Effects of metformin on the prevention of bisphosphonate-related osteonecrosis of the jaw-like lesions in rats

Abstract

In this study, we aimed to investigate the effect of glucose metabolism on bone healing after tooth extraction in an osteoporosis rat model administered zoledronic acid (ZA) and dexamethasone (DX). Methods: In total, 24 male Wistar rats (4 weeks old) were randomly assigned to four groups: Control (subcutaneous physiological saline), ZD (subcutaneous ZA and DX twice a week), Ins+ZD (subcutaneous insulin followed by ZD treatment), and Met+ZD (oral metformin followed by ZD treatment). Blood was collected every two weeks. Two weeks after treatment initiation, the first molar tooth on the right maxilla was extracted from all rats. Four weeks later, the rats were sacrificed, and bone healing was assessed. Maxillae samples were fixed and scanned using micro-computed tomography for quantifying areas of bone defects. Hematoxylin-eosin and tartrate-resistant acid phosphatase (TRAP) staining were performed to evaluate bone apoptosis and osteoclast number. Results: In all experimental groups, body weight was statistically lower than that in the Control group, with no changes observed in uncarboxylated osteocalcin concentrations. The radiological analysis revealed that insulin or metformin administration improved healing in the tooth extraction socket (p < 0.01). Histological examination revealed that the osteonecrosis area was reduced in the Ins+ZD and Met+ZD groups (p < 0.01). TRAP staining presented increased osteoclast numbers in the ZD group when compared with that observed in the Control. Conclusions: Tooth extraction with long-term ZA and DX administration inhibited bone remodeling and induced bisphosphonate-related osteonecrosis of the jaw-like lesions. Metformin exerted protective effects against osteonecrosis of the jaw.

The Function of Metformin in Aging-Related Musculoskeletal Disorders

“…In a glucocorticoid-induced osteoporosis model, oral metformin (200 mg/kg/day) had a dual protective effect, i.e., it both inhibited bone resorption and promoted bone formation in trabeculae (Zhao et al, 2019), Another study identified a similar osteoprotective effect of metformin in ketogenic diet-induced osteoporosis mice (Liu et al, 2019). In addition, metformin was able to prevent osteonecrosis, and the area of osteonecrosis in the jaws of rats given metformin was significantly reduced compared to the control group (Nakagawa et al, 2021). Besides preclinical studies, a study discovered that metformin use in patients with type 2 diabetes reduced the risk of osteoporosis/vertebral fracture by 30-40% (Tseng, 2021).…”

Establishment and assessment of rodent models of medication-related osteonecrosis of the jaw (MRONJ)

“… Histopathological assessments Healing conditions 59 , 60 , 63 , 98 Histological sections show the soft tissue healing with the distance between the edges of the epithelia, and bone defects with the length of the necrotic bone exposed towards the oral cavity. Necrotic bone 49 , 57 – 59 , 64 , 69 , 72 , 96 , 100 The presence of necrotic bone represents the occurrence of MRONJ. The definition of necrotic bone depends on the number of confluent empty or karyolytic osteocytic lacunae.…”

“… Empty bone lacunae 30 , 45 , 95 , 96 , 98 The proportion or the number of empty bone lacunae in a certain area indicates the degree of osteocyte loss, which present the bone necrosis. TRAP + osteoclast 44 , 49 , 57 , 58 , 64 , 67 , 69 , 72 , 93 , 95 – 101 The TRAP + osteoclasts present the bone resorption, commonly used indicators including numbers of osteoclast per area or per bone line. Osteoblast 30 , 44 , 49 , 64 , 67 , 93 , 97 Generally identified by hematoxylin-eosin staining or marked by alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), or receptor activators of NF-κB ligand (RANKL), commonly used indicators including numbers of osteoclast per area or per bone line.…”

“… TRAP + osteoclast 44 , 49 , 57 , 58 , 64 , 67 , 69 , 72 , 93 , 95 – 101 The TRAP + osteoclasts present the bone resorption, commonly used indicators including numbers of osteoclast per area or per bone line. Osteoblast 30 , 44 , 49 , 64 , 67 , 93 , 97 Generally identified by hematoxylin-eosin staining or marked by alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), or receptor activators of NF-κB ligand (RANKL), commonly used indicators including numbers of osteoclast per area or per bone line. Blood vessels 65 , 67 , 69 The extent of angiogenic inhibition is assessed by the density of blood vessels generally marked by CD31.…”

“… Serological assessments VEGF 67 , 98 , 103 Serum VEGF presents the angiogenic ability of MRONJ. GluOC 64 /CTX-1 98 /TRAcP-5b 64 /P1NP 64 Bone metabolism markers of MRONJ under further exploration. Radiographic assessments μCT To present bone healing conditions, bone sequestra formation of MRONJ, with parameters of bone volume/tissue volume 30 , 48 , 59 , 60 , 69 , 95 – 98 , 100 , 101 , 103 , 104 , trabecular separation 69 , 96 , 98 , 100 , 104 , trabecular thickness, trabecular number and bone volume/tissue volume representing bone morphological markers related to the early stage of MRONJ.…”