Porphyromonas gingivalis infection modifies oral microcirculation and aortic vascular function in the stroke-prone spontaneously hypertensive rat (SHRSP).

The functional modulation of vascular endothelial cells associated with stroke and periodontal disease has not yet been clarified. The objective of this study is to analyze the vascular endothelial function of periodontitis and stroke animal models. We examined endothelial function and gingival blood flow in oral microcirculation in vivo and measured the isometric tension in vitro of the aorta in animal models for lifestyle-related diseases, such as periodontitis and stroke. Gingival reactive hyperemia (GRH) was measured using laser Doppler flowmetry. Wistar Kyoto rats (WKY) were used as control animals; Porphyromonas gingivalis (P. gingivalis) infected WKY (WKY + Pg) as the periodontitis model; stroke-prone spontaneously hypertensive rat (SHRSP) as the stroke model; and a final group consisting of P. gingivalis infected SHRSP (SHRSP + Pg). Furthermore, for each group, the relaxation of descending aortic ring preparations was measured using a force transducer. The GRH was estimated by maximum response (peak), time taken for the maximum response to fall to one half (T1/2), and increased total amount of blood flow (mass). The relative change in T1/2 and mass increased in SHRSP + Pg compared to WKY. However, mass significantly increased in WKY (758.59 ± 88.21 ml/min/100 g s to 1755.55 ± 226.10 ml/min/100 g s) and SHRSP (1214.87 ± 141.61 ml/min/100 g s to 2674.32 ± 675.48 ml/min/100 g s) after treatment with acetylcholine. In addition, T1/2 and mass significantly increased in WKY + Pg (624.18 ± 96.36 ml/min/100 g s to 2629.90 ± 612.01 ml/min/100 g s) and SHRSP + Pg (1116.36 ± 206.24 ml/min/100 g s to 1952.76 ± 217.39 ml/min/100 g s) after treatment with nitroglycerin. Furthermore, the endothelium-dependent relaxation of ring preparations, evoked by acetylcholine, was attenuated in SHRSP compared with WKY, but not in SHRSP + Pg. This attenuation effect in SHRSP could be prevented by superoxide dismutase pretreatment. Our results suggest altered endothelial function may occur in gingival tissue in animal models experiencing both periodontitis and stroke. Therefore, these results indicate the disruption of vascular function in oral microcirculation may be caused by the interaction between the oxidative stress induced by periodontitis and nitric oxide in periodontitis, similar to the interactions present in stroke cases.

Medical-grade collagen peptide in injectables provides antioxidant protection.

Medical-grade collagen peptide is used as an additive agent in pharmaceutical formulations; however, it is unknown as to whether the compound exerts antioxidant effects in vitro. In this study, we evaluated the antioxidant effects of medical-grade collagen peptide on reactive oxygen species such as hydroxyl radical, superoxide anion radical and singlet oxygen using electron spin resonance and spin trapping. We confirmed that medical-grade collagen peptide directly inhibited hydroxyl radical generated by the Fenton reaction or by ultraviolet irradiation of hydrogen peroxide, and singlet oxygen. In addition, an antioxidant effect of medical-grade collagen peptide on singlet oxygen was observed in peptide fractions 12-22. The total amount of antioxidant amino acids (Gly, Hyp, Glu, Ala, Cys, Met and His) constituted more than half of the total amino acids in these fractions. These results suggest that the observed antioxidant properties of medical-grade collagen peptide are due to the compound containing antioxidant amino acids. Medical-grade collagen peptide, which is used in pharmaceuticals, and especially in injectables, could provide useful antioxidant properties to protect the active ingredient from oxidation.

Direct assessment of the antioxidant properties of midazolam by electron spin resonance spectroscopy.

Some antioxidant anesthetics directly inhibit lipid peroxidation mediated via the generation of reactive oxygen species (ROS). To date, the scavenging effects of midazolam on ROS have not been directly assessed. We investigated the inhibitory effect of midazolam on ROS [hydroxyl radical (HO(·)) and superoxide (O (2) (·-) )] by in vitro X-band electron spin resonance with the spin-trapping agent 5,5-dimethyl-1-pyrroline-N-oxide. Our results indicated that HO(·) and O (2) (·-) were not affected by midazolam at clinically relevant concentrations, but were directly scavenged by midazolam at high concentrations (i.e., >4.6 and >1.5 mM, respectively).

Porphyromonas gingivalis-induced alveolar bone loss is accelerated in the stroke-prone spontaneously hypertensive rat.

Porphyromonas gingivalis (P. gingivalis) is one of the prominent periodontal pathogens and is the most important bacteria involved in the onset and exacerbation of periodontitis. P. gingivalis is an anaerobic, Gram-negative coccobacillus that plays a role in the progression of periodontal disease by promoting alveolar bone resorption. The aim of the present study was to examine P. gingivalis-induced osteoclastic bone resorption in the stroke-prone spontaneously hypertensive rat (SHRSP), in which oxidative stress induced by reactive oxygen species (ROS) is increased. In the present study, we used animals orally challenged with P. gingivalis as a chronic inflammation model. Horizontal bone loss around the maxillary molars was assessed morphometrically. Animals were divided into four groups: (1) P. gingivalis-non-infected Wister Kyoto Rat (WKY), (2) orally challenged with P. gingivalis WKY (WKY + Pg), (3) P. gingivalis-non-infected SHRSP, and (4) orally challenged with P. gingivalis SHRSP (SHRSP + Pg). Alveolar bone resorption was significantly increased in the orally challenged with P. gingivalis groups, and was accelerated in the SHRSP group. Histological analysis revealed that the infiltration of inflammatory cells was absent in all groups. However, the infiltration of osteoclasts was observed in the SHRSP + Pg and SHRSP groups. We examined P. gingivalis-induced alveolar bone loss in both the SHRSP and WKY. The results obtained demonstrated that P. gingivalis-induced alveolar bone loss would be involved in hypertension and stroke animal model, such as SHRSP and/or periodontal disease.

Gingival vascular functions are altered in type 2 diabetes mellitus model and/or periodontitis model.

The association of vascular reactivity between diabetes and periodontal disease has not been clarified. Gingival blood flow was measured by laser Doppler flowmetry for 31 weeks in Wistar rats, Wistar rats orally challenged with Porphyromonas gingivalis (Wistar rats + Porphyromonas gingivalis), Goto-Kakizaki rats, and Goto-Kakizaki rats orally challenged with Porphyromonas gingivalis (Goto-Kakizaki rats + Porphyromonas gingivalis). Effects of alveolar bone resorption on periodontal tissue was enhanced in Wistar rats + Porphyromonas gingivalis, and Goto-Kakizaki rats, with this effect being significantly enhanced by Goto-Kakizaki rats + Porphyromonas gingivalis. Using the L-band electron spin resonance technique, we succeeded in measuring oxidative stress as decay rate constant (K(1) and K(2)) of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy in the oral and maxillofacial region of the animal models. The decay rate constant (K(1)) of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy was significantly greater in the oral and maxillofacial region of Goto-Kakizaki rats + Porphyromonas gingivalis compared to Wistar rats, Wistar rats + Porphyromonas gingivalis and Goto-Kakizaki rats groups. Gingival reactive hyperemia was attenuated by periodontal disease, and this effect was also remarkable in the diabetes mellitus model. Taken together, we found that vascular endothelial function was decreased in diabetes mellitus and/or periodontal disease animal models due to increasing oxidative stress in the gingival circulation.

Assessments of salivary antioxidant activity using electron spin resonance spectroscopy.

OBJECTIVE: In recent years, the function of saliva has been focused on evaluation of general status. The relationship between salivary antioxidant activity and periodontal disease progression is unclear. The aim of this study is to assess the relationship between periodontal disease and salivary antioxidant activity towards various reactive oxygen species (ROS) using electron spin resonance (ESR) technique. METHODS: We demonstrated that whole saliva derived rats or human subjects scavenged ROS such as superoxide (O(2)(·-)) and hydroxyl radical (HO(·)) using ESR spectroscopy with spin trapping agent. In addition, we assessed the relationship between antioxidants activity towards ROS and periodontal index with superoxide dismutase (SOD) activity in human subject saliva. RESULTS: Antioxidant activity towards O(2)(·-) was increased by Porphyromonas gingivalis (P. gingivalis) infection in rat, although antioxidant activity towards HO(·) was not changed. In human, a strong correlation (r = 0.88, p < 0.01) recognized between salivary antioxidant activity towards O(2)(·-) and probing pocket depth (PPD). In addition, the intensity of salivary antioxidant activity depended on SOD activity level. SOD activity was also correlated with PPD. CONCLUSIONS: Rat salivary antioxidant activity towards O(2)(·-) was up-regulated by the inflammatory response caused by P. gingivalis infection. Similar response was recognized in human saliva with periodontal index. Additionally, a linear correlation between antioxidant activity towards O(2)(·-) and SOD activity was verified by ESR technique. Therefore, evaluation of the salivary antioxidant activity towards O(2)(·-) might be an effective parameter for the objective assessment of periodontal disease progression.