Effects of glucosamine on tooth pulpal nociceptive responses in the rat

AbstractBackground/purposed-Glucosamine hydrochloride (DGL) has a variety of biological activities and is noted as a nutritional supplement that is effective for improvement and care of various disorders, such as osteoarthritis and atherosclerosis. Although, it has been reported that DGL has a significant pain relief effect in treating osteoarthritis, little is known about its effect on dental pain. The applicability of DGL as a medicament to control pain in pulpalgia has not been reported. In this study, using an in vitro rat mandible-inferior alveolar nerve preparation (jaw-nerve preparation), the effect of DGL on nociceptive responses in the tooth pulpal nerve was examined.Materials and methodsThe effect of DGL on nociceptive responses for 20 male Wistar albino rats was evaluated using an in vitro jaw-nerve preparation. Bradykinin (BK), used as a chemical nociceptive stimulant, was applied near the exposed tooth pulp. Sixty seconds after BK application, the surface of the exposed pulp was treated with DGL solution or physiological saline (control).ResultsThe nerve firing rate was 2.06±0.21Hz (n=10) after 5 minutes of saline application, and 0.76±0.16Hz (n=10) after 5 minutes of DGL application. The DGL group showed significantly lower nerve firing rate than the control group.ConclusionBK-induced nociceptive responses were significantly suppressed by direct application of DGL. Our results suggest that DGL might have a pain relief effect in dental pain

SURVEY OF DENTAL STUDENTS’ ATTITUDE REGARDING ORIENTAL MEDICINE/COMPLEMENTARY AND ALTERNATIVE MEDICINE: COMPARISON BETWEEN TWO JAPANESE DENTAL SCHOOLS

Background: The present study aimed to examine the impact of “curricula for undergraduate education in oriental medicine (OM)/complementary and alternative medicine (CAM)” on student awareness of OM. A questionnaire survey was conducted involving the Nagasaki University School of Dentistry (NUSD), a university that implements educationin OM as part of its undergraduate curriculum, and Tokyo Dental College (TDC), which does not teach OM. Materials and methods: The third- and fifth-year students of both NUSD and TDC underwent the anonymous questionnaire survey, which included questions regarding their knowledge of OM and CAM, interests in these subjects, and their opinions on the necessity of teaching OM in the undergraduate dental education, and the results were collected for analysis. Results: Whereas 33% of 5th year NUSD students had knowledge of OM/CAM was 33%, only 10% of 5th year TDC students reported knowledge on the subject. 69% of 5th year NUSD students interested in OM/CAM, while 5th yearTDC students who interest them were only 45%. Although 77% of 5th year NUSD students were in favor of OM education implemented in the Faculty of Dentistry, the percentages of TDC students of that were smaller (46% in 3rdyear and 48% in 5th year). Whereas 26% of 5th year TDC students did not recognize the necessity of oriental medicine education, only one 5th year NUSD student (2%) did not so. Conclusion: Introduction of education in OM in the undergraduate dental education program helps students to increase their interests in dental clinical applications

Neuronal Activity in the Subthalamic Cerebrovasodilator Area under Partial-Gravity Conditions in Rats

The reduced-gravity environment in space is known to cause an upward shift in body fluids and thus require cardiovascular adaptations in astronauts. In this study, we recorded in rats the neuronal activity in the subthalamic cerebrovasodilator area (SVA), a key area that controls cerebral blood flow (CBF), in response to partial gravity. -Partial gravity{norm of matrix} is the term that defines the reduced-gravity levels between 1 g (the unit gravity acceleration on Earth) and 0 g (complete weightlessness in space). Neuronal activity was recorded telemetrically through chronically implanted microelectrodes in freely moving rats. Graded levels of partial gravity from 0.4 g to 0.01 g were generated by customized parabolic-flight maneuvers. Electrophysiological signals in each partial-gravity phase were compared to those of the preceding 1 g level-flight. As a result, SVA neuronal activity was significantly inhibited by the partial-gravity levels of 0.15 g and lower, but not by 0.2 g and higher. Gravity levels between 0.2-0.15 g could represent a critical threshold for the inhibition of neurons in the rat SVA. The lunar gravity (0.16 g) might thus trigger neurogenic mechanisms of CBF control. This is the first study to examine brain electrophysiology with partial gravity as an experimental parameter

Hypergravity Conditioning on Ileal Movements in Rats

Introduction: Stress is a common trigger for various physiological disturbances, including feeding disorders. One of the possible mechanisms for feeding disorders may be linked to changes in intestinal movement caused by stress. Therefore, here we investigated in vitro stress-induced changes in ileal movement. Methods: Rats (female Wistar, SPF) were divided into Control (1 G) and hypergravity (hyperG) groups. HyperG stress was applied daily for 10 min by a centrifugal apparatus for 1 to 30 d. Under barbiturate anesthesia, a 1-cm long section of the ileum was isolated and fixed in a Magnus-type chamber filled with tyrode solution. Intestinal movement was evoked by applying acetylcholine (Ach, 10? 7?10? 5 g ・ ml? 1). Antagonistic effects of adrenalin (Adr, 10? 4 g ・ ml? 1) on the Ach-evoked movements were also observed. Results: Clear ileum movements were observed after Ach application. The movement pattern was phasic (early) and tonic (late). Peak amplitude of the phasic wave was dose-dependent on the Ach concentration. No significant differences in the averaged peak amplitude between control and hyperG groups were observed. The peak amplitude was decreased by Adr application in both the control and hyperG groups; however, the degree of the decrement was higher in hyperG than in control at 1 d after stress loading. Discussion: The present study indicates that gravity stress modified ileal movement. Although basic ileum movements evoked by Ach were not influenced by stress, they were modified by Adr at a quite early stage after stress loading, suggesting an increase in the sensitivity of Adr receptors, but not of Ach receptors in the ileum

Age Differences in Naloxone Reversibility of Electroacupuncture on the Jaw Opening Reflex in Rats

Background: Electroacupuncture is one of the most popular physical treatments for clinical pain, but the potential influence of a patient’s age on the effectiveness of electroacupuncture treatment has not been clearly established. Objectives: The present study aimed to detect a potential difference in electroacupuncture- induced analgesia between juvenile and adult rats.Methods: In this study, we investigated the effects of electroacupuncture treatment on the nociceptive jaw-opening reflex evoked by tooth-pulp stimulation in juvenile and adult rats.Results: Our results showed there were age differences in electroacupuncture-induced analgesic effects in rats, especially with naloxone antagonization. The ratio of naloxonereversibility against electroacupuncture analgesia was greater in adult rats than in juvenile rats.Conclusion: These results suggest that electroacupuncture analgesia is produced mainly by the non-opioid system in juvenile rats and by the opioid system in adult rats

Carbenoxolone-sensitive and cesium-permeable potassium channel in the rod cells of frog taste discs

The rod cells in frog taste discs display the outward current and maintain the negative resting potential in the condition where internal K+ is replaced with Cs+. We analyzed the properties of the Cs+-permeable conductance in the rod cells. The current-voltage (I/V) relationships obtained by a voltage ramp were bell-shaped under Cs+ internal solution. The steady state I/V relationships elicited by voltage steps also displayed the bell-shaped outward current. The activation of the current accelerated with the depolarization and the inactivation appeared at positive voltage. The gating for the current was maintained even at symmetric condition (Cs+ external and internal solutions). The wing cells did not show the properties. The permeability for K+ was a little larger than that for Cs+. Internal Na+ and NMDG+ could not induce the bell-shaped outward current. Carbenoxolone inhibited the bell-shaped outward Cs+ current dose dependently (IC50: 27μM). Internal arachidonic acid (20μM) did not induce the linear current-voltage (I-V) relationship which is observed in two-pore domain K+ channel (K2P). The results suggest that the resting membrane potentials in the rod cells are maintained by the voltage-gated K+ channels

Suppressive Effects of D-Glucosamine on the 5-HT Sensitive Nociceptive Units in the Rat Tooth Pulpal Nerve

It is well known that D-glucosamine hydrochloride (DGL) has a variety of biological activities and is regarded as a nutritional supplement effective in improving various disorders, including osteoarthritis and atherosclerosis. Although it has been reported that DGL has a significant pain relief effect in treating osteoarthritis, little is known about the characteristics of the effects of this compound on dental pain. The present study was undertaken to evaluate the applicability of DGL as a medicament to control pulpalgia. Using an in vitro rat mandible-inferior alveolar nerve preparation (jaw-nerve preparation), we evaluated the effects of DGL on 5-hydroxytryptamine (5-HT) sensitive nociceptive responses in the tooth pulpal nerve. 5-HT-induced nociceptive responses were fairly suppressed by direct application of DGL, suggesting that DGL have a pain relief effect on patients with dental pain

Suppressive Effects of D-Glucosamine on the 5-HT Sensitive Nociceptive Units in the Rat Tooth Pulpal Nerve

It is well known that D-glucosamine hydrochloride (DGL) has a variety of biological activities and is regarded as a nutritional supplement effective in improving various disorders, including osteoarthritis and atherosclerosis. Although it has been reported that DGL has a significant pain relief effect in treating osteoarthritis, little is known about the characteristics of the effects of this compound on dental pain. The present study was undertaken to evaluate the applicability of DGL as a medicament to control pulpalgia. Using an in vitro rat mandible-inferior alveolar nerve preparation (jaw-nerve preparation), we evaluated the effects of DGL on 5-hydroxytryptamine (5-HT) sensitive nociceptive responses in the tooth pulpal nerve. 5-HT-induced nociceptive responses were fairly suppressed by direct application of DGL, suggesting that DGL have a pain relief effect on patients with dental pain

Effects of midazolam on acquisition and extinction of conditioned taste aversion memory in rats.

Some intravenous anesthetic agents such as midazolam are known to induce anterograde and retrograde amnesia. We analyzed the effect of midazolam by the conditioned taste aversion (CTA) acquisition and retention. After the rats were offered 0.1% sodium saccharin (Sac) as conditioned stimulus (CS), an intraperitoneal (i.p.) injection of several concentrations (5-30mg/kg) of midazolam was followed by an i.p. injection of 0.15M LiCl (2% of body weight) as unconditioned stimulus (US). The rats, which acquired CTA by every CS-US paradigm, strongly avoided Sac on the 1st test day after conditioning and maintained the avoidance for 3 days. We have already reported that Sac intake abruptly increased on the 2nd test day and the almost complete extinction occurred on the 3rd test day after conditioning by injection of subhypnotic dose of propofol before LiCl-injection. In contrast, we found that subhypnotic dose of midazolam suppressed not only CTA acquisition, but also CTA retention. On the other hand, an alpha2-adrenergic blocker, yohimbin (1mg/kg) suppressed only the CTA retention. These results suggest that the subhypnotic doses of midazolam firstly affect the acquisition mechanism of the CTA memory (CTAM), resulting the suppression of the retention of CTAM