Anti-aging effects of co-enzyme Q10 on periodontal tissues.

Oxidative stress is associated with age-related reactions. The anti-oxidative effects of a reduced form of co-enzyme Q10 (rCoQ10) suppress oxidative stress, which may contribute to the prevention of age-related inflammatory reactions. We examined the effects of topically applied rCoQ10 on periodontal inflammatory reactions in a rat aging model. Male Fischer 344 rats, 2 (n = 6) and 4 mos (n = 18) of age, were used. All of the two-month-old rats and 6 of the four-month-old rats were sacrificed and 12 remaining four-month-old rats received topically applied ointment with or without 1% rCoQ10 on the gingival surface until they reached 6 mos of age. The rats showed an age-dependent increase in circulating oxidative stress. RCoQ10 decreased oxidative DNA damage and tartrate-resistant acid-phosphatase-positive osteoclasts in the periodontal tissue at 6 mos of age as compared with the control. The same conditions lowered gene expression of caspase-1 and interleukin-1ß in the periodontal tissue. Furthermore, Nod-like receptor protein 3 inflammasomes were less activated in periodontal tissues from rCoQ10-treated rats as compared with the control rats. Our results suggest that rCoQ10 suppresses age-related inflammatory reactions and osteoclast differentiation by inhibiting oxidative stress.

Effects of electrical stimulation on periodontal tissue remodeling in rats.

BACKGROUND AND OBJECTIVE: Electric current is used to promote wound healing. However, it is unclear whether electrical stimulation contributes to gingival tissue remodeling. This study examined the effects of electrical stimulation on gingival tissue remodeling in a rat periodontitis model. MATERIAL AND METHODS: Male Wistar rats (n = 28, 8 wks of age) were divided into four groups of seven rats each. The control group did not receive any treatment for 6 wks. In the other groups, periodontitis was ligature-induced for 4 wks. After 4 wks, the rats with periodontitis were given daily electrical stimulation of 0, 50 or 100 µA for 2 wks. RESULTS: The periodontitis group stimulated with 0 µA showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue compared with the control group (p < 0.05). The two remaining groups treated with 50 or 100 µA of electrical stimulation exhibited a lower density of polymorphonuclear leukocytes (p < 0.05) and a higher density of collagen than the group stimulated with 0 µA (p < 0.05). They also showed higher expression of fibroblast growth factor-2 than the group treated with 0 µA of electrical stimulation (p < 0.05). CONCLUSION: Electric stimulation may offer a novel approach to promote gingival tissue remodeling in periodontal lesions.

Effects of topical application of inorganic polyphosphate on tissue remodeling in rat inflamed gingiva.

BACKGROUND AND OBJECTIVE: Inorganic polyphosphate [poly(P)] is a biopolymer found in almost all cells and tissues, and which promotes tissue remodeling. However, there is limited information on how poly(P) affects the connective tissue in inflamed gingiva. This study examined the effects of topical application of poly(P) on gingival connective tissue and its remodeling in a rat periodontitis model. MATERIAL AND METHODS: Male Wistar rats (n = 36, 8 wk of age) were used in this 6-wk study. The rats were divided into six groups of six rats each. The control group received no treatment. In the other groups, periodontitis was ligature-induced for 4 wk. After 4 wk, the rats with periodontitis were further divided into five groups, and were left untreated (periodontitis group) or subjected to topical application of oral rinses containing 0, 0.1, 1 or 5% poly(P) for 2 wk. RESULTS: The periodontitis and 0% poly(P) groups showed a higher density of polymorphonuclear leukocytes and a lower density of collagen in gingival tissue than the control group (p < 0.05). In contrast, groups treated with more than 1% poly(P) exhibited a lower density of polymorphonuclear leukocytes (p < 0.05) and a higher density of collagen than the periodontitis and 0% poly(P) groups (p < 0.05). A higher expression of fibroblast growth factor-2 was observed in the gingiva of rats treated with 1% poly(P) than in those treated with 0% poly(P) (p < 0.05). CONCLUSION: Topical application of poly(P) may induce connective tissue remodeling, contributing to improvement of inflamed gingiva in rats.

Occlusal disharmony increases amyloid-ß in the rat hippocampus.

Amyloid-ß plays a causative role in Alzheimer's disease. Occlusal disharmony causes chronic psychological stress, and psychological stress increases amyloid-ß accumulation. The purpose of the present study was to investigate whether occlusal disharmony-induced psychological stress affects the accumulation of amyloid-ß and its related gene expressions in the rat hippocampus. Eight-week-old male Wistar rats (n = 18) were divided into three groups of six rats each: (1) a control group that received no treatment for 8 weeks; (2) an occlusal disharmony group that underwent cutoff maxillary molar cusps for 8 weeks; and (3) a recovered group that underwent cutoff maxillary molar cusps for 4 weeks followed by recovery for 4 weeks. Occlusal disharmony increased plasma corticosterone levels in a time-dependent manner. Levels of amyloid-ß 40 and 42, glucocorticoid receptor (Gr) protein, and cleaved caspase 3 (Casp3) as well as gene expressions of amyloid precursor protein, beta-secretase, Casp3, and Gr in the hippocampus in the occlusal disharmony group were significantly higher than those in the control group (P < 0.016). These findings were significantly improved by recovery of occlusion (P < 0.016). These results indicate that psychological stress induced by occlusal disharmony reversibly induces amyloid-ß 40 and 42 in the rat hippocampus through the glucocorticoid signal.