Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2) and transient receptor potential vanilloid subfamily member 1 (TRPV1) have been studied extensively and documented to play important roles. In this study, experiments using aortic arch-aortic nerve preparations isolated from rats revealed that both ASIC2 and TRPV1 are functionally necessary, as blocking either abrogated nearly all pressure-dependent neural discharge. However, whether ASIC2 and TRPV1 work in coordination remained unclear. So we carried out cell-attached patch-clamp recordings in HEK293T cells co-expressing ASIC2 and TRPV1 and found that inhibition of ASIC2 completely blocked stretch-activated currents while inhibition of TRPV1 only partially blocked these currents. Immunofluorescence staining of aortic arch-aortic adventitia from rats showed that ASIC2 and TRPV1 are co-localized in the aortic nerve endings, and co-immunoprecipitation assays confirmed that the two proteins form a compact complex in HEK293T cells and in baroreceptors. Moreover, protein modeling analysis, exogenous co-immunoprecipitation assays, and biotin pull-down assays indicated that ASIC2 and TRPV1 interact directly. In summary, our research suggests that ASIC2 and TRPV1 form a compact complex and function synergistically in the mechano-electrical transduction of arterial baroreceptors. The model of synergism between MSCs may have important biological significance beyond ASIC2 and TRPV1.
Acid Sensing Ion Channels/physiology* ; Animals ; HEK293 Cells ; Humans ; Pressoreceptors/physiology* ; Rats ; TRPV Cation Channels/physiology*

Transient receptor potential vanilloid 4 (TRPV4) channel is a member of transient receptor potential superfamily. TRPV4 is selectively permeable to calcium. Activation of the TRPV4 channel induces an increase in intracellular calcium concentration and plays an important role under physiological and pathological conditions. Especially, there is evidence showing that TRPV4 is involved in cerebral ischemic reperfusion injury. The present paper reviewed some research progress about the role of TRPV4 in cerebral ischemic reperfusion injury.
Brain Ischemia ; Calcium ; physiology ; Humans ; Reperfusion Injury ; TRPV Cation Channels ; physiology

The aim of the present study was to investigate the influence of osmotic pressure on myocardial contractility and the possible mechanism. Electrical stimulation was used to excite papillary muscles of the left ventricle of Sprague-Dawley (SD) rats. The contractilities of myocardium in hyposmotic, isosmotic, and hyperosmotic perfusates were recorded. The influences of agonist and antagonist of the transient receptor potential vanilloid 4 (TRPV4) on the contractility of myocardium under hyposmotic, isosmotic and hyperosmotic conditions were observed. The results were as follows: (1) Compared with that under isosmotic condition (310 mOsm/L), the myocardial contractility was increased by 11.5%, 21.5% and 25.0% (P<0.05) under hyposmotic conditions when the osmotic pressure was at 290, 270 and 230 mOsm/L, respectively; and was decreased by 16.0%, 23.7% and 55.2% (P<0.05) under hyperosmotic conditions when the osmotic pressure was at 350, 370 and 390 mOsm/L, respectively. (2) When ruthenium red (RR), an antagonist of TRPV4, was added to the hyposmotic perfusate (270 mOsm/L), the positive inotropic effect of hyposmia was restrained by 36% (P<0.01); and when RR was added to the hyperosmotic perfusate (390 mOsm/L), the inhibitory effect of hyperosmia on myocardial contractility was increased by 56.1% (P<0.01). (3) When 4-α-phorbol-12,13-didecanoate (4α-PDD), an agonist of TRPV4, was added to the isosmotic perfusate (310 mOsm/L), the myocardial contractility did not change; and when 4α-PDD was added to the hyperosmotic perfusate (390 mOsm/L), the inhibition of myocardial contractility by hyperosmia was increased by 27.1% (P<0.01). These results obtained indicate that TRPV4 is possibly involved in the osmotic pressure-induced inotropic effect.
Animals ; Heart ; physiology ; Myocardial Contraction ; physiology ; Osmotic Pressure ; Phorbol Esters ; pharmacology ; Rats ; Rats, Sprague-Dawley ; TRPV Cation Channels ; physiology

OBJECTIVETo observe the intestinal movement of transient receptor potential vanilloid 1 or vanilloid receptor 1 (TRPV1) knockout mice after stimulated by electroacupuncture (EA), and to primarily explore the roles of TRPV1 receptor in the jejunal motility regulated by acupuncture.

METHODSNormal wild-type CL57BL/6 and TRPV1 gene knockout mice were recruited in two groups, the B6 group and the TRPV1 group, 15 in each group. The thermal threshold and the mechanical pain threshold were respectively detected using JL-F digital photo thermal analyzer instrument and ALMEMO2450 machine. The difference between the two thresholds were compared. Meanwhile, a self-made pressure head was placed in the jejunum. The internal pressure was monitored. When the pressure was stable, 2 mA 2/15 Hz EA at Quchi (LI11), Tianshu (ST25), Shangjuxu (ST37), and Dachangshu (BL25) to observe the changes of intestinal pressure value between before and after EA. The curve of internal pressures was recorded.

RESULTS(1) The stimulation of light/heat and mechanical stimulation were obviously slowed in the TRPV1 group than in the B6 group (P < 0.01). (2) In the intestinal pressure observation experiment, the bowel movement was not obviously seen in the two groups when acupunctured at Quchi (LI11) and Shangjuxu (ST37) (P > 0.05). (3) Acupuncture at Tianshu (ST25) and Dachangshu (BL25) of TRPV1 knockout mice could lead to intestinal movement (P < 0.05), mainly inhibited bowel movement. The changing degree was equivalent to that of B6 mice.

CONCLUSIONSUnder the physiological condition, TRPV1 might be mediated by thermal and mechanical stimulation. But TRPV1 mediated acupuncture effect was quite complex, indicating TRPV1 mice might be one of intestinal movement mediating factors.

Animals ; Electroacupuncture ; Gastrointestinal Motility ; Jejunum ; physiology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; TRPV Cation Channels ; physiology

OBJECTIVETo review the relationship between the immune system and the mechanism of pain. Data sources Related researches published in the period of 1987-2005 were systematically reviewed. Study selection Articles about the immune system and pain were selected. Data extraction Data were mainly extracted from 74 articles which are listed in the reference section of this review.

RESULTSPain was classically viewed as being mediated solely by neurons. However, growing evidence has showed the possible relationships between the immune system and the central nervous system. In this article, we reviewed the role of the immune system in the development of pain, together with the importance of the glia in this process. These findings suggest a novel approach to pain control in the future.

CONCLUSIONSThe immune system plays a potential but important role in the development of pain.

Animals ; Brain ; immunology ; Humans ; Immune System ; physiology ; Interleukin-1 ; physiology ; Neuroglia ; physiology ; Pain ; etiology ; immunology ; TRPV Cation Channels ; physiology ; Tumor Necrosis Factor-alpha ; physiology ; Wounds and Injuries ; immunology

The neurotrophin and glial cell line-derived neurotrophic factor (GDNF) family of growth factors have been extensively studied because of their proven ability to regulate development of the peripheral nervous system. The neurotrophin family, which includes nerve growth factor (NGF), NT-3, NT4/5 and BDNF, is also known for its ability to regulate the function of adult sensory neurons. Until recently, little was known concerning the role of the GNDF-family (that includes GDNF, artemin, neurturin and persephin) in adult sensory neuron function. Here we describe recent data that indicates that the GDNF family can regulate sensory neuron function, that some of its members are elevated in inflammatory pain models and that application of these growth factors produces pain in vivo. Finally we discuss how these two families of growth factors may converge on a single membrane receptor, TRPV1, to produce long-lasting hyperalgesia.
Animals ; Glial Cell Line-Derived Neurotrophic Factors ; physiology ; Humans ; Hyperalgesia ; physiopathology ; Nerve Tissue Proteins ; physiology ; Neurturin ; physiology ; Nociceptors ; cytology ; TRPV Cation Channels ; physiology

AIMTo investigate the expression and distribution of the members of the transient receptor potential (TRP) channel members of TRP melastatin (TRPM) and TRP vanilloid (TRPV) subfamilies in rat prostatic tissue.

METHODSProstate tissue was obtained from male Sprague-Dawley rats. Reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time polymerase chain reaction (PCR) were used to check the expression of all TRPM and TRPV channel members with specific primers. Immunohistochemistry staining for TRPM8 and TRPV1 were also performed in rat tissues.

RESULTSTRPM2, TRPM3, TRPM4, TRPM6, TRPM7, TRPM8, TRPV2 and TRPV4 mRNA were detected in all rat prostatic tissues. Very weak signals for TRPM1, TRPV1 and TRPV3 were also detected. The mRNA of TRPM5, TRPV5 and TRPV6 were not detected in all RT-PCR experiments. Quantitative real-time RT-PCR showed that TRPM2, TRPM3, TRPM4, TRPM8, TRPV2 and TRPV4 were the most abundantly expressed TRPM and TRPV subtypes, respectively. Fluorescence immunohistochemistry indicated that TRPM8 and TRPV1 are highly expressed in both epithelial and smooth muscle cells.

CONCLUSIONOur results demonstrate that mRNA or protein for TRPM1, TRPM2, TRPM3, TRPM4, TRPM6, TRPM7, TRPM8, TRPV1, TRPV2, TRPV3 and TRPV4 exist in rat prostatic tissue. The data presented here assists in elucidating the physiological function of TRPM and TRPV channels.

Animals ; Clusterin ; genetics ; physiology ; Immunohistochemistry ; Male ; Prostate ; physiology ; RNA, Messenger ; genetics ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; TRPV Cation Channels ; genetics ; physiology

Artemin is a neuronal survival and differentiation factor in the glial cell line-derived neurotrophic factor family. Its receptor GFRalpha3 is expressed by a subpopulation of nociceptor type sensory neurons in the dorsal root and trigeminal ganglia (DRG and TG). These neurons co-express the heat, capsaicin and proton-sensitive channel TRPV1 and the cold and chemical-sensitive channel TRPA1. To further investigate the effects of artemin on sensory neurons, we isolated transgenic mice (ARTN-OE mice) that overexpress artemin in keratinocytes of the skin and tongue. Enhanced levels of artemin led to a 20% increase in the total number of DRG neurons and increases in the level of mRNA encoding TRPV1 and TRPA1. Calcium imaging showed that isolated sensory neurons from ARTN-OE mice were hypersensitive to the TRPV1 agonist capsaicin and the TRPA1 agonist mustard oil. Behavioral testing of ARTN-OE mice also showed an increased sensitivity to heat, cold, capsaicin and mustard oil stimuli applied either to the skin or in the drinking water. Sensory neurons from wildtype mice also exhibited potentiated capsaicin responses following artemin addition to the media. In addition, injection of artemin into hindpaw skin produced transient thermal hyperalgesia. These findings indicate that artemin can modulate sensory function and that this regulation may occur through changes in channel gene expression. Because artemin mRNA expression is up-regulated in inflamed tissue and following nerve injury, it may have a significant role in cellular changes that underlie pain associated with pathological conditions. Manipulation of artemin expression may therefore offer a new pain treatment strategy.
Animals ; Hot Temperature ; Hyperalgesia ; metabolism ; Keratinocytes ; physiology ; Mice ; Mice, Transgenic ; Nerve Tissue Proteins ; genetics ; metabolism ; Nociceptors ; physiology ; Skin ; cytology ; TRPA1 Cation Channel ; TRPV Cation Channels ; metabolism ; Tongue ; cytology ; Transient Receptor Potential Channels ; metabolism

OBJECTIVETo determine the effects of transient receptor potential vanilloid type 1 (TRPV1) channel ablation and a chemokine receptor 2 (CCR2) antagonist on salt-sensitive hypertension-induced renal injury.

METHODSWild-type (WT) and TRPV1-null mutant (TRPV1(-/-)) mice were subjected to uninephrectomy and deoxycorticosterone acetate (DOCA)-salt treatment for 4 weeks with or without a CCR2 antagonist, RS504393 (n=8 for all the 4 groups). Sham WT and TRPV1(-/-) mice (both n=7) underwent uninephrectomy without receiving DOCA and saline. Systolic blood pressure, urinary excretion of albumin, 8-isoprostane and creatinine clearance for 24 hours were assayed during the experimental period and at the end of the 4-week treatment. The morphological analysis was performed in renal histological sections, including glomerulosclerosis, tubulointerstitial injury, and monocyte/macrophage infiltration.

RESULTSCompared to the corresponding control mice, DOCA-salt treatment in both WT and TRPV1(-/-) mice led to increased systolic blood pressure (SBP), enhanced urinary excretion of albumin and 8-isoprostane, decreased creatinine clearance, increased glomerulosclerosis and tubulointerstitial injury associated with enhanced monocyte/macrophage infiltration (all P<0.05), all of which were much more severe in TRPV1(-/-) mice compared to WT mice with the exception of blood pressure (all P<0.05). RS5043943 attenuated DOCA-salt-induced changes in renal function and morphology in WT and TRPV1(-/-) mice (all P<0.05). There was no difference in blood pressure among DOCA-salt WT and TRPV1(-/-) mice with or without RS505393 with the exception of sham WT and TRPV1(-/-) mice (all P>0.05).

CONCLUSIONSCCR2 antagonist inhibits DOCA-salt-induced renal injury and monocyte/macrophage infiltration in WT and TRPV1(-/-) mice with the greater in the latter strain. Activation of TRPV1 attenuates salt-sensitive hypertension-induced renal injury possibly via inhibition of CCR2-induced monocyte/macrophage infiltration.

Animals ; Hypertension ; complications ; pathology ; Kidney Diseases ; etiology ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Receptors, CCR2 ; antagonists & inhibitors ; physiology ; Sodium Chloride ; adverse effects ; TRPV Cation Channels ; physiology

OBJECTIVE: To identify the subtype of transient receptor potential (TRPs) channel involved in stretch-induced injury of human brain microvascular endothelial cells (HBMEC) and to explore the mechanism responsible for eNOS expression.
 METHODS: TRPs expression was examined by Western blot and immunocytofluoresence in the cultured HBMEC. Mechanical stretch was performed by mini-type multi-functional bio-impact machine. The levels of free calcium ion in cells were examined by the flow cytometry. The eNOS expression was detected by Western blot.
 RESULTS: The mRNA and protein expression of TRPV4 was detected in HBMEC by qRT-PCR, Western blot and immunocytofluoresence. The levels of free calcium ion in the stretch-treated HBMEC was significantly decreased in the presence of TRPV4 specific inhibitor (P<0.001), but there was no difference in calcium levels between the stretch and the control or unspecific inhibitor group (P=0.072 or 0.308). The levels of eNOS protein in the stretch-treated HBMEC were reduced in the presence of TRPV4 specific inhibitor or NOS inhibitor (P<0.05), but it was not changed compared with that in the control group (P>0.05).
 CONCLUSION The eNOS expression is up-regulated under the condition of mechanic stretch, which is related to the activation of TRPV4, resulting in the influx of calcium.
Brain ; cytology ; Calcium ; metabolism ; Cells, Cultured ; Endothelial Cells ; physiology ; Humans ; Nitric Oxide Synthase Type III ; metabolism ; Stress, Mechanical ; TRPV Cation Channels ; physiology