Various stimuli induce pain when applied to the surface of exposed dentin. However, the mechanisms underlying dentinal pain remain unclear. We investigated intercellular signal transduction between odontoblasts and trigeminal ganglion (TG) neurons following direct mechanical stimulation of odontoblasts. Mechanical stimulation of single odontoblasts increased the intracellular free calcium concentration ([Ca(2+)]i) by activating the mechanosensitive-transient receptor potential (TRP) channels TRPV1, TRPV2, TRPV4, and TRPA1, but not TRPM8 channels. In cocultures of odontoblasts and TG neurons, increases in [Ca(2+)]i were observed not only in mechanically stimulated odontoblasts, but also in neighboring odontoblasts and TG neurons. These increases in [Ca(2+)]i were abolished in the absence of extracellular Ca(2+) and in the presence of mechanosensitive TRP channel antagonists. A pannexin-1 (ATP-permeable channel) inhibitor and ATP-degrading enzyme abolished the increases in [Ca(2+)]i in neighboring odontoblasts and TG neurons, but not in the stimulated odontoblasts. G-protein-coupled P2Y nucleotide receptor antagonists also inhibited the increases in [Ca(2+)]i. An ionotropic ATP (P2X3) receptor antagonist inhibited the increase in [Ca(2+)]i in neighboring TG neurons, but not in stimulated or neighboring odontoblasts. During mechanical stimulation of single odontoblasts, a connexin-43 blocker did not have any effects on the [Ca(2+)]i responses observed in any of the cells. These results indicate that ATP, released from mechanically stimulated odontoblasts via pannexin-1 in response to TRP channel activation, transmits a signal to P2X3 receptors on TG neurons. We suggest that odontoblasts are sensory receptor cells and that ATP released from odontoblasts functions as a neurotransmitter in the sensory transduction sequence for dentinal pain.

No abstract

Aim: It has been reported that if nutrient intake is unbalanced, muscle mass, muscle strength and physical performance declines, and therefore it is important to maintain chewing ability to keep a balanced nutrient intake. However, the relationship between chewing ability and sarcopenia has not been previously reported. Therefore, this study investigated the relationship between chewing ability and sarcopenia in addition to known sarcopenia-related factors.Methods: We examined 761 subjects (average age 73.0 ± 5.1 years), who lived in the Itabashi city of Tokyo. Our research was designed to examine the relationship between chewing ability and sarcopenia. We performed regression analysis to analyze the relationship with sarcopenia-related factors with consideration of the age of the subjects.Results: The 761 subjects were divided into two groups in terms of the stage of sarcopenia according to whether there was a deterioration of muscle strength or physical performance. Furthermore, we performed logistic regression analyses on the value as a dependent variable, including known 3 sarcopenia-related factors. There were significant correlations of sarcopenia with age (odds ratio (OR) = 2.37, 95% CI = 1.52-3.70), BMI (OR = 0.75, CI = 0.69-0.81) and chewing ability (OR = 2.18, CI = 1.21-3.93).Conclusions: This study shows that chewing ability is related to sarcopenia、 which is equal to the relationship with the known factor of age by odds ratio.

In order to find informative salivary biomarkers specific to oral cancer we examined expression of 4 kinds of cytokine in saliva. Levels of interleukins (IL-1␤, -6, -8) and osteopontin were measured by ELISA using whole saliva samples collected from 19 patients with oral cancer (9 men, 10 women; mean age, 60.9 years) and 20 healthy persons (15 men, 5 women; mean age, 32 years). Expression of the 4 cytokines was higher in patients with oral cancer than in healthy controls. The difference was significant in IL-6, in particular.The results suggest that saliva offers a potential target for a screening test aimed at detection of precancerous lesions.

The factors that affect swallowing function in AD patients were examined. The swallowing function of severe AD patients was poor, and an association between AD and dysphagia was shown. Defective rinsing ability was identified as a risk factor for dysphagia. Therefore, observation of daily rinsing ability appears to be useful to identify signs of dysphagia in AD patients.