Kousuke Honda

Theophylline attenuates hippocampal blood flow responses induced by tooth pulp stimulation in rats.

In this study, we performed tests to determine whether tooth pulp stimulation (TPS) increases hippocampal blood flow (HBF), and if so, to investigate whether the increase in HBF is mediated via the activation of adenosine receptors. We measured HBF in urethane-anesthetized rats using laser Doppler flowmetry (LDF) and examined the effect of theophylline, a nonselective adenosine receptor antagonist, on TPS-induced HBF responses. TPS increased HBF, and its response was significantly attenuated by the intraperitoneal administration of theophylline (20 mg/kg). These results suggest that the HBF response induced by TPS may be, at least in part, produced through adenosine receptors.

Relationship between Degenerative Bone Changes of Condylar Surface and Articular Disc Disorders in Symptomatic Osteoarthrosis of Temporomandibular Joints

Abstract Purpose: We investigate the relation of bone changes of the condylar surface to disc displacement and discuss the development of joint symptoms in osteoarthrosis of temporomandibular (TM) joints. Subjects and Methods: Seventy-seven patients with an image diagnosis of degenerative bone changes of the unilateral condylar surface accompanied with joint symptoms were studied. The bone changes were assessed by panoramic radiographs and classified into two groups: pathologic bone changes (PBC) including erosion, osteophyte and deformity, and adaptive bone changes (ABC) including flattening and concavity. Magnetic resonance imaging was performed on the subjective TM joints to examine the configuration and position of articular discs. A visual analogue scale was used for evaluation of joint pain. Results: Erosion and deformity showed significantly higher prevalence than the other three kinds of bone changes in the joints with anterior disc displacement without reduction (ADWoR) as compared to those with anterior disc displacement with reduction (ADWR). The cases with the vertical disc position to the condyle ranging from 60° to less than 150° were more frequent than those ranging from 0° to less than 60° in the PBC group, whereas the cases with the vertical disc position to the condyle ranging from 0° to less than 60° were more frequent than those ranging from 60° to less than 150° in the ABC group. The average degree of joint pain when chewing but not jaw opening was higher in the joints with ADWoR than in those with ADWR, and in the PBC group than in the ABC group. Conclusion: The bone changes of the condylar surface diagnosed as PBC tended to induce more advanced disc displacement and chewing pain than those diagnosed as ABC.

Effects of repeated tooth pulp stimulation on concentrations of plasma catecholamines, corticosterone, and glucose in rats.

Abstract In this study, we examined whether tooth pulp stimulation (TPS) affects the stress responses in anesthetized rats. As for stress response indices, we monitored changes in the concentrations of plasma catecholamines (CAs) (adrenaline, noradrenaline, and dopamine), corticosterone (CS), and glucose (Glu). We observed that repeated TPS attenuated plasma adrenaline, dopamine, CS, and Glu levels compared with those of sham-TPS. After administering naloxone, an opioid antagonist, repeated TPS reversed the decreases in plasma CAs, CS, and Glu. These findings showed that the effects of repeated TPS may be mediated by endogenous opioid administration. Our findings suggest that repeated TPS can induce stress-analgesia and that an endogenous descending pain modulation system exists.