• Journal of Korean Dental Science
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• v.4 no.2
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• pp.73-78
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• 2011

Purpose: $HCO_3{^-}$ is the most important ion to buffer the acidity of saliva. The transport of $HCO_3{^-}$ is mediated by electrogenic $Na^+/HCO_3{^-}$ cotransporter 1 (NBCe1), which expressed in various tissues including salivary glands, kidney and pancreas, etc. This experiment was performed to investigate regulatory site of NBCe1involved in the pH regulation using various mutants of NBCe1. Materials and Methods: Human parotid gland NBCe1 (hpNBCe1) and mutants by deletion of 1~285 bp and 1~1,035 bp were prepared. After microinjection of each cRNA to oocytes of Xenopus laevis, they were incubated for 2~3 days. The function of each protein was tested by electrophysiological method. Results: When oocytes were exposed to the $HCO_3{^-}$ buffered solution, 1~285 bp deleted mutant hpNBCe1 evoked a marked hyperpolarization ranging from -90 mV to -160 mV (average: -134 mV; n=12) compared to the full length of hpNBCe1. Although 1~1,035 bp deleted mutant hpNBCe1 was also expressed in the plasma membrane, but it did not show any changes of membrane potentials. Conclusion: Our deletion mutant study demonstrated that 1~285 bp of the NBCe1 is the major domain to determine $HCO_3{^-}$ transport ratio.

• Journal of Korean Dental Science
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• v.10 no.2
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• pp.45-52
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• 2017

Calcium has versatile roles in diverse physiological functions. Among these functions, intracellular $Ca^{2+}$ plays a key role during the secretion of salivary glands. In this review, we introduce the diverse cellular components involved in the saliva secretion and related dynamic intracellular $Ca^{2+}$ signals. Calcium acts as a critical second messenger for channel activation, protein translocation, and volume regulation, which are essential events for achieving the salivary secretion. In the secretory process, $Ca^{2+}$ activates $K^+$ and $Cl^-$ channels to transport water and electrolyte constituting whole saliva. We also focus on the $Ca^{2+}$ signals from intracellular stores with discussion about detailed molecular mechanism underlying the generation of characteristic $Ca^{2+}$ patterns. In particular, inositol triphosphate signal is a main trigger for inducing $Ca^{2+}$ signals required for the salivary gland functions. The biphasic response of inositol triphosphate receptor and $Ca^{2+}$ pumps generate a self-limiting pattern of $Ca^{2+}$ efflux, resulting in $Ca^{2+}$ oscillations. The regenerative $Ca^{2+}$ oscillations have been detected in salivary gland cells, but the exact mechanism and function of the signals need to be elucidated. In future, we expect that further investigations will be performed toward better understanding of the spatiotemporal role of $Ca^{2+}$ signals in regulating salivary secretion.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.3
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• pp.129-132
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• 2004

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.1
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• pp.45-49
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• 2010

R-type $Ca_v2.3$ high voltage-activated $Ca^{2+}$ channels in peripheral sensory neurons contribute to pain transmission. Recently we have demonstrated that, among the six $Ca_v2.3$ isoforms ($Ca_v2.3a{\sim}Ca_v2.3e$), the $Ca_v2.3e$ isoform is primarily expressed in trigeminal ganglion (TG) nociceptive neurons. In the present study, we further investigated expression patterns of $Ca_v2.3$ isoforms in the dorsal root ganglion (DRG) neurons. As in TG neurons, whole tissue RT-PCR analyses revealed the presence of two isoforms, $Ca_v2.3a$ and $Ca_v2.3e$, in DRG neurons. Single-cell RT-PCR detected the expression of $Ca_v2.3e$ mRNA in 20% (n=14/70) of DRG neurons, relative to $Ca_v2.3a$ expression in 2.8% (n=2/70) of DRG neurons. $Ca_v2.3e$ mRNA was mainly detected in small-sized neurons (n=12/14), but in only a few medium-sized neurons (n=2/14) and not in large-sized neurons, indicating the prominence of $Ca_v2.3e$ in nociceptive DRG neurons. Moreover, $Ca_v2.3e$ was preferentially expressed in tyrosine-kinase A (trkA)-positive, isolectin B4 (IB4)-negative and transient receptor potential vanilloid 1 (TRPV1)-positive neurons. These results suggest that $Ca_v2.3e$ may be the main R-type $Ca^{2+}$ channel isoform in nociceptive DRG neurons and thereby a potential target for pain treatment, not only in the trigeminal system but also in the spinal system.

• International Journal of Oral Biology
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• v.42 no.3
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• pp.91-97
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• 2017

Although anti-aging activities of melatonin, a hormone secreted by the pineal gland, have been reported in senescence-accelerated mouse models and several types of cells, its impact and mechanism on the senescence of human dental pulp cells (HDPCs) remains unknown. In this study, we examined the impact of melatonin on cellular premature senescence of HDPCs. Here, we found that melatonin markedly inhibited senescent characteristics of HDPCs after exposure to hydrogen peroxide ($H_2O_2$), including the increase in senescence-associated ${\beta}$-galactosidase (SA-${\beta}$-gal)-positive HDPCs and the upregulation of p21 protein, an indicator for senescence. In addition, as melatonin attenuated $H_2O_2$-stimulated phosphorylation of c-Jun N-terminal kinase (JNK), while selective inhibition of JNK activity with SP600125 significantly attenuated $H_2O_2$-induced increase in SA-beta-gal activity. Results reveal that melatonin antagonizes premature senescence of HDPCs via JNK pathway. Thus, melatonin may have therapeutic potential to prevent stress-induced premature senescence, possibly correlated with development of dental pulp diseases, and to maintain oral health across the life span.

• International Journal of Oral Biology
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• v.34 no.2
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• pp.73-79
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• 2009

Cytosolic $Ca^{2+}$ is an important regulator of tumor cell proliferation and metastasis. Recently, the strategy of blocking receptors and channels specific to certain cancer cell types has emerged as a potentially viable future treatment. Oral squamous cell carcinoma is an aggressive form of cancer with a high metastasis rate but the receptor-mechanisms involved in $Ca^{2+}$ signaling in these tumors have not yet been elucidated. In our present study, we report that bradykinin induces $Ca^{2+}$ signaling and its modulation in the human oral squamous carcinoma cell line, HSC-3. Bradykinin was found to increase the cytosolic $Ca^{2+}$ levels in a concentration-dependent manner. This increase was inhibited by pretreatment with the phospholipase C-${\beta}$ inhibitor, U73122, and also by 2-aminoethoxydiphenyl borate, an inhibitor of the inositol 1,4,5-trisphosphate receptor. Pretreatment with extracellular ATP also inhibited the peak bradykinin-induced $Ca^{2+}$ rise. In contrast, the ATP-induced rise in cytosolic $Ca^{2+}$ was not affected by pretreatment with bradykinin. Pretreatment of the cells with either forskolin or phorbol 12-myristate 13-acetate (activators of adenylyl cyclase and protein kinase C, respectively) prior to bradykinin application accelerated the recovery of cytosolic $Ca^{2+}$ to baseline levels. These data suggest that bradykinin receptors are functional in $Ca^{2+}$ signaling in HSC-3 cells and may therefore represent a future target in treatment strategies for human oral squamous cell carcinoma.

• International Journal of Oral Biology
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• v.40 no.2
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• pp.71-77
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• 2015

The activation of glial cells in the spinal cord has been contribute to the initiation and maintenance of pain facilitation induced by peripheral inflammation and nerve injury. The present study investigated effects of botulinum toxin type A (BoNT-A), injected subcutaneously or intracisternally, on the expression of microglia and astrocytes in rats. Complete Freund's Adjuvant (CFA)-induced inflammation was employed as an orofacial chronic inflammatory pain model. A subcutaneous injection of $40{\mu}L$ CFA into the vibrissa pad was performed under 3% isoflurane anesthesia in SD rats. Immunohistochemical analysis for changes in Iba1 (a microglia marker) and GFAP (an astrocyte marker), were performed 5 days after CFA injection. Subcutaneous injection of CFA produced increases in Iba1 and GFAP expression, in the ipsilateral superficial lamia I and II in the medullary dorsal horn of rats. Subcutaneous treatment with BoNT-A attenuated the up-regulation of Iba1 and GFAP expressions induced by CFA injection. Moreover, intracisternal injection of BoNT-A also attenuated the up-regulated Iba1 and GFAP expressions. These results suggest that the anti-nociceptive action of BoNT-A is mediated by modulation activation of glial cells, including microglia and astrocyte.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.271-277
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• 1998

• 대한약리학회:학술대회논문집
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• 2006.10a
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• pp.68-68
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• 2006

• Journal of Korean Dental Hygiene Science
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• v.4 no.1
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• pp.11-18
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• 2021

Background: The present study aimed to analyze which curriculum is the most relevant to dental hygiene students when they participate in clinical practice in order to provide a useful reference for preparing educational guidance in this field. Method: The survey utilized in the present study consisted of six questions about general characteristics, such as grade, satisfaction with major, amount of clinical practice, period of clinical practice, place of clinical practice, and the most interesting are during clinical practice. When evaluating curriculum relevancy, the following were ranked on a 5-point Likert scale, where 5 = very useful, 4 = comparatively useful, 3 = normal, 2 = comparatively unuseful, 1 = very unuseful: difference in requirements in the field of clinical practice, reason for this difference, and question about the utility of each curriculum. On this scale, higher points implied higher relevance. Result: The highest groups of curricula regarding curriculum utility were as follows: operative dentistry (59.6%), pre-clinical practice (55.2%), dental materials and clinical practice (54.4%), and prosthetic dentistry (49.6%). The lowest groups of curricula regarding curriculum utility were as follows: oral physiology (2.0%), oral histology and embryology (1.6%), and oral microbiology (1.2%). These results imply a lack of connection between the curriculum and tasks in clinical practice. Conclusion: Based on the results of the present study, it appears that both theory and practice courses of the clinical curriculum must be conducted systematically, and that there is a need to conduct education for the fundamental curricula, such as oral physiology, oral histology and embryology, and oral microbiology, regarding the relevance of tasks practiced in clinics.