Periodontitis In Diabetic Rats Research Articles

A whole-course-repair system based on ROS/glucose stimuli-responsive EGCG release and tunable mechanical property for efficient treatment of chronic periodontitis in diabetic rats.

Elevated glucose levels, multiple pro-inflammatory cytokines and the generation of excessive reactive oxygen species (ROS) are pivotal characteristics within the microenvironments of chronic periodontitis with diabetes mellitus (CPDM). Control of inflammation and modulation of immune system are required in the initial phase of CPDM treatment, while late severe periodontitis requires a suitable scaffold to promote osteogenesis, rebuild periodontal tissue and reduce alveolar bone resorption. Herein, a whole-course-repair system is introduced by an injectable hydrogel using phenylboronic acid functionalized oxidized sodium alginate (OSA-PBA) and carboxymethyl chitosan (CMC). Epigallocatechin-3-gallate (EGCG) was loaded to simultaneously adjust the mechanical property of the OSA-PBA/CMC + EGCG hydrogel (OPCE). This hydrogel has distinctive adaptability, injectability, and ROS/glucose-triggered release of EGCG, making it an ideal drug delivery carrier. As expected, OPCE hydrogel shows favourable antioxidant and anti-inflammatory properties, along with a regulatory influence on the phenotypic transition of macrophages, providing a favourable immune microenvironment. Apart from that, it provides a favourable mechanical support for osteoblast/osteoclast differentiation regulation at the late proliferation stage of periodontal regeneration. The practical therapeutic effects of OPCE hydrogels were also confirmed when applied for treating periodontitis in diabetic rats. In summary, OPCE hydrogel may be a promising whole-course-repair system for the treatment of CPDM.

The adiponectin receptor agonist AdipoAI attenuates periodontitis in diabetic rats by inhibiting gingival fibroblast-induced macrophage migration.

Low-grade inflammation, which is a common feature of both diabetes and periodontitis, partly accounts for the complexity and refractory of the diabetes-associated periodontitis. Adiponectin (APN), the most abundant adipokine in human blood, has been widely reported to have anti-inflammatory functions. Herein, we investigated the ability of an APN receptor agonist, AdipoAI, to alleviate diabetes-associated periodontitis. Furthermore, we revealed the possible mechanism underlying its anti-inflammatory effects. The maxillary first molar of Zucker diabetic fatty (ZDF) rats was ligated to construct a diabetes-associated periodontitis model, and the rats were administered AdipoAI by gavage. We examined diabetes-related indexes, pathological changes in insulin target organs, alveolar bone resorption and systemic and local inflammation. In vitro, transwell assays were used to evaluate monocyte/macrophage migration induced by human gingival fibroblasts (hGFs) with/without AdipoAI treatment. Additionally, we examined chemokine expression levels in hGFs and hGF-induced monocyte/macrophage migration upon siRNA knockdown of Adiponectin receptors (AdipoRs) expression. Expression of AdipoR1/AdipoR2 and inflammation-related signalling pathways was examined by IHC and WB, which was followed by confirmation with an NF-κB P65 inhibitor (BAY 11-7082). AdipoAI lowered fasting blood glucose and serum insulin in ZDF rats and alleviated inflammation in insulin target tissues. Locally, AdipoAI reduced alveolar bone absorption and inflammation in gingiva. Mechanistically, AdipoAI inhibited hGF-induced monocyte/macrophage migration by reducing CCL2 secretion. In hGFs, AdipoAI attenuated LPS-induced activation of NF-κB P65 and CCL2 expression, which was dependent on AdipoR1. AdipoAI, with its ability to alleviate inflammatory damage in tissues, is a candidate for diabetes-associated periodontitis treatment.

Probiotic Lactobacillus rhamnosus EM1107 prevents hyperglycemia, alveolar bone loss, and inflammation in a rat model of diabetes and periodontitis.

This study evaluated the antihyperglycemic, anti-bone-resorptive, and anti-inflammatory efficacy of the probiotic Lactobacillus rhamnosus EM1107 in an experimental model of ligature-induced periodontitis in diabetic rats treated with metformin (Met). A total of 114 male Wistar rats was randomly divided into six groups: (1) control, (2) experimental periodontitis (EP), (3) EP + diabetes mellitus (DM), (4) EP + probiotic (Prob), (5) EP + DM + Prob, and (6) EP + DM + Prob + Met. The animals received probiotic gavage during the 30 days of the experiment. DM was induced on the 14th day of the experiment with a single injection of streptozotocin into the penile vein, followed by ligature for EP induction and Met gavage on the 19th day and euthanasia on the 30th day. Heart blood, gingival and periodontal tissue, and hemimaxillae were collected. Biomolecular analysis, immunoenzymatic assays, histomorphology, and microtomographic analysis were performed. Data were statistically analyzed (p<0.05). There was a significant reduction in interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the Prob groups (p<0.05) as well as in blood glucose levels in the Prob and Met groups (p<0.001). In addition, histomorphological analysis revealed that the Prob groups had a reduction in inflammatory infiltrate. Tartrate-resistant acid phosphatase (TRAP) and microtomographic analyses showed that the EP/DM/Prob/Met group had significantly lower linear and volumetric bone loss than those who had no treatment (p<0.01). SOD and GPx immunostaining decreased in all groups receiving probiotics. The findings suggest the immunoinflammatory efficacy of the probiotic L. rhamnosus EM1107 administered either alone or in association with Met in type 1 DM associated with periodontitis.

Therapeutic Potential of Liraglutide for Diabetes-Periodontitis Comorbidity: Killing Two Birds with One Stone.

Background The relationship between diabetes and periodontitis is bidirectional, and there is now consensus that periodontitis and diabetes are comorbid. There is a quest for a drug that can be used to treat both conditions simultaneously. This study evaluated the anti-inflammatory and osteoprotective effects of liraglutide (LIRA) on periodontitis in diabetic rats. Methods Male Wistar rats (n = 46) were randomly divided into four groups: control group (n = 8), LIRA group (n = 8), diabetes-associated periodontitis+0.9% saline group (diabetic periodontitis (DP)+NaCl group, n = 15), and diabetes-associated periodontitis+LIRA group (DP+LIRA group, n = 15). LIRA treatment lasted for 4 weeks (300 μg/kg/d) after establishment of a rat model of DP. The expression of IL-6, TNF-α, and IL-1β was detected by enzyme-linked immunosorbent assay. The morphological changes of periodontal tissues were observed by hematoxylin–eosin staining. The absorption of alveolar bone and its ultrastructural changes were observed by histomorphometry and microcomputed tomography. The expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in alveolar bone was detected by immunohistochemistry. The levels of Runx2 mRNA and ALP mRNA in the gingival epithelium were examined by quantitative real-time polymerase chain reaction. Results LIRA decreased alveolar bone resorption, improved the microstructure of alveolar bone, and reduced periodontal inflammation and damage (P < 0.05). LIRA also reduced blood glucose level and inhibited the secretion of serum IL-6, TNF-α, and IL-1β (P < 0.05). In addition, after treatment with LIRA, the ratio of RANKL/OPG was reduced, and the expression levels of ALP mRNA and Runx2 mRNA were upregulated (P < 0.05). Conclusions LIRA not only controls blood glucose level but also reduces inflammation and bone loss and enhances osteogenic differentiation in diabetes-associated periodontitis. Those indicate that LIRA may be used as a potential medicine for the adjunctive therapy of diabetes-periodontitis comorbidity.

The Effect of Two Different Doses of Astaxanthin on Alveolar Bone Loss in an Experimental Model of Periodontitis in Diabetic Rats.

This study evaluated the effects of astaxanthin (ASX) on alveolar bone loss, receptor activator of nuclear factor-κB ligand (RANKL), and osteoprotegerin (OPG) activity in ligature-induced periodontitis in diabetic rats. Diabetes mellitus (DM) was induced with 50 mg/kg intraperitoneal streptozotocin in 40 male Wistar rats. The Wistar rats were divided into six experimental groups: non-ligated (NL; n = 6); ligature only (L; n = 6); DM only (D; n = 6); DM + ligature (DP; n = 6); DM + ligature + 1 mg/kg/day ASX (ASX 1 group; n = 8); and DM + ligature + astaxanthin 5 mg/kg/day ASX (ASX 5 group; n = 8). Silk ligatures were placed along the gingival margin of the left mandibular first molar tooth. The study duration was 11 days, after which the animals were euthanised. Changes in alveolar bone levels were clinically measured, and RANKL and OPG activities were immunohistochemically examined. Alveolar bone loss was the most significant in the DP group (p < 0.05). Decreased alveolar bone loss was observed in the ASX 5 group (p < 0.05). Although RANKL activity was highest in the DP group, it was observed at lower levels in the groups to which ASX was administered. OPG activity did not differ between groups (p > 0.05). The results of this study suggested that 1 and 5 mg/kg ASX administration reduced RANKL activity and alveolar bone loss in rats with experimentally induced periodontitis.

PH and lipase-responsive nanocarrier-mediated dual drug delivery system to treat periodontitis in diabetic rats.

Precise and controlled drug delivery to treat periodontitis in patients with diabetes remains a significant clinical challenge. Nanoparticle-based drug delivery systems offer a potential therapeutic strategy; however, the low loading efficiency, non-responsiveness, and single effect of conventional nanoparticles hinder their clinical application. In this study, we designed a novel self-assembled, dual responsive, and dual drug-loading nanocarrier system, which comprised two parts: the hydrophobic lipid core formed by 1, 2-Distearoyl-sn-glycero-3-phosphoethanolamine-Poly (ethylene glycol) (DSPE-PEG) loaded with alpha-lipoic acid (ALA); and a hydrophilic shell comprising a poly (amidoamine) dendrimer (PAMAM) that electrostatically adsorbed minocycline hydrochloride (Mino). This unique design allows the controlled release of antioxidant/ALA under lipase stimulation from periodontal pathogens and antimicrobial/Mino under the low pH of the inflammatory microenvironment. In vivo and in vitro studies confirmed that this dual nanocarrier could inhibit the formation of subgingival microbial colonies while promoting osteogenic differentiation of cells under diabetic pathological conditions, and ameliorated periodontal bone resorption. This effective and versatile drug-delivery strategy has good potential applications to inhibit diabetes-associated periodontal bone loss.

Injectable hydrogels with high drug loading through B–N coordination and ROS-triggered drug release for efficient treatment of chronic periodontitis in diabetic rats

The clinical management of chronic periodontitis with diabetes mellitus (CPDM) is a long-standing thorny issue. The excessive production of reactive oxygen species (ROS) is one of the important implications in CPDM. In the present study, oxidized dextran (OD) and phenylboronic acid-functionalized poly (ethylene imine) (PBA-PEI) were used to develop a novel injectable local drug delivery system (LDDS) which could simultaneously improve drug loading efficiency (doxycycline (Doxy) and metformin (Met)) through B–N coordination and achieve ROS-triggered drug release locally. The injectable LDDS exhibited appropriate adhesiveness to gingival tissue, good biocompatibility, and remarkable antibacterial effect against S. aureus, E. coli, and P. gingivalis. Furthermore, the favorable synergistic effect of Doxy and Met was also verified in vivo in a CPDM rat model through the morphometry and histological observations of alveolar bone, immunohistochemistry staining, and the detection of the expression level of immune-inflammatory mediators in gingival tissue. The results show that the double drug-loaded PBA-PEI/OD hydrogel, as a novel promising therapeutic agent, may be a favorable potential candidate for the CPDM management in the dental clinic.

Effects of taxifolin on bone formation and apoptosis in experimental periodontitis in diabetic rats

ABSTRACT We investigated the therapeutic potential of taxifolin for treatment of alveolar bone loss (ABL) in experimental periodontitis in diabetic rats. Diabetes mellitus (DM) was induced by streptozotocin. Rats were divided into six groups: untreated control; DM only (D) group; ligature only (P) group; DM + ligature (DP) group; DM + ligature + 5 mg/kg/day taxifolin (Taxi-5) group; DM + ligature + 10 mg/kg/day taxifolin (Taxi-10) group. Experimental periodontitis was induced by ligation of the first molar and allowed to progress for 30 days before performing cone-beam computed tomographic (CBCT), histomorphometric and immunohistochemical analyses of periodontal tissue destruction. ABL was assessed using CBCT. ABL was greatest in the P and DP groups. Decreased ABL was observed in the Taxi-5 and Taxi-10 groups. Bone morphogenic protein (BMP-2), osteocalcin (OCN), receptor activator of nuclear factor kappa-Β ligand (RANKL), alkaline phosphatase (ALP), type I collagen, B cell lymphoma-associated X (Bax), and B-cell lymphoma 2 (Bcl-2) levels were investigated using immunohistochemistry. The Taxi-5 and Taxi-10 groups exhibited decreased RANKL expression, but increased BMP-2, ALP, type I collagen and OCN levels compared to the P and DP groups. Bax activity was increased in the D, P and DP groups. Taxi-5 and Taxi-10 groups exhibited increased Bcl-2 activity. Our findings suggest that taxifolin can reduce apoptosis and improve alveolar bone formation in diabetic rats with periodontitis.

Hyperglycemia modulates M1/M2 macrophage polarization via reactive oxygen species overproduction in ligature-induced periodontitis.

Periodontitis in diabetic patients is characterized by enhanced inflammation and aggravated tissue damage in comparison with that in non-diabetic counterparts. The progression of periodontal damage under diabetic condition can be partly ascribed to hyperglycemia-induced disturbance between immune activation and inflammation resolution, where macrophages are capable of participating given their plasticity in response to different stimuli. Herein, we aimed to investigate the changes of macrophage polarization in periodontitis under diabetic condition and the underlying mechanism. Type-1 diabetes was induced by the injection of streptozotocin (STZ, 60mg/kg) in Sprague-Dawley rats. Rats in N-acetyl cysteine (NAC)-treated groups received NAC dissolved in drinking water (200mg/kg/day). Experimental periodontitis was induced by ligating 3-0 silk around left maxillary second molars for 4weeks. Alveolar bone destruction was tested by micro-computed tomography and tartrate-resistant acid phosphatase (TRAP) staining. M1/M2 macrophage polarization in periodontal tissue was detected by immunohistochemistry staining. RAW264.7 were cultured in normal glucose (5.5mM) or high glucose environment (25mM) with or without NAC (8mmol/L). LPS (100ng/ml) and IL-4 (20ng/ml) were used to induce M1macrophages and M2 macrophages, respectively. M1/M2 macrophage polarization was detected by qRT-PCR, immunofluorescent staining, and flow cytometry. Reactive oxygen species (ROS) accumulation was detected by fluorogenic probes. RANKL (100ng/ml) were applied to induce osteoclastogenic differentiation of RAW264.7, and osteoclast formation was examined by TRAP staining. Rats with diabetes displayed enhanced macrophages infiltration and M1 macrophage polarization in periodontal lesions compared with vehicle-treated rats. Under LPS or IL-4 stimulation, high glucose culture of RAW264.7 elevated ROS level and increased the expression of M1 macrophage markers (iNOS, TNF-α, and IL-6) whereas decreased the expression of M2 macrophage markers (Arg-1 and CD206). Supernatants of high glucose-treated M1/M2 macrophages enhanced osteoclast formation compared to normal glucose-cultured cells. Decreasing ROS level via NAC partially reversed the effect of high glucose on M1/M2 macrophage polarization. Meanwhile, daily intake of NAC in rodent models inhibited M1 macrophage polarization, which subsequently ameliorated alveolar bone loss and decreased osteoclast numbers in periodontitis in diabetic rats. These findings demonstrated that hyperglycemia could polarize macrophage toward M1 macrophages via overproducing ROS under inflammatory condition, which might take responsibility for aggravated periodontal damage in periodontitis under diabetic condition. Inhibiting M1 macrophages and restoring M2 macrophages by ROS scavenger is hopefully a potential adjunct treatment strategy for diabetic periodontitis.

The Antioxidant Effect of Curcumin and Rutin on Oxidative Stress Biomarkers in Experimentally Induced Periodontitis in Hyperglycemic Wistar Rats.

Background: There is a growing interest in the correlation between antioxidants and periodontal disease. In this study, we aimed to investigate the effect of oxidative stress and the impact of two antioxidants, curcumin and rutin, respectively, in the etiopathology of experimentally induced periodontitis in diabetic rats. Methods: Fifty Wistar albino rats were randomly divided into five groups and were induced with diabetes mellitus and periodontitis: (1) (CONTROL)—control group, (2) (DPP)—experimentally induced diabetes mellitus and periodontitis, (3) (DPC)—experimentally induced diabetes mellitus and periodontitis treated with curcumin (C), (4) (DPR)—experimentally induced diabetes mellitus and periodontitis treated with rutin (R) and (5) (DPCR)—experimentally induced diabetes mellitus and periodontitis treated with C and R. We evaluated malondialdehyde (MDA) as a biomarker of oxidative stress and reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG and catalase (CAT) as biomarkers of the antioxidant capacity in blood harvested from the animals we tested. The MDA levels and CAT activities were also evaluated in the gingival tissue. Results: The control group effect was statistically significantly different from any other groups, regardless of whether or not the treatment was applied. There was also a significant difference between the untreated group and the three treatment groups for variables MDA, GSH, GSSG, GSH/GSSG and CAT. There was no significant difference in the mean effect for the MDA, GSH, GSSG, GSH/GSSG and CAT variables in the treated groups of rats with curcumin, rutin and the combination of curcumin and rutin. Conclusions: The oral administration of curcumin and rutin, single or combined, could reduce the oxidative stress and enhance the antioxidant status in hyperglycemic periodontitis rats.

Chemoprevention of Experimental Periodontitis in Diabetic Rats with Silk Fibroin Nanoparticles Loaded with Resveratrol.

Objective: the objective of the present work is to study the effectiveness of treatment with silk fibroin nanoparticles loaded with resveratrol in experimental periodontitis in a diabetic rat model. Introduction: Periodontitis is an inflammatory pathology highly related to other diseases, such as type II diabetes. Both diseases have a specific inflammatory condition, with Interleukin (IL)-6, IL-1β and Transforming Grow Factor (TGF)-1β being the most relevant proinflammatory factors. Silk fibroin (SF) nanoparticles loaded with resveratrol (Res-SFN) are a new alternative as a treatment. Methods: 40 diabetic Sprague Dawley male rats were used and periodontitis was induced by ligation. The animals were divided into 5 treatment groups, and 1 mL of treatment was administered once a day for 4 weeks. The groups were: I: Carboxymethyl cellulose (CMC) 0.8%, II: CMC 0.8% + SF 1%, III: CMC 0.8% + RES-SFN 3 mg/mL, IV: CMC 0.8% + SF 1% + RES-SFN 3 mg/mL, V: Water. A peripheral blood sample was taken every week to quantify the inflammatory profile by ELISA (IL-6, IL-1β and TGF-1β). After 4 weeks the sacrifice was carried out and biopsies of the gum were taken. Results: Treatment with SF and RES-SFN reduced the amount of chemical inflammation mediators (with the exception of IL-1β in comparisons I-IV and II-IV (p > 0.05)), as well as the anatomopathological variables linked to it, in a significant way (p < 0.05). Conclusion: treatment with RES-SFN has reduced local inflammation in this experimental periodontitis model.

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.

Impact of natural curcumin on the progression of experimental periodontitis in diabetic rats.

To evaluate the role of natural curcumin (CURC) on experimental periodontitis (EP) in animals with diabetes mellitus (DM). One hundred rats were assigned to DM+placebo (PLA); DM+CURC; DM+insulin (INS); DM+CURC+INS; and Non-DM. Diabetes was induced by streptozotocin. After 3days, they were initiated CURC and PLAC solutions and insulin administrations, daily for 30days. This included a period of 19days prior to EP induction (ligature at the first mandibular and the second maxillary molar) and then additional 11days. Specimens from the mandible were processed for morphometric examination of bone level. Gingival tissues from mandibular molars were collected for quantification of IL-1β, IL-4, IL-6, IL-17, IFN-γ, and TNF-α using a Luminex/MAGpix assay. Gingivae from maxillary molars were subjected to RT-PCR for assessment of Runx2, RANKL, OPG, SIRT, Dkk1, and Sost levels. Lower linear bone loss was detected in ligated molars of DM+CURC+INS vs DM+PLAC and DM+INS groups (P<0.05). In ligated sites from DM rats treated with CURC+INS, IL-6, IL-1β, INF-γ, and TNF-α levels were the lowest in comparison with PLAC and/or INS and CURC as monotherapies (P<0.05). CURC, independently of INS, increased Runx2 and SIRT when compared to DM+PLAC (P<0.05) in ligated sites, whereas only CURC+INS reduced the RANKL/OPG ratio when compared to DM+PLAC (P<0.05). Natural CURC, when associated with INS, reduces the DM-induced loss of supporting alveolar bone and promotes favorable modulation on osteo-immune-inflammatory mediators.

Adjunctive antimicrobial photodynamic therapy using methylene blue/ethanol formulation in experimental periodontitis in diabetic rats: short-term results.

The aim of this study was to evaluate the effect of an MB experimental formulation (ethanol 20%) in aPDT used as an adjuvant to scaling and root planing (SRP) in the periodontal treatment of diabetic rats. Forty male Wistar rats received streptozotocin-intraperitonial injections to induce diabetes. After 14days, 5 animals were allocated in the non-ligate group (NLG), and 35 animals received ligature at the first right mandibular molar to induce periodontitis. After 7days, the ligature was removed and the animals were randomized into 4 groups: LG (without treatment, n = 5), SRPG (SRP, n = 10), aPDTW (SRP+aPDT-MB/water, n = 10), and aPDTEt (SRP + aPDT-MB/water/ethanol/carboxymethylcellulose, n = 10). Animals were euthanized after 7days. Data of bone loss (BL) area, degree of inflammatory cell response, and collagen fibers percentages were statistically analyzed (p < 0.05). Percentage of animals that presented mild and severe inflammatory infiltrate was 10% and 40% for SRPG, 20% and 30% for aPDTW, and 50% and 0% for aPDTEt, respectively. BL area (mm2) was statistically higher in the LG (0.39 ± 0.15) than NLG (0.05 ± 0.02). aPDTEt showed the lowest value of BL (0.08 ± 0.03), followed by aPDTW (0.21 ± 0.15) and SRPG (0.31 ± 0.18). Statistical differences were verified between aPDTEt and SRPG. In relation to the LG, aPDTEt, aPDTW, and SRPG recovered the equivalent 80%, 46%, and 20% of the BL. aPDTEt showed collagen content statistically higher than SRPG and LG, and presented higher mean values than NLG (p > 0.05). Our findings showed aPDTEt presented promising results. aPDT using MB/ethanol can have potential as an adjunctive periodontal treatment in diabetics.

Managing perimucositis and peri-implantitis with melatonin: A new approach

Melatonin (n-acetyl-5-methoxytryptamine) is a substance secreted by multiple organs including the pineal gland, retina, bone marrow, the gastrointestinal track, and the immune system. Its main function is the regulation of the circadian rhythm (day–night cycles). It plays an anti-inflammatory, antioncotic, and immunomodulatory role by scavenging free-radicals and through interactions with cell membrane and intracellular proteins. Melatonin is capable of entering the oral cavity by diffusing into the saliva from blood. As the majority of the melatonin remains bound to serum albumin, the amount of melatonin in saliva is approximately one-third of that present in the blood. The existence of MT1 receptors on healthy and cancerous oral mucosal cells is suggestive that melatonin may act as an anti-inflammatory or antioncotic agent in the oral cavity; for example, its anti-inflammatory effects have been reported on human gingival fibroblasts. Furthermore, intraperitoneal melatonin has been reported to reduce periodontitis in diabetic rats. Similarly, topical application of melatonin in diabetic patients has diminished the progression of periodontal bone loss as evident by the downregulation of pro-inflammatory factors. Hence, it has been suggested that melatonin may be used in the management of perimucositis and peri-implantitis in the field of dental implants. The aim of this review is to critically analyze and summarize the research focusing on the potential of melatonin in the fields of oral implantology.

Physical Exercise Improves Glycemic and Inflammatory Profile and Attenuates Progression of Periodontitis in Diabetic Rats (HFD/STZ).

The authors aimed to evaluate the effects of physical exercise on the metabolism and progression of periodontal disease (PD), induced by ligature in diabetic rats induced by high fat diet and streptozotocin (HFD/STZ). Diabetes Mellitus (DM) was induced by four weeks of a hyperlipidic diet associated with a single low-dose of streptozotocin (35 mg/kg/animal). The exercise groups swam for 60 min/day for eight weeks (five times/week). In the last two weeks of exercise, a ligature was placed around the right and left mandibular first molars. The authors determined alveolar bone loss by morphometry. Blood biochemical profile and serum levels of IL-10 and TNF-α were evaluated by colorimetric and enzyme-linked immunosorbent assays (ELISA), respectively. The diabetic animals subjected to exercise showed decreased alveolar bone loss, lower glycemia, triacylglycerols and glycosylated hemoglobin levels than the controls. Total cholesterol and its fractions (High density lipoprotein—HDL-c, Low density lipoprotein—LDL-c and Very low density lipoprotein—VLDL-c) remained similar among the groups. Animals with PD showed higher levels of TNF-α and lower levels of IL-10, when compared to animals without PD. In diabetic animals with PD, physical exercise decreased TNF-α levels and increased IL-10 levels as well as the IL10/TNF-α ratio. In conclusion, eight weeks of physical exercise improved glycemic control and systemic inflammatory profile, and attenuated alveolar bone loss in rats with DM and PD.

Metformin Hydrochloride-Loaded PLGA Nanoparticle in Periodontal Disease Experimental Model Using Diabetic Rats.

Evidence shows that metformin is an antidiabetic drug, which can exert favorable anti-inflammatory effects and decreased bone loss. The development of nanoparticles for metformin might be useful for increased therapeutic efficacy. The aim of this study was to evaluate the effect of metformin hydrochloride-loaded Poly (d,l-Lactide-co-glycolide) (PLGA)/(MET-loaded PLGA) on a ligature-induced periodontitis model in diabetic rats. MET-loaded PLGA were characterized by mean diameter, particle size, polydispensity index, and entrapment efficiency. Maxillae were scanned using Microcomputed Tomography (µCT) and histopathological and immunohistochemical analysis. IL-1β and TNF-α levels were analyzed by ELISA immunoassay. Quantitative RT-PCR was used (AMPK, NF-κB p65, HMGB1, and TAK-1). The mean diameter of MET-loaded PLGA nanoparticles was in a range of 457.1 ± 48.9 nm (p < 0.05) with a polydispersity index of 0.285 (p < 0.05), Z potential of 8.16 ± 1.1 mV (p < 0.01), and entrapment efficiency (EE) of 66.7 ± 3.73. Treatment with MET-loaded PLGA 10 mg/kg showed low inflammatory cells, weak staining by RANKL, cathepsin K, OPG, and osteocalcin, and levels of IL-1β and TNF-α (p < 0.05), increased AMPK expression gene (p < 0.05) and decreased NF-κB p65, HMGB1, and TAK-1 (p < 0.05). It is concluded that MET-loaded PLGA decreased inflammation and bone loss in periodontitis in diabetic rats.

Effects of local administration of tiludronic acid on experimental periodontitis in diabetic rats.

Tiludronic acid (TIL) presents antiresorptive and anti-inflammatory properties and has not been evaluated in the periodontitis-diabetes mellitus (DM) association to date, to the best knowledge of the authors. This study evaluates effects of local administration of TIL on experimental periodontitis (EP) in rats with streptozotocin-induced DM. Thirty-two animals (Rattus norvegicus albinus, Wistar) were divided into groups DM/C (Control), DM/EP, DM/EP/TIL1, and DM/EP/TIL3. In EP groups, a ligature was placed around mandibular first molars. In groups DM/EP/TIL1 and DM/EP/TIL3, TIL solutions (1 and 3mg/kg, respectively) were injected into the gingival tissue of mandibular molars every other day for 10 days, until euthanasia. Periodontal tissues were analyzed by microcomputed tomography (micro-CT), histomorphometry, immunohistochemistry (tartrate-resistant acid phosphatase [TRAP], receptor activator of nuclear factor-κB ligand [RANKL], osteoprotegerin, cleaved caspase 3), and quantitative reverse transcription-polymerase chain reaction (interleukin [IL]-1β, vascular endothelial growth factor [VEGF]). In micro-CT analyses, groups DM/EP/TIL1 and DM/EP/TIL3 presented reduced alveolar bone resorption (P<0.05). Group DM/EP/TIL3 presented decreased attachment loss (P<0.05). The amount of TRAP-positive multinucleated cells was decreased in TIL groups (P<0.05). Group DM/EP/TIL3 presented a lower immunolabeling pattern for RANKL (P<0.05). TIL treatment decreased genic expression of IL-1β, and in group DM/EP/TIL3, expression of VEGF was increased (P<0.05). Local administration of TIL promoted a protective effect against tissue destruction in EP in diabetic rats, and the dosage of 3mg/kg of TIL promoted the best results regarding its antiresorptive and anti-inflammatory effects.

Effect of Low-Dose Doxycycline and Bisphosphonate on Osteoprotegrin Expression in Ligature Induced Periodontitis in Diabetic Rats (An Experimental Study)

Objective: To evaluate the effect of mono and combined therapy of low dose doxycycline (LDD) and Bisphosphonate (BPs) on ligature-induced periodontitis in Diabetic rats by immunohistochemical analysis of the expression of osteoprotegerin (OPG) and by immunohistomorphometric analysis. Methods: Fifty adult Wistar rats were divided into five study groups as follows: 1) group 1 = diabetes control; 2) group 2 = diabetes + periodontitis; 3) group 3 = diabetes + periodontitis + LDD; 4) group 4 = diabetes + periodontitis + clodronate; and 5) group 5 = diabetes + periodontitis + LDD + clodronate.LDD and clodronate were given as a single agent or as combination therapy during the 7 days of the post-experimental periodontitis period.On day 7, the rats were sacrificed, the mobility of the toothwas recorded, and block biopsies were removed. The gingival tissues were analyzed histologically and immunohistochemically for expression of OPG. Data analysis was performed statistically by Kruskal-Wallis and post hoc Tukey tests. Results: The greatest mean value was recorded in group5, followed by group 4, then group 3. Using Tukey’s post hoc test; there was a significant difference (p<.0001) between groups1, 2, 4 and 5 respectively while non significant difference was found between group 1and 3. Comparing group 2 with groups 3, 4 and 5 a significant difference was found. Comparing groups 3 with groups 4and 5 non significant difference was found between groups 3 and 4 while a significant difference was found between groups3 and 5. Lastely, non significant difference was found between groups 4 and 5.

The histopathological and morphometric investigation of the effects of systemically administered boric acid on alveolar bone loss in ligature-induced periodontitis in diabetic rats

Objective. The purpose of this study was to evaluate the effects of systemically administered boric acid on alveolar bone loss, histopathological changes and oxidant/antioxidant status in ligature-induced periodontitis in diabetic rats. Materials and methods. Forty-four Wistar rats were divided into six experimental groups: (1) non-ligated (NL, n = 6) group, (2) ligature only (LO, n = 6) group, (3) Streptozotocin only (STZ, n = 8) group, (4) STZ and ligature (STZ+LO, n = 8) group, (5) STZ, ligature and systemic administration of 15 mg/kg/day boric acid for 15 days (BA15, n = 8) group and (6) STZ, ligature and systemic administration of 30 mg/kg/day boric acid for 15 days (BA30, n = 8) group. Diabetes mellitus was induced by 60 mg/kg streptozotocin. Silk ligatures were placed at the gingival margin of lower first molars of the mandibular quadrant. The study duration was 15 days after diabetes induction and the animals were sacrificed at the end of this period. Changes in alveolar bone levels were clinically measured and tissues were histopathologically examined. Serum total antioxidant status (TAS), total oxidant status (TOS), calcium (Ca) and magnesium (Mg) levels and oxidative stress index (OSI) were evaluated. Primary outcome was alveolar bone loss. Seconder outcome (osteoblast number) was also measured. Results. At the end of 15 days, the alveolar bone loss was significantly higher in the STZ+LO group compared to the other groups (p < 0.05). There was no significant difference in alveolar bone loss between the STZ+LO 15 mg/kg boric acid and STZ+LO 30 mg/kg boric acid groups (p > 0.05). Systemically administered boric acid significantly decreased alveolar bone loss compared to the STZ+LO group (p < 0.05). The osteoblast number in the BA30 group was significantly higher than those of the NL, STZ and STZ+LO groups (p < 0.05). Inflammatory cell infiltration was significantly higher in the STZ+LO group the other groups (p < 0.05). Serum TAS levels were significantly higher in the NL and LO groups than the other groups (p < 0.05). The differences in TOS levels were not found to be significant among all the groups (p > 0.05). The OSI values of the BA30 group were significantly lower than the STZ+LO group (p < 0.05). Also, the differences in serum calcium and magnesium levels were insignificant among the all groups (p > 0.05). Conclusion. Within the limits of this study, it can be suggested that BA, when administered systemically, may reduce alveolar bone loss in the diabetic rat model.