Effect of menthol on hypobaric hypoxia-induced pulmonary arterial hypertension in mice and its mechanism / 中国药理学通报

Aim To study the effect of menthol on hypobaric hypoxia-induced pulmonary arterial hypertension and explore the underlying mechanism in mice. Methods 10 to 12 weeks old wild type (WT) mice and TRPM8 gene knockout (TRPM8

Role of corneal cold thermoreceptors in the occurrence and development of dry eye / 中华实验眼科杂志

Dry eye is a multifactorial disease caused by changes in tear quality, volume and dynamics.Disturbance of tear film as the main character is accompanied by discomfort, visual disorder, and damage to the ocular surface and nerves.Cold thermoreceptors existing on the ocular surface are sensitive to alterations in corneal temperature and tear osmolality.They can give rise to the sensations of cold and pain, and regulate tear secretion, and are considered to be associated with the clinical manifestations of dry eye in some ways.This article reviewed the progress of corneal cold thermoreceptors in the regulation of corneal sensation and tear secretion, the related factors of corneal sensory regulation, and the clinical applications of TRPM8-related drugs, so as to provide ideas for the treatment of dry eye.

Relationship Between TRPV1 and TRPM8 in Reflux Esophagitis Models / 胃肠病学

Background: Studies have shown that transient receptor potential (TRP) channels play important roles in gastroesophageal reflux disease (GERD), however, the relationship between TRPV1 and TRPM8 in reflux esophagitis (RE) remains unclear. Aims: To investigate the expressions of TRPV1, TRPM8 and their correlation in guinea pigs with RE. Methods: Thirty male guinea pigs aged 3⁃4 weeks were randomly divided into 3 groups: blank control group, negative control group and model group, with 10 animals in each group. Guinea pigs in model group and negative control group were given esophageal perfusion with 0.1 mol/L HCl containing 0.5% pepsin and normal saline, respectively, once a day for 14 days; guinea pigs in blank control group were free to drink sterile water for 14 days. On day 15, the esophagus was dissected for macroscopic and histopathological examination, and Western blotting and/or real⁃time PCR were used to detect the expression levels of TRPV1, TRPM8, GNAQ (an isoform of G protein), and the tight junction proteins and proinflammatory cytokines in esophageal tissue. The co⁃localization of TRPV1 and TRPM8 was assessed by immunofluorescence. Results: Esophageal mucosal congestion, hyperplasia of esophageal epithelial cells, infiltration of inflammatory cells, as well as up⁃regulation of proinflammatory cytokines and down⁃regulation of tight junction proteins were observed in esophageal tissue of guinea pigs in model group, which indicated the successful RE model construction. As compared with the negative control group, expression levels of TRPV1 and GNAQ mRNA and protein were significantly increased, while expression levels of TRPM8 mRNA and protein were significantly reduced in esophageal tissue of guinea pigs in model group (all P<0.05). TRPV1 and TRPM8 channels were co ⁃ localized in the lamina propria of esophageal mucosa. Conclusions: There is a certain equilibrium mechanism between TRPV1 and TRPM8 channels in RE models. G protein⁃coupled receptor signaling pathway and the downstream TRPV1/TRPM8 might be involved in the occurrence and development of GERD.

Function of TRPM8 Ion Channel and Regulation Mechanism of Its Post-translational Modification / 中国生物化学与分子生物学报

TRPM8 (transient receptor potential melastatin 8), also known as a cold and menthol receptor and a member of the TRP (transient receptor potential) channel superfamily, locates on the cell membrane or organelle membrane.. TRPM8 is a non-selective cation channel, which can be used as either a cold and heat sensor or cold and pain sensor to conduct signal transduction. It plays an important role in maintaining intracellular homeostasis and controlling ion in cells. It has been found that PTM (post-translational modification) of TRPM8 affects the occurrence and development of many diseases by regulating the function of TRPM8 channel. Therefore, it is necessary to explore the PTM process of TRPM8 to gain a deeper understanding for the function and regulatory mechanism of TRPM8. At present, several types of post-translational modifications of TRPM8 have been reported, including phosphorylation, ubiquitination and glycosylation, which can regulate protein interactions and change the activity of TRPM8 ion channels, leading to modulation of cell proliferation, migration and apoptosis. It is noteworthy that the expression of TRPM8 level is closely related to many kinds of cancers, such as prostate cancer, bladder cancer and breast cancer. This review focus on the structure of TRPM8 ion channels, systematically elaborate the translational modifications, activator and antagonist of TRPM8 protein, and the regulation of some proteins on TRPM8 channel activity. At the same time, we summarize the recent progress of TRPM8 in prostate cancer, bladder cancer and breast cancer, which would provide new directions and new ideas for the treatment of cancer.

Implications of Transient Receptor Potential Cation Channels in Migraine Pathophysiology / 神经科学通报·英文版

Migraine is a common and debilitating headache disorder. Although its pathogenesis remains elusive, abnormal trigeminal and central nervous system activity is likely to play an important role. Transient receptor potential (TRP) channels, which transduce noxious stimuli into pain signals, are expressed in trigeminal ganglion neurons and brain regions closely associated with the pathophysiology of migraine. In the trigeminal ganglion, TRP channels co-localize with calcitonin gene-related peptide, a neuropeptide crucially implicated in migraine pathophysiology. Many preclinical and clinical data support the roles of TRP channels in migraine. In particular, activation of TRP cation channel V1 has been shown to regulate calcitonin gene-related peptide release from trigeminal nerves. Intriguingly, several effective anti-migraine therapies, including botulinum neurotoxin type A, affect the functions of TRP cation channels. Here, we discuss currently available data regarding the roles of major TRP cation channels in the pathophysiology of migraine and the therapeutic applicability thereof.

Feasibility of TRPM8 Agonist Agent for Management of Skin Graft Donor Site

A clinical and mechanistic study of topical bingpian-induced analgesia / 中国药理学与毒理学杂志

OBJECTIVE Bingpian is an almost pure chemical with a chemical composition of (+)-borneol and has been historically used as a topical analgesic in traditional Chinese medicine for millen-nia. However, the clinical efficacy of topical bingpian lacks stringent evidence-based clinical studies and the underlying molecular mechanisms are unclear.This study verified the analgesic efficacy of topi-cal bingpian in humans, and elucidated the underling mechanisms in animal models of pain. METH-ODS The analgesic efficacy of topical bingpian was examined in a randomized,double-blind,placebo-controlled clinical study at the Shanghai Changzheng Hospital. Capsaicin, formalin, CFA or thermal caused pain/hyperalgesia were established in different mouse models,and bingpian-induced analgesia and the underlying mechanisms were studied in these models.The molecular targets of bingpian were examined by calcium imaging, patch-clamp recording and enzymatic activity assay in mouse sensory neurons or transfected HEK 293 cells. RESULTS (1)Topical application of bingpian leads to significantly greater pain relief than placebo does in a randomized, double-blind, placebo-controlled clinical study involving 122 patients with postoperative pain.(2)TRPM8 channel is the most sensitive molecular target of bingpian and mediates topical bingpian-induced analgesia in mice. (3)A downstream glutamatergic mechanism in the spinal cord contributes to topical bingpian-induced analgesia. (4)Bingpian shows mechanistic differences and advantages as a topical analgesic when compared with menthol.

The clinnical significance of TRPM8 ion channels over-expressed in pancreatic cancer / 中华肝胆外科杂志

Objective TRPM8 as a clinical biomarker and potential drug target may provide a guidance in accurately judging the malignant potential and prognosis of pancreatic cancer.Downregulating the expression of TRPM8 leads to inhibition of the proliferation of pancreatic cancer cells and this may provide a new target for personalized pancreatic cancer treatment.Methods The pancreatic cancer tissues of 77 patients and the normal pancreas tissues of 30 persons were collected and examined by immunohistochemistry.PCR,gene knockout,Western Blot,CCK8 and patch clamp experiments were performed on pancreatic cancer cell lines BxPC-3,PANC1 and normal pancreatic cell line HPCY-5.Results Immunohistochemistry and Western Blot experiments showed that the TRPM8 channel protein was highly expressed in cancer cells,and the high expression of channel proteins was related to the degree of tumor differentiation (P ＜ 0.05).The detection of the TRPM8 mRNA in pancreatic cancer cell lines BxPC-3 and PANC1 by QPCR showed absolutely high expressions relative to the normal cell line HPCY-5.The results of patch clamp and CCK8 showed that the membrane currents and proliferation of tumor cells were significantly decreased after TRPM8 gene knockout,and the difference is significant (P ＜ 0.05).Conclusions The TRPM8 ion channel was higher in pancreatic cancer cells than that in normal pancreatic cells.Overexpression of TRPM8 was closely related to tumor cell proliferation and invasion ability.

Distribution of Cold Receptor Transient Receptor Potential Melastatin 8-Immunopositive Axons in the Mouse Dental Pulp and Periodontal Tissue

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.

TRPM8 channel in neoplasms / 国际外科学杂志

Transient receptor potential (TRP) channels affect several inflammatory and neoplastic conditions.and are widely distributed and activated by multiple stimuli.Mean while,as the sensor to the changes in cellular local environments,TRP channels have multiple functions,including thermal,mechanical and taste sensing,as well as ion homeostasis maintaining.They can regulate muscle contractions,transmitter release,cell multiplication,cell differentiation,genetic transcription,apoptosis and molecular death.TRPM8,a nonselective cation channel,was originally cloned as a prostate-specific protein.Now,TRPM8 is found in carcinoma of colon,lung cancer,mammary cancer,pancreatic cancer and cutaneum carcinoma.The aim of this review is to summarize data reported so far on the expression and functional role of TRPM8 channels in different types of cancers.

Effects of Nefopam on Streptozotocin-Induced Diabetic Neuropathic Pain in Rats

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.

Effects of Nefopam on Streptozotocin-Induced Diabetic Neuropathic Pain in Rats

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.

Function of the Cold Receptor (TRPM8) Associated with Voiding Dysfunction in Bladder Outlet Obstruction in Rats / 대한배뇨장애요실금학회지

PURPOSE: Bladder outlet obstruction (BOO) causes storage and voiding dysfunction in the lower urinary tract. We investigated the expression of transient receptor potential cation channel subfamily M member 8 (TRPM8) to evaluate the relationship between TRPM8 expression and overactive bladder (OAB) in a rat model of BOO. METHODS: Fifty female Sprague-Dawley rats were divided into 4 groups; normal (n=10), normal-menthol (n=10), BOO (n=15), BOO-menthol (n=15). After 3 weeks, cystometry was performed by infusing physiological saline and menthol (3 mM) into the bladder at a slow infusion rate. The histological changes and expression of TRPM8 in the bladder were investigated by Masson's trichrome staining, immunofluorescence and reverse transcription-polymerase chain reaction. RESULTS: Cystometry showed that the intercontraction interval (ICI; 428.2+/-23.4 vs. 880.4+/-51.2, P<0.001), micturition pressure (MP; 25.7+/-1.01 vs. 71.80+/-3.01, P<0.001), and threshold pressure (2.9+/-0.25 vs. 9.2+/-1.58, P<0.01) were significantly increased in BOO rats. The bladder wall was significantly dilated compared with the control. Detrusor muscle hypertrophy and a thick mucosa layer were observed in BOO bladder. After menthol treatment, ICIs were decreased and MPs were increased in the menthol treatment groups. TRPM8-positive cells and mRNA were predominantly increased in the bladder and dorsal root ganglia of all groups compared with the normal group. CONCLUSIONS: Increased bladder wall thickness and proportion of collagen probably affect voiding dysfunction. Furthermore, an increase of TRPM8 expression in BOO may induce entry of Ca2+ from the extracellular space or stores. The increase of Ca2+ probably causes contraction of smooth muscle in BOO. However, OAB symptoms were not observed after menthol treatment although the expression of TRPM8 was abundant in the bladder epithelium after menthol treatment. Although OAB in BOO models may be caused by complex pathways, regulation of TRPM8 presents possibilities for OAB treatment.

The Expression of the Ca++ Channel alpha2delta Subunit and TRPM8 in the Dorsal Root Ganglion of Sympathetically Maintained Pain and Sympathetic Independent Pain Rat Models / 대한통증학회지

BACKGROUND: Peripheral nerve injury induces up-regulation of the calcium channel alpha2delta (alpha2delta) subunit and TRPM8 in the dorsal root ganglion (DRG) which might contribute to allodynia development. We investigated the expression of the alpha2delta 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 alpha2delta 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 alpha2delta 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 alpha2delta 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 progress in TRPM8 research / 中国药理学通报

TRP(transient receptor potential) ion channel is a kind of membrane proteins which are widespreadly present in various cells,which is used to identify various mixed flavor and warm,heat,cold,and other temperature.Originally cloned as a proatate-specific protein.TRPM8 is now best known as a cold-and menthol-activated channel implicated in thermosensation.We provide a brief review of current knowledge concerning the biophysical properties,gating mechanisms,pharmacology and(patho)physiology of this TRP channel.