Rapid Decoding of Hand Gestures in Electrocorticography Using Recurrent Neural Networks.

Brain-computer interface (BCI) is a direct communication pathway between brain and external devices, and BCI-based prosthetic devices are promising to provide new rehabilitation options for people with motor disabilities. Electrocorticography (ECoG) signals contain rich information correlated with motor activities, and have great potential in hand gesture decoding. However, most existing decoders use long time windows, thus ignore the temporal dynamics within the period. In this study, we propose to use recurrent neural networks (RNNs) to exploit the temporal information in ECoG signals for robust hand gesture decoding. With RNN's high nonlinearity modeling ability, our method can effectively capture the temporal information in ECoG time series for robust gesture recognition. In the experiments, we decode three hand gestures using ECoG signals of two participants, and achieve an accuracy of 90%. Specially, we investigate the possibility of recognizing the gestures in a time interval as short as possible after motion onsets. Our method rapidly recognizes gestures within 0.5 s after motion onsets with an accuracy of about 80%. Experimental results also indicate that the temporal dynamics is especially informative for effective and rapid decoding of hand gestures.

An automatic patient-specific seizure onset detection method using intracranial electroencephalography.

OBJECTIVE: This study presents a multichannel patient-specific seizure detection method based on the empirical mode decomposition (EMD) and support vector machine (SVM) classifier. MATERIALS AND METHODS: The EMD is used to extract features from intracranial electroencephalography (EEG). A machine-learning algorithm is used as a classifier to discriminate between seizure and nonseizure intracranial EEG epochs. A postprocessing algorithm is proposed to reject artifacts and increase the robustness of the method. The proposed method was evaluated using 463 hours of intracranial EEG recordings from 17 patients with a total of 51 seizures in the Freiburg EEG database. RESULTS: The proposed method had better performance than most of the existing seizure detection systems, including an average sensitivity of 92%, false detection rate (FDR) of 0.17/hour, and time delay (TD) of 12 sec. Moreover, the FDR could be further reduced by a TD extension. CONCLUSIONS: Given its high sensitivity and low FDR, the proposed patient-specific seizure detection method can greatly assist clinical staff with automatically marking seizures in long-term EEG or detecting seizure onset online with high performance. Early and accurate seizure detection using this method may serve as a practical tool for planning epilepsy interventions.

Gradually increased training intensity benefits rehabilitation outcome after stroke by BDNF upregulation and stress suppression.

Physical training is necessary for effective rehabilitation in the early poststroke period. Animal studies commonly use fixed training intensity throughout rehabilitation and without adapting it to the animals' recovered motor ability. This study investigated the correlation between training intensity and rehabilitation efficacy by using a focal ischemic stroke rat model. Eighty male Sprague-Dawley rats were induced with middle cerebral artery occlusion/reperfusion surgery. Sixty rats with successful stroke were then randomly assigned into four groups: control (CG, n = 15), low intensity (LG, n = 15), gradually increased intensity (GIG, n = 15), and high intensity (HG, n = 15). Behavioral tests were conducted daily to evaluate motor function recovery. Stress level and neural recovery were evaluated via plasma corticosterone and brain-derived neurotrophic factor (BDNF) concentration, respectively. GIG rats significantly (P < 0.05) recovered motor function and produced higher hippocampal BDNF (112.87 ± 25.18 ng/g). GIG and LG rats exhibited similar stress levels (540.63 ± 117.40 nM/L and 508.07 ± 161.30 nM/L, resp.), which were significantly lower (P < 0.05) than that (716.90 ± 156.48 nM/L) of HG rats. Training with gradually increased intensity achieved better recovery with lower stress. Our observations indicate that a training protocol that includes gradually increasing training intensity should be considered in both animal and clinical studies for better stroke recovery.

Application of microscopical techniques in the study of autolysosome dynamics in PC12 neurites.

Autophagy is a principal degradation pathway for the turnover of intracellular proteins or cytoplasmic organelles in response to starvation. During autophagic activation, autophagosomes fuse with lysosomes to form autolysosomes where incorporated materials are degraded. However, the dynamics of autolysosomes in neurites of live cells was still poorly known. In this study, various subsets of microscope were applied to analyse the autophagy induction and highly dynamic transport of autolysosomes in rat PC12 neurites. Beading formation was found in degenerating PC12 neurites under phase contrast light microscope after serum deprivation. The monomeric red fluorescence protein-green fluorescence protein-light chain 3-labelled autolysosomes accumulated throughout PC12 neurites after 18 h of serum deprivation as revealed by fluorescence microscope analysis. The single-membrane autolysosomes were also visualized in PC12 cells under transmission electron microscope. Moreover, fluorescence recovery after photobleaching experiment, which was conducted by confocal laser scanning microscope, demonstrated that autolysosomes were motile vesicles and moved along PC12 neurites during starvation. The directional transport of monomeric red fluorescence protein -labelled autolysosomes in neurites was further monitored by a motorized video microscope. Both anterograde and retrograde transport of autolysosomes were observed. In addition, the autolysosomes were precisely mapped by using 2D Gaussian fitting and then their highly dynamic movement was robustly tracked by using multidimensional assignment. Collectively, by using different microscopical techniques, our results confirmed the dynamic transport of autolysosomes in starved PC12 neurites and may provide valuable insight into understanding the biophysical characteristics of autolysosomes in neurites under physiological and pathological conditions.

Microtubule and kinesin/dynein-dependent, bi-directional transport of autolysosomes in neurites of PC12 cells.

Autophagy, a major degradative pathway of the lysosomal system, has been implicated in various neurodegenerative diseases. During autophagic process, organelles and proteins are encapsulated in double-membrane vacuoles called autophagosomes, which finally fuse with lysosomes to form autolysosomes where incorporated materials are degraded. Despite extensive investigations in identifying the molecular components that participate in autophagy, little is known about routes and dynamics of autophagosomes/autolysosomes in the neurites of live cells. Hence, in the present study, we aim to investigate the biophysical characteristics of neuritic transport of autolysosomes in PC12 cells. Our study demonstrated that monomeric red fluorescence protein-light chain 3 (mRFP-LC3)-labeled autolysosomes were motile and moved along PC12 neurites in both anterograde and retrograde directions with a bias towards the nucleus during starvation. By using image processing, quantitative analysis was made to show the dynamic biophysical characteristics of these vesicles. The average velocity of anterograde and retrograde transport was 0.33±0.04µm/s and 0.39±0.05µm/s, respectively. Disruption of microtubules by nocodazole completely abolished their movements, suggesting the neuritic transport of autolysosomes depends on microtubules. The directional transport of autolysosomes was also affected by blockage of motor protein activity. Altogether, our study documents many aspects of the highly dynamic movement of autolysosome in PC12 neurites. Autolysosomes transported in a bi-directional manner along microtubules by dynein and kinesin motor proteins. These findings provide valuable insight into understanding the mechanism and control of autophagy in neurites under physiological and pathological conditions.

The effects of voluntary, involuntary, and forced exercises on brain-derived neurotrophic factor and motor function recovery: a rat brain ischemia model.

BACKGROUND: Stroke rehabilitation with different exercise paradigms has been investigated, but which one is more effective in facilitating motor recovery and up-regulating brain neurotrophic factor (BDNF) after brain ischemia would be interesting to clinicians and patients. Voluntary exercise, forced exercise, and involuntary muscle movement caused by functional electrical stimulation (FES) have been individually demonstrated effective as stroke rehabilitation intervention. The aim of this study was to investigate the effects of these three common interventions on brain BDNF changes and motor recovery levels using a rat ischemic stroke model. METHODOLOGY/PRINCIPAL FINDINGS: One hundred and seventeen Sprague-Dawley rats were randomly distributed into four groups: Control (Con), Voluntary exercise of wheel running (V-Ex), Forced exercise of treadmill running (F-Ex), and Involuntary exercise of FES (I-Ex) with implanted electrodes placed in two hind limb muscles on the affected side to mimic gait-like walking pattern during stimulation. Ischemic stroke was induced in all rats with the middle cerebral artery occlusion/reperfusion model and fifty-seven rats had motor deficits after stroke. Twenty-four hours after reperfusion, rats were arranged to their intervention programs. De Ryck's behavioral test was conducted daily during the 7-day intervention as an evaluation tool of motor recovery. Serum corticosterone concentration and BDNF levels in the hippocampus, striatum, and cortex were measured after the rats were sacrificed. V-Ex had significantly better motor recovery in the behavioral test. V-Ex also had significantly higher hippocampal BDNF concentration than F-Ex and Con. F-Ex had significantly higher serum corticosterone level than other groups. CONCLUSION/SIGNIFICANCE: Voluntary exercise is the most effective intervention in upregulating the hippocampal BDNF level, and facilitating motor recovery. Rats that exercised voluntarily also showed less corticosterone stress response than other groups. The results also suggested that the forced exercise group was the least preferred intervention with high stress, low brain BDNF levels and less motor recovery.

The effects of voluntary, involuntary, and forced exercises on motor recovery in a stroke rat model.

Stroke rehabilitation with different exercise paradigms has been investigated, but a comparison study on motor recovery after voluntary, involuntary, and forced exercises is limited. The current study used a rat brain ischemia model to investigate the effects of voluntary wheel running, involuntary muscle movement caused by functional electrical stimulation (FES), and forced treadmill exercise on motor recovery and brain BDNF changes. The results showed that voluntary exercise is the most effective intervention in upregulating the hippocampal BDNF level, and facilitating motor recovery after brain ischemia.

Neural decoding based on probabilistic neural network.

Brain-machine interface (BMI) has been developed due to its possibility to cure severe body paralysis. This technology has been used to realize the direct control of prosthetic devices, such as robot arms, computer cursors, and paralyzed muscles. A variety of neural decoding algorithms have been designed to explore relationships between neural activities and movements of the limbs. In this paper, two novel neural decoding methods based on probabilistic neural network (PNN) in rats were introduced, the PNN decoder and the modified PNN (MPNN) decoder. In the experiment, rats were trained to obtain water by pressing a lever over a pressure threshold. Microelectrode array was implanted in the motor cortex to record neural activity, and pressure was recorded by a pressure sensor synchronously. After training, the pressure values were estimated from the neural signals by PNN and MPNN decoders. Their performances were evaluated by a correlation coefficient (CC) and a mean square error (MSE). The results show that the MPNN decoder, with a CC of 0.8657 and an MSE of 0.2563, outperformed the traditionally-used Wiener filter (WF) and Kalman filter (KF) decoders. It was also observed that the discretization level did not affect the MPNN performance, indicating that the MPNN decoder can handle different tasks in BMI system, including the detection of movement states and estimation of continuous kinematic parameters.

Salidroside stimulated glucose uptake in skeletal muscle cells by activating AMP-activated protein kinase.

In the present study, we reported the metabolic effects of salidroside, one of the active components of Rhodiola Rosea, on skeletal muscle cells. Salidroside dose-dependently stimulated glucose uptake in differentiated L6 rat myoblast cells. Inhibitor of AMP-activated protein kinase (AMPK) by pretreating the cells with compound C potently reduced salidroside-stimulated glucose uptake, while inhibition of phosphatidylinositol 3-kinase (PI3K) by wortmannin exhibited no significant inhibitory effect on salidroside-mediated glucose transport activation. Western blotting analyses revealed that salidroside increased the phosphorylation level of AMPK and acetyl-CoA carboxylase (ACC). In addition, salidroside enhanced insulin-mediated Akt activation and glucose uptake, and such enhancement can be specifically inhibited by compound C. In summary, AMPK activation was involved in the effects of salidroside on glucose transport activation and insulin sensitivity. Salidroside can be further developed as potential compound for the anti-diabetic therapy.

[Three-dimensional motion analysis for GLUT4 vesicles in TIRF microscopy].

In this paper, GLUT4 vesicles are observed in real-time under TIRF microscopy and a new three-dimensional single particle tracking algorithm according to the unique features of TIRF is put forward. Firstly a fluorescence correction procedure was processed to solve the problem of fluorescence bleaching over time and mobile vesicles were segmented by an adaptive background subtraction method. Kalman filtering was then introduced to track the granules so as to reduce the searching range and to avoid the disturbance of background noise and false targets. In the experiments the algorithm was applied in analyzing the long-distance movement of GLUT4 vesicles. The experimental results indicate that the algorithm has achieved robust tracking of the vesicles in the imaging plane and has effectively calculated the position in the direction orthogonal to the imaging plane.

Dynamics of nitric oxide and peroxynitrite during global brain ischemia/reperfusion in rat hippocampus: NO-sensor measurement and modeling study.

The dynamics of nitric oxide (NO) and peroxynitrite concentration changes during brain ischemia/reperfusion are poorly understood. In this paper, a NO-selective sensor was used to measure NO concentration changes in the rat brain hippocampus during global brain ischemia/reperfusion. Four-vessel occlusion model of transient global brain ischemia was used. Global cerebral ischemia was induced by occluding both common carotid arteries with artery nips (for 20 min) and reperfusion was induced by loosening the artery nips. Results showed that the changes of NO concentration during global brain ischemia/reperfusion could be divided into different stages. Together with the effects of O2 tension changes and NO synthase (NOS) on nitric oxide levels, we determined five stages in the NO concentration profile: (1) acute O2-limited decrease stage; (2) O2-limited steady stage; (3) neuronal NOS activation stage; (4) acute O2-recovery elevation stage; and (5) O2-recovery steady stage. In addition, a chemical reaction network model was constructed to simulate the dynamics of peroxynitrite during the reperfusion stage, and the effects of a change in the NO formation rate on the dynamics of peroxynitrite were investigated specifically. Results show the rate of NO formation has a great influence on peroxynitrite dynamics.

Inhibition of excitatory amino acid efflux contributes to protective effects of puerarin against cerebral ischemia in rats.

OBJECTIVE: To investigate whether the protective effects of puerarine (Pur) against cerebral ischemia is associated with depressing the extracellular levels of amino acid transmitters in brain of rats. METHODS: Male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion (MCAO) for 60 min followed by 24 h reperfusion. Pur (50, 100 mg/kg, i.p.) was administered at the onset of MCAO. The infarct rate and edema rate were detected on TTC (2,3,5-triphenyltetrazolium chloride)-stained coronal sections. The extracellular levels of amino acid transmitters were monitored in striatum of rats with ischemic/reperfusion injury using in vivo microdialysis technique. Furthermore, the protective effects of Pur against glutamate-induced neurotoxicity were detected. Glutamate-induced apoptotic and necrotic cells in hippocampus were estimated by flow cytometric analysis of Annexin-V and PI labeling cells. RESULTS: Pur (100 mg/kg) significantly decreased infarct size by 31.6% (P<0.05), reduced edema volume (P<0.05), and improved neurological functions (P<0.05) following MCAO. In these rats, the ischemia-induced extracellular levels of aspartate (Asp), glutamate (Glu), y-aminobutyric acid (GABA), and taurine (Tau) were significantly reduced in striatum of vehicle-treated animals by 54.7%, 56.7%, 75.8%, and 68.1% (P<0.01 and P<0.05). Pur reduced the peak values of Glu and Asp more obviously than those of GABA and Tau, and the rate of Glu/GABA during MCAO markedly decreased in Pur-treated MCAO rats, compared with the vehicle-treated MCAO rats. Meanwhile, apoptosis and necrosis induced by Glu in cultured hippocampal neurons were significantly reduced after Pur treatment. CONCLUSION: Acute treatment with Pur at the onset of occlusion significantly depresses ischemia-induced efflux of amino acids, especially, excitotoxicity in the striatum, a mechanism underlying the neuroprotective effect on cellular survival.

[Protective effects of breviscapine against cultured rat hippocampal neuronal toxicity induced by glutamate].

The aim of this study was to investigate the effects of breviscapine on cultured rat hippocampal neuronal toxicity induced by glutamate. Primary hippocampal neurons were prepared from 2 day-old SD rats. After 8 days cultured in vitro, the cultures subjected to 30 min treatment of 0.1, 0.5 and 1.0 mmol x L(-1) L-glutamate, separately. Breviscapine (10, 20 and 40 micromol x L(-1)) was added into the cultures during 30 min treatment of L-glutamate and for the following 24 h respectively. After 24 h of L-glutamate treatment, flow cytometric analysis of Annexin V (marks apoptosis) and PI (propidium iodide, marks necrosis) labeling cells showed that L-glutamate dose-dependently induced hippocampal neuronal apoptosis and necrosis. In agreement with these results, RT-PCR experiments indicated a biphasic regulation of X-chromosome-linked inhibitor of apoptosis protein (XIAP) mRNA after L-glutamate treatment, i. e up-regulation by 0.1 mmol x L(-1) L-glutamate and down-regulation by 0.5 and 1.0 mmol x L(-1) L-glutamate. However, breviscapine markedly reduced apoptosis and necrosis due to toxicity of 0.5 mmol L(-1) L-glutamate. Compared with the vehicle-treated L-glutamate group, the apoptosis was reduced by 30.4% and 40.1%, and necrosis was reduced by 32.5% and 38.8%, after treatment by breviscapine of 20 and 40 micromol x L(-1). Meanwhile, breviscapine obviously reversed the down-regulation of XIAP expression induced by L-glutamate (up-regulation by 45.1% and 54.9% when compared with that of the vehicle-treated glutamate group). The results from the detection of confocal laser scanning microscopy with Fluo-3, a Ca2+ probe showed an obvious increase in intracellular Ca2+ during L-glutamate treatment; and breviscapine of 20 or 40 micromol x L(-1) significantly slowed down glutamate-induced Ca2+ influx and lowered the intracellular Ca2+ peak in hippocampal neurons (P < 0.01). These results suggest that neuroprotective effect of breviscapine against glutamate excitotoxicity was associated with inhibition of the accumulation of intracellular Ca2+ and up-regulation of XIAP expression in hippocampal neurons.

B-type natriuretic peptide enhances mild hypoxia-induced apoptotic cell death in cardiomyocytes.

In the case of left ventricle remodeling after myocardial infarction, cardiomyocyte apoptosis is attributed to increased cardiac workload by the stimulus such as chronic hypoxia. B-Type natriuretic peptide, being known as a reliable prognostic of cardiovascular pathology, plays an important role in the myocardial infarction. However, the action of B-type natriuretic peptide on cardiomyocytes undergoing apoptosis is unclear. In the present study, B-type natriuretic peptide have exhibited the enhancive effects on the mild hypoxia-induced cardiomyocyte apoptosis with the manifestation of facilitating phosphatidylserine evagination and increasing typical fragmented nuclei. In addition, B-type natriuretic peptide aggravated the dissipation of delta psi(m), the depletion of intracellular ATP and the increase of caspase-3 activity. 8-Bromo-cGMP, which increased cGMP independent of B-type natriuretic peptide, could mimic B-type natriuretic peptide's effects; whereas cGMP-dependent protein kinase inhibitor, Rp-8-br-cGMP inhibited that. Further study revealed the enhancive effect of BNP on down-regulation of Bcl-2 mRNA expression in the presence of mild hypoxia. In conclusion, the present study demonstrated that B-type natriuretic peptide aggravated the cardiomyocyte apoptosis by influencing hypoxia-induced mitochondrial death pathway, which is true at least in this oxygen deprivation model; and this effect was partially realized through intracellular cGMP.

Bi-directional transport of GLUT4 vesicles near the plasma membrane of primary rat adipocytes.

Insulin stimulates glucose uptake into adipocytes by mobilizing intracellular membrane vesicles containing GLUT4 proteins to the plasma membrane. Here we applied time-lapse total internal reflection fluorescence microscopy to study moving parameters and characters of exogenously expressed GLUT4 vesicles in basal, insulin and nocodazole treated primary rat adipocytes. Our results showed that microtubules were essential for long-range transport of GLUT4 vesicles but not obligatory for GLUT4 distribution in rat adipocytes. Insulin reduced the mobility of the vesicles, made them tethered/docked to the PM and finally had constitutive exocytosis. Moreover, long-range bi-directional movements of GLUT4 vesicles were visualized for the first time by TIRFM. It is likely that there are interactions between insulin signaling and microtubules, to regulating GLUT4 translocation in rat adipocytes.

[Effect of dialysis time in vivo on recovery of amino acids for micro-dialysis probe].

OBJECTIVE: To investigate the variety of vitro recovery of amino acids for microdialysis probe after different dialysis time in vivo. METHODS: Probes were dialyzed in the amino acids standard solutions with microdialysis system,amino acid standard solutions and the microdialysate of probe were detected by the method of precolumn derivation with HPLC-RF. RESULT: After using different time of probe made by regenerated cellulose membrane, the vitro recoveries of Asp, Glu and GABA were not completely same (Asp: F=19.669, P=0.000; Glu: F=103.955, P=0.000; GABA: F=3.454, P=0.040); while the vitro recovery of Tau had no obvious difference(F=2.001, P=0.152). After using 6 h in vivo, recovery remain percentage (RRP) of Asp, Glu,Tau and GABA was 64.34 %, 67.36%, 103.11 % and 98.23 %, respectively, the recoveries of Asp, Glu decreased obviously (Asp: P < 0.01,Glu: P <0.05). After using 12 h in vivo, the RRP of Asp, Glu, Tau and GABA was 43.44 %, 24.42%, 77.45 % and 67.36 %, respectively, the recoveries of Asp, Glu and GABA decreased obviously (Asp: P < 0.001, Glu: P < 0.001, GABA: P < 0.05). After using 24 h in vivo, the RRP of Asp, Glu,Tau and GABA was 36.26 %, 12.24 %, 89.48 % and 71.35 %, respectively, the recoveries of Asp, Glu, GABA decreased obviously (Asp: P < 0.0001, Glu: P < 0.0001, GABA: P < 0.01). CONCLUSION: Dialysis in vivo could lead to the decline of recovery of probe, the decline is more obvious after longer dialysis. So when making brain dialysis experiments, the use time of probe should not be too long. To improve the validity of data, some calibration should be made on the recoveries of probe.

Activity of Ginkgo biloba extract and quercetin on thrombomodulin expression and tissue-type plasminogen activator secretion by human umbilical vein endothelial cells.

OBJECTIVE: In order to investigate the pharmacological properties of Ginkgo biloba extract (GBE) on improving blood circulation, the regulating action of GBE and quercetin (a main flavonoid ingredient in GBE) on thrombomodulin (TM) expression and tissue-type plasminogen activator (t-PA) secretion was studied. METHODS: Using flow cytometer and gel image system respectively, we evaluated the TM expression and the t-PA secretion by human umbilical vein endothelial cells (HUVECs) in vitro. RESULTS: The increase of TM expression on HUVECs surface was induced by GBE rather than quercetin in a dose- and time-dependent manner. Both GBE and quercetin increased the t-PA release significantly. CONCLUSION: The effect of GBE on improving blood circulation may be partly attributed to its promoting TM expression and t-PA secretion by endothelial cells, and quercetin participated in the effect of GBE on t-PA secretion. However, the action of GBE on increasing TM expression needs further study.

Astragaloside IV improved barrier dysfunction induced by acute high glucose in human umbilical vein endothelial cells.

The purpose of the present study was to examine the effects of astragaloside IV, a saponin isolated from Astragalus membranaceus (Fisch) Bge, on the impairment of barrier function induced by acute high glucose in cultured human vein endothelial cells. High glucose (27.8 mM) induced a decrease in transendothelial electrical impedance and an increase in cell monolayer permeability in human umbilical vein endothelial cells. Endothelial barrier dysfunction stimulated by high glucose was accompanied by translocation and activation of protein kinase C (PKC), the redistribution of F-actin and formation of intercellular gaps, suggesting that increases in PKC activity and rearrangement of F-actin could be associated with endothelial barrier dysfunction induced by acute high glucose. Application of astragaloside IV inhibited high glucose-induced endothelial barrier dysfunction in a dose-dependent manner, which is compatible with inhibition of PKC translocation and improvement of F-actin rearrangements. Western blot analysis revealed that high glucose-induced PKC alpha and beta2 overexpression in the membrane fraction were significantly reduced by astragaloside IV. These findings indicate that astragaloside IV protected endothelial cells from high glucose-induced barrier impairment by inhibiting PKC activation, as well as improving cytoskeleton remodeling.

A preadipocyte differentiation assay as a method for screening potential anti-type II diabetes drugs from herbal extracts.

A cell-based method for screening drug candidates from herbal extracts that have possible anti-type II diabetic effects was established. The differentiation of preadipocytes into adipocytes was used as a sensitive primary indicator of a drug's potential effect on type II diabetes. We established a quantitative method by using a computer image analysis system for assessing the morphological alterations. The assay was validated by screening compounds extracted from Chinese herbs and the known drug rosiglitazone for their capability of modulating PPARgamma gene expression and glucose uptake by adipocytes. Two drug candidates having possible anti-type II diabetic effects were identified.

Effects of astragaloside IV on pathogenesis of metabolic syndrome in vitro.

AIM: To investigate the diverse pharmacological actions of astragaloside IV from the perspective of metabolic syndrome, and to investigate the effect of the drug on the pathogenesis of metabolic syndrome. METHODS: Adipogenesis was used as an indicator of the effect of astragaloside IV on preadipocyte differentiation, and was measured by using an oil red O assay. Glucose uptake was determined by measuring the transport of [2-(3)H]-deoxyglucose into the cells. The concentrations of peroxisome proliferator-activated receptor-gamma (PPARgamma) and aP2 mRNA were determined by using reverse transcription-polymerase chain reaction. Apoptosis and viability loss of endothelial cells were detected by using flow cytometry and the WST-1 assay, respectively. Intracellular free Ca2+ was labeled with Fluo-3 AM and measured by using a laser scanning confocal microscope. RESULTS: Astragaloside IV can significantly potentiate insulin-induced preadipocyte differentiation at concentrations of 3, 10, and 30 microg/mL, improve high glucose-induced insulin resistance in adipocytes at a concentration of 30 microg/mL, and prevent tumor necrosis factor (TNF)-alpha-induced apoptosis and viability loss at concentrations of 10 and 30 microg/mL, and 30 microg/mL, respectively, in endothelial cells. Furthermore, we found that these effects were partly due to the promotion of PPARgamma expression and to the inhibition of abnormal TNF-alpha-induced intracellular free Ca(2+) accumulation in endothelial cells. CONCLUSION: The diverse pharmacological actions of astragaloside IV can all be linked to metabolic syndrome pathogenesis. Our study provides a new insight into the mechanism by which astragaloside IV exerts its effect.