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1.
Neuroscience Bulletin ; (6): 149-165, 2022.
Article in English | WPRIM | ID: wpr-929077

ABSTRACT

Leptin, an adipocyte-derived peptide hormone, has been shown to facilitate breathing. However, the central sites and circuit mechanisms underlying the respiratory effects of leptin remain incompletely understood. The present study aimed to address whether neurons expressing leptin receptor b (LepRb) in the nucleus tractus solitarii (NTS) contribute to respiratory control. Both chemogenetic and optogenetic stimulation of LepRb-expressing NTS (NTSLepRb) neurons notably activated breathing. Moreover, stimulation of NTSLepRb neurons projecting to the lateral parabrachial nucleus (LPBN) not only remarkably increased basal ventilation to a level similar to that of the stimulation of all NTSLepRb neurons, but also activated LPBN neurons projecting to the preBötzinger complex (preBötC). By contrast, ablation of NTSLepRb neurons projecting to the LPBN notably eliminated the enhanced respiratory effect induced by NTSLepRb neuron stimulation. In brainstem slices, bath application of leptin rapidly depolarized the membrane potential, increased the spontaneous firing rate, and accelerated the Ca2+ transients in most NTSLepRb neurons. Therefore, leptin potentiates breathing in the NTS most likely via an NTS-LPBN-preBötC circuit.


Subject(s)
Leptin/pharmacology , Membrane Potentials , Neurons/metabolism , Solitary Nucleus/metabolism
2.
Journal of Biomedical Engineering ; (6): 695-702, 2021.
Article in Chinese | WPRIM | ID: wpr-888229

ABSTRACT

Patch clamp is a technique that can measure weak current in the level of picoampere (pA). It has been widely used for cellular electrophysiological recording in fundamental medical researches, such as membrane potential and ion channel currents recording, etc. In order to obtain accurate measurement results, both the resistance and capacitance of the pipette are required to be compensated. Capacitance compensations are composed of slow and fast capacitance compensation. The slow compensation is determined by the lipid bilayer of cell membrane, and its magnitude usually ranges from a few picofarads (pF) to a few microfarads (μF), depending on the cell size. The fast capacitance is formed by the distributed capacitance of the glass pipette, wires and solution, mostly ranging in a few picofarads. After the pipette sucks the cells in the solution, the positions of the glass pipette and wire have been determined, and only taking once compensation for slow and fast capacitance will meet the recording requirements. However, when the study needs to deal with the temperature characteristics, it is still necessary to make a recognition on the temperature characteristic of the capacitance. We found that the time constant of fast capacitance discharge changed with increasing temperature of bath solution when we studied the photothermal effect on cell membrane by patch clamp. Based on this phenomenon, we proposed an equivalent circuit to calculate the temperature-dependent parameters. Experimental results showed that the fast capacitance increased in a positive rate of 0.04 pF/℃, while the pipette resistance decreased. The fine data analysis demonstrated that the temperature rises of bath solution determined the kinetics of the fast capacitance mainly by changing the inner solution resistance of the glass pipette. This result will provide a good reference for the fine temperature characteristic study related to cellular electrophysiology based on patch clamp technique.


Subject(s)
Cell Membrane , Electric Capacitance , Membrane Potentials , Patch-Clamp Techniques , Temperature
3.
The Korean Journal of Physiology and Pharmacology ; : 111-119, 2020.
Article in English | WPRIM | ID: wpr-787133

ABSTRACT

In vascular smooth muscle, K⁺ channels, such as voltage-gated K⁺ channels (Kv), inward-rectifier K⁺ channels (Kir), and big-conductance Ca²⁺-activated K⁺ channels (BK(Ca)), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (I(Kv) and I(Kir)) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) I(Kv) was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) I(Kv) inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) I(Kir) was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) I(BKCa) did not differ between branches. Moreover, in PAH rats, I(Kir) and I(Kv) decreased in SCSMCs, but not in RCSMCs or LCSMCs, and I(BKCa) did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in I(Kv) and I(Kir) occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller I(Kir) in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K⁺ concentration under increased activity of the myocardium.


Subject(s)
Animals , Rats , Coronary Vessels , Heart Diseases , Heart Failure , Hyperemia , Hypertension , Hypertrophy, Right Ventricular , Ischemia , Membrane Potentials , Monocrotaline , Muscle, Smooth , Muscle, Smooth, Vascular , Myocardium , Myocytes, Smooth Muscle , Patch-Clamp Techniques , Potassium Channels , Septum of Brain
4.
Korean Circulation Journal ; : 250-263, 2020.
Article in English | WPRIM | ID: wpr-811353

ABSTRACT

BACKGROUND AND OBJECTIVES: To reveal the detail mechanism of miR-484 on myocardial ischemia-reperfusion (MI/R) injury.METHODS: Rats model of MI/R injury was established based on control (Con; sham operate) group, ischemia-reperfusion (I/R) group, miR-484 treatment (miR) group, and I/R-negative control (IR-C) group, followed by pathological and interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β expression evaluation. Then the myocardial apoptosis, as well as the expression of miR-484, caspase-3, and caspase-9 in myocardium were examined. Finally, the regulatory relation between miR-484 and SMAD family member 7 (SMAD7) was predicated, followed by verification analysis.RESULTS: Compared with Con group, the expression of miR-484 in I/R and IR-C group was decreased. Compared with I/R and IR-C group, the expression of miR-484 was increased in miR group. Compared with Con group, the expression levels of IL-6, TNF-α, and IL-1β in cardiac myocytes of I/R group and IR-C group were increased. Compared with Con group, the apoptotic index, membrane potential of I/R, and the expression of caspase-3/9 were increased in IR-C group. Compared with the I/R and IR-C groups, the apoptotic index of myocardial cells in the ischemic region was decreased, the membrane potential was increased, and the expression of caspase-3/9 was decreased significantly in the miR group. SMAD7 was the target gene of miR-484.CONCLUSIONS: MiR-484 protected myocardial cells from I/R injury by suppressing caspase-3 and caspase-9 expression during cardiomyocyte apoptosis. MiR-484 reduced the expression of IL-6, TNF-α, and IL-1β in MI/R. MiR-484 might alleviate the decreasing of mitochondrial membrane potential in MI/R cells.


Subject(s)
Animals , Humans , Rats , Apoptosis , Caspase 3 , Caspase 9 , Interleukin-6 , Interleukins , Membrane Potential, Mitochondrial , Membrane Potentials , Myocardium , Myocytes, Cardiac , Reperfusion Injury , Tumor Necrosis Factor-alpha
5.
Biomolecules & Therapeutics ; : 290-301, 2019.
Article in English | WPRIM | ID: wpr-763015

ABSTRACT

Paeonol has neuroprotective function, which could be useful for improving central nervous system disorder. The purpose of this study was to characterize the functional mechanism involved in brain transport of paeonol through blood-brain barrier (BBB). Brain transport of paeonol was characterized by internal carotid artery perfusion (ICAP), carotid artery single injection technique (brain uptake index, BUI) and intravenous (IV) injection technique in vivo. The transport mechanism of paeonol was examined using conditionally immortalized rat brain capillary endothelial cell line (TR-BBB) as an in vitro model of BBB. Brain volume of distribution (V(D)) of [³H]paeonol in rat brain was about 6-fold higher than that of [¹⁴C]sucrose, the vascular space marker of BBB. The uptake of [³H]paeonol was concentration-dependent. Brain volume of distribution of paeonol and BUI as in vivo and inhibition of analog as in vitro studies presented significant reduction effect in the presence of unlabeled lipophilic compounds such as paeonol, imperatorin, diphenhydramine, pyrilamine, tramadol and ALC during the uptake of [³H]paeonol. In addition, the uptake significantly decreased and increased at the acidic and alkaline pH in both extracellular and intracellular study, respectively. In the presence of metabolic inhibitor, the uptake reduced significantly but not affected by sodium free or membrane potential disruption. Similarly, paeonol uptake was not affected on OCTN2 or rPMAT siRNA transfection BBB cells. Interestingly. Paeonol is actively transported from the blood to brain across the BBB by a carrier mediated transporter system.


Subject(s)
Animals , Rats , Blood-Brain Barrier , Brain , Carotid Arteries , Carotid Artery, Internal , Central Nervous System , Diphenhydramine , Endothelial Cells , Hydrogen-Ion Concentration , In Vitro Techniques , Membrane Potentials , Perfusion , Pyrilamine , RNA, Small Interfering , Sodium , Tramadol , Transfection
6.
Biomedical Engineering Letters ; (4): 425-434, 2019.
Article in English | WPRIM | ID: wpr-785531

ABSTRACT

Heart rate variability (HRV) is governed by the autonomic nervous system (ANS) and is routinely used to estimate the state of body and mind. At the same time, recorded HRV features can vary substantially between people. A model for HRV that (1) correctly simulates observed HRV, (2) reliably functions for multiple scenarios, and (3) can be personalised using a manageable set of parameters, would be a significant step forward toward understanding individual responses to external influences, such as physical and physiological stress. Current HRV models attempt to reproduce HRV characteristics by mimicking the statistical properties of measured HRV signals. The model presented here for the simulation of HRV follows a radically different approach, as it is based on an approximation of the physiology behind the triggering of a heart beat and the biophysics mechanisms of how the triggering process—and thereby the HRV—is governed by the ANS. The model takes into account the metabolisation rates of neurotransmitters and the change in membrane potential depending on transmitter and ion concentrations. It produces an HRV time series that not only exhibits the features observed in real data, but also explains a reduction of low frequency band-power for physically or psychologically high intensity scenarios. Furthermore, the proposed model enables the personalisation of input parameters to the physiology of different people, a unique feature not present in existing methods. All these aspects are crucial for the understanding and application of future wearable health.


Subject(s)
Autonomic Nervous System , Biophysics , Heart Rate , Heart , Membrane Potentials , Neurotransmitter Agents , Physiology , Stress, Physiological , Vital Signs
7.
Journal of Neurogastroenterology and Motility ; : 189-204, 2019.
Article in English | WPRIM | ID: wpr-765940

ABSTRACT

The internal anal sphincter (IAS) plays an important role in the maintenance of fecal continence since it generates tone and is responsible for > 70% of resting anal pressure. During normal defecation the IAS relaxes. Historically, tone generation in gastrointestinal muscles was attributed to mechanisms arising directly from smooth muscle cells, ie, myogenic activity. However, slow waves are now known to play a fundamental role in regulating gastrointestinal motility and these electrical events are generated by the interstitial cells of Cajal. Recently, interstitial cells of Cajal, as well as slow waves, have also been identified in the IAS making them viable candidates for tone generation. In this review we discuss four different mechanisms that likely contribute to tone generation in the IAS. Three of these involve membrane potential, L-type Ca²⁺ channels and electromechanical coupling (ie, summation of asynchronous phasic activity, partial tetanus, and window current), whereas the fourth involves the regulation of myofilament Ca²⁺ sensitivity. Contractile activity in the IAS is also modulated by sympathetic motor neurons that significantly increase tone and anal pressure, as well as inhibitory motor neurons (particularly nitrergic and vasoactive intestinal peptidergic) that abolish contraction and assist with normal defecation. Alterations in IAS motility are associated with disorders such as fecal incontinence and anal fissures that significantly decrease the quality of life. Understanding in greater detail how tone is regulated in the IAS is important for developing more effective treatment strategies for these debilitating defecation disorders.


Subject(s)
Anal Canal , Defecation , Fecal Incontinence , Gastrointestinal Motility , Interstitial Cells of Cajal , Membrane Potentials , Motor Neurons , Muscle, Smooth , Muscles , Myocytes, Smooth Muscle , Myofibrils , Quality of Life , Receptor, Platelet-Derived Growth Factor alpha , Tetanus
8.
Healthcare Informatics Research ; : 131-138, 2019.
Article in English | WPRIM | ID: wpr-740231

ABSTRACT

OBJECTIVES: This study proposes a method for classifying three types of resting membrane potential signals obtained as images through diagnostic needle electromyography (EMG) using TensorFlow-Slim and Python to implement an artificial-intelligence-based image recognition scheme. METHODS: Waveform images of an abnormal resting membrane potential generated by diagnostic needle EMG were classified into three types—positive sharp waves (PSW), fibrillations (Fibs), and Others—using the TensorFlow-Slim image classification model library. A total of 4,015 raw waveform data instances were reviewed, with 8,576 waveform images subsequently collected for training. Images were learned repeatedly through a convolutional neural network. Each selected waveform image was classified into one of the aforementioned categories according to the learned results. RESULTS: The classification model, Inception v4, was used to divide waveform images into three categories (accuracy = 93.8%, precision = 99.5%, recall = 90.8%). This was done by applying the pretrained Inception v4 model to a fine-tuning method. The image recognition model was created for training using various types of image-based medical data. CONCLUSIONS: The TensorFlow-Slim library can be used to train and recognize image data, such as EMG waveforms, through simple coding rather than by applying TensorFlow. It is expected that a convolutional neural network can be applied to image data such as the waveforms of electrophysiological signals in a body based on this study.


Subject(s)
Artificial Intelligence , Boidae , Classification , Clinical Coding , Electromyography , Membrane Potentials , Methods , Needles
9.
Acta Physiologica Sinica ; (6): 600-606, 2018.
Article in Chinese | WPRIM | ID: wpr-777225

ABSTRACT

Basolateral inwardly-rectifying K channels (Kir) play an important role in the control of resting membrane potential and transepithelial voltage, thereby modulating water and electrolyte transport in the distal part of nephron. Kir4.1 and Kir4.1/Kir5.1 heterotetramer are abundantly expressed in the basolateral membrane of late thick ascending limb (TAL), distal convoluted tubule (DCT), connecting tubule (CNT) and cortical collecting duct (CCD). Loss-of-function mutations in KCNJ10 cause EAST/SeSAME syndrome in humans associated with epilepsy, ataxia, sensorineural deafness and water-electrolyte metabolism imbalance, which is characterized by salt wasting, hypomagnesaemia, hypokalaemia and metabolic alkalosis. In contrast, mice lacking Kir5.1 have severe renal phenotype apart from hypokalaemia such as high chlorine metabolic acidosis and hypercalcinuria. The genetic knockout or functional inhibition of Kir4.1 suppresses Na-Cl cotransporter (NCC) expression and activity in the DCT. However, the downregulation of Kir4.1 increases epithelial Na channel (ENaC) expression in the collecting duct. Recently, factors regulating expression and activity of Kir4.1 and Kir4.1/Kir5.1 were identified, such as cell acidification, dopamine, insulin and insulin-like growth factor-1. The involved mechanisms include PKC, PI3K, Src family protein tyrosine kinases and WNK-SPAK signal transduction pathways. Here we review the progress of renal tubule basolateral Kir, and mainly discuss the function and regulation of Kir4.1 and Kir4.1/Kir5.1.


Subject(s)
Animals , Humans , Mice , Cell Membrane , Kidney Tubules , Metabolism , Kidney Tubules, Distal , Membrane Potentials , Potassium Channels, Inwardly Rectifying , Metabolism
10.
Neuroscience Bulletin ; (6): 759-768, 2018.
Article in English | WPRIM | ID: wpr-777023

ABSTRACT

Cyproheptadine (CPH), a first-generation antihistamine, enhances the delayed rectifier outward K current (I) in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH (10 µmol/L) significantly reduced the current density required to generate action potentials (APs) and increased the instantaneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential (RMP), decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mimicked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium (TEA) to block I channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive I channels as well as other TEA-insensitive K channels, probably I and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.


Subject(s)
Animals , Female , Cyproheptadine , Pharmacology , Histamine H1 Antagonists , Pharmacology , Membrane Potentials , Physiology , Mice, Inbred C57BL , Patch-Clamp Techniques , Potassium Channel Blockers , Pharmacology , Potassium Channels , Metabolism , Prefrontal Cortex , Physiology , Pyramidal Cells , Physiology , Receptors, sigma , Metabolism , Tetraethylammonium , Pharmacology , Tissue Culture Techniques
11.
The Korean Journal of Physiology and Pharmacology ; : 697-703, 2018.
Article in English | WPRIM | ID: wpr-727855

ABSTRACT

Myoblast fusion depends on mitochondrial integrity and intracellular Ca²⁺ signaling regulated by various ion channels. In this study, we investigated the ionic currents associated with [Ca²⁺]i regulation in normal and mitochondrial DNA-depleted (ρ0) L6 myoblasts. The ρ0 myoblasts showed impaired myotube formation. The inwardly rectifying K⁺ current (I(Kir)) was largely decreased with reduced expression of KIR2.1, whereas the voltage-operated Ca²⁺ channel and Ca²⁺-activated K⁺ channel currents were intact. Sustained inhibition of mitochondrial electron transport by antimycin A treatment (24 h) also decreased the I(Kir). The ρ0 myoblasts showed depolarized resting membrane potential and higher basal [Ca²⁺]ᵢ. Our results demonstrated the specific downregulation of I(Kir) by dysfunctional mitochondria. The resultant depolarization and altered Ca²⁺ signaling might be associated with impaired myoblast fusion in ρ0 myoblasts.


Subject(s)
Antimycin A , Down-Regulation , Electron Transport , Ion Channels , Membrane Potentials , Mitochondria , Muscle Development , Muscle Fibers, Skeletal , Myoblasts , Oxidative Phosphorylation
12.
Journal of Veterinary Science ; : 483-491, 2018.
Article in English | WPRIM | ID: wpr-758837

ABSTRACT

The hypothalamic paraventricular nucleus (PVN) contains two types of neurons projecting to either the rostral ventrolateral medulla (PVN(RVLM)) or the intermediolateral horn (IML) of the spinal cord (PVN(IML)). These two neuron groups are intermingled in the same subdivisions of the PVN and differentially regulate sympathetic outflow. However, electrophysiological evidence supporting such functional differences is largely lacking. Herein, we compared the electrophysiological properties of these neurons by using patch-clamp and retrograde-tracing techniques. Most neurons (>70%) in both groups spontaneously fired in the cell-attached mode. When compared to the PVN(IML) neurons, the PVN(RVLM) neurons had a lower firing rate and a more irregular firing pattern (p < 0.05). The PVN(RVLM) neurons showed smaller resting membrane potential, slower rise and decay times, and greater duration of spontaneous action potentials (p < 0.05). The PVN(RVLM) neurons received greater inhibitory synaptic inputs (frequency, p < 0.05) with a shorter rise time (p < 0.05). Taken together, the results indicate that the two pre-sympathetic neurons differ in their intrinsic and extrinsic electrophysiological properties, which may explain the lower firing activity of the PVN(RVLM) neurons. The greater inhibitory synaptic inputs to the PVN(RVLM) neurons also imply that these neurons have more integrative roles in regulation of sympathetic activity.


Subject(s)
Animals , Action Potentials , Fires , Horns , Inhibitory Postsynaptic Potentials , Membrane Potentials , Neurons , Paraventricular Hypothalamic Nucleus , Patch-Clamp Techniques , Spinal Cord , Spinal Cord Lateral Horn
13.
Neuroscience Bulletin ; (6): 1007-1016, 2018.
Article in English | WPRIM | ID: wpr-775489

ABSTRACT

Exploring the transition from inter-ictal to ictal epileptiform discharges (IDs) and how GABA receptor-mediated action affects the onset of IDs will enrich our understanding of epileptogenesis and epilepsy treatment. We used Mg-free artificial cerebrospinal fluid (ACSF) to induce epileptiform discharges in juvenile mouse hippocampal slices and used a micro-electrode array to record the discharges. After the slices were exposed to Mg-free ACSF for 10 min-20 min, synchronous recurrent seizure-like events were recorded across the slices, and each event evolved from inter-ictal epileptiform discharges (IIDs) to pre-ictal epileptiform discharges (PIDs), and then to IDs. During the transition from IIDs to PIDs, the duration of discharges increased and the inter-discharge interval decreased. After adding 3 μmol/L of the GABA receptor agonist muscimol, PIDs and IDs disappeared, and IIDs remained. Further, the application of 10 μmol/L muscimol abolished all the epileptiform discharges. When the GABA receptor antagonist bicuculline was applied at 10 μmol/L, IIDs and PIDs disappeared, and IDs remained at decreased intervals. These results indicated that there are dynamic changes in the hippocampal network preceding the onset of IDs, and GABA receptor activity suppresses the transition from IIDs to IDs in juvenile mouse hippocampus.


Subject(s)
Animals , Male , Mice , Animals, Newborn , Bicuculline , Pharmacology , Disease Models, Animal , Epilepsy , Pathology , GABA-A Receptor Agonists , Pharmacology , GABA-A Receptor Antagonists , Therapeutic Uses , Hippocampus , Metabolism , In Vitro Techniques , Magnesium , Metabolism , Pharmacology , Membrane Potentials , Mice, Inbred C57BL , Muscimol , Pharmacology , Nerve Net , Receptors, GABA-A , Metabolism
14.
Annals of Laboratory Medicine ; : 395-401, 2018.
Article in English | WPRIM | ID: wpr-717062

ABSTRACT

Mitochondria are the powerhouses of the cell as well as the primary site of hematopoiesis, which also occurs in the cytoplasm. Hematopoietic stem cells (HSCs) are characterized by a very high turnover rate, and are thus considered to be relatively free from the age-related insults generated by mitochondria. However, HSCs are also subject to these age-related insults, including the incidence of myeloid proliferative diseases, marrow failure, hematopoietic neoplasms, and deterioration of the adaptive human immune system. Recently, NAD⁺ dietary supplements, known as niacin or vitamin B₃, including tryptophan, nicotinic acid, nicotinamide, and the newly identified NAD⁺ precursor nicotinamide riboside, have been shown to play a role in restoring adult stem cell function through the amelioration of mitochondrial dysfunction. This insight motivated a study that focused on reversing aging-related cellular dysfunction in adult mouse muscle stem cells by supplementing their diet with nicotinamide riboside. The remedial effect of nicotinamide riboside enhanced mitochondrial function in these muscle stem cells in a SIRT1-dependent manner, affecting cellular respiration, membrane potential, and production of ATP. Accordingly, numerous studies have demonstrated that sirtuins, under nuclear/mitochondrial control, have age-specific effects in determining HSC phenotypes. Based on the evidence accumulated thus far, we propose a clinical intervention for the restoration of aged HSC function by improving mitochondrial function through NAD⁺ precursor supplementation.


Subject(s)
Adult , Animals , Humans , Mice , Adenosine Triphosphate , Adult Stem Cells , Aging , Bone Marrow , Cell Respiration , Cytoplasm , Diet , Dietary Supplements , Hematologic Neoplasms , Hematopoiesis , Hematopoietic Stem Cells , Immune System , Incidence , Membrane Potentials , Mitochondria , Niacin , Niacinamide , Phenotype , Sirtuins , Stem Cells , Tryptophan , Vitamins
15.
The Korean Journal of Physiology and Pharmacology ; : 311-319, 2018.
Article in English | WPRIM | ID: wpr-728612

ABSTRACT

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (ΔΨ(m)). Therefore, pharmacological manipulation of ΔΨ(m) can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ΔΨ(m) against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity (100 µM, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate (100 µM)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of Ca²⁺ (5 µM). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ΔΨ(m) were completely abolished in K⁺-free medium on pure isolated mitochondria. Taken together, results demonstrate that K⁺ influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial K⁺ influx is probably mediated, at least in part, by activation of mitochondrial K⁺ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.


Subject(s)
Animals , Rats , Brain , Calcium , Cell Death , Cell Survival , Citrus , Fluorescence , Fluorometry , Glutamic Acid , Membrane Potential, Mitochondrial , Membrane Potentials , Membranes , Mitochondria , Neurodegenerative Diseases , Neurons , Neuroprotective Agents , Reactive Oxygen Species
16.
Ann. hepatol ; 16(2): 297-303, Mar.-Apr. 2017. tab, graf
Article in English | LILACS | ID: biblio-887236

ABSTRACT

ABSTRACT Introduction and aim. The inability to distinguish cancer (CSCs) from normal stem cells (NSCs) has hindered attempts to identify safer, more effective therapies for hepatocellular carcinoma (HCC). The aim of this study was to document and compare cell membrane potential differences (PDs) of CSCs and NSCs derived from human HCC and healthy livers respectively and determine whether altered GABAergic innervation could explain the differences. Material and methods. Epithelial cell adhesion molecule (EpCAM) positive stem cells were isolated from human liver tissues by magnetic bead separations. Cellular PDs were recorded by microelectrode impalement of freshly isolated cells. GABAA receptor subunit expression was documented by reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence. Results. CSCs were significantly depolarized (-7.0 ± 1.3 mV) relative to NSCs (-23.0 ± 1.4 mV, p < 0.01). The depolarized state was associated with different GABAA receptor subunit expression profiles wherein phasic transmission, represented by GAGAA α3 subunit expression, was prevalent in CSCs while tonic transmission, represented by GABAA α6 subunit expression, prevailed in NSCs. In addition, GABAA subunits α3, β3, γ3 and δ were strongly expressed in CSCs while GABAA π expression was dominant in NSCs. CSCs and NSCs responded similarly to GABAA receptor agonists (ΔPD: 12.5 ± 1.2 mV and 11.0 ± 3.5 mV respectively). Conclusion. The results of this study indicate that CSCs are significantly depolarized relative to NSCs and these differences are associated with differences in GABAA receptor subunit expression. Together they provide new insights into the pathogenesis and possible treatment of human HCC.


Subject(s)
Humans , Neoplastic Stem Cells/metabolism , Receptors, GABA-A/metabolism , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/metabolism , GABA-A Receptor Agonists/pharmacology , Epithelial Cell Adhesion Molecule/metabolism , Liver/cytology , Liver Neoplasms/metabolism , Phenotype , Stem Cells/drug effects , Neoplastic Stem Cells/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Biomarkers/metabolism , Fluorescent Antibody Technique , Immunomagnetic Separation , Receptors, GABA-A/drug effects , Receptors, GABA-A/genetics , Reverse Transcriptase Polymerase Chain Reaction , Protein Subunits , Liver Neoplasms/genetics , Membrane Potentials/drug effects
17.
Medical Principles and Practice. 2017; 26 (4): 375-380
in English | IMEMR | ID: emr-189638

ABSTRACT

Objective: To detect urinary volatile organic compounds [VOCs] in patients with idiopathic membranous nephropathy [iMN] and normal controls, and to examine whether or not urinary VOCs can act as biomarkers for the diagnosis of iMN independent of renal biopsy


Materials and Methods: Gas chromatography/mass spectrometry [GC/MS] was used to assess the urine collected from 63 iMN patients and 15 normal controls. The statistical methods of principal component analysis and partial least squares discriminant analysis were performed to process the final data in Common Data Format which were converted from GC/MS data


Results: Six VOCs in the urine samples of iMN patients exhibited significant differences from those of normal controls: carbamic acid monoammonium salt, 2-pentanone, 2,4-di-methyl-pentanal, hydrogen azide, thiourea, and 4-hepta-none were significantly higher than in controls [p < 0.05]


Conclusions: Six urinary VOCs were isolated from patients with iMN using GC/MS. The analysis of urinary VOCs using GC/MS could be developed into a non-invasive method for the detection of iMN.


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Glomerulonephritis, Membranous , Membrane Potentials , Biomarkers , Gas Chromatography-Mass Spectrometry , Urine
18.
Journal of Neurogastroenterology and Motility ; : 117-123, 2017.
Article in English | WPRIM | ID: wpr-110253

ABSTRACT

BACKGROUND/AIMS: Myenteric plexus interstitial cells of Cajal (ICC-MY) are involved in the generation of gut pacemaker activity and neuronal communication. We performed patch clamp on ICC-MY in situ to observe the changes of pacemaker activity in response to neural modulations. METHODS: A fresh longitudinal muscle with myenteric plexus (LMMP) from mouse jejunum was prepared. ICC-MY and ganglion neurons embedded in the layer of longitudinal muscles were targeted by patch clamping in whole-cell configuration in a model of current or voltage clamp. Neurogenic modulators were applied to evaluate their effects on ICC pacemaker activity. RESULTS: In situ ICC-MY showed spontaneous and rhythmical voltage oscillations with a frequency of 27.2 ± 3.9 cycles/min, amplitude of 32.6 ± 6.3 mV, and resting membrane potential of −62.2 ± 2.8 mV. In situ neurons showed electrically evocable action potential in single or multiple spikes. Pacemaker activity was modulated by neuronal activators through receiving a neuronal input. Application of tetrodotoxin depolarized pacemaker potentials in a dose dependent manner, and decreased the amplitude at tetrodotoxin 0.3 μM for about 40 ± 10%; capsaicin (1 μM) ameliorated ICC-MY K+ current for about 49 ± 14.8%; and, nitric oxide hyperpolarized pacemaker potential and decreased the amplitude and frequency. CONCLUSIONS: The in situ preparation patch clamp study further demonstrates that the pacemaker activity is an intrinsic property of ICC. The neurogenic activators change and shape pacemaker potential and activity in situ. LMMP preparation in situ patch clamp provides an ideal platform to study the functional innervation of the ICC and the enteric neural system, thereby, for evaluating the neural regulation of pacemaker activity, especially in disorder models.


Subject(s)
Animals , Mice , Action Potentials , Capsaicin , Constriction , Enteric Nervous System , Ganglion Cysts , Interstitial Cells of Cajal , Jejunum , Membrane Potentials , Muscles , Myenteric Plexus , Neurons , Nitric Oxide , Tetrodotoxin
19.
Brain & Neurorehabilitation ; : e4-2017.
Article in English | WPRIM | ID: wpr-97887

ABSTRACT

Transcranial direct current stimulation (tDCS) is one of the brain stimulation techniques, which considered as an alternative treatment for Alzheimer's disease (AD). In AD, cognitive, behavior, and functional deteriorations are the result of synaptic dysfunction, neural circuit destabilization, and disrupted network activity, which are mainly caused by amyloid and tau deposition. tDCS modified neuronal resting membrane potential, synaptic plasticity, cortical neurotransmitters, astrocytes, cerebral blood flow, and functional connectivity, which could restore cognitive impairment. However, several small clinical studies that have been conducted so far have produced inconsistent results in patients with AD. Therefore, more systematic clinical studies are needed in the future.


Subject(s)
Humans , Alzheimer Disease , Amyloid , Astrocytes , Brain , Cerebrovascular Circulation , Cognition Disorders , Membrane Potentials , Neuronal Plasticity , Neurons , Neurotransmitter Agents , Transcranial Direct Current Stimulation
20.
International Journal of Oral Biology ; : 55-61, 2017.
Article in Korean | WPRIM | ID: wpr-54240

ABSTRACT

Recent studies indicate that mitochondria are an important source of reactive oxygen species (ROS) in the spinal dorsal horn. In our previous study, application of malate, a mitochondrial electron transport complex I substrate, induced a membrane depolarization, which was inhibited by pretreatment with ROS scavengers. In the present study, we used patch clamp recording in the substantia geletinosa (SG) neurons of spinal slices, to investigate the cellular mechanism of mitochondrial ROS on neuronal excitability. DNQX (an AMPA receptor antagonist) and AP5 (an NMDA receptor antagonist) decreased the malate-induced depolarization. In an external calcium free solution and addition of tetrodotoxin (TTX) for blockade of synaptic transmission, the malateinduced depolarization remained unchanged. In the presence of DNQX, AP5 and AP3 (a group I metabotropic glutamate receptor (mGluR) antagonist), glutamate depolarized the membrane potential, which was suppressed by PBN. However, oligomycin (a mitochondrial ATP synthase inhibitor) or PPADS (a P2 receptor inhibitor) did not affect the substrates-induced depolarization. These results suggest that mitochondrial substrate-induced ROS in SG neuron directly acts on the postsynaptic neuron, therefore increasing the ion influx via glutamate receptors.


Subject(s)
Animals , Rats , Calcium , Electron Transport Complex I , Glutamic Acid , Membrane Potentials , Membranes , Mitochondria , Mitochondrial Proton-Translocating ATPases , N-Methylaspartate , Neurons , Oligomycins , Reactive Oxygen Species , Receptors, AMPA , Receptors, Glutamate , Receptors, Metabotropic Glutamate , Spinal Cord Dorsal Horn , Substantia Gelatinosa , Synaptic Transmission , Tetrodotoxin
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