Electroacupuncture: a new approach to open the blood-brain barrier in rats recovering from middle cerebral artery occlusion

Specific Mode Electroacupuncture Stimulation Mediates the Delivery of NGF Across the Hippocampus Blood-Brain Barrier Through p65-VEGFA-TJs to Improve the Cognitive Function of MCAO/R Convalescent Rats

Cognitive impairment frequently presents as a prevalent consequence following stroke, imposing significant burdens on patients, families, and society. The objective of this study was to assess the effectiveness and underlying mechanism of nerve growth factor (NGF) in treating post-stroke cognitive dysfunction in rats with cerebral ischemia-reperfusion injury (MCAO/R) through delivery into the brain using specific mode electroacupuncture stimulation (SMES). From the 28th day after modeling, the rats were treated with NGF mediated by SMES, and the cognitive function of the rats was observed after treatment. Learning and memory ability were evaluated using behavioral tests. The impact of SMES on blood-brain barrier (BBB) permeability, the underlying mechanism of cognitive enhancement in rats with MCAO/R, including transmission electron microscopy, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and TUNEL staining. We reported that SMES demonstrates a safe and efficient ability to open the BBB during the cerebral ischemia repair phase, facilitating the delivery of NGF to the brain by the p65-VEGFA-TJs pathway.

Transcriptome Analysis of the Striatum of Electroacupuncture-treated Naïve and Ischemic Stroke Mice

Objectives

Electroacupuncture (EA) has been demonstrated to aid stroke recovery. However, few investigations have focused on identifying the potent molecular targets of EA by comparing EA stimulation between naïve and disease models. Therefore, this study was undertaken to identify the potent molecular therapeutic mechanisms underlying EA stimulation in ischemic stroke through a comparison of mRNA sequencing data obtained from EA-treated naïve control and ischemic stroke mouse models.

Methods

Using both naïve control and middle cerebral artery occlusion (MCAO) mouse models, EA stimulation was administered at two acupoints, Baihui (GV20) and Dazhui (GV14), at a frequency of 2 Hz. Comprehensive assessments were conducted, including behavioral evaluations, RNA sequencing to identify differentially expressed genes (DEGs), functional enrichment analysis, protein-protein interaction (PPI) network analysis, and quantitative real-time PCR.

Results

EA stimulation ameliorated the ischemic insult-induced motor dysfunction in mice with ischemic stroke. Comparative analysis between control vs. MCAO, control vs. control + EA, and MCAO vs. MCAO + EA revealed 4,407, 101, and 82 DEGs, respectively. Of these, 30, 7, and 1 were common across the respective groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed upregulated DEGs associated with the regulation of inflammatory immune response in the MCAO vs. MCAO + EA comparison. Conversely, downregulated DEGs in the control vs. control + EA comparison were linked to neuronal development. PPI analysis revealed major clustering related to the regulation of cytokines, such as Cxcl9, Pcp2, Ccl11, and Cxcl13, in the common DEGs of MCAO vs. MCAO + EA, with Esp8l1 identified as the only common downregulated DEG in both EA-treated naïve and ischemic models.

Conclusion

These findings underscore the diverse potent mechanisms of EA stimulation between naïve and ischemic stroke mice, albeit with few overlaps. However, the potent mechanisms underlying EA treatment in ischemic stroke models were associated with the regulation of inflammatory processes involving cytokines.

Acupuncture modulates the gut microbiota in Alzheimer's disease: current evidence, challenges, and future opportunities

Alzheimer's disease, one of the most severe and common neurodegenerative diseases, has no effective cure. Therefore it is crucial to explore novel and effective therapeutic targets. The gut microbiota - brain axis has been found to play a role in Alzheimer's disease by regulating the neuro-immune and endocrine systems. At the same time, acupuncture can modulate the gut microbiota and may impact the course of Alzheimer's disease. In this Review, we discuss recent studies on the role of acupuncture on the gut microbiota as well current challenges and future opportunities of acupuncture as potential treatment for the prevention and treatment of Alzheimer's disease.

Acupuncture with specific mode electro-stimulation effectively and transiently opens the BBB through Shh signaling pathway

To explore a new method that patients with brain diseases such as stroke sequelae are hindered by blood-brain barrier (BBB) in clinical treatment. Research preliminarily found that acupuncture with specific mode electro-stimulation (EA) to open BBB-assisted drug delivery may be is an effective means to improve the clinical efficacy of brain disease patients. So here we further explore the features and mechanism. Middle cerebral artery occlusion/R recovery rats were employed as the animal model. Laser Doppler monitoring cerebral blood flow decreased to 45 ± 10% of the baseline value as modeling criteria and TTC staining observed infarcted areas of brain tissue. The permeability of FITC-Dextran and EB in the frontal lobe of rats was observed by microscope. After that, Western blot and Immunofluorescence staining for the detection of the shh and Gli1 signal molecule, Claudin-5 Occludin ZO-1 tight junction (TJ) proteins. EA can open the BBB stably and effectively, and has the characteristics of starting to close soon after the end of EA; EA inhibits the Shh-Gli1 signaling pathway, and downregulates Occludin ZO-1 TJ proteins. These results suggest that EA is safe and reversible in opening the BBB, and its mechanism is related to the inhibition of Shh signaling pathway to down-regulate the expression of TJ proteins.

The blood-brain barrier: structure, regulation, and drug delivery

Blood-brain barrier (BBB) is a natural protective membrane that prevents central nervous system (CNS) from toxins and pathogens in blood. However, the presence of BBB complicates the pharmacotherapy for CNS disorders as the most chemical drugs and biopharmaceuticals have been impeded to enter the brain. Insufficient drug delivery into the brain leads to low therapeutic efficacy as well as aggravated side effects due to the accumulation in other organs and tissues. Recent breakthrough in materials science and nanotechnology provides a library of advanced materials with customized structure and property serving as a powerful toolkit for targeted drug delivery. In-depth research in the field of anatomical and pathological study on brain and BBB further facilitates the development of brain-targeted strategies for enhanced BBB crossing. In this review, the physiological structure and different cells contributing to this barrier are summarized. Various emerging strategies for permeability regulation and BBB crossing including passive transcytosis, intranasal administration, ligands conjugation, membrane coating, stimuli-triggered BBB disruption, and other strategies to overcome BBB obstacle are highlighted. Versatile drug delivery systems ranging from organic, inorganic, and biologics-derived materials with their synthesis procedures and unique physio-chemical properties are summarized and analyzed. This review aims to provide an up-to-date and comprehensive guideline for researchers in diverse fields, offering perspectives on further development of brain-targeted drug delivery system.

Electro-acupuncture treatment inhibits the inflammatory response by regulating γδ T and Treg cells in ischemic stroke

BACKGROUND

Electro-acupuncture (EA) is an effective and safe treatment for ischemic stroke. It is not only capable of reducing cerebral damage but also alleviating intestinal inflammation. However, its mechanism has not been fully elucidated.

METHODS

All rats were randomly divided into three experimental groups: the SHAM group, the MCAO group, and the MEA (MCAO+EA) group. Ischemic-reperfusion (I/R) injury was induced by MCAO surgery. Rats in the MEA group were treated with EA stimulation in the "Baihui" acupoint (1 mA, 2/15 Hz, 20 min for each time). The Real-time (RT)-qPCR was used to evaluate the mRNA expression of inflammation factors in the ischemic brain and the small intestine after I/R injury. In addition, our research evaluated the effects of EA on regulatory T cells (Tregs) and γδ T cells in the small intestine and brain via Flow cytometry analysis. Finally, we applied CM-Dil and CFSE injection and explored the potential connections of T cells between the ischemic hemisphere and the small intestine.

RESULTS

Our results suggested that EA treatment could significantly reduce the inflammation response in the ischemic brain and small intestine 3 days after I/R injury in rats. To be specific, EA increased the percentage of Tregs in the brain and the small intestine and decreased intestinal and cerebral γδ T cells. Concomitantly, after EA treatment, the percentage of cerebral CD3⁺TCRγδ⁺CFSE⁺ cells dropped from 12.06% to 6.52% compared with the MCAO group.

CONCLUSIONS

These findings revealed that EA could regulate the Tregs and γδ T cells in the ischemic brain and the small intestine, which indicated its effect on inhibiting inflammation. And, EA could inhibit the mobilization of intestinal T cells, which may contribute to the protection of EA after ischemic stroke.

Electroacupuncture of the trigeminal nerve causes N-methyl-D-aspartate receptors to mediate blood-brain barrier opening and induces neuronal excitatory changes

The blood-brain barrier (BBB) is an important structure for maintaining environmental stability in the central nervous system (CNS). Our previous study showed that specific parameters of electroacupuncture (EA) at the head points Shuigou (GV26) and Baihui (GV20) can open the BBB; however, the mechanism by which stimulation of body surface acupuncture points on the head results in peripheral stimulation and affects the status of the central BBB and the neuronal excitatory changes has not been elucidated. We used laser spectroscopy, the In Vivo Imaging System (IVIS), immunofluorescence and immunoblotting to verified the role of the trigeminal nerve in BBB opening during EA, and we applied the central N-methyl-D-aspartate (NMDA) receptors blocker MK-801 to verify the mediating role of NMDA receptors in EA-induced BBB opening. Next, electroencephalogram (EEG) and in vivo calcium imaging techniques were applied to verify the possible electrical patterns of BBB opening promoted by different intensities of EA stimulation. The results showed that the trigeminal nerve plays an important role in the alteration of BBB permeability promoted by EA stimulation of the head acupoints. Brain NMDA receptors play a mediating role in promoting BBB permeability during EA of the trigeminal nerve, which may affect the expression of the TJ protein occludin, and thus alter BBB permeability. The analysis of the electrical mechanism showed that there was no significant change in the rhythm of local field potentials (LFP) in different brain regions across frequency bands immediately after EA of the trigeminal nerve at different intensities. However, the local primary somatosensory (S1BF) area corresponding to the trigeminal nerve showed a transient reduction in the delta rhythm of LFP with no change in the high-frequency band, and the action potential (spike) with short inter spike interval (ISI) varied with EA intensity. Meanwhile, EA of the trigeminal nerve resulted in rhythmic changes in calcium waves in the S1BF region, which were influenced by different EA intensities. This study provides a research perspective and a technical approach to further explore the mechanism of EA-induced BBB opening and its potential clinical applications.

The barrier and interface mechanisms of the brain barrier, and brain drug delivery

Three different barriers are formed between the cerebrovascular and the brain parenchyma: the blood-brain barrier (BBB), the blood-cerebrospinal fluid barrier (BCSFB), and the cerebrospinal fluid-brain barrier (CBB). The BBB is the main regulator of blood and central nervous system (CNS) material exchange. The semipermeable nature of the BBB limits the passage of larger molecules and hydrophilic small molecules, Food and Drug Administration (FDA)-approved drugs for the CNS have been generally limited to lipid-soluble small molecules. Although the complexity of the BBB affects CNS drug delivery, understanding the composition and function of the BBB can provide a platform for the development of new methods for CNS drug delivery. This review summarizes the classification of the brain barrier, the composition and role of the basic structures of the BBB, and the transport, barrier, and destruction mechanisms of the BBB; discusses the advantages and disadvantages of different drug delivery methods and prospects for future drug delivery strategies.

Genome-Wide Transcription Analysis of Electroacupuncture Precondition-Induced Ischemic Tolerance on SD Rat With Ischemia-Reperfusion Injury

Acupuncture promotes the recovery of neurological function by the overall improvement of ischemic brain injury. It is not only regarded as a rehabilitative treatment but also a pretreatment method for stroke. However, its mechanism has not been fully elucidated. In this study, rats were treated with electroacupuncture (EA) at Baihui (GV20) for 30 min/day for 6 days, ahead of conducting cerebral ischemia–reperfusion (I/R) injury. Infarction volume, Evans blue leakage, and neurological deficits were evaluated at 24 h after I/R injury. Then, the ipsilateral ischemic brain was isolated for RNA sequencing (RNA-Seq) to identify molecular consequences. The results showed that EA pretreatment decreased blood–brain barrier (BBB) permeability, reduced brain infarction volume, and improved neurological outcomes. EA pretreatment could upregulate expression of antivirus and immunity activity-associated genes (such as Ifit1, Ifit3, Irf7, and Oasla) and downregulate expression of matrix disruption-associated genes (Col24a1, Col11a1, Col27a1, etc.) in healthy rats. In addition, it could partially reverse or ameliorate genome-wide transcription changes of the ipsilateral ischemic brain. For the first time, this study provides insight into genomic network modulation of a healthy rat with EA treatment and a EA-preconditioned rat under subsequent I/R injury, which is helpful in explaining acupuncture precondition-induced ischemic tolerance of stroke. It also provides new strategies and targets for the prevention of ischemic stroke.

Electroacupuncture alleviates ischaemic brain injury by regulating the miRNA-34/Wnt/autophagy axis

Electroacupuncture (EA), a modern form of acupuncture therapy, has been widely used for the treatment of ischaemic brain injury. However, the molecular mechanism by which EA improves ischaemic brain injury remains unclear. In the current study, middle cerebral artery occlusion (MCAO) rats were treated with EA. The infarct volumes and apoptosis of neurocytes were assessed to determine the therapeutic effect of EA. The differentially expressed miRNAs between the control, MCAO and MCAO treated with EA groups were detected by high-throughput sequencing. The results indicated that EA treatment decreased neurocyte apoptosis and ischaemic infarct volume. Between the three groups, miR-34, miR-235 and miR-275 were found to be significantly different. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway data suggest that the Wnt pathway may play an important role in ischaemic brain injury and in the treatment of EA. Our data documented that miR-34 was obviously increased in the MCAO group, while EA treatment decreased miR-34 expression. WNT1 was the target of miR-34 and was confirmed by a luciferase reporter assay. A previous study suggested that the Wnt pathway mediates autophagy in EA-pretreated MCAO mice. Our data further confirmed that EA treatment after MCAO also alleviated autophagy in the MCAO group. Our results suggest that EA treatment alleviates ischaemic brain injury by inhibiting autophagy through the miR-34/Wnt pathway.

Specific Frequency Electroacupuncture Stimulation Transiently Enhances the Permeability of the Blood-Brain Barrier and Induces Tight Junction Changes

The blood-brain barrier (BBB) plays an important role in both the physiological state and pharmacological state of the brain. Transiently enhancing the permeability of the BBB may allow the use of more types of medications for neuropsychiatric diseases. Our previous research revealed that electroacupuncture (EA) stimulation at certain parameters can enhance the permeability of the BBB in Sprague-Dawley rats, but this phenomenon is not well characterized. We propose that specific frequency EA can transiently open the BBB and may be related to the change of tight junctions (TJ). To find the best EA frequency among commonly used frequencies, preliminarily explore the mechanism, we detected BBB permeability by measuring the intensity of Evans Blue and 20 kDa FITC-dextran fluorescence in the cerebral cortex. Then, we used a laser spectrometer, immunofluorescence, western blotting, and transmission electron microscopy to detect the mechanism of BBB opening. Finally, measured brain water content, AQP4, GFAP, Iba1, and used the DeadEnd^TM Fluorometric TUNEL System to clear whether the stimulation caused obvious negative effects. The results show that EA stimulation at 2/100 Hz maximally increased BBB permeability, and the BBB closed within 12 h after EA stimulation was removed. EA stimulation increased blood perfusion, c-fos levels, and Substance P expression in the cerebral cortex, decreased ZO-1 and occludin levels and induced ultrastructural changes in TJ morphology. EA stimulation at specific parameters did not cause brain edema, activation of glial cells, or cell apoptosis. This study shows that EA stimulation induces a reversible, frequency-dependent alteration of BBB permeability and proposes a hypothetical mechanism of BBB opening related to vasodilation and TJ disruption. Transiently enhancing the permeability of the BBB with EA at specific parameters may be a new strategies for delivering therapeutics to the central nervous system. Further study of this technology is needed.

Mechanisms Involved in the Neuroprotection of Electroacupuncture Therapy for Ischemic Stroke

Stroke is one of the main causes of death all over the world. As the combination of acupuncture and electric stimulation, electroacupuncutre is a safe and effective therapy, which is commonly applied in ischemic stroke therapy in both experimental studies and clinical settings. The review was performed via searching for related articles in the databases of OVID, PUBMED, and ISI Web of Science from their respective inceptions to May 2018. In this review, we summarized the mechanism of EA for ischemic stroke via a series of factors, consisting of apoptosis related-factors, inflammatory factors, autophagy-related factors, growth factors, transcriptional factors, cannabinoid CB1 receptors, and other factors. In summary, EA stimulation may effectively alleviate ischemic brain injury via a series of signal pathways and various other factors.