• International Journal of Oral Biology
• /
• v.42 no.4
• /
• pp.169-174
• /
• 2017

Transient receptor potential melastatin 8 (TRPM8) plays a crucial role in innocuous cool sensation, acute cold pain and cold-induced hyperalgesia during pathologic conditions. To help understand TRPM8-mediated cold perception in the dental pulp and periodontal tissues, we examined the distribution of TRPM8-immunopositive (+) axons in molar and incisor pulp and periodontal tissues using transgenic mice expressing a genetically encoded axonal tracer in TRPM8+ neurons. In the radicular pulp of the molar teeth, a small number of TRPM8+ axons were observed. TRPM8+ axons branched frequently and extensively in the core of coronal pulp, forming a network in the peripheral pulp. Some TRPM8+ axons ascended between odontoblasts and were observed in the dentinal tubule. TRPM8+ axons were linear-shaped in the radicular pulp, whereas many TRPM8+ axons showed portions shaped like beads connected with thin axonal stands at the peripheral pulp. TRPM8 was densely expressed in the bead portions. In the incisor pulp, TRPM8+ axons were occasionally observed in the core of the coronal pulp and rarely observed at the peripheral pulp. TRPM8+ axons were occasionally observed and showed a linear shape rather than a bead-like appearance in the periodontal ligament and lamina propria of the gingival tissue. These findings, showing differential distribution of TRPM8+ axons between radicular and coronal portions of the molar pulp, between incisor and molar pulp, and between dental pulp and periodontal tissues, may reflect differential cold sensitivity in these regions.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.4
• /
• pp.1551-1556
• /
• 2014

Background: Transient receptor potential melastatin 8 (TRPM8), a principle membrane receptor involved in calcium ion influx and cell signal transduction, has been found to be up-regulated in some cancer types, including melanomas. Efficiency of menthol, an agonist of TRPM8, in killing melanoma cancer cells has been reported previously, but the mechanisms remain unclear. We here determined whether in vitro cytotoxic effects of menthol on A-375 human malignant melanoma cells might be related to TRPM8 transcript expression. Materials and Methods: The $PrestoBlue^{(R)}$ cell viability assay was used to assess the in vitro cytotoxic effect of menthol after 24h of treatment. RT-PCR was used to quantify TRPM8 transcript expression levels in normal and menthol-treated cells. Cell morphology was observed under inverted phase contrast light microscopy. Results: TRPM8 transcript expression was found at low levels in A-375 cells and down-regulated in a potentially dose-dependent manner by menthol. Menthol exerted in vitro cytotoxic effects on A-375 cells with an $IC_{50}$ value of 11.8 ${\mu}M$, which was at least as effective as 5-fluorouracil ($IC_{50}=120{\mu}M$), a commonly applied chemotherapeutic drug. Menthol showed no dose-dependent cytotoxicity on HeLa cells, a TRPM8 non-expressing cell line. Conclusions: The cytotoxic effects on A-375 cells caused by menthol might be related to reduction of the TRPM8 transcript level. This suggests that menthol might activate TRPM8 to increase cytosolic $Ca^{2+}$ levels, which leads to cytosolic $Ca^{2+}$ imbalance and triggers cell death.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.44 no.1
• /
• pp.15-21
• /
• 2018

Skin-aging is accelerated by the increased expression of MMP-1 caused by the increased skin temperature induced by IR/visible light as well as UV. Thus, the control of skin temperature is important to inhibit heat-induced aging. Many studies have been conducted to lower the skin temperature through the controlling transient receptor potential melastatin 8 channel (TRPM8), which is known as the cold and menthol receptor 1 (CMR1) and is activated at temperature below $25^{\circ}C$. In this study, we first investigated the effect of Ganoderma lucidum extract (GLE) on the TRPM8 expression. Results showed that GLE, hexane (Hex) fractions and water fractions increased the TRPM8 expression in a dose dependent manner. Active compound in Hex fractions were separated by chromatography and analyzed by $^1H$ and $^{13}C$ NMR spectroscopy. The isolated compounds were identified as ergosterol and it also significantly increased the TRPM8 expression. Taken together, these results strongly suggest that G. lucidum extract and ergosterol have the potential as a new cooling ingredient in the cosmetics.

• Korean Journal of Acupuncture
• /
• v.33 no.4
• /
• pp.204-212
• /
• 2016

Objectives : The aim of the study is to investigate the effects of moxibustion on the pain behavior and expression of TRPM8 in the dorsal root ganglion(DRG) in the rat model of ambient cold(AC) exposed osteoarthritis(OA). Methods : OA was induced by the injection of $50{\mu}l$ of 2% monosodium iodoacetate(MIA) into the knee joint cavity. To examine the level of pain, weight bearing forces(WBFs) of affected limb was measured. For the AC exposure, the animals were housed in 6 h/day at $4^{\circ}C$ for 14 days after MIA injection. Moxibustion treatment was performed at EX-LE4 and EX-LE5 with 5 cons(1, 7 or 10 mg) per day for 13 days from 5 days after MIA injection. The expressions of TRPM8 in DRG were measured by western blotting analysis. Results : The WBFs of MIA-AC group were decreased significantly compared to MIA group at 2, 3, 6, 7, 8 and 9 days after arthritis induction. After the first 6 h-AC exposure, expressions of TRPM8 in MIA-AC group were increased significantly compared to those of naive group. After moxibustion treatment, only the WBFs of 7 mg treated group were restored significantly. Moreover, the over-expressions of TRPM8 were attenuated by the moxibustion treatment in AC exposed rats. Conclusions : The data suggest that AC can increase arthritic knee pain via up-regulated TRPM8 and moxibustion treatment improve the arthritic pain via modulation of TRPM8 expression in DRG in the rat model of AC exposed MIA induced arthritis.

• The Korean Journal of Pain
• /
• v.21 no.1
• /
• pp.11-17
• /
• 2008

Background: Peripheral nerve injury induces up-regulation of the calcium channel alpha2delta (${\alpha}2{\delta}$) subunit and TRPM8 in the dorsal root ganglion (DRG) which might contribute to allodynia development. We investigated the expression of the ${\alpha}2{\delta}$ subunit and TRPM8 in the DRG of sympathetically maintained pain (SMP) and sympathetic independent pain (SIP) rat model. Methods: For the SMP model, the L5 and L6 spinal nerves were ligated tightly distal to the DRG. For the SIP model, the tibial and sural nerves were transected, while the common peroneal nerve was spared. After a 7 day postoperative period, tactile and cold allodynia were assessed using von Frey filaments and acetone drops, respectively. Expression of the ${\alpha}2{\delta}$ subunit and TRPM8 in the L5 and L6 DRG were subsequently examined by a Western blot. Results: There were no significant differences between the two models for the thresholds of tactile and cold allodynia. Expression of the ${\alpha}2{\delta}$ subunit in the ipsilateral DRG to the injury was increased as determined on a Western blot as compared to that in the contralateral or sham-operated DRG of the SMP model, but there was no difference in expression seen with the use of the SIP model. There was no difference in the expression of TRPM8 in the ipsilateral DRG to the injury and the contralateral or sham-operated DRG of either model. Conclusions: Up-regulation of the ${\alpha}2{\delta}$ subunit in injured DRG may play a role that contributes to tactile allodynia development in SMP, but not TRPM8 to cold allodynia after peripheral nerve injury.

• The Korean Journal of Pain
• /
• v.27 no.4
• /
• pp.326-333
• /
• 2014

Background: Nefopam is a centrally acting non-opioid analgesic agent. Its analgesic properties may be related to the inhibitions of monoamine reuptake and the N-methyl-D-aspartate (NMDA) receptor. The antinociceptive effect of nefopam has been shown in animal models of acute and chronic pain and in humans. However, the effect of nefopam on diabetic neuropathic pain is unclear. Therefore, we investigated the preventive effect of nefopam on diabetic neuropathic pain induced by streptozotocin (STZ) in rats. Methods: Pretreatment with nefopam (30 mg/kg) was performed intraperitoneally 30 min prior to an intraperitoneal injection of STZ (60 mg/kg). Mechanical and cold allodynia were tested before, and 1 to 4 weeks after drug administration. Thermal hyperalgesia was also investigated. In addition, the transient receptor potential ankyrin 1 (TRPA1) and TRP melastatin 8 (TRPM8) expression levels in the dorsal root ganglion (DRG) were evaluated. Results: Pretreatment with nefopam significantly inhibited STZ-induced mechanical and cold allodynia, but not thermal hyperalgesia. The STZ injection increased TRPM8, but not TRPA1, expression levels in DRG neurons. Pretreatment with nefopam decreased STZ-induced TRPM8 expression levels in the DRG. Conclusions: These results demonstrate that a nefopam pretreatment has strong antiallodynic effects on STZ-induced diabetic rats, which may be associated with TRPM8 located in the DRG.

• International Journal of Oral Biology
• /
• v.31 no.4
• /
• pp.135-140
• /
• 2006

Temperature signaling can be initiated by members of transient receptor potential (thermo-TRP) channels. Hot and cold substances applied to teeth usually elicit pain sensation. Since odontoblasts constitute a well-defined layer between the pulp and the mineralized dentin, being first to encounter thermal stimulation from oral cavity, they may be involved in sensory transduction process, in addition to their primary function as formation of dentin. We investigated whether thermo-TRP channels are expressed in a odontoblast cell line, MDPC-23. The expressions of thermo-TRP channels were examined using reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, fluorometric calcium imaging. Analysis of RT-PCR revealed mRNA expression of TRPV1, TRPV2, TRPV4 and TRPM8, but no TRPV3, TRPA1. Immunohistochemical approach failed to detect TRPV1 expression. Whereas the application of 4-phorbol-12,13-didecanoate($10\;{\mu}M$, a TRPV4 agonist), menthol(1 mM, a TRPM8 agonist) and icilin($10\;{\mu}M$, a TRPM8 agonist) produced the enhancement of intracellular calcium concentration, capsaicin($1\;{\mu}M$, a TRPV1 agonist) did not. Our results suggest that subfamily of thermo-TRP channels expressed in odontoblasts may serve as thermal or mechanical transducer in teeth.

• Journal of the Korean Burn Society
• /
• v.22 no.2
• /
• pp.30-33
• /
• 2019

Purpose: Wound healing and scar management of donor site after skin graft should not be overlooked. Patients continue to complain of dryness, itching sensation. Such discomfort can cause irritation to the patients and lead to delayed healing or secondary infection. Thus, the author predicted Eucalyptus Oil, which acts on Transient Receptor Potential Melastatin 8 would be effective in regulating scar by reducing itching sensation in donor site when combining conventional silicone materials. Methods: The study was performed on 30 patients who underwent split thickness skin graft with lateral thigh as donor site between January 2017 and August 2018. First, primary evaluation of fully epithelized donor site scar three weeks after surgery was conducted. Control group (n=15) applied silicone gel (Kelo-cote, USA) solely two times a day. study group (n=15) applied Eucalyptus oil, combined with silicone gel. After 3 months of follow up, donor scar was evaluated using Vancouver scar scale and VAS scores of subjective patient reports regarding pain and itching sensation. Results: It was confirmed that both groups showed stable scar improvement comparing scar quality for 3 months. After 3 months, scar quality in study group showed superiority in pigmentation, pliability and pruritus compared to control group. Conclusion: Application of Eucalyptus Oil combined with conventional silicone gel is favorable to scar management and may give additional benefit of alleviating pruritis symptoms.

• The Korea Journal of Herbology
• /
• v.31 no.6
• /
• pp.63-71
• /
• 2016

Objective : To suggest a scientific evidence of Aconitum carmichaeli Debx. (Aconiti Lateralis Radix Preparata: ALRP) as one of cooling and heating medicines on the regulation of body temperature, we investigated the effects of ALRP water extract on hypothyroidism. Methods : Hypothyroidism was induced by intradermal injection with PTU for 4 weeks in SD rats. ALRP extract or L-thyroxine as a control drug was orally administrated for 2 weeks with PTU injection in rats. The physiological and serological parameters were measured in rats. The histological change of thyroid tissues was observed by H&E staining, and also the expression of thermo-regulating proteins was determined by Western blot in dorsal root ganglia and brain tissues of rats. Results : The administration of ALRP extract in PTU-induced hypothyroidism rats was significantly increased body temperature, but did not changes on body weight, food and water intake. ALRP extract did not effect on the levels of TSH and T4 in the hypothyroidism rats. ALRP extract significantly decreased the levels of GPT, glucose, HDL-cholesterol, LDL-cholesterol, and total cholesterol in the hypothyroidism rats. In histological observation, the enlarged epithelium and atrophic follicles with higher concentration of follicular cells on hypothyroidism were improved by ALRP extract. In addition, ALRP extract increased the expression of TRPV1 and TRPM8 ion channel proteins in hypothyroidism rats. Conclusion : These results indicate that ALRP extract can improve PTU-induced hypothyroidism through regulation of body temperature and lipid accumulation. The action mechanism of ALRP extract is related with body temperature control by thermoregulation with TRP ion channels.

• The Korea Journal of Herbology
• /
• v.33 no.4
• /
• pp.77-85
• /
• 2018

Objective : This study was intended to examine the effects of water extract of Prunellae Spica (PS), which is a herb with 'cold' nature based on hot and cold theory of traditional Korean medicine. Methods : Hyperthyroidism was induced in SD rats by LT4 (0.5 mg/kg, i.p.) daily for four weeks. After 2 weeks of LT4 injection, rats were divided randomly into four groups; normal, LT4-induced hyperthyroid control, PS extract (500 mg/kg, p.o.)-treated group, and propylthiouracil (PTU, 10 mg/kg, s.c.)-treated positive group. After 2 weeks of drug treatment, all rats were sacrificed and harvested blood samples and thyroid tissues. The changes of body weight, food and water intake, and body temperature were measured weekly. Serological markers were analyzed in sera using an enzyme-based assay, and thyroid tissues were stained with Hematoxylin & Eosin (H&E). Brain and dorsal root ganglion (DRG) tissues were isolated and analyzed the expression of transient receptor potential (TRP) channels by Western blot. Results : PS extract administration attenuated the loss of body weight and the increase of body temperature in LT4-induced hyperthyroidism rats. PS extract increased the level of thyroid stimulating hormone (TSH) and decreased tiiodothyronine (T3) and tetraiodothyronine (T4). In action mechanism, PS extract regulated the expression of transient receptor potential channel subfamily V member 1 (TRPV1) and transient Receptor Potential channel subfamily M member 8 (TRPM8), the thermoregulators. Conclusion : To conclude, PS extract can improve the symptoms of hyperthyroidism through regulation of the thyroid hormones imbalance and thermoregulation via TRP channels.