Metformin Ameliorates Periapical Lesions through Suppression of Hypoxia-induced Apoptosis of Osteoblasts
Journal
Journal of Endodontics
Journal Volume
44
Journal Issue
12
Pages
1817-1825
Date Issued
2018
Author(s)
EDDIE HSIANG HUA LAI
Yang C.-N.
Hong C.-Y.
Su I.-H.
Abstract
Introduction: Intramuscular injection of metformin has been shown to inhibit the progression of periapical lesions in rats by decreasing the number of receptor activator of nuclear factor-κβ ligand– and tartrate-resistant acid phosphatase–positive cells. In this study, we investigated the effect of metformin on hypoxia-induced apoptosis of osteoblasts and the therapeutic activity of intracanal metformin in induced periapical lesions in rats. Methods: The influence of metformin on hypoxia-induced mitochondrial superoxide production in human osteoblasts was examined by using MitoSOX (Invitrogen, Carlsbad, CA) fluorescence dye signaling. The release of cytochrome c from mitochondria and the cleavage of procaspase-9 and poly(adenosine diphosphate–ribose) polymerase were evaluated by Western blot analysis. Apoptotic cell fraction was assessed by DNA content flow cytometry. In a rat model of induced periapical lesions, the effect of intracanal metformin on disease progression was appraised by 2-dimensional radiography and micro–computed tomographic imaging. Oxidative lesions and apoptotic activity of osteoblasts in vivo were estimated, respectively, by 8-hydroxy-2′-deoxyguanosine staining and terminal deoxynucleotidyl transferase dUTP nick end labeling. Results: Metformin inhibited hypoxia-enhanced mitochondrial superoxide production in osteoblasts. Metformin suppressed hypoxia-induced cytochrome c release from mitochondria and the cleavage of procaspase-9 and poly(adenosine diphosphate–ribose) polymerase. Metformin repressed hypoxia-augmented apoptotic cell fraction. In a rat model, intracanal metformin diminished the size of periapical lesions and the oxidative damage and apoptotic activity in osteoblasts. Conclusions: Hypoxia increased oxidative stress in osteoblasts and enhanced cell death through activation of the mitochondrial pathway of apoptosis. Metformin attenuated the oxidative and cytotoxic action of hypoxia. The therapeutic effect of metformin on periapical lesions is partially caused by its antioxidative activity. ? 2018 American Association of Endodontists
SDGs
Other Subjects
biomedical and dental materials; caspase 9; cytochrome c; metformin; nicotinamide adenine dinucleotide adenosine diphosphate ribosyltransferase; superoxide; animal; apoptosis; cell culture; cell hypoxia; chemical phenomena; disease model; drug effect; human; metabolism; mitochondrion; osteoblast; oxidative stress; pathology; Sprague Dawley rat; tooth periapical disease; Animals; Apoptosis; Caspase 9; Cell Hypoxia; Cells, Cultured; Cytochromes c; Depression, Chemical; Disease Models, Animal; Humans; Metformin; Mitochondria; Osteoblasts; Oxidative Stress; Periapical Diseases; Poly(ADP-ribose) Polymerases; Rats, Sprague-Dawley; Root Canal Irrigants; Superoxides
Type
journal article