Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but the mechanism remains unclear. Voltage-gated sodium channels (VGSCs) play important roles in excitability of pain sensing neurons and many of them are important nociceptors. Here, we report that several isoflavones including 3'-methoxydaidzein (3MOD), genistein (GEN) and daidzein (DAI) show abilities to block VGSCs and thus to attenuate chemicals and heat induced acute pain or chronic constriction injury (CCI) induced pain hypersensitivity in mice. Especially, 3MOD shows strong analgesic potential without inducing addiction through inhibiting subtypes Na1.7, Na1.8 and Na1.3 with the IC of 181 ± 14, 397 ± 26, and 505 ± 46 nmol·L, respectively, providing a promising compound or parent structure for the treatment of pain pathologies. This study reveals a pain-alleviating mechanism of dietary isoflavones and may provide a convenient avenue to alleviate pain.
Analgesics ; administration & dosage ; chemistry ; Animals ; Humans ; Isoflavones ; administration & dosage ; chemistry ; Male ; Mice ; Mice, Inbred C57BL ; Pain ; drug therapy ; genetics ; metabolism ; Voltage-Gated Sodium Channel Blockers ; administration & dosage ; Voltage-Gated Sodium Channels ; genetics ; metabolism

Voltage-gated sodium (Na) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Na channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Na channels, with Na1.1 and Na1.5 each harboring more than 400 mutations. Na channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Na channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Ca) channel Ca1.1 provides a template for homology-based structural modeling of the evolutionarily related Na channels. In this Resource article, we summarized all the reported disease-related mutations in human Na channels, generated a homologous model of human Na1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Na channels, the analysis presented here serves as the base framework for mechanistic investigation of Na channelopathies and for potential structure-based drug discovery.
Animals ; Calcium Channels, L-Type ; chemistry ; genetics ; metabolism ; Channelopathies ; genetics ; metabolism ; Humans ; Mutation ; NAV1.1 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; NAV1.5 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; NAV1.7 Voltage-Gated Sodium Channel ; chemistry ; genetics ; metabolism ; Protein Domains ; Rabbits ; Structure-Activity Relationship

OBJECTIVETo explore the protective mechanism of electroacupuncture (EA) at "Neiguan" (PC 6) on ischemic myocardial injury, and to explain the response patterns and characteristics of the specific effect of acupoints along meridians in sodium channel in the level of cardiac organ.

METHODSA total of 60 SPF male rats were randomly divided into a blank group, a model group, a non-acupoint group, a Neiguan group and a Lieque group, 12 cases in each one. Except the blank group, rats in the remaining group were treated with subcutaneous injection of isoprenaline to establish the model of myocardial ischemia. Rats in the Neiguan group, Lieque group and non- acupoint group were treated with EA, dilatational wave, with a frequency of 2 Hz/20 Hz. The intensity was 2-3 mA. The needles were retained for 20 min per time, once a day for consecutive 7 days. In the blank group and control group, the rats were grasped and fixed at the treating time each day. The western-blot method was used to test the expression of voltage-gated sodium channel alpha subunit (Nav 1.5), protein tyrosine kinase (PTKs) and protein tyrosine phosphatase (PTPs).

RESULTSThe expression of Nav 1.5 and PTKs in the model group was lower than that in the blank group (both P<0. 01); the expression in the Neiguan group and Lieque group was higher than that in the model group (all P < 0.01); the expression of Nav 1.5 and PTKs in the Neiguan group was higher than that in the Lieque group (both P < 0.01). The expression of PTPs in the model group and non-acupoint group was higher than that in the blank group (both P < 0.01); the expression of PTPs in the Neiguan group and Lieque group was significantly down-regulated, which was lower than the model group (both P < 0.01); the down-regulation in the Neiguan group was significantly different from that in the Lieque group (P < 0.05).

CONCLUSIONEA at "Neiguan" (PC 6), by down-regulating the expression of PTPs, up-regulating the expression of Nav 1.5 and PTKs, is likely to achieve the aim of regulation on sodium channel activity and calcium overload, further to improve myocardial ischemia, which provides experimental basis for the theory of the specific effect of acupoints along meridians.

Acupuncture Points ; Animals ; Disease Models, Animal ; Electroacupuncture ; Humans ; Male ; Myocardial Ischemia ; genetics ; metabolism ; therapy ; Myocardium ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium Channels ; genetics ; metabolism

OBJECTIVETo investigate the role of interleukin-17 (IL-17) in alveolar fluid clearance in mice with acute lung injury (ALI) and explore the possible mechanism.

METHODSSixteen IL-17-knockout mice and 16 wild-type mice were both randomized for intratracheal instillation of PBS (control) on lipopolysaccharide (LPS) to induce ALI. Forty-eight hours after the treatments, the wet-dry ratio (W/D) of the lungs, IL-8 in the bronchoalveolar lavage fluid (BALF) and histopathological changes of the lung tissues were examined. The expressions of epithelial sodium channel α subunit (α-ENaC) was detected with Western blotting and liver kinase B1 (LKB1) was detected with immunohistochemistry.

RESULTSCompared with wild-type mice treated with LPS, IL-17 knockout mice showed significantly decreased W/D of the lungs (9.739∓3.3 vs 5.351∓0.56) and IL-8 level in the BALF (67.50∓7.33 vs 41.00∓3.16 pg/mL) following LPS challenge. Pathological examination revealed reduced alveolar edema fluid aggregations and lower lung injury score in IL-17 knockout mice with also higher expression levels of ENaC and LKB1 compared with the wild-type mice.

CONCLUSIONKnocking out IL-17 in mice not only alleviates inflammation of the lung tissue following ALI but also reduces the loss of ENaC protein and promotes alveolar fluid clearance, mechanism of which is probably associated with LKB1.

Acute Lung Injury ; metabolism ; Animals ; Bronchoalveolar Lavage Fluid ; chemistry ; Epithelial Sodium Channels ; metabolism ; Gene Knockout Techniques ; Interleukin-17 ; genetics ; metabolism ; Interleukin-8 ; metabolism ; Lipopolysaccharides ; Lung ; pathology ; Mice ; Protein-Serine-Threonine Kinases ; metabolism

The present study was designed to search for compounds with analgesic activity from the Schizophyllum commune (SC), which is widely consumed as edible and medicinal mushroom world. Thin layer chromatography (TLC), tosilica gel column chromatography, sephadex LH 20, and reverse-phase high performance liquid chromatography (RP-HPLC) were used to isolate and purify compounds from SC. Structural analysis of the isolated compounds was based on nuclear magnetic resonance (NMR). The effects of these compounds on voltage-gated sodium (NaV) channels were evaluated using patch clamp. The analgesic activity of these compounds was tested in two types of mouse pain models induced by noxious chemicals. Five phenolic acids identified from SC extracts in the present study included vanillic acid, m-hydroxybenzoic acid, o-hydroxybenzeneacetic acid, 3-hydroxy-5-methybenzoic acid, and p-hydroxybenzoic acid. They inhibited the activity of both tetrodotoxin-resistant (TTX-r) and tetrodotoxin-sensitive (TTX-s) NaV channels. All the compounds showed low selectivity on NaV channel subtypes. After intraperitoneal injection, three compounds of these compounds exerted analgesic activity in mice. In conclusion, phenolic acids identified in SC demonstrated analgesic activity, facilitating the mechanistic studies of SC in the treatment of neurasthenia.
Analgesics ; administration & dosage ; chemistry ; isolation & purification ; Animals ; Humans ; Hydroxybenzoates ; administration & dosage ; chemistry ; isolation & purification ; Mice ; Neurasthenia ; drug therapy ; genetics ; metabolism ; Schizophyllum ; chemistry ; Voltage-Gated Sodium Channel Blockers ; administration & dosage ; chemistry ; isolation & purification ; Voltage-Gated Sodium Channels ; genetics ; metabolism

This study is to explore a new method of investigating molecular basis for electrophysiological properties of early fetal cardiomyocytes. Single embryonic cardiomyocytes of mouse early developmental heart (E10.5) were obtained by a collagenase B digestion approach. After recording spontaneous action potential using whole cell patch clamp technique, the single cell was picked by a glass micropipette, followed by a standard RT-PCR to explore the expression levels of several ion channel genes. Three phenotypes of cardiomyocytes were demonstrated with distinct properties: ventricular-like, atrial-like, and pacemaker-like action potentials. Ventricular-like and atrial-like cells were characterized with much negative maximum diastolic potential (MDP) and a higher V(max) (maximum velocity of depolarization) compared to pacemaker-like cells. MDP of ventricular-like cells was the most negative. In parallel, stronger expression of SCN5a, SCN1b and Kir2.1 were observed in ventricular-like and atrial-like cells compared to that of pacemaker-like cells, where Kir2.1 in ventricular-like cells was the most abundant. Cardiomyocytes with distinct electrophysiological properties had distinct gene expression pattern. Single cell RT-PCR combined with patch clamp technique could serve as a precise detector to analyze the molecular basis of the special electrophysiological characteristics of cardiomyocytes.
Animals ; Electrophysiological Phenomena ; Female ; Fetus ; Male ; Mice ; Myocytes, Cardiac ; metabolism ; physiology ; NAV1.5 Voltage-Gated Sodium Channel ; genetics ; metabolism ; Patch-Clamp Techniques ; Potassium Channels, Inwardly Rectifying ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction ; Voltage-Gated Sodium Channel beta-1 Subunit ; genetics ; metabolism

OBJECTIVETo observe the effects of ginsenoside Rg1 on the functional expression of human neural stem cells (hNSCs).

METHODThe membrane electrophysiological properties and sodium and potassium ion channels in the hNSCs induced by Rg1 were analyzed using the whole-cell patch-clamp.

RESULTOn the 7th day, the neuron-like cells derived from ginsenoside Rg1 (20 mg x L(-1))-induced NSCs show: (1) The resting membrane potential: (-45.70 +/- 2.63) mV, the membrane capacitance: (26.89 +/- 1.91) pF, the membrane input impedance: (877.51 +/- 20.44) MH (P < 0.05 compared with the control group, respectively); (2) The detection rate of inward sodium current which is rapidly activated and inactivated in voltage-dependence was 50%, and its average peak value was (711.48 +/- 158.03) pA (P < 0.05 compared with the control group); (3) The outward potassium currents were composed of rapidly activated and inactivated transient outward potassium current and delayed rectifier outward potassium current, and its average peak value was (1 070.42 +/- 177.18) pA (P < 0.05 compared with the control group).

CONCLUSIONGinsenoside Rg1 can promote the functional expression and maturity of hNSCs.

Cells, Cultured ; Gene Expression ; drug effects ; Ginsenosides ; pharmacology ; Humans ; Membrane Potentials ; drug effects ; Neural Stem Cells ; cytology ; drug effects ; Patch-Clamp Techniques ; Plant Extracts ; pharmacology ; Potassium Channels ; genetics ; metabolism ; Sodium Channels ; genetics ; metabolism

Voltage-gated sodium channels are critical for the generation and conduction of nerve impulses. Recent studies show that in primary sensory neurons, the expression and dynamic regulation of several sodium channel subtypes play important roles in neuropathic pain. A number of SCN9A (encoding Nav1.7) gene point mutations are related with human genetic pain disorders. Transgenic and specific knockout techniques have revealed that Nav1.3, Nav1.8, Nav1.9 are important for the development and maintenance of neuropathic pain condition. Specific blockers of these sodium channels have been demonstrated to be effective in alleviating allodynia and hyperalgesia. Here we reviewed the roles of sodium channels in neuropathic pain, which may be applicable for the development of new drugs with enhanced efficacy for neuropathic pain treatment.
Animals ; Humans ; Neuralgia ; genetics ; metabolism ; physiopathology ; Neurons ; metabolism ; physiology ; Sodium Channels ; genetics ; metabolism ; physiology

Kv2.1 channel currents in pancreatic beta-cells are thought to contribute to action potential repolarization and thereby modulate insulin secretion. Because of its central role in this important physiological process, Kv2.1 channel is a promising target for the treatment of type 2 diabetes. Jingzhaotoxin-XI (JZTX-XI) is a novel peptide neurotoxin isolated from the venom of the spider Chilobrachys jingzhao. Two-microelectrode voltage clamp experiments had showed that the toxin inhibited Kv2.1 potassium currents expressed in Xenopus Laevis oocytes. In order to investigate the structure-function relationship of JZTX-XI, the natural toxin and a mutant of JZTX-XI in which Arg3 was replaced by Ala, were synthesized by solid-phase chemistry method with Fmoc-protected amino acids on the PS3 automated peptide synthesizer. Reverse-phase high performance liquid chromatography (RP-HPLC) and matrix assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) were used to monitor the oxidative refolding process of synthetic linear peptides to find the optimal renaturation conditions of these toxins. The experiments also proved that the relative molecular masses of refolded peptides were in accordance with their theoretical molecular masses. RP-HPLC chromatogram of co-injected native and refolded JZTX-XI was a single peak. Under the whole-cell patch-clamp mode, JZTX-XI could completely inhibit hKv2.1 and hNav1.5 channels currents expressed in HEK293T cells with IC50 values of 95.8 nmol/L and 437.1 nmol/L respectively. The mutant R3A-JZTX-XI could also inhibit hKv2.1 and hNav1.5 channel currents expressed in HEK293T cells with IC50 values of 1.22 micromol/L and 1.96 micromol/L respectively. However, the prohibitive levels of R3A-JZTX-XI on hKv2.1 and hNav1.5 channels were reduced by about 12.7 times and 4.5 times respectively, indicating that Arg3 was a key amino acid residue relative to the hKv2.1 channel activity of JZTX-XI, but it is also an amino acid residue correlated with the binding activity of JZTX-XI to hNav1.5 channel. Our findings should be helpful to develop JZTX-XI into a molecular probe and drug candidate targeting to Kv2.1 potassium channel in the pancreas.
Animals ; HEK293 Cells ; Humans ; Insulin-Secreting Cells ; metabolism ; Mutant Proteins ; genetics ; pharmacology ; NAV1.5 Voltage-Gated Sodium Channel ; metabolism ; Neurotoxins ; chemical synthesis ; genetics ; pharmacology ; Protein Refolding ; Shab Potassium Channels ; antagonists & inhibitors ; metabolism ; Sodium Channel Blockers ; pharmacology ; Spider Venoms ; genetics ; pharmacology ; Transfection

BACKGROUNDThe amiloride-sensitive epithelial sodium channel α-subunit (α-ENaC) is an important factor for alveolar fluid clearance during acute lung injury. The relationship between adenosine receptor A(2a) (A(2a)AR) expressed in alveolar epithelial cells and α-ENaC is poorly understood. We targeted the A(2a)AR in this study to investigate its role in the expression of α-ENaC and in acute lung injury.

METHODSA549 cells were incubated with different concentrations of A(2a)AR agonist CGS-21680 and with 100 µmol/L CGS-21680 for various times. Rats were treated with lipopolysaccharide (LPS) after CGS-21680 was injected. Animals were sacrificed and tissue was harvested for evaluation of lung injury by analysis of the lung wet-to-dry weight ratio, lung permeability and myeloperoxidase activity. RT-PCR and Western blotting were used to determine the mRNA and protein expression levels of α-ENaC in A549 cells and alveolar type II epithelial cells.

RESULTSBoth mRNA and protein levels of α-ENaC were markedly higher from 4 hours to 24 hours after exposure to 100 µmol/L CGS-21680. There were significant changes from 0.1 µmol/L to 100 µmol/L CGS-21680, with a positive correlation between increased concentrations of CGS-21680 and expression of α-ENaC. Treatment with CGS-21680 during LPS induced lung injury protected the lung and promoted α-ENaC expression in the alveolar epithelial cells.

CONCLUSIONActivation of A(2a)AR has a protective effect during the lung injury, which may be beneficial to the prognosis of acute lung injury.

Acute Lung Injury ; metabolism ; Adenosine ; analogs & derivatives ; pharmacology ; Animals ; Blotting, Western ; Cell Line ; Epithelial Sodium Channels ; genetics ; metabolism ; Humans ; Male ; Phenethylamines ; pharmacology ; Pulmonary Alveoli ; cytology ; metabolism ; Purinergic P1 Receptor Agonists ; pharmacology ; Rats ; Receptors, Purinergic P1 ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction