Transcutaneous electrical nerve stimulation (TENS) improves the diabetic cytopathy (DCP) via up-regulation of CGRP and cAMP

Signalling pathways underlying pulsed electromagnetic fields in bone repair

Pulsed electromagnetic field (PEMF) stimulation is a prospective non-invasive and safe physical therapy strategy for accelerating bone repair. PEMFs can activate signalling pathways, modulate ion channels, and regulate the expression of bone-related genes to enhance osteoblast activity and promote the regeneration of neural and vascular tissues, thereby accelerating bone formation during bone repair. Although their mechanisms of action remain unclear, recent studies provide ample evidence of the effects of PEMF on bone repair. In this review, we present the progress of research exploring the effects of PEMF on bone repair and systematically elucidate the mechanisms involved in PEMF-induced bone repair. Additionally, the potential clinical significance of PEMF therapy in fracture healing is underscored. Thus, this review seeks to provide a sufficient theoretical basis for the application of PEMFs in bone repair.

The Effect of Transcutaneous Electrical Nerve Stimulation in Peripheral and Central Hemodynamic Parameters on Resistant Hypertension: A Case Report

Resistant hypertension (RH) is characterized by being difficult to control, even with the use of various antihypertensive drugs and is associated with target organ lesions and other comorbidities. Thus, new treatment alternatives such as transcutaneous electrical nerve stimulation (TENS) can offer benefits to resistant hypertensive patients by reducing blood pressure (BP) in a non-invasive way and without the need for the association of more antihypertensive drugs. In this case, a patient with RH was submitted to three weekly applications of TENS on the stellate ganglion lasting 40 min each for 1 month. Peripheral and central hemodynamic assessments were performed by 24-h ambulatory BP monitoring (ABPM) before and after TENS applications. After completion of the TENS applications, significant reductions in office systolic (SBP) and diastolic BP (DBP) were observed. There was also a decrease in peripheral SBP and DBP in the 24-h ABPM and sleep and SBP during wakefulness. Additionally, central parameters including central SBP and pulse wave velocity presented a significant reduction in the 24-h ABPM, during the wakefulness and sleep. TENS is able to attenuate the sympathetic hyperactivity present in RH cases and decrease the peripheral and central hemodynamic parameters of a resistant hypertensive patient.

Effect of Electroacupuncture on Bladder Dysfunction via Regulation of MLC and MLCK Phosphorylation in a Rat Model of Type 2 Diabetes Mellitus

Previous studies observed have reported that electroacupuncture (EA) is effective in relieving diabetic bladder dysfunction (DBD); however, little is known about the mechanism. Therefore, we explored the effects and mechanisms of EA on DBD in streptozotocin–high-fat diet- (STZ–HFD-) induced diabetic rats. The Sprague-Dawley male rats were divided randomly into four groups: normal group, diabetes mellitus group (DM group), DM with EA treatment group (EA group), and DM with sham EA treatment group (sham EA group). After 8 weeks of EA treatment, the body weight, serum glucose, bladder weight, and cystometrogram were evaluated. The bladder wall thickness was examined by abdominal ultrasound imaging. After the transabdominal ultrasound measurements, hematoxylin-eosin (HE) staining was used to observe the bladder mucosa layer. The bladder detrusor smooth muscle cells (SMCs) and fibroblasts were observed under transmission electron microscopy (TEM). The phospho-myosin light chain (p-MLC), phospho-myosin light chain kinase (p-MLCK), and phospho-myosin phosphatase target subunit 1 (p-MYPT1) levels in the bladder were examined using Western blot. The bladder weight, serum glucose, bladder wall thickness, volume threshold for micturition, and postvoid residual (PVR) volume in the diabetic rats were significantly higher than those in the control animals. EA treatment significantly reduced the bladder weight, bladder wall thickness, volume threshold for micturition, and PVR volume in diabetic rats. EA caused a significant increase in the MLC dephosphorylation and MLCK phosphorylation levels in the group compared to the sham EA and model groups. EA reduced the infiltration of inflammatory cells in the bladder mucosa layer of diabetic rats. In addition, EA repaired the damaged bladder detrusor muscle of diabetic rats by reducing mitochondrial damage of the SMCs and fibroblasts. Therefore, EA could reduce the bladder hypertrophy to ameliorate DBD by reversing the impairment in the mucosa layer and detrusor SMCs, which might be mainly mediated by the regulation of p-MLC and p-MLCK levels.

CGRP protects bladder smooth muscle cells stimulated by high glucose through inhibiting p38 MAPK pathway in vitro

This study aimed to explore the effect of calcitonin gene-related peptide (CGRP) on bladder smooth muscle cells (BSMCs) under high glucose (HG) treatment in vitro. BSMCs from Sprague-Dawley rat bladders were cultured and passaged in vitro. The third-generation cells were cultured and divided into control group, HG group, HG + CGRP group, HG + CGRP + asiatic acid (AA, p-p38 activator) group, CGRP group, AA group, HG + CGRP + CGRP-8-37 (CGRP receptor antagonist) group and HG + LY2228820 (p38 MAPK inhibitor) group. The cell viability, apoptosis, malondialdehyde (MDA) and superoxide dismutase (SOD) levels of BSMCs were observed by the relevant detection kits. The expressions of α-SM-actin, p38 and p-p38 were detected by qRT-PCR or Western blot analysis. Compared with the control group, the cell viability, SOD and α-SM-actin levels of BSMCs were decreased and apoptotic cells, MDA and p-p38 levels were increased after HG treatment, while these changes could be partly reversed when BSMCs were treated with HG and CGRP or LY2228820 together. Moreover, AA or CGRP-8-37 could suppress the effect of CGRP on BSMCs under HG condition. Our data indicate that CGRP protects BSMCs from oxidative stress induced by HG in vitro, and inhibit the α-SM-actin expression decrease through inhibiting the intracellular p38 MAPK signaling pathway.

The Effects of Calcitonin Gene-Related Peptide on Bone Homeostasis and Regeneration

PURPOSE OF REVIEW

The goals of this review are two folds: (1) to describe the recent understandings on the roles of calcitonin gene-related peptide-α (CGRP) in bone homeostasis and the underlying mechanisms of related neuronal regulation and (2) to propose innovative CGRP-modulated approaches for enhancing bone regeneration in challenging bone disorders.

RECENT FINDINGS

CGRP is predominantly produced by the densely distributed sensory neuronal fibers in bone, declining with age. Under mechanical and biochemical stimulations, CGRP releases and exerts either physiological or pathophysiological roles. CGRP at physiological level orchestrates the communications of bone cells with cells of other lineages, affecting not only osteogenesis, osteoclastogenesis, and adipogenesis but also angiogenesis, demonstrating with pronounced anabolic effect, thus is essential for maintaining bone homeostasis, with tuned nerve-vessel-bone network. In addition, its effects on immunity and cell recruitment are also crucial for bone fracture healing. Binding to the G protein-coupled receptor composited by calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) on cellular surface, CGRP triggers various intracellular signaling cascades involving cyclic adenosine monophosphate (cAMP) and cAMP response element-binding protein (CREB). Peaking at early stage post-fracture, CGRP promotes bone formation, displaying with larger callus. Then CGRP gradually decreases over time, allowing normal or physiological bone remodeling. By elevating CGRP at early stage, low-intensity pulsed ultrasound (LIPUS), electrical stimulation, and magnesium-based bio-mineral products may promisingly accelerate bone regeneration experimentally in medical conditions like osteoporosis, osteoporotic fracture, and spine fusion. Excess CGRP expression is commonly observed in pathological conditions including cancer metastatic lesions in bone and fracture delayed- or non-healing, resulting in persistent chronic pain. To date, these discoveries have largely been limited to animal models. Clinical applications are highly desirable. Compelling evidence show the anabolic effects of CGRP on bone in animals. However, further validation on the role of CGRP and the underlying mechanisms in human skeletons is required. It remains unclear if it is type H vessel connecting neuronal CGRP to osteogenesis, and if there is only specific rather than all osteoprogenitors responsible to CGRP. Clear priority should be put to eliminate these knowledge gaps by integrating with high-resolution 3D imaging of transparent bulk bone and single-cell RNA-sequencing. Last but not the least, given that small molecule antagonists such as BIBN4096BS can block the beneficial effects of CGRP on bone, concerns on the potential side effects of humanized CGRP-neutralizing antibodies when systemically administrated to treat migraine in clinics are arising.

Therapeutic effect of integrin-linked kinase gene-modified bone marrow-derived mesenchymal stem cells for streptozotocin-induced diabetic cystopathy in a rat model

Background

Diabetic cystopathy (DCP) is a chronic complication of diabetes mainly within the submucosal and muscular layers of the bladder due to the hyperglycemia-induced ischemia. As no effective therapies are currently available, the administration of optimized mesenchymal stem cells (MSCs) provides a potential treatment of DCP. Thus far, new strategy, such as genetic modification of MSCs, has been developed and has shown promising outcomes of various disorders.

Methods

This study was conducted using integrin-linked kinase (ILK) gene-modified bone marrow-derived stem cells (BMSCs) for streptozotocin (STZ)-induced diabetic cystopathy in a rat model. In total, 68 male Sprague-Dawley rats were randomized into five groups: sham control (control group, n = 10); DCP model alone (DM group, n = 10); DCP rats intravenously treated with BMSCs (BMSC group, n = 16); DCP rats accepted adenoviral vector-infected BMSCs (Ad-null-BMSC group, n = 16) and DCP rats accepted ILK adenoviral vector-infected BMSCs (Ad-ILK-BMSC group, n = 16). Diabetic rats accepted cell transplantation in the experimental group (2 rats per group) were sacrificed for the bladder tissue on the third day, 7th day, and 14th day of treatment respectively ahead of schedule. At 4 weeks after treatment, all rats in five groups accepted urodynamic studies to evaluate bladder function and were sacrificed for bladder tissue.

Results

Our data showed that the underactive bladder function was significantly improved in DCP rats intravenously treated with ILK gene-modified BMSCs compared to those in the DM, BMSCs, and Ad-null-BMSC group. Meanwhile, we found that gene-modified BMSC treatment significantly promoted the activation of the AKT/GSK-3β pathway by increasing phosphorylation and led to the enhancement of survival. In addition, the expression levels of angiogenesis-related protein vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and stromal cell-derived factor-1 (SDF-1) were significantly higher in the Ad-ILK-BMSC group than that in the DM, BMSCs, and Ad-null-BMSC group as assessed by enzyme-linked immunosorbent assay and western blot. As two indicators of vascular endothelial cell markers, the expression of von Willebrand factor (vWF) and CD31 by western blot and immunofluorescent staining revealed that the percentage of the vascular area of the bladder tissue significantly increased in Ad-ILK-BMSC group compared with the BMSCs and Ad-null-BMSC group on the 14th day of treatment. Histological and immunohistochemical staining (hematoxylin and eosin (HE), vWF, Ki67, and TUNNEL) on the bladder tissue revealed statistically different results between groups.

Conclusion

ILK gene-modified BMSCs restored the bladder function and histological construction via promoting the process of angiogenesis and protecting cells from high glucose-associated apoptosis in STZ-induced DCP rat model, which provides a potential for the treatment of patients with DCP.

CGRP Reduces Apoptosis of DRG Cells Induced by High-Glucose Oxidative Stress Injury through PI3K/AKT Induction of Heme Oxygenase-1 and Nrf-2 Expression

Dorsal root ganglion (DRG) neurons, which are sensitive to oxidative stress due to their anatomical and structural characteristics, play a complex role in the initiation and progression of diabetic bladder neuropathy. We investigated the hypothesis that the antioxidant and antiapoptotic effects of CGRP may be partly related to the expression of Nrf2 and HO-1, via the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, thus reducing apoptosis and oxidative stress responses. This study shows that CGRP activates the PI3K/AKT pathway, thereby inducing increased expression of Nrf2 and HO-1 and resulting in the decrease of reactive oxygen species and malondialdehyde levels and reduced neuronal apoptosis. These effects were suppressed by LY294002, an inhibitor of the PI3K/AKT pathway. Therefore, regulation of Nrf2 and HO-1 expression by the PI3K/AKT pathway plays an important role in the regulation of the antioxidant and antiapoptotic responses in DRG cells in a high-glucose culture model.

Lentivirus mediated over expression of CGRP inhibited oxidative stress in Schwann cell line

CGRP is reported to be implicated in the process of diabetes and neuronal disease. However, the role and underlying mechanism of CGRP involved in diabetic neuropathy is unknown. Schwann cells play a central role in diabetic neuropathy, therefore the protective effect of CGRP on Schwann cells exposed to high glucose is determined. In the present study, full-length CGRP cDNA was isolated and then transferred to gateway adapted lentivirus expression vector by LR recombination reaction. Afterwards, the CGRP bearing recombinant virus was prepared in 293 FT cells and used to infect Schwann cells. The viability and superoxide anions of Schwann cells were evaluated following stimulation with high glucose, and levels of SOD, MDA and NOX1 were assessed. The results suggested that CGRP expression was up-regulated following lentivirus transfection. Lenti-CGRP increased cell viability in high glucose, but the effect was transient. Further lenti-CGRP protected against oxidative stress in Schwann cells triggered by high glucose and lenti-CGRP was effective in increasing SOD and decreasing MDA level. Meanwhile, the increased level of NOX1 caused by high glucose was reversed by lenti-CGRP overexpression. We therefore, suggest that lenti-CGRP may play a role in inhibiting oxidative stress in Schwann cell lines following hyperglycemic stimulation.

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

OBJECTIVE

The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored.

METHODS

51 patients received craniotomy were divided randomly into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG..

RESULTS

No significant difference existed between groups A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant difference in TNF-α, IgM and IgA level at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8.

CONCLUSION

EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy.

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

OBJECTIVE

The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored.

METHODS

51 patients received craniotomy were randomly divided into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG.

RESULTS

No significant difference existed between group A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant differences in TNF-α, IgM and IgA levels at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8.

CONCLUSION

EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy.

Calcitonin gene-related peptide: physiology and pathophysiology

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

Dorsal root ganglion electrical stimulation promoted intertransverse process spinal fusion without decortications and bone grafting: a proof-of-concept study

BACKGROUND CONTEXT

Periosteum, endosteum, and bone are innervated by sensory nerves expressing calcitonin gene-related peptide (CGRP), which is a known osteoanabolic peptide and plays an important role in fracture healing and spinal fusion. Synthesis and release of CGRP are found in sensory neurons located in the dorsal root ganglions (DRGs) and can be upregulated by electrical stimulation (ES) at DRG.

PURPOSE

To prove our study hypothesis on the potential of precise ES at DRG through implantable microelectrical stimulation system (IMESS) for its effect on promoting spinal fusion in a rat model without decortications and bone grafting.

STUDY DESIGN

An experimental animal study.

METHODS

A novel IMESS was developed for stimulating L4-L6 DRG in rats. Sixteen rats were used and divided equally into the control group without ES and the ES group, with a daily 20 minutes ES to DRG for 6 weeks. At the end of 6 weeks, radiography and microcomputed tomography were conducted to evaluate new bone formation and spinal fusion. Bilateral L4-L6 DRGs were harvested for immunohistochemistry and quantification of neurons with upregulated CGRP expression.

RESULTS

In the ES group, rate of radiographic fusion with complete and uninterrupted bony bridging was 100% (8/8) at the right L4/L5 transverse processes and 75% (6/8) at the right L5/L6 transverse processes. Bony callus formation was absent at the left L4-L6 transverse processes in the ES group and in bilateral L4-L6 transverse processes in the control group.

CONCLUSIONS

We proved for the first time that precise ES at DRG through IMESS effectively promoted intertransverse process fusion in rat model without decortications and bone grafting. Electrical stimulation at DRG might be an attractive minimal invasive bioengineering approach and an alternative therapy for intertransverse process fusion that is increasingly being used for the treatment of degenerative spine disorders.

Electrical stimulation as an adjunctive treatment of painful and sensory diabetic neuropathy

BACKGROUND

The objective of this review is to evaluate the use of electrical stimulation to treat diabetic neuropathy. Application of electrical stimulation may provide a novel treatment option for large and small fiber neuropathy in persons with diabetes. Large and small nerve neuropathy alters pain, proprioception, touch perception, and motor function, which cause burning foot pain and serve as protective mechanisms from ulcerations.

METHODS

A content search for clinical trials involving electrical stimulation, neuropathy, and diabetes was conducted through PubMed. Randomized clinical trials and prospective studies with outcome measures affecting the lower extremity function were selected for review.

RESULTS

We identified eight studies in which electrical stimulation was used to treat diabetic neuropathy. Six studies evaluated small fiber neuropathy. Two studies evaluated patients with both small and large fiber neuropathy and reported significant improvement in vibration and monofilament testing and reduction in symptoms in the electrical stimulation treatment group. Six of the eight painful neuropathy studies identified significant improvement in symptoms. There were no studies that evaluated electrical stimulation to treated diabetic motor neuropathy, fall prevention or postural instability.

CONCLUSIONS

Electrical stimulation may be an effective alternative and adjunctive therapy to current interventions for diabetic peripheral neuropathy.