Prolonged Electrical Stimulation Research Articles

Stability of Conducting Polymer-Coated Carbon Microfibers for Long-Term Electrical Stimulation of Injured Neural Tissue.

Electroactive microfiber-based scaffolds aid neural tissue repair. Carbon microfibers (CMFs) coated with the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly[(4-styrenesulfonic acid)-co-(maleic acid)] (PEDOT:PSS-co-MA) provide efficient support and guidance to regrowing axons across spinal cord lesions in rodents and pigs. We investigated the electrical and structural performance of PEDOT:PSS-co-MA-coated carbon MFs (PCMFs) for long-term, biphasic electrical stimulation (ES). Chronopotentiometry and electrochemical impedance spectroscopy (EIS) allowed the characterization of charge transfer in PCMFs during ES in vitro, and morphological changes were assessed by scanning electron microscopy (SEM). PCMFs that were 4 mm long withstood two-million-biphasic pulses without reaching cytotoxic voltages, with a 6 mm length producing optimal results. Although EIS and SEM unveiled some polymer deterioration in the 6 mm PCMFs, no significant changes in voltage excursions appeared. For the preliminary testing of the electrical performance of PCMFs in vivo, we used 12 mm long, 20-microfiber assemblies interconnected by metallic microwires. PCMFs-assemblies were implanted in two spinal cord-injured pigs and submitted to ES for 10 days. A cobalt-alloy interconnected assembly showed safe voltages for about 1.5 million-pulses and was electrically functional at 1-month post-implantation, suggesting its suitability for sub-chronic ES, as likely required for spinal cord repair. However, improving polymer adhesion to the carbon substrate is still needed to use PCMFs for prolonged ES.

Batch Fabrication of Microelectrode Arrays with Glassy Carbon Microelectrodes and Interconnections for Neurochemical Sensing: Promises and Challenges.

Flexible multielectrode arrays with glassy carbon (GC) electrodes and metal interconnection (hybrid MEAs) have shown promising performance in multi-channel neurochemical sensing. A primary challenge faced by hybrid MEAs fabrication is the adhesion of the metal traces with the GC electrodes, as prolonged electrical and mechanical stimulation can lead to adhesion failure. Previous devices with GC electrodes and interconnects made of a homogeneous material (all GC) demonstrated exceptional electrochemical stability but required miniaturization for enhanced tissue integration and chronic electrochemical sensing. In this study, we used two different methods for the fabrication of all GC-MEAs on thin flexible substrates with miniaturized features. The first method, like that previously reported, involves a double pattern-transfer photolithographic process, including transfer-bonding on temporary polymeric support. The second method requires a double-etching process, which uses a 2 µm-thick low stress silicon nitride coating of the Si wafer as the bottom insulator layer for the MEAs, bypassing the pattern-transfer and demonstrating a novel technique with potential advantages. We confirmed the feasibility of the two fabrication processes by verifying the practical conductivity of 3 µm-wide 2 µm-thick GC traces, the GC microelectrode functionality, and their sensing capability for the detection of serotonin using fast scan cyclic voltammetry. Through the exchange and discussion of insights regarding the strengths and limitations of these microfabrication methods, our goal is to propel the advancement of GC-based MEAs for the next generation of neural interface devices.

Alternating current stimulation promotes neurite outgrowth and plasticity in neurons through activation of the PI3K/AKT signaling pathway.

As a commonly used physical intervention, electrical stimulation (ES) has been demonstrated to be effective in the treatment of central nervous system disorders. Currently, researchers are studying the effects of electrical stimulation on individual neurons and neural networks, which are dependent on factors such as stimulation intensity, duration, location, and neuronal properties. However, the exact mechanism of action of electrical stimulation remains unclear. In some cases, repeated or prolonged electrical stimulation can lead to changes in the morphology or function of the neuron. In this study, immunofluorescence staining and Sholl analysis are used to assess changes in the neurite number and axon length to determine the optimal pattern and stimulation parameters of ES for neurons. Neuronal death and plasticity are detected by TUNEL staining and microelectrode array assays, respectively. mRNA sequencing and bioinformatics analysis are applied to predict the key targets of the action of ES on neurons, and the identified targets are validated by western blot analysis and qRT-PCR. The effects of alternating current stimulation (ACS) on neurons are more significant than those of direct current stimulation (DCS), and the optimal parameters are 3 μA and 20 min. ACS stimulation significantly increases the number of neurites, the length of axons and the spontaneous electrical activity of neurons, significantly elevates the expression of growth-associated protein-43 (GAP-43) without significant changes in the expression of neurotrophic factors. Furthermore, application of PI3K/AKT-specific inhibitors significantly abolishes the beneficial effects of ACS on neurons, confirming that the PI3K/AKT pathway is an important potential signaling pathway in the action of ACS.

Bipolar cells containing protein kinase Cα mediate attentional facilitation of the avian retinal ganglion cells by the retinopetal signal.

Birds have a well-developed retinopetal system projecting from the midbrain to the contralateral retina. The signal sent to the retina through the retinopetal system facilitates visual responses of the retinal ganglion cells (RGCs), and the retinopetal signals function as attentional signals during visual search. Thus, the retinopetal signal somehow reaches and facilitates visual responses of the RGCs. However, the tertiary neuron of the retinopetal system, the isthmo-optic target cell (IOTC), is unlikely to contact most RGCs directly, because the IOTCs form axon terminals localized in the outermost sublayer (lamina 1) of the inner plexiform layer (IPL) where few RGC dendrites terminate. Therefore, some other intrinsic retinal neurons must be involved in the centrifugal attentional enhancement of visual responses of the RGCs. We investigated connections of the target cells of the IOTCs in chicken and quail, using light and electron microscopic immunohistochemistry. We show that axon terminals of the IOTC make synaptic contacts with protein kinase Cα (PKCα)-immunoreactive (ir) bipolar cells (PKCα-BCs) in lamina 1 of the IPL. Furthermore, with prolonged electrical stimulation of the isthmo-optic nucleus (ION) on one side, whose neurons send their axons to the contralateral retina and make synaptic contacts there with IOTCs, phosphorylation of cAMP response element-binding protein was observed in the PKCα-BCs in the contralateral retina, but not in the ipsilateral retina. This suggests that electrical stimulation of ION activated PKCα-BCs through synapses from IOTCs to PKCα-BCs, thus stimulating transcription in PKCα-BCs. Thus, centrifugal attentional signals may facilitate visual responses of RGCs via the PKCα-BCs.

Ping-pong gaze with “staircase” saccades in coma: An oculographic analysis using EEG (P3-9.005)

<h3>Objective:</h3> We report two cases of comatose patients with saccadic ping-pong gaze and the oculographic analyses of these eye movements using EEG only. <h3>Background:</h3> Ping-pong gaze is a form of periodic alternating gaze deviation in coma with each cycle lasting for a few seconds. These eye movements are typically described as “smooth”. Saccadic ping-pong gaze has been rarely described. The underlying anatomy and physiology are poorly understood. <h3>Design/Methods:</h3> We analyzed the eye movement artifact in two comatose patients. The eye acts like an electrical dipole with the anterior being more positive than the posterior. This leads to a characteristic movement artifact on EEG, which can be used to study the type and direction of eye movements. In this study, we analyzed multiple pages of the eye movement artifact on EEG for both patients. We used a prolonged time constant (TC) of 10s to characterize eye position and direction. A prolonged TC gets as close as possible to DC oculographic analysis. <h3>Results:</h3> Both patients demonstrated ping-pong gaze on EEG analysis, alternating direction every 2–5 seconds. In the patient with anoxic brain injury, the eye movement was smooth and it acquired a saccadic character when patient was stimulated. In the patient with hyperammonemic encephalopathy, the transition between smooth and saccadic was spontaneous. When the saccadic phase was analyzed with TC=10s, the waveform appeared like a “staircase” of saccades, marching toward one extreme over 2–5 seconds and then immediately switching direction. <h3>Conclusions:</h3> We report a novel finding of ping-pong gaze with “staircase” saccades in coma. Staircase saccades have been elicited by prolonged electrical stimulation of superior colliculus. We suggest that the presence of such eye movements indicate a supra-collicular level of injury, whereas isolated smooth ping-pong gaze likely indicates an infra-collicular level of injury. This could reflect a “lighter” state of consciousness in coma. <b>Disclosure:</b> Dr. Fotedar has nothing to disclose.

Initial Variability and Time-Dependent Changes of Neuronal Response Features Are Cell-Type-Specific.

Different cell types are commonly defined by their distinct response features. But several studies proved substantial variability between cells of the same type, suggesting rather the appraisal of response feature distributions than a limitation to “typical” responses. Moreover, there is growing evidence that time-dependent changes of response features contribute to robust and functional network output in many neuronal systems. The individually characterized Touch (T), Pressure (P), and Retzius (Rz) cells in the medicinal leech allow for a rigid analysis of response features, elucidating differences between and variability within cell types, as well as their changes over time. The initial responses of T and P cells to somatic current injection cover a wide range of spike counts, and their first spike is generated with a high temporal precision after a short latency. In contrast, all Rz cells elicit very similar low spike counts with variable, long latencies. During prolonged electrical stimulation the resting membrane potential of all three cell types hyperpolarizes. At the same time, Rz cells reduce their spiking activity as expected for a departure from the spike threshold. In contrast, both mechanoreceptor types increase their spike counts during repeated stimulation, consistent with previous findings in T cells. A control experiment reveals that neither a massive current stimulation nor the hyperpolarization of the membrane potential is necessary for the mechanoreceptors’ increase in excitability over time. These findings challenge the previously proposed involvement of slow K+-channels in the time-dependent activity changes. We also find no indication for a run-down of HCN channels over time, and a rigid statistical analysis contradicts several potential experimental confounders as the basis of the observed variability. We conclude that the time-dependent change in excitability of T and P cells could indicate a cell-type-specific shift between different spiking regimes, which also could explain the high variability in the initial responses. The underlying mechanism needs to be further investigated in more naturalistic experimental situations to disentangle the effects of varying membrane properties versus network interactions. They will show if variability in individual response features serves as flexible adaptation to behavioral contexts rather than just “randomness”.

Characterising seizure development, behavioural comorbidities and neuroinflammation in a self-sustained electrical status epilepticus model of mesial temporal lobe epilepsy in C57BL/6J mice

ObjectiveStatus epilepticus (SE) models in rodents are commonly used to research mesial temporal lobe epilepsy (mTLE) in translational epilepsy research. However, due to differences in susceptibility of mice strains to chemoconvulsants, developing this model in mice is challenging. Mice offer experimental advantages; in particular, the ability to use transgenic strains could provide novel insights about neurobiological mechanisms or ease of genetic modification to test potential therapeutic targets. This study aimed to characterise the neuroinflammation, epileptic seizures and behavioural comorbidities after self-sustained Electrical Status Epilepticus (SSSE) in C57BL/6J mice. MethodsSSSE was induced in C57BL/6J mice via prolonged electrical stimulation through a bipolar electrode implanted in the ventral hippocampus. Video electroencephalography (vEEG) monitoring was then performed between 1st month (acute timepoint) and 4th month (chronic timepoint). Brain tissues were collected at two timepoints for gene expression and immunohistochemical analysis: 7-days and 16-weeks post-SE. Additionally, at the chronic timepoint, animals underwent a series of neurobehavioural tests. ResultsSixty percent of animals that underwent SSSE developed spontaneous seizures within the first month, and an additional 25% developed seizures at the chronic timepoint. The number of seizures per week during the chronic period ranged from 0.2 to 15.7. Mortality rate was ~9% during or after SSSE. SSSE animals displayed significant spatial memory impairment and depression-like behaviour compared to sham animals. mRNA expression of inflammatory cytokines was upregulated at 7-days following SE, but equal to sham levels at 16-weeks. SignificanceThis study provides evidence that SSSE in C57BL/6J mice induces epileptic seizures consistent with those seen in patients with mTLE, along with cognitive and behavioural comorbidities. This model therefore has the potential to be used experimentally to uncover mechanisms to target against epileptogenesis, or to test novel treatment approaches.

The effect of canakinumab on COVID19-associated cardiomyocyte contractile dysfunction and arrhythmias

Abstract Background Cardiac injury associated with cytokine release occurs in almost 20% of SARS-CoV-2 positive patients during hospitalization and mortality is particularly high in these patients. Cardiac enzyme (e.g. troponin or creatinine kinase (CK)) elevations are a frequently reported finding, indicating myocardial damage and arrhythmias are the cause for ICU transfer in up to 12% of patients. However, the mechanistic role of COVID19 associated cytokine-storm for the concomitant cardiac dysfunction and associated arrhythmias is unclear. In addition, the role of anti-inflammatory therapy approaches to mitigate this cardiac dysfunction remains elusive. Methods We investigated the effects of COVID19-associated inflammatory response on cardiac cellular function as well as its cardiac arrhythmogenic potential in rat and induced pluripotent stem cell derived cardiomyocytes (iPSc-CM). Moreover, we evaluated the therapeutic potential of the IL1-beta antagonist Canakinumab using state of the art in-vitro confocal and ratiometric high-throughput microscopy. Results Isolated rat ventricular cardiomyocytes were exposed to control or COVID19 plasma from intensive care unit patients with severe ARDS and impaired cardiac function (LVEF 41±5%; 1/3 of patients on veno-venous extracorporeal membrane oxygenation; CK 154±43 U/l). Cardiomyocytes showed decreased Ca2+ transient amplitudes and altered baseline Ca2+ concentrations leading to impaired cellular contractile function upon electrical field-stimulation and exposure to patient plasma (n=276 control and 359 COVID19 cells; Fura). In addition, we used iPSc-CM to explore the long-term effect of patient plasma on cardiac electrical and mechanical function in a translational setting (24h incubation; Fluo). In iPSc, spontaneous Ca2+ release events (i.e. Ca2+ waves and Ca2+ sparks) were more likely to occur upon incubation with COVID19 plasma and nuclear as well as cytosolic Ca2+ release were altered. Co-incubation with Canakinumab had no effect on pro-arrhythmogenic Ca2+ release or Ca2+ signaling during excitation-contraction coupling but influenced cellular automaticity upon prolonged electrical stimulation. Conclusion Plasma derived from COVID19 patients exerts acute cardio-depressant and chronic pro-arrhythmogenic effects in rat and iPS-derived cardiomyocytes. Chronic co-incubation with Canakinumab had no beneficial effect on cellular Ca2+ signaling during excitation-contraction coupling. Funding Acknowledgement Type of funding sources: None.

Two-photon calcium imaging of neuronal and astrocytic responses: the influence of electrical stimulus parameters and calcium signaling mechanisms

Objective. Electrical brain stimulation has been used to ameliorate symptoms associated with neurologic and psychiatric disorders. The astrocytic activation and its interaction with neurons may contribute to the therapeutic effects of electrical stimulation. However, how the astrocytic activity is affected by electrical stimulation and its calcium signaling mechanisms remain largely unknown. This study is to explore the influence of electrical stimulus parameters on cellular calcium responses and corresponding calcium signaling mechanisms, with a focus on the heretofore largely overlooked astrocytes. Approach. Using in vivo two-photon microscopy in mouse somatosensory cortex, the calcium activity in neurons and astrocytes were recorded. Main results. The cathodal stimulation evoked larger responses in both neurons and astrocytes than anodal stimulation. Both neuronal and astrocytic response profiles exhibited the unimodal frequency dependency, the astrocytes prefer higher frequency stimulation than neurons. Astrocytes need longer pulse width and higher current intensity than neurons to activate. Compared to neurons, the astrocytes were not capable of keeping sustained calcium elevation during prolonged electrical stimulation. The neuronal Ca2+ influx involves postsynaptic effects and direct depolarization. The Ca2+ surge of astrocytes has a neuronal origin, the noradrenergic and glutamatergic signaling act synergistically to induce astrocytic activity. Significance. The astrocytic activity can be regulated by manipulating stimulus parameters and its calcium activation should be fully considered when interpreting the mechanisms of action of electrical neuromodulation. This study brings considerable benefits in the application of electrical stimulation and provides useful insights into cortical signal transduction, which contributes to the understanding of mechanisms underlying the therapeutic efficacy of electrical stimulation for neurorehabilitation applications.

Electrical stimulation of hindlimb skeletal muscle has beneficial effects on sublesional bone in a rat model of spinal cord injury.

Spinal cord injury (SCI) results in marked atrophy of sublesional skeletal muscle and substantial loss of bone. In this study, the effects of prolonged electrical stimulation (ES) and/or testosterone enanthate (TE) on muscle mass and bone formation in a rat model of SCI were tested. Compared to sham-transected animals, a significant reduction of the mass of soleus, plantaris and extensor digitorum longus (EDL) muscles was observed in animals 6weeks post-SCI. Notably, ES or ES+TE resulted in the increased mass of the EDL muscles. ES or ES+TE significantly decreased mRNA levels of muscle atrophy markers (e.g., MAFbx and MurF1) in the EDL. Significant decreases in bone mineral density (BMD) (-27%) and trabecular bone volume (-49.3%) at the distal femur were observed in animals 6weeks post injury. TE, ES and ES+TE treatment significantly increased BMD by +6.4%, +5.4%, +8.5% and bone volume by +22.2%, and +56.2% and+ 60.2%, respectively. Notably, ES alone or ES+TE resulted in almost complete restoration of cortical stiffness estimated by finite element analysis in SCI animals. Osteoblastogenesis was evaluated by colony-forming unit-fibroblastic (CFU-F) staining using bone marrow mesenchymal stem cells obtained from the femur. SCI decreased the CFU-F+ cells by -56.8% compared to sham animals. TE or ES+TE treatment after SCI increased osteoblastogenesis by +74.6% and +67.2%, respectively. An osteoclastogenesis assay revealed significantly increased TRAP+ multinucleated cells (+34.8%) in SCI animals compared to sham animals. TE, ES and TE+ES treatment following SCI markedly decreased TRAP+ cells by -51.3%, -40.3% and -46.9%, respectively. Each intervention greatly reduced the ratio of RANKL to OPG mRNA of sublesional long bone. Collectively, our findings demonstrate that after neurologically complete paralysis, dynamic muscle resistance exercise by ES reduced muscle atrophy, downregulated genes involved in muscle wasting, and restored mechanical loading to sublesional bone to a degree that allowed for the preservation of bone by inhibition of bone resorption and/or by facilitating bone formation.

Excitation of the Pre-frontal and Primary Visual Cortex in Response to Transcorneal Electrical Stimulation in Retinal Degeneration Mice

Retinal degeneration (rd) is one of the leading causes of blindness in the modern world today. Various strategies including electrical stimulation are being researched for the restoration of partial or complete vision. Previous studies have demonstrated that the effectiveness of electrical stimulation in somatosensory, frontal and visual cortices is dependent on stimulation parameters including stimulation frequency and brain states. The aim of the study is to investigate the effect of applying a prolonged electrical stimulation on the eye of rd mice with various stimulation frequencies, in awake and anesthetized brain states. We recorded spontaneous electrocorticogram (ECoG) neural activity in prefrontal cortex and primary visual cortex in a mouse model of retinitis pigmentosa (RP) after prolonged (5-day) transcorneal electrical stimulation (pTES) at various frequencies (2, 10, and 20 Hz). We evaluated the absolute power and coherence of spontaneous ECoG neural activities in contralateral primary visual cortex (contra Vcx) and contralateral pre-frontal cortex (contra PFx). Under the awake state, the absolute power of theta, alpha and beta oscillations in contra Vcx, at 10 Hz stimulation, was higher than in the sham group. Under the anesthetized state, the absolute power of medium-, high-, and ultra-high gamma oscillations in the contra PFx, at 2 Hz stimulation, was higher than in the sham group. We also observed that the ultra-high gamma band coherence in contra Vcx-contra PFx was higher than in the sham group, with both 10 and 20 Hz stimulation frequencies. Our results showed that pTES modulates rd brain oscillations in a frequency and brain state-dependent manner. These findings suggest that non-invasive electrical stimulation of retina changes patterns of neural oscillations in the brain circuitry. This also provides a starting point for investigating the sustained effect of electrical stimulation of the retina to brain activities.

Mechanistic insights into store-operated Ca2+ entry during excitation-contraction coupling in skeletal muscle

Skeletal muscle fibres support store-operated Ca2+-entry (SOCE) across the t-tubular membrane upon exhaustive depletion of Ca2+ from the sarcoplasmic reticulum (SR). Recently we demonstrated the presence of a novel mode of SOCE activated under conditions of maintained [Ca2+]SR. This phasic SOCE manifested in a fast and transient manner in synchrony with excitation contraction (EC)-coupling mediated SR Ca2+-release (Communications Biology 1:31, doi: https://doi.org/10.1038/s42003-018-0033-7). Stromal interaction molecule 1 (STIM1) and calcium release-activated calcium channel 1 (ORAI1), positioned at the SR and t-system membranes, respectively, are the considered molecular correlate of SOCE. The evidence suggests that at the triads, where the terminal cisternae of the SR sandwich a t-tubule, STIM1 and ORAI1 proteins pre-position to allow for enhanced SOCE transduction.Here we show that phasic SOCE is not only shaped by global [Ca2+]SR but provide evidence for a local activation within nanodomains at the terminal cisternae of the SR. This feature may allow SOCE to modulate [Ca2+]SR during EC coupling. We define SOCE to occur on the same timescale as EC coupling and determine the temporal coherence of SOCE activation to SR Ca2+ release. We derive a delay of 0.3 ms reflecting diffusive Ca2+-equilibration at the luminal ryanodine receptor 1 (RyR1) channel mouth upon SR Ca2+-release. Numerical simulations of Ca2+-calsequestrin binding estimates a characteristic diffusion length and confines an upper limit for the spatial distance between STIM1 and RyR1. Experimental evidence for a 4- fold change in t-system Ca2+-permeability upon prolonged electrical stimulation in conjunction with numerical simulations of Ca2+-STIM1 binding suggests a Ca2+ dissociation constant of STIM1 below 0.35 mM. Our results show that phasic SOCE is intimately linked with RyR opening and closing, with only μs delays, because [Ca2+] in the terminal cisternae is just above the threshold for Ca2+ dissociation from STIM1 under physiological resting conditions.This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.

Intense Activity of the Raphe Spinal Pathway Depresses Motor Activity via a Serotonin Dependent Mechanism.

Motor fatigue occurring during prolonged physical activity has both peripheral and central origins. It was previously demonstrated that the excitability of motoneurons was decreased when a spillover of serotonin could activate extrasynaptic 5-HT1A receptors at the axon initial segment (AIS) of motoneurons. Here we investigated the impact of massive synaptic release of serotonin on motor behavior in an integrated preparation of the adult turtle performing fictive scratching behaviors. We found that a prolonged electrical stimulation of the raphe spinal pathway induced a reversible inhibition of the motor behavior that lasted several tens of seconds. The effect disappeared when the spinal cord was perfused with an antagonist for 5-HT1A receptors. By demonstrating a direct impact of serotonin on motor behavior, we suggest a central role of this monoamine behind central fatigue.

Some Autonomic Deficits of Acute or Chronic Cervical Spinal Contusion Reversed by Interim Brainstem Stimulation.

Prolonged electrical stimulation of the hindbrain's nucleus raphe magnus (NRM) or of its major midbrain input region, the periaqueductal gray (PAG), was previously found in rats to promote recovery from sensory-motor and histological deficits of acute thoracic spinal cord injury (SCI). Here, some visceral deficits of acute and chronic midline cervical (C5) contusion are similarly examined. Cranially implanted wireless stimulators delivered intermittent 8 Hz, 30-70 μA cathodal pulse trains to a brainstem microelectrode. Injured controls were given inactive stimulators; rats without injuries or implants were also compared. Rectal distension or squeezing of the forepaws caused an exaggerated rise in mean arterial pressure in injured, untreated rats under anesthesia on post-injury week 6, probably reflecting autonomic dysreflexia (AD). These pressor responses became normal when 7 days of unilateral PAG stimulation was started on the injury day. Older untreated injuries (weeks 18-19) showed normal pressor responses, but unexpectedly had significant resting and nociceptive bradycardia, which was reversed by 3 weeks of PAG stimulation started on weeks 7 or 12. Subsequent chronic studies examined gastric emptying (GE), as indicated by intestinal transit of gavaged dye, and serum chemistry. GE and fasting serum insulin were reduced on injury weeks 14-15, and were both normalized by ∼5 weeks of PAG stimulation begun in weeks 7-8. Increases in calcitonin gene-related peptide, a prominent visceral afferent neurotransmitter, measured near untreated injuries (first thoracic segment) in superficial dorsal laminae were reversed by acutely or chronically initiated PAG stimulation. The NRM, given 2-3 weeks of stimulation beginning 2 days after SCI, prevented abnormalities in both pressor responses and GE on post-injury week 9, consistent with its relaying of repair commands from the PAG. The descending PAG-NRM axis thus exhibits broadly restorative influences on visceral as well as sensory-motor deficits, improving chronic as well as acute signs of injury.

NaV1.7 and pain: contribution of peripheral nerves.

The sodium channel NaV1.7 contributes to action potential (AP) generation and propagation. Loss-of-function mutations in patients lead to congenital indifference to pain, though it remains unclear where on the way from sensory terminals to central nervous system the signalling is disrupted. We confirm that conditional deletion of NaV1.7 in advillin-expressing sensory neurons leads to impaired heat and mechanical nociception in behavioural tests. With single-fiber recordings from isolated skin, we found (1) a significantly lower prevalence of heat responsiveness to normally mechanosensitive C-fibers, although (2) the rare heat responses seemed quite vigorous, and (3) heat-induced calcitonin gene-related peptide release was normal. In biophysical respects, although electrical excitability, rheobase, and chronaxy were normal, (4) axonal conduction velocity was 20% slower than in congenic wild-type mice (5) and when challenged with double pulses (<100 milliseconds interval), the second AP showed more pronounced latency increase (6). On prolonged electrical stimulation at 2 Hz, (7) activity-dependent slowing of nerve fiber conduction was markedly less, and (8) was less likely to result in conduction failure of the mutant single fibers. Finally, recording of compound APs from the whole saphenous nerve confirmed slower conduction and less activity-dependent slowing as well as the functional absence of a large subpopulation of C-fibers (9) in conditional NaV1.7 knockouts. In conclusion, the clear deficits in somatic primary afferent functions shown in our study may be complemented by previously reported synaptic dysfunction and opioidergic inhibition, together accounting for the complete insensitivity to pain in the human mutants lacking NaV1.7.

Comparing the Effects of Acupuncture and Pharmacologic Therapies on Delayed Gastric Emptying: A Prospective, Block-Randomized, Single-Blinded, Parallel Clinical Trial

Background: Nutritional therapy in the forms of parenteral or enteral nutrition is an important factor of care and appears to positively impact the clinical outcomes of critically ill patients. Objectives: This study aimed to compare the effects of acupuncture and prokinetic drugs on delayed gastric emptying (DGE) in intensive care unit patients. Methods: In a prospective, block-randomized, single-blinded, parallel group trial, 60 fully sedated, mechanically ventilated surgical patients were enrolled in two groups with 30 patients in each group in Besat hospital in Hamadan, Iran from February 2011 to October 2012. Patients in the drug treatment group received 10 mg of IV metoclopramide every eight hours. For patients with whom persistent DGE was seen, 500 mg of IV erythromycin every 24 hours was added. Patients in the acupuncture group received bilateral prolonged intermittent transcutaneous electrical acupoint stimulation of acupuncture point Neiguan. The intervention was performed for six consecutive days or until the cessation of gradual residual volume. Results: A demographic analysis of the participants revealed no significant differences between groups (P > 0.05). Although the results of the RANOVA model for DGE did not show a significant time trend (P > 0.05) in both acupuncture and drug groups, comparing means of the both acupuncture and drug groups in all the time points after the intervention were significant (P = 0.024): 711.83 ± 193.28 vs. 755.00 ± 166.79 (P = 0.358), 564.17 ± 672.35 vs. 628.50 ± 176.77 (P = 0.614), 324.00 ± 146.49 vs. 472.00 ± 188.47 (P < 0.001), 209.00 ± 136.34 vs. 340.00 ± 211.89 (P < 0.006), 152.67 ± 118.93l vs. 276.17 ± 202.43 (P < 0.006), and 119.67 ± 101.59 vs. 225.67 ± 184.22 (P < 0.008) from the first to last steps, respectively. Conclusions: Although neither acupuncture nor the drug interventions had significant effects on the improvement and obviation of DGE, the acupuncture had greater effects than prokinetic drugs on the reduction of DGE.

Prolonged electrical stimulation causes no damage to sacral nerve roots in rabbits.

Previous studies have shown that, anode block electrical stimulation of the sacral nerve root can produce physiological urination and reconstruct urinary bladder function in rabbits. However, whether long-term anode block electrical stimulation causes damage to the sacral nerve root remains unclear, and needs further investigation. In this study, a complete spinal cord injury model was established in New Zealand white rabbits through T9–10 segment transection. Rabbits were given continuous electrical stimulation for a short period and then chronic stimulation for a longer period. Results showed that compared with normal rabbits, the structure of nerve cells in the anterior sacral nerve roots was unchanged in spinal cord injury rabbits after electrical stimulation. There was no significant difference in the expression of apoptosis-related proteins such as Bax, Caspase-3, and Bcl-2. Experimental findings indicate that neurons in the rabbit sacral nerve roots tolerate electrical stimulation, even after long-term anode block electrical stimulation.

Computational modeling of chemotactic signaling and aggregation of microglia around implantation site during deep brain stimulation

It is well established that prolonged electrical stimulation of brain tissue causes massive release of ATP in the extracellular space. The released ATP and the products of its hydrolysis, such as ADP and adenosine, become the main elements mediating chemotactic sensitivity and motility of microglial cells via subsequent activation of P2Y2,12 as well as A3A and A2A adenosine receptors. The size of the sheath around the electrode formed by the microglial cells is an important criterion for the optimization of the parameters of electrical current delivered to brain tissue. Here, we study a purinergic signaling pathway underlying the chemotactic motion of microglia towards the implanted electrode during deep brain stimulation. We present a computational model describing formation of a stable aggregate around the implantation site due to the joint chemo-attractive action of ATP and ADP together with a mixed influence of extracellular adenosine. The model was built in accordance with the classical Keller-Segel approach and includes an equation for the cells’ density as well as equations describing the hydrolysis of extracellular ATP via successive reaction steps ATP →ADP →AMP →adenosine. The results of our modeling allowed us to reveal the dependence of the width of the encapsulating layer around the electrode on the amount of ATP released due to permanent electrical stimulation. The dependences of the aggregates’ size on the parameter governing the nonlinearity of interaction between extracellular adenosine and adenosine receptors are also analyzed.

Chronic invasive electrical stimulation at treatment of obstetric brachial plexus injury

Introduction. Annually up 0.35 to 5 to 1000 of newborns suffer severe injury of brachial plexus at delivery. The majority of newborns require surgery to restore proper functioning of brachial plexus. Materials and methods. 22 patients with implications of injury of brachial plexus at delivery underwent surgery during which the electrical stimulation system has been implanted. We performed neurolysis and decompression of neural structures of brachial plexus in all of patients, followed by implantation of platinum-based electrodes upon abovementioned neural structures of brachial plexus. Every single patient who underwent surgery applied individual system for prolonged electrical stimulation “Нейси-3M”. This individual system allows one to perform electrical stimulation several times a day during a long period of time, this approach significantly increases the efficacy of treatment. Results. In 19 (86%) patients range of motion improved significantly, strength of muscles of shoulder and upper extremity, sensation also improved significantly. Conclusion. Prolonged electrical stimulation of structures of brachial plexus is safe and effective method of influence on functional status of injured at delivery neuromuscular apparatus of upper extremity.

Effect of combined thermal and electrical muscle stimulation on cardiorespiratory fitness and adipose tissue in obese individuals

To better understand how prolonged electrical muscle stimulation can improve cardiorespiratory risk markers in obese subjects, we investigated the effect of prolonged combined thermal and electrical muscle stimulation (cTEMS) on peak oxygen consumption (VO2peak) and body composition with subsequent lipolytic and mitochondrial activity in adipocytes. Eleven obese (BMI ≥ 30 kg/m(2)) individuals received cTEMS in three 60-minute sessions per week for 8 weeks. Activity levels and dietary habits were kept unchanged. Before and after the stimulation period, functional capacity was assessed by VO2peak, and body composition was analysed. Lipolytic activity was determined in abdominal adipose tissue by 24 hours of microdialysis on a sedentary day, and adipose tissue biopsies were taken for the gene expression analysis. Eight weeks of cTEMS significantly increased VO2peak from 28.9 ± 5.7 to 31.7 ± 6.2 ml/kg/min (p < 0.05), corresponding to an average increase of 1.2% per week. Oxygen uptake and work capacity also increased at the anaerobic threshold. Mean microdialytic glycerol concentration over 24 hours, an index of sedentary lipolytic activity, increased from 238 ± 60 to 306 ± 55 µM (p < 0,0001), but no significant changes in body composition were observed. In addition, PGC-1α and carnitine-palmitoyltransferase-2 mRNAs were significantly upregulated in subcutaneous abdominal adipose tissue. In obese individuals with unchanged lifestyles, 8 weeks of cTEMS significantly improved functional capacity towards a higher fatigue resistance. This increase also gave rise to elevated lipolytic activity and increased mitochondrial activity in abdominal adipose tissue.