X Yu1,2, Z Gong2, Q Lin2, W Wang2, S Liu1, S Li1. 1. Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Department of Periodontology, School and Hospital of Stomatology, Shandong University, Jinan, Shandong, China. 2. Department of Endodontics, Jinan Stomatological Hospital, Jinan, Shandong, China.
Abstract
BACKGROUND: Nerve and its related factors in the occurrence and development of periodontitis are worthy of further study. Denervation research is a useful addition to nerve and innervation studies. The aim of this study is to establish a rat model of inferior alveolar nerve transection combined with ligature-induced periodontitis to elucidate the effects of denervation on ligature-induced rat periodontitis. MATERIAL AND METHODS: Sixty-four Wistar rats were distributed to the four groups randomly: ligation (L); denervation (D); ligation+denervation (LD); and normal (N) as control. A ligation-inducing rat experimental periodontitis model was established in the L and LD groups. Rats in the D and LD groups also underwent the transection of the right inferior alveolar nerve simultaneously. Four weeks after the operation, the mandibles were taken out for micro-computed tomography analysis. Osteoclast number was observed through TRAP staining. The gingival tissues around the first molars were homogenized and measured by enzyme-linked immunosorbent assay for interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Collagen fibers were observed using Picro-Sirius Red staining. Nuclear factor (NF)-κB p65 and IκBα phosphorylation and osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) ratio in the gingival tissues were detected by western blotting. RESULTS: Denervation strongly promoted ligature-induced alveolar bone loss in the LD group. The alveolar bone loss of the LD group was significantly increased compared with the L group. Furthermore, denervation aggravated trabecular bone breakdown in the bone specific parameters, including percentage bone area, trabecular thickness and bone mineral density. Increased TRAP-positive osteoclasts were detected in alveolar bone of the LD group. More serious collagen fiber destructions and increased expressions of IL-1β and TNF-α were found in the LD group. NF-κB p65 and IκBα phosphorylation were also significantly upregulated in the LD group. OPG/RANKL ratio in the gingival extracts was markedly decreased in the LD group compared with the L group. Decreased OPG/RANKL ratio was observed in the D group, compared with the N group. CONCLUSION: Denervation effectively aggravates ligature-induced rat periodontitis by the NF-κB signaling pathway for excessive production of IL-1β and TNF-α and increased osteoclasts for decreased OPG/RANKL ratio. The rat model of inferior alveolar nerve transection that combined ligature-induced periodontitis provides an animal model to observe further the change of nerve-related factors in the occurrence and development of periodontitis, so as to select positive nerve-related factors to regulate inflammation and promote periodontal regeneration in the future.
BACKGROUND: Nerve and its related factors in the occurrence and development of periodontitis are worthy of further study. Denervation research is a useful addition to nerve and innervation studies. The aim of this study is to establish a rat model of inferior alveolar nerve transection combined with ligature-induced periodontitis to elucidate the effects of denervation on ligature-induced ratperiodontitis. MATERIAL AND METHODS: Sixty-four Wistar rats were distributed to the four groups randomly: ligation (L); denervation (D); ligation+denervation (LD); and normal (N) as control. A ligation-inducing rat experimental periodontitis model was established in the L and LD groups. Rats in the D and LD groups also underwent the transection of the right inferior alveolar nerve simultaneously. Four weeks after the operation, the mandibles were taken out for micro-computed tomography analysis. Osteoclast number was observed through TRAP staining. The gingival tissues around the first molars were homogenized and measured by enzyme-linked immunosorbent assay for interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Collagen fibers were observed using Picro-Sirius Red staining. Nuclear factor (NF)-κB p65 and IκBα phosphorylation and osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) ratio in the gingival tissues were detected by western blotting. RESULTS: Denervation strongly promoted ligature-induced alveolar bone loss in the LD group. The alveolar bone loss of the LD group was significantly increased compared with the L group. Furthermore, denervation aggravated trabecular bone breakdown in the bone specific parameters, including percentage bone area, trabecular thickness and bone mineral density. Increased TRAP-positive osteoclasts were detected in alveolar bone of the LD group. More serious collagen fiber destructions and increased expressions of IL-1β and TNF-α were found in the LD group. NF-κB p65 and IκBα phosphorylation were also significantly upregulated in the LD group. OPG/RANKL ratio in the gingival extracts was markedly decreased in the LD group compared with the L group. Decreased OPG/RANKL ratio was observed in the D group, compared with the N group. CONCLUSION: Denervation effectively aggravates ligature-induced ratperiodontitis by the NF-κB signaling pathway for excessive production of IL-1β and TNF-α and increased osteoclasts for decreased OPG/RANKL ratio. The rat model of inferior alveolar nerve transection that combined ligature-induced periodontitis provides an animal model to observe further the change of nerve-related factors in the occurrence and development of periodontitis, so as to select positive nerve-related factors to regulate inflammation and promote periodontal regeneration in the future.