically, the subjects who had mean values higher than the median shared higher PSQI scores (10.8 versus 9.8). The same subjects reported more frequent home-work conflict and more sleep disorders. We found a negative correlation between IL-1β at 8:00 a.m. and Cortdiff (the difference between cortisol at 8:00 a.m.-cortisol at 2:00 p.m.), and that high IL-1β at 8:00 a.m. was associated with low Cortdiff. Based on our results we would like to propose this approach in health surveillance, in order to prevent mental and/or physical disorders, however our study is surely preliminary. The interesting perspectives and hypotheses cited in this paper, in which the roles of IL-1β and norepinephrine appear central and important, could remain hypothetical if not supported by more robust observation in order to produce, truly, new knowledge. In the future we will deepen this study with a larger sample, and if these results will be confirmed, this approach could allow preventing, not only mental and physical disorders, but also immuno-mediated diseases, and, perhaps, cancer.

Associations between Melatonin, Neuroinflammation, and Brain Alterations in Depression

Pro-inflammatory systemic conditions that can cause neuroinflammation and subsequent alterations in brain regions involved in emotional regulation have been suggested as an underlying mechanism for the pathophysiology of major depressive disorder (MDD). A prominent feature of MDD is disruption of circadian rhythms, of which melatonin is considered a key moderator, and alterations in the melatonin system have been implicated in MDD. Melatonin is involved in immune system regulation and has been shown to possess anti-inflammatory properties in inflammatory conditions, through both immunological and non-immunological actions. Melatonin has been suggested as a highly cytoprotective and neuroprotective substance and shown to stimulate all stages of neuroplasticity in animal models. The ability of melatonin to suppress inflammatory responses through immunological and non-immunological actions, thus influencing neuroinflammation and neurotoxicity, along with subsequent alterations in brain regions that are implicated in depression, can be demonstrated by the antidepressant-like effects of melatonin. Further studies that investigate the associations between melatonin, immune markers, and alterations in the brain structure and function in patients with depression could identify potential MDD biomarkers.

Melatonin prevents peri‑implantitis via suppression of TLR4/NF-κB

Peri‑implantitis, which is characterized by peri‑implant mucositis and alveolar bone resorption, significantly shortens the service life of dental implants. Melatonin is well-known for its anti-inflammatory and osteoprotective activities. Nevertheless, the effects and mechanisms of melatonin to prevent peri‑implantitis remain unknown. In this study, the lipopolysaccharide-induced peri‑implantitis model was established after the titanium implants were osseointegrated, and the rats received daily administrations of melatonin. The gingival fibroblasts and osteoclasts/osteoblasts were also co-cultured to simulate the inflammatory environment in vitro. We found that prophylactic administration of melatonin decreased proinflammatory cytokine levels and osteoclast numbers, attenuated alveolar bone resorption, and reduced the incidence of peri‑implantitis in vivo. Furthermore, melatonin suppressed osteoclastic formation and function in the inflammatory co-culture environment, while melatonin promoted osteoblastic differentiation and function in the in vitro model. Mechanistically, melatonin reduced TLR4 protein levels, and inhibited activation of NF-κB to downregulate the levels of TNF, IL-1β, and IL-6. These data showed that melatonin was a potent agent to prevent peri‑implantitis through inhibiting TLR4/NF-κB signaling. Our findings provide a novel strategy to prevent peri‑implantitis, and expand the applications of melatonin. STATEMENT OF SIGNIFICANCE: Dental implants have become the first choice for restoring partial and full edentulism, but its service life is seriously affected by peri‑implantitis. Exploration of novel and effective approaches to prevent peri‑implantitis is an important and urgent need. In the present study, we have reported for the first time that prophylactic administration of melatonin delayed the occurrence and reduced the incidence of peri‑implantitis by decreasing proinflammatory cytokine levels, inhibiting osteoclastogenesis, and promoting osteogenesis. The study is expected to have an important significance on the prevention of peri‑implantitis.

Melatonin effects on bone: Implications for use as a therapy for managing bone loss

Melatonin is the primary circadian output signal from the brain and is mainly synthesized in pinealocytes. The rhythm and secretion of melatonin are under the control of an endogenous oscillator located in the SCN or the master biological clock. Disruptions in circadian rhythms by shift work, aging, or light at night are associated with bone loss and increased fracture risk. Restoration of nocturnal melatonin peaks to normal levels or therapeutic levels through timed melatonin supplementation has been demonstrated to provide bone-protective actions in various models. Melatonin is a unique molecule with diverse molecular actions targeting melatonin receptors located on the plasma membrane or mitochondria or acting independently of receptors through its actions as an antioxidant or free radical scavenger to stimulate osteoblastogenesis, inhibit osteoclastogenesis, and improve bone density. Its additional actions on entraining circadian rhythms and improving quality of life in an aging population coupled with its safety profile make it an ideal therapeutic candidate for protecting against bone loss in susceptible populations. The intent of this review is to provide a focused discussion on bone loss and disorders of the bone as it relates to melatonin and conditions that modify melatonin levels with the hope that future therapies include those that include melatonin and correct those factors that modify melatonin levels like circadian disruption.

Periodontitis Exacerbates and Promotes the Progression of Chronic Kidney Disease Through Oral Flora, Cytokines, and Oxidative Stress

Periodontitis is a type of systemic immune inflammation that is caused by the complex infection of a variety of microorganisms in the subgingival plaque and the imbalance of the microbial ecological environment in the mouth. Periodontitis and chronic kidney disease (CKD) share many risk factors, such as obesity, smoking, and age. A growing body of data supports a strong correlation between periodontitis and kidney disease. Evidence supports the role of periodontal inflammation and elevated serum inflammatory mediators in renal atherosclerosis, renal deterioration, and end-stage renal disease (ESRD) development. Periodontitis is a risk factor for kidney disease. However, to our knowledge, there are few studies detailing the possible link between periodontitis and CKD. This review summarizes the possible mechanisms underlying periodontitis and CKD. More importantly, it highlights novel and potential pathogenic factors for CKD, including bacteria, pro-inflammatory mediators and oxidative stress. However, most research on the relationship between periodontitis and systemic disease has not determined causality, and these diseases are largely linked by bidirectional associations. Future research will focus on exploring these links to contribute to new treatments for CKD.

Role of NLRP3 inflammasome in COVID-19 and periodontitis: Possible protective effect of melatonin

Daily new information emerges regarding the COVID-19, infection of SARS-CoV-2, which is considered a global pandemic. Angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) are required to complete the viral invasion pathway and are present in the oral mucosa, gingiva and periodontal pocket. Thus, increasing the likelihood of periodontitis and gingivitis caused by COVID-19. The cytokine storm during COVID-19 similarly arises during periodontal inflammation. Studies have reported that NOD-Like Receptor family pyrin domain-containing 3 (NLRP3) inflammasome is significant in the cytokine storm. Recently, the course of the COVID-19 has been related to the melatonin levels in both COVID-19 and periodontal diseases. It is known that melatonin prevents the activation of NLRP3 inflammasome. In light of these findings, we think that melatonin treatment during COVID-19 or periodontal diseases may prevent the damage seen in periodontal tissues by preventing the activation of NLRP3 inflammasome.

The Effect of Melatonin on Periodontitis

BACKGROUND

Periodontitis is a chronic disease with a complex etiology that includes bacterial colonization, excessive inflammation, and oxidative stress. The hormone melatonin has antioxidant properties and might contribute to alleviating chronic conditions by reducing oxidative stress. The aim of this study was to analyze the effect of exogenous melatonin on periodontitis in an animal model of the disease as well as in patients with periodontitis.

METHODS

In rats with ligature-induced periodontitis, melatonin was administered in drinking water for two weeks. In the human study, patients with treatment-resistant periodontitis were asked to rinse their mouths with a solution containing melatonin or placebo every evening for two weeks. Periodontal status as well as salivary markers of oxidative stress were assessed at the end of the study.

RESULTS

Neither radiography nor μCT revealed any significant effects of melatonin on alveolar bone loss. Gum recession was the only improved macroscopic measure in rats (p < 0.05). Analysis of salivary markers of oxidative stress revealed no effects of treatment in rats or humans despite clearly elevated melatonin concentrations in melatonin treated groups.

CONCLUSION

Our results do not support the use of melatonin for the treatment of periodontitis. However, the negative outcome is limited by the short duration of the study and the chosen route of application as well as the dose of melatonin.

Anti-Inflammatory Effects of Melatonin and 5-Methoxytryptophol on Lipopolysaccharide-Induced Acute Pulpitis in Rats

Aim

The aim of this study was to investigate the possible therapeutic impacts of two pineal hormones, melatonin and 5-methoxytryptophol (5-MTX), in a rat model of acute pulpitis by analyzing biochemical and histopathological parameters.

Methods

This research was done using 32 male and female Wistar albino rats with weight between 200 and 250 g. The rats were randomly divided into four groups: a control group (rats without any treatment), acute pulpitis (AP) group, AP+melatonin group, and AP+5-MTX group. In the AP-induced groups, the crowns of the upper left incisors were removed horizontally. Lipopolysaccharide solution was applied to the exposed pulp tissue before the canal orifices were sealed with a temporary filling material. Melatonin (10 mg/kg) and 5-MTX (5 mg/kg) were administered intraperitoneally. The rats were sacrificed 24 hours after pulp injury, and trunk blood and pulp samples were collected. The concentrations of TNF-α, IL-1β, MMP-1, and MMP-2 in sera and pulp samples were determined using ELISA assay kits.

Results

TNF-α, IL-1β, MMP-1, and MMP-2 levels in the serum and pulp tissues were considerably higher in the AP group than the control group (p < 0.01‐0.001). In the AP+melatonin and AP+5-MTX groups, TNF-α, IL-1β, MMP-1, and MMP-2 levels in the serum and pulp tissues were significantly lower than in the AP group (p < 0.05‐0.001).

Conclusions

Both melatonin and 5-MTX provided protective effects on acute pulpitis, which indicates they may be promising as a therapeutic strategy for oral disease.

Molecular links between endocrine, nervous and immune system during chronic stress

INTRODUCTION

The stress response is different in various individuals, however, the mechanisms that could explain these distinct effects are not well known and the molecular correlates have been considered one at the time. Particular harmful conditions occur if the subject, instead to cope the stressful events, succumb to them, in this case, a cascade reaction happens that through different signaling causes a specific reaction named "sickness behaviour." The aim of this article is to review the complex relations among important molecules belonging to Central nervous system (CNS), immune system (IS), and endocrine system (ES) during the chronic stress response.

METHODS

After having verified the state of art concerning the function of cortisol, norepinephrine (NE), interleukin (IL)-1β and melatonin, we describe as they work together.

RESULTS

We propose a speculative hypothesis concerning the complex interplay of these signaling molecules during chronic stress, highlighting the role of IL-1β as main biomarker of this effects, indeed, during chronic stress its increment transforms this inflammatory signal into a nervous signal (NE), in turn, this uses the ES (melatonin and cortisol) to counterbalance again IL-1β. During cortisol resistance, a vicious loop occurs that increments all mediators, unbalancing IS, ES, and CNS networks. This IL-1β increase would occur above all when the individual succumbs to stressful events, showing the Sickness Behaviour Symptoms. IL-1β might, through melatonin and vice versa, determine sleep disorders too.

CONCLUSION

The molecular links here outlined could explain how stress plays a role in etiopathogenesis of several diseases through this complex interplay.

Effects of melatonin on insulin signaling and inflammatory pathways of rats with apical periodontitis

AIM

To verify the effects of melatonin supplementation on insulin sensitivity, plasma concentrations of inflammatory cytokines, insulin signalling and inflammatory pathways in the soleus (SM) and extensor digitorum longus (EDL) muscles of rats with apical periodontitis (AP).

METHODOLOGY

Seventy-two Wistar rats were distributed into 4 groups: (a) control (C), (b) control supplemented with melatonin (M), (c) AP (AP), and (d) AP supplemented with melatonin (AP + M). AP was induced by pulp exposure of the maxillary and mandibular right first and second molars to the oral environment. After AP induction, oral supplementation with 5 mg kg^-1 melatonin (diluted in drinking water) for 60 days was initiated. At the end of the treatment, the following were analysed: (1) plasma concentrations of insulin and inflammatory cytokines (TNF-α, IL-6, IL-1β and IL-10) using ELISA kits; (2) glycaemia using enzymatic assay; (3) insulin resistance using homoeostasis model assessment of insulin resistance (HOMA-IR) index; and (4) phosphorylation status of pp185 tyrosine, Akt serine, IKKα/β, and JNK in SM and EDL using Western blot. Analysis of variance of two or three factors was performed, followed by the Bonferroni test. P values < 0.05 were considered statistically significant.

RESULTS

AP promoted insulin resistance, significantly increased (P < 0.05) plasma concentrations of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β), significantly decreased (P < 0.05) the concentration of anti-inflammatory cytokine IL-10, impaired insulin signalling in SM, and increased IKKα/β phosphorylation status in SM and EDL. Melatonin supplementation in rats with AP improved insulin sensitivity, significantly decreased (P < 0.05) TNF-α and IL-1β, significantly increased (P < 0.05) IL-10 plasma concentrations, and changed the insulin signalling in soleus muscle and IKKα/β phosphorylation status in SM and EDL muscles.

CONCLUSIONS

Melatonin is a potent adjuvant treatment for improving apical periodontitis-associated changes in insulin sensitivity, insulin signalling and inflammatory pathways. In addition, the negative impact of AP on general health was also demonstrated.

Protective effect of melatonin against herbicides-induced hepatotoxicity in rats

Exposure to the herbicides Paraquat and Roundup® may cause cell lesions due to an increase in oxidative stress levels in different biological systems, even in the liver. The aim of this study was to analyze the effect of melatonin on liver of rats exposed to herbicides. A total of 35 rats were randomly divided into seven equal-sized groups: control, Paraquat, Roundup®, Paraquat + Roundup®, Paraquat + melatonin, Roundup® + melatonin, and Paraquat + Roundup® + melatonin. Samples of blood and hepatic tissue were collected at the end of the seventh day of exposure and treatment with melatonin. Body weight, hematological parameters, and histopathological, biochemical analyses and determination of oxidative stress levels in liver were evaluated. Body weight was compromised (P < 0.01). Alterations of hematologic parameters were significant when compared to control (P < 0.001). Biochemically, serum levels of albumin decreased (P < 0.001), but serum levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase increased (P < 0.001). Histopathology revealed necrotic hepatocytes, portal and central-lobular inflammatory infiltrate, congestion of capillaries. Serum levels of thiobarbituric acid reactive substances were found to be significantly elevated (P < 0.05; P < 0.001), and serum level of reduced glutathione was significantly lower (P < 0.05; P < 0.001). The groups treated concomitantly with melatonin revealed results similar to those of the control. However, melatonin acted as a protective agent for the liver against experimentally induced hepatic toxicity, promoting prevention of body weight, oxidative stress, and normalization of hematological and biochemical parameters.

ROS-Scavenging Nanomaterials to Treat Periodontitis

The incidence of periodontitis is very high, and up to 45-50% of people are suffering from periodontitis. Periodontitis is caused by pathogens that invade teeth-supporting tissues such as gingiva, periodontal ligament, and alveolar bone. Pathogens trigger host immune responses characterized by the overproduction of reactive oxygen species (ROS). The development of effective ROS scavengers through nanotechnology has been emerging as a promising strategy for the treatment of periodontitis. Nanomaterial-based antioxidants can effectively scavenge ROS, prevent ROS-mediated tissue damage, and relieve inflammation in periodontitis. This mini-review focuses on the generation of ROS in periodontitis and its molecular mechanism of destroying periodontal tissue. Meanwhile, we summarize the research progress of ROS-scavenging nanomaterials in the treatment of periodontitis and discuss the challenges and prospects of its application.

Effects of vitamin C local application on ligature-induced periodontitis in diabetic rats

Objective:

This study evaluated the effects of local vitamin C treatment on tissue advanced glycation end products (AGE), interleukin (IL)-6, 8-hydroxy-2-deoxyguanosine (8-OHdG), and matrix metalloproteinases (MMP)-8 in tissues; serum C-terminal telopeptide fragments (CTX); and alveolar bone loss (ABL) in rats.

Methodology:

35 male Sprague Dawley rats were divided equally into five groups: 1) control (C), 2) experimental periodontitis (P), 3) experimental diabetes (D), 4) experimental diabetes and experimental periodontitis (D + P), and 5) experimental diabetes–experimental periodontitis–locally applied vitamin C (D + P + LvitC). Diabetes was induced in rats with alloxan monohydrate, after which periodontitis was induced by ligature placement in the right mandibular first molar teeth for 11 days. In the treatment group, vitamin C was administered locally three times with two-days interval after ligature removal. The animals were sacrificed, and the samples were analyzed histometrically and immunohistochemically.

Results:

CTX, 8-OHdG, and AGE values significantly decreased in the treatment group compared to the D + P group. IL-6 and MMP-8 values decreased in the treatment group compared to the D + P group, but this is not significant. ABL was significantly reduced by the local delivery of vitamin C.

Conclusion:

This study reveals that vitamin C treatment may be beneficial to reduce serum CTX and gingival MMP-8 levels, oxidative stress, inflammation, and AGE accumulation in periodontal tissue. Vitamin C may be an immunomodulator and antioxidant locally applied in the treatment of periodontitis to reduce the adverse effects of diabetes in periodontal tissues.

Melatonin is an effective protector of gingival cells damaged by the cytotoxic effect of glutamate and DL-buthionine sulfoximine

BACKGROUND AND OBJECTIVE

Cellular damage related to oxidative stress (OS) is implicated in periodontal diseases (PD). Melatonin (MEL) has multiple functions, and it has been described as a potential treatment for PD. We aim at evaluating the protective effects of MEL on an in vitro model of cellular damage triggered by glutamate (GLUT) and DL-buthionine sulfoximine (BSO), on gingival cells (GCs) in culture.

MATERIAL AND METHODS

A primary culture of GCs from Wistar rats was developed in order to test the protective property of MEL; BSO and GLUT were administered alone as well as in combination with MEL. The viability and apoptosis were measured with MTT assay and TUNEL, respectively, and the concentration of superoxide anion ( O 2 - ) was measured with the NBT method.

RESULTS

The combination of BSO and GLUT treatment resulted in a decreased viability of GCs. This was evidenced by the increase in both the production of superoxide anion and apoptosis. After MEL administration, the oxidant and pro-apoptotic effects of BSO and GLUT were totally counteracted.

CONCLUSIONS

These findings demonstrated that MEL has an effective protective role on GCs subjected to cellular damage in a model of OS and cytotoxicity triggered by BSO and GLUT. Consequently, MEL could be used as a therapeutic agent in PD which begin with a significative loss of GCs.

The effect of melatonin on prevention of bisphosphonate-related osteonecrosis of the jaw: an animal study in rats

Objectives

Melatonin induces human stem cells, converts pre-osteoblasts to mature osteoblasts, and reduces the duration of this transition. However, melatonin itself prevents activation of osteoclasts. Here, we evaluate the role of melatonin in prevention of bisphosphonate-related osteonecrosis of the jaw.

Materials and Methods

In this experimental-interventional study, 30 rats were evaluated in 3 groups. The first and second groups received saline and zoledronic acid, respectively, for 4 weeks and the third group received 4 weeks of zoledronic acid and 3 weeks of melatonin simultaneously. First-right-maxillary-molar extraction was performed for all animals, which were sacrificed after 4 weeks of recovery. The extraction sockets were examined histologically for the presence of osteonecrosis, number of osteoclasts and fibroblasts, severity of inflammation, and vascularization. Data were analyzed by chi-square, one-way ANOVA, Tukey, Kruskal–Wallis and Fisher’s exact statistical tests (α=0.05).

Results

Osteonecrosis was observed in 20%, 90%, and 70% of the first, second and third groups, respectively (P=0.008). The lowest number of osteoclasts and fibroblasts was seen in the third group.

Conclusion

Melatonin may effectively prevent some undesirable side effects of bisphosphonates. However, further studies are required to confirm the results of this study.

Immune modulatory and antioxidant effects of locally administrated vitamin C in experimental periodontitis in rats

Background: Vitamin C is an important water-soluble vitamin with antioxidant and immune-modulatory actions. The aim of this study was to investigate the effects of locally applied vitamin C on alveolar bone resorption in rats with experimental periodontitis.Methods: Twenty-one male Sprague-Dawley rats divided into three groups with seven animals in each group: (1) control, (2) experimental periodontitis and 3) experimental periodontitis-local vitamin C treatment group. After ligature was removed, 50 μL vitamin C was locally administered into the subperiosteum of the buccal gingiva of periodontitis vitamin C (PvitC) group rats for three times in intervals of 2 days. At the end of the study, the animals were scarified, and serum and gingival samples were collected for analysis of serum IL-1β, oxidative stress index (OSI), CTX and malondialdehyde (MDA) levels and gingival MMP-8 immunostaining. Alveolar bone loss and attachment loss were determined based on measurements on histological sections obtained from rat mandibles.Results: Serum MDA and OSI levels which are related to the oxidative stress were significantly lower in the PvitC group as compared with those in the P group (p < .05). Serum CTX levels which are related to the bone resorption were significantly lower in the PvitC group as compared with those in the P group (p < .05). The numeric density of MMP-8-positive cells was significantly lower in the PvitC group compared to P group (p < .05). Alveolar bone loss and attachment loss were significantly lower in the PvitC group compared to P group (p < .05)Conclusions: The local vitamin C administration provided protection against inflammation-induced alveolar bone resorption by decreasing oxidative stress and inflammation-induced tissue breakdown vitamin C may be a therapeutic agent that can be used in periodontitis treatment.

Stem cell-based bone and dental regeneration: a view of microenvironmental modulation

In modern medicine, bone and dental loss and defects are common and widespread morbidities, for which regenerative therapy has shown great promise. Mesenchymal stem cells, obtained from various sources and playing an essential role in organ development and postnatal repair, have exhibited enormous potential for regenerating bone and dental tissue. Currently, mesenchymal stem cells (MSCs)-based bone and dental regeneration mainly includes two strategies: the rescue or mobilization of endogenous MSCs and the application of exogenous MSCs in cytotherapy or tissue engineering. Nevertheless, the efficacy of MSC-based regeneration is not always fulfilled, especially in diseased microenvironments. Specifically, the diseased microenvironment not only impairs the regenerative potential of resident MSCs but also controls the therapeutic efficacy of exogenous MSCs, both as donors and recipients. Accordingly, approaches targeting a diseased microenvironment have been established, including improving the diseased niche to restore endogenous MSCs, enhancing MSC resistance to a diseased microenvironment and renormalizing the microenvironment to guarantee MSC-mediated therapies. Moreover, the application of extracellular vesicles (EVs) as cell-free therapy has emerged as a promising therapeutic strategy. In this review, we summarize current knowledge regarding the tactics of MSC-based bone and dental regeneration and the decisive role of the microenvironment, emphasizing the therapeutic potential of microenvironment-targeting strategies in bone and dental regenerative medicine.

Anti-inflammatory and antiresorptive functions of melatonin on experimentally induced periapical lesions

AIM

To investigate the effects of systemically administered melatonin on inflammation and alveolar bone resorption in rats with experimentally induced periapical lesions.

METHODOLOGY

Thirty adult Sprague Dawley rats were divided equally into negative, positive control and melatonin groups. The pulp chambers of their mandibular first molars were exposed to the oral environment to induce experimental periapical lesions in the positive control and melatonin groups. The melatonin group received daily intraperitoneal injections of melatonin at a dose of 10 mg kg^-1 . After 21 days, the animals were euthanized; the hemi-mandible parts were prepared for radiological, histopathological, immunohistochemical (IL-1β, RANK, RANKL, OPG and tartrate-resistant acid phosphatase (TRAP) and Brown-Brenn (bacteria) evaluations. Data were analysed by Kruskal-Wallis (for non-parametric data) and one-way anova tests (for parametric data) (P < 0.05).

RESULTS

The area of radiographic periapical bone loss was significantly smaller in rats that were given daily intraperitoneal injections of melatonin (P < 0.01). The histopathological scores of the melatonin group were significantly lower than those of positive control group (P < 0.01). Histomorphometrically, the area of periapical bone loss in the melatonin group was significantly smaller than the positive control group (P < 0.01). The expression of IL1-β, RANK and RANKL was significantly higher in the positive control group, whereas OPG was significantly higher in the melatonin group (P < 0.01). The number of osteoclasts was significantly greater in the positive control group by TRAP staining analyses (P < 0.01). The scores for bacteria localization using Brown-Brenn staining in the melatonin group was significantly lower than that of the positive control group (P < 0.01).

CONCLUSIONS

Melatonin demonstrated antiresorptive effects on bone associated with experimentally induced periapical lesions in rats via its anti-inflammatory activity. Further studies are necessary to evaluate its possible effects on the healing of periapical lesions.

Therapeutic effects of caffeic acid phenethyl ester on alveolar bone loss in rats with endotoxin-induced periodontitis

Background/purpose

Caffeic acid phenethyl ester (CAPE) is an antioxidant which is decreases the bone resorption and enhances the bone healing. The aim of this study was to investigate the effects of administering systemic CAPE on alveolar bone loss in rats with experimental periodontitis.

Materials and methods

Thirty male Sprague Dawley rats were divided into three groups: control, endotoxin-induced periodontitis (EP), and EP treated with CAPE (EP-CAPE). Endotoxin was injected into the gingiva of test rats on days 1, 3, and 5, whereas saline was injected into the control rats. The EP-CAPE group received 10 mmol/kg/day CAPE intraperitoneally for 28 consecutive days. Saline was given in the control and EP groups in the same manner. At the end of the study, intracardiac blood samples were obtained, and the rats were sacrificed. Alveolar bone loss was analyzed with histometric measurements. The oxidative stress index (OSI) was used to evaluate the oxidative stress. The receptor activator of the nuclear factor kappa B ligand (RANKL) level was analyzed stereologically.

Results

CAPE administration significantly decreased the serum OSI and interleukin-1β levels. Alveolar bone loss was statistically higher in the EP group compared with the EP-CAPE group (P < 0.05). Immunohistochemical analyses of the RANKL were significantly lower in the EP-CAPE group than in the EP group (P < 0.05).

Conclusion

This experimental study revealed that CAPE administration significantly prevented alveolar bone loss and stimulated periodontal tissue healing.

Melatonin expression in periodontitis and obesity: An experimental in-vivo investigation

BACKGROUND AND OBJECTIVE

Melatonin deficiency has been associated with obesity and systemic inflammation. This study aims to evaluate whether melatonin could interfere with the mechanisms of co-morbidity linking obesity and periodontitis.

MATERIAL AND METHODS

Twenty-eight male Wistar rats were randomly divided in 4 groups: control group (Con) (fed with standard diet); high-fat diet group (HFD) (fed with a diet containing 35.2% fat); Con group with induced periodontitis (Con-Perio) and HFD group with induced periodontitis (HFD-Perio). To induce periodontitis, the method of oral gavages with Porphyromonas gingivalis ATCC W83K1 and Fusobacterium nucleatum DMSZ 20482 was used. Circulating melatonin levels were analyzed by multiplex immunoassays. Periodontitis was assessed by alveolar bone loss (micro-computed tomography and histology) and by surrogate inflammatory outcomes (periodontal pocket depth, modified gingival index and plaque dental index).

RESULTS

Plasma melatonin levels were significantly decreased (P < .05) in the obese rats with periodontitis when compared with controls or with either obese or periodontitis rats. Alveolar bone loss increased 27.71% (2.28 µm) in HFD-Perio group compared with the Con group. The histological analysis showed marked periodontal tissue destruction with osteoclast activity, particularly in the HFD-Perio group. A significant negative correlation (P < .05) was found between periodontal pocket depth, modified gingival index and circulating melatonin levels.

CONCLUSION

Obese and periodontitis demonstrated significantly lower melatonin concentrations when compared with controls, but in obese rats with periodontitis these concentrations were even significantly lower when compared with either periodontitis or obese rats. These results may indicate that melatonin deficiency could be a key mechanism explaining the co-morbidity effect in the association between obesity and periodontitis.

Effects of Chicory Leaf Extract on Serum Oxidative Stress Markers, Lipid Profile and Periodontal Status in Patients With Chronic Periodontitis

AIM

The aim of present study was to evaluate the effects of chicory leaf extract on serum oxidative stress markers, lipid profile, and periodontal status in patients with chronic periodontitis.

METHODS

In this double-blind, randomized controlled clinical trial 40 patients with chronic periodontitis were allocated to intervention and control groups. The intervention group received a 1-gram chicory leaf methanolic extract capsule twice daily for 8 weeks. In the control group, participants received a placebo capsule (containing 1 gram wheat flour) twice daily for 8 weeks. All participants had nonsurgical periodontal therapy during the study. Anthropometric measurements, dietary intake, total antioxidant capacity (TAC), malondialdehyde (MDA), uric acid, lipid profile (total cholesterol [TC], triglycerides [TG], low-density lipoprotein cholesterol [LDL-C], and high-density lipoprotein cholesterol [HDL-C]), and pocket depth (PD) were assessed before and after intervention.

RESULTS

The results showed that mean serum TAC, uric acid, and HDL-C increased and mean serum MDA, TG, LDL-C, and TC decreased significantly in the intervention group compared to their baseline and the control group post-intervention. A significant difference was observed in mean PD between the two groups.

CONCLUSION

Chicory leaf extract as an adjunct nutritional approach with nonsurgical periodontal therapy may be helpful in controlling periodontal status.

Contributions of Bioactive Molecules in Stem Cell-Based Periodontal Regeneration

Periodontal disease is a widespread disease, which without proper treatment, may lead to tooth loss in adults. Because stem cells from the inflammatory microenvironment created by periodontal disease exhibit impaired regeneration potential even under favorable conditions, it is difficult to obtain satisfactory therapeutic outcomes using traditional treatments, which only focus on the control of inflammation. Therefore, a new stem cell-based therapy known as cell aggregates/cell sheets technology has emerged. This approach provides sufficient numbers of stem cells with high viability for treating the defective site and offers new hope in the field of periodontal regeneration. However, it is not sufficient for regenerating periodontal tissues by delivering cell aggregates/cell sheets to the impaired microenvironment in order to suppress the function of resident cells. In the present review, we summarize some promising bioactive molecules that act as cellular signals, which recreate a favorable microenvironment for tissue regeneration, recruit endogenous cells into the defective site and enhance the viability of exogenous cells.

Antioxidant effects of melatonin in heart tissue after induction of experimental periodontitis in rats

The aim of this study was to evaluate the effects of melatonin on the oxidative stress in heart tissues after induction of experimental periodontitis in rats. Thirty Wistar Albino male rats were divided into four groups as follows: healthy + saline solution (Hs, n = 7), healthy + melatonin (Hm, n = 7), periodontitis + saline solution (Ps, n = 8), and periodontitis + melatonin (Pm, n = 8). Experimental periodontitis was induced using a ligature placed at the gingival margin of the maxillary second molars. Melatonin was applied intraperitoneally (10 mg/kg) every day for 2 weeks. After sacrificing the rats, serum levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) levels, and melatonin levels were evaluated. The Pm group exhibited lower alveolar bone loss than the Ps group. Melatonin levels increased in the periodontitis groups, and the Pm group had lower MDA levels and higher GSH-Px levels than the Ps group. These findings suggest that melatonin administration reduces MDA and increases GSH-Px levels in heart tissue, and these effects may be due to its antioxidant properties. Further studies are needed to understand the effects of melatonin on the association between periodontitis and cardiovascular disease.

Oxidative Stress and Antioxidants in the Diagnosis and Therapy of Periodontitis

Oxidative stress has been implicated in the pathogenesis of numerous diseases. However, large interventional studies with antioxidants failed to show benefits in the prevention or treatment of cardiovascular diseases, cancer, or diabetes mellitus. Numerous clinical studies have confirmed the association of oxidative stress markers and periodontitis. Technical and biological variability is high for most of the analyzed markers and none of them seems to be optimal for routine clinical use. In a research setting, analysis of a palette of oxidative stress markers is needed to cover lipid peroxidation, protein oxidation, and the antioxidant status. The source of reactive oxygen species and their role in the pathogenesis of periodontitis remains unclear. Interventional experiments indicate that oxidative stress might be more than just a simple consequence of the inflammation. Small studies have confirmed that some antioxidants could have therapeutic value at least as an addition to the standard non-surgical treatment of periodontitis. A clear evidence for the efficiency of antioxidant treatment in large patient cohorts is lacking. Potentially, because lowering of oxidative stress markers might be a secondary effect of anti-inflammatory or antibacterial agents. As the field of research of oxidative stress in periodontitis gains attraction and the number of relevant published papers is increasing a systematic overview of the conducted observational and interventional studies is needed. This review summarizes the currently available literature linking oxidative stress and periodontitis and points toward the potential of adjuvant antioxidant treatment, especially in cases where standard treatment fails to improve the periodontal status.

Treatment of experimental periodontal disease by laser therapy in simvastatin-modified rats

Low intensity laser can be used as a promising alternative in the treatment of periodontal disease.

Melatonin and periodontal tissues: Molecular and clinical perspectives

Periodontal disease is a frequent chronic inflammatory pathology that implies the destruction of the tissues supporting the teeth, which represents a high sanitary cost. It usually appears associated with other systemic conditions such as diabetes, metabolic syndrome, depression and Alzheimer disease among others. The presence of melatonin and its receptors in the oral cavity supports the hypothesis that this hormone could play a role in homeostasis of periodontal tissues. In the present review we will discuss the potential role of melatonin, a circadian synchronizing hormone, with proved antiinflammatory and antioxidant profile, in the pathogenesis and treatment of periodontitis. Particular emphasis will be placed on the role of the indolamine in the treatment of periodontal disease when this oral condition is comorbid with other pathologies that would also benefit from the therapeutic potential of melatonin and its analogs through diverse mechanisms.

Lidocaine Prevents Oxidative Stress-Induced Endothelial Dysfunction of the Systemic Artery in Rats With Intermittent Periodontal Inflammation

BACKGROUND

Periodontal inflammation causes endothelial dysfunction of the systemic artery. However, it is unknown whether the use of local anesthetics during painful dental procedures alleviates periodontal inflammation and systemic endothelial function. This study was designed to examine whether the gingival or systemic injection of lidocaine prevents oxidative stress-induced endothelial dysfunction of the systemic artery in rats with intermittent periodontal inflammation caused by lipopolysaccharides (LPS).

METHODS

Some rats received 1500 µg LPS injections to the gingiva during a week interval from the age of 8 to 11 weeks (LPS group). Lidocaine (3 mg/kg), LPS + lidocaine (3 mg/kg), LPS + lidocaine (1.5 mg/kg), and LPS + lidocaine (3 mg/kg, IP) groups simultaneously received gingival 1.5 or 3 mg/kg or IP 3 mg/kg injection of lidocaine on the same schedule as the gingival LPS. Isolated aortas or mandibles were subjected to the evaluation of histopathologic change, isometric force recording, reactive oxygen species, and Western immunoblotting.

RESULTS

Mean blood pressure and heart rate did not differ among the control, LPS, LPS + lidocaine (3 mg/kg), and lidocaine (3 mg/kg) groups. LPS application reduced acetylcholine (ACh, 10 to 10 mol/L)-induced relaxation (29% difference at ACh 3 × 10 mol/L, P = .01), which was restored by catalase. Gingival lidocaine (1.5 and 3 mg/kg) dose dependently prevented the endothelial dysfunction caused by LPS application (24.5%-31.1% difference at ACh 3 × 10 mol/L, P = .006 or .001, respectively). Similar to the gingival application, the IP injection of lidocaine (3 mg/kg) restored the ACh-induced dilation of isolated aortas from rats with the LPS application (27.5% difference at ACh 3 × 10 mol/L, P < .001). Levels of reactive oxygen species were double in aortas from the LPS group (P < .001), whereas the increment was abolished by polyethylene glycol-catalase, gingival lidocaine (3 mg/kg), or the combination. The LPS induced a 4-fold increase in the protein expression of tumor necrosis factor-α in the periodontal tissue (P < .001), whereas the lidocaine (3 mg/kg) coadministration partly reduced the levels. Lidocaine application also decreased the protein expression of the nicotinamide adenine dinucleotide phosphate oxidase subunit p47phox, which was enhanced by the gingival LPS (5.6-fold increase; P < .001).

CONCLUSIONS

Lidocaine preserved the aortic endothelial function through a decrease in arterial reactive oxygen species produced by nicotinamide adenine dinucleotide phosphate oxidase and periodontal tumor necrosis factor-α levels in rats with periodontal inflammation. These results suggest the beneficial effect of the gingival application of local anesthetics on the treatment of periodontal diseases on endothelial function of systemic arteries.

Oral Mucositis: Melatonin Gel an Effective New Treatment

The current treatment for cervico-facial cancer involves radio and/or chemotherapy. Unfortunately, cancer therapies can lead to local and systemic complications such as mucositis, which is the most common dose-dependent complication in the oral cavity and gastrointestinal tract. Mucositis can cause a considerably reduced quality of life in cancer patients already suffering from physical and psychological exhaustion. However, the role of melatonin in the treatment of mucositis has recently been investigated, and offers an effective alternative therapy in the prevention and/or management of radio and/or chemotherapy-induced mucositis. This review focuses on the pathobiology and management of mucositis in order to improve the quality of cancer patients' lives.

Melatonin: A Review of Its Potential Functions and Effects on Dental Diseases

Melatonin is a hormone synthesised and secreted by the pineal gland and other organs. Its secretion, controlled by an endogenous circadian cycle, has been proven to exert immunological, anti-oxidant, and anti-inflammatory effects that can be beneficial in the treatment of certain dental diseases. This article is aimed at carrying out a review of the literature published about the use of melatonin in the dental field and summarising its potential effects. In this review article, an extensive search in different databases of scientific journals was performed with the objective of summarising all of the information published on melatonin use in dental diseases, focussing on periodontal diseases and dental implantology. Melatonin released in a natural way into the saliva, or added as an external treatment, may have important implications for dental disorders, such as periodontal disease, as well as in the osseointegration of dental implants, due to its anti-inflammatory and osseoconductive effects. Melatonin has demonstrated to have beneficial effects on dental pathologies, although further research is needed to understand the exact mechanisms of this molecule.

Orthodontic treatment modifies the oxidant-antioxidant balance in saliva of clinically healthy subjects

PURPOSE

The aim of our study was to analyse salivary markers of oxidative stress and an antioxidant response in clinically healthy subjects with fixed orthodontic appliances.

MATERIAL/METHODS

37 volunteers were included in the study. Unstimulated (UWS) and stimulated (SWS) whole saliva were analysed for oxidative and antioxidant status and nickel levels immediately before the insertion of the appliances, an one week after and twenty four weeks after the insertion of fixed appliances.

RESULTS

A significant increase in tiobarbituric acid reactive substance (TBARS) and total oxidant status (TOS) one week, and total protein concentration twenty four weeks after the attachment of orthodontic appliances was found in the saliva. The markers of antioxidant status: superoxide dismutase (SOD), catalase (CAT), uric acid (UA), peroxidase (Px), and total antioxidant status (TAS) were not changed in all periods in UWS. In SWS a significant decrease in SOD1 and CAT was found whereas Px was increased one week after treatment and UA twenty four weeks following treatment. TAS was decreased in UWS and SWS twenty four weeks after orthodontic treatment. Oxidative status index (OSI) was elevated both in UWS and SWS one week after orthodontic treatment in comparison to the results obtained before and twenty four weeks. One week after treatment an increased concentration of nickel was also observed.

CONCLUSIONS

Orthodontic treatment modifies the oxidative-antioxidative balance in the saliva of clinically healthy subjects. Increased nickel concentration in saliva, released from orthodontic appliances, seems to be responsible for changes in the oxidative status of the saliva.

Visualization of Oxidative Stress Induced by Experimental Periodontitis in Keap1-Dependent Oxidative Stress Detector-Luciferase Mice

The aim of this study was to investigate whether a Keap1-dependent oxidative stress detector-luciferase (OKD-LUC) mouse model would be useful for the visualization of oxidative stress induced by experimental periodontitis. A ligature was placed around the mandibular first molars for seven days to induce periodontitis. Luciferase activity was measured with an intraperitoneal injection of d-luciferin on days 0, 1, and 7. The luciferase activity in the periodontitis group was significantly greater than that in the control group at seven days. The expressions of heme oxygenase-1 (HO-1) and malondialdehyde in periodontal tissue were significantly higher in the periodontitis group than in the control group. Immunofluorescent analysis confirmed that the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) occurred more frequently in the periodontitis group than in the control group. This study found that under oxidative stress induced by experimental periodontitis, the Nrf2/antioxidant defense pathway was activated and could be visualized from the luciferase activity in the OKD-LUC model. Thus, the OKD-LUC mouse model may be useful for exploring the mechanism underlying the relationship between the Nrf2/antioxidant defense pathway and periodontitis by enabling the visualization of oxidative stress over time.

Dietary arginine silicate inositol complex inhibits periodontal tissue loss in rats with ligature-induced periodontitis

The purpose of this study was to induce experimental periodontitis in rats previously fed diets containing arginine silicate inositol (ASI) complex and examine the biochemical, immunological, and radiological effects. Fifty two 8-week-old female Sprague Dawley rats were equally divided into four groups. The control group included those fed a standard rat diet with no operation performed during the experiment. The periodontitis, ASI I, and ASI II groups were subjected to experimental periodontitis induction for 11 days after being fed a standard rat diet alone, a diet containing 1.81 g/kg ASI complex, or a diet containing 3.62 g/kg ASI complex, respectively, for 8 weeks. Throughout the 11-day duration of periodontitis induction, all rats were fed standard feed. The rats were euthanized on the eleventh day, and their tissue and blood samples were collected. In the periodontitis group, elevated tissue destruction parameters and reduced tissue formation parameters were found, as compared to the ASI groups. Levels of enzymes, cytokines, and mediators associated with periodontal tissue destruction were lower in rats fed a diet containing ASI complex after experimental periodontitis. These results indicate that ASI complex could be an alternative agent for host modulation.

Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response

Aim

“Perioceutics” including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential “perioceutics” treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation.

Methods

Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA).

Results

Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgpA, rgpB, hagA, and ragA), while increasing the mRNA expression of ferritin (ftn) or hemolysin (hem). They did not show obvious cytotoxicity toward HGFs. They inhibited Pg-LPS-induced IL-6 and IL-8 secretion, which was reversed by luzindole, the melatonin receptor antagonist.

Conclusion

Melatonin receptor agonists can inhibit planktonic and biofilm growth of Porphyromonas gingivalis by affecting the virulent properties, as well as Pg-LPS-induced inflammatory response. Our study provides new evidence that melatonin receptor agonists might be useful as novel “perioceutics” agents to prevent and treat Porphyromonas gingivalis-associated periodontal diseases.