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

Abstract

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.

Insight into the roles of melatonin in bone tissue and bone‑related diseases (Review)

“…injection of melatonin (10 mg/kg) for 21 days, radiological periapical bone loss and osteoclasts were decreased, the OPG level was increased, and the IL-1β, RANK and RANKL levels were decreased, as compared with the positive control. In addition, the bacteria localization score has been shown to be significantly lower following melatonin treatment (130). Renn et al (131) reported that preventive melatonin supplementation suppressed the Toll-like receptor 4/myeloid differentiation factor 88 pathway to inhibit the activation of pro-inflammatory cytokines and normalize the balance between RANKL and OPG, thus suppressing the progression of periodontitis.…”

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

“…Additionally, Saritekin et al . (2019) demonstrated that the administration of melatonin decreases the inflammatory process and bone destruction in periapical lesions caused experimentally in rats.…”

Cardiac, biochemical and histopathological analysis reveals impaired heart function in hypertensive rats with apical periodontitis

“…The borders of the radiographic lesions of the mesial root canals were marked. The total area of the lesions was calculated (mm 2 ), also verified in pixels, and compared between groups (Sarıtekin et al, 2019). All radiographs of right hemimandibles were coded randomly ordered and analysed using the ImageJ program by two independent blinded authors.…”