Effects of electroacupuncture on blood-brain barrier after cerebral ischemia-reperfusion in rat

Mobilizing endogenous neuroprotection: the mechanism of the protective effect of acupuncture on the brain after stroke

Given its high morbidity, disability, and mortality rates, ischemic stroke (IS) is a severe disease posing a substantial public health threat. Although early thrombolytic therapy is effective in IS treatment, the limited time frame for its administration presents a formidable challenge. Upon occurrence, IS triggers an ischemic cascade response, inducing the brain to generate endogenous protective mechanisms against excitotoxicity and inflammation, among other pathological processes. Stroke patients often experience limited recovery stages. As a result, activating their innate self-protective capacity [endogenous brain protection (EBP)] is essential for neurological function recovery. Acupuncture has exhibited clinical efficacy in cerebral ischemic stroke (CIS) treatment by promoting the human body's self-preservation and "Zheng Qi" (a term in traditional Chinese medicine (TCM) describing positive capabilities such as self-immunity, self-recovery, and disease prevention). According to research, acupuncture can modulate astrocyte activity, decrease oxidative stress (OS), and protect neurons by inhibiting excitotoxicity, inflammation, and apoptosis via activating endogenous protective mechanisms within the brain. Furthermore, acupuncture was found to modulate microglia transformation, thereby reducing inflammation and autoimmune responses, as well as promoting blood flow restoration by regulating the vasculature or the blood-brain barrier (BBB). However, the precise mechanism underlying these processes remains unclear. Consequently, this review aims to shed light on the potential acupuncture-induced endogenous neuroprotective mechanisms by critically examining experimental evidence on the preventive and therapeutic effects exerted by acupuncture on CIS. This review offers a theoretical foundation for acupuncture-based stroke treatment.

Electroacupuncture Reduces Seizure Activity and Enhances GAD 67 and Glutamate Transporter Expression in Kainic Acid Induced Status Epilepticus in Infant Rats

Status epilepticus (SE) is one of the most significant complications in pediatric neurology. Clinical studies have shown positive effects of electroacupuncture (EA) as a therapeutic alternative in the control of partial seizures and secondary generalized clonic seizures. EA promotes the release of neurotransmitters such as GABA and some opioids. The present study aimed to evaluate the anticonvulsive and neuromodulatory effects of Shui Gou DM26 (SG_DM26) acupuncture point electrostimulation on the expression of the glutamate decarboxylase 67 (GAD67) enzyme and the glutamate transporter EAAC1 in an early SE model. At ten postnatal days (10-PD), male rats weighing 22-26 g were divided into 16 groups, including control and treatment groups: Simple stimulation, electrostimulation, anticonvulsant drug treatment, and combined treatment-electrostimulation and pentobarbital (PB). SE was induced with kainic acid (KA), and the following parameters were measured: Motor behavior, and expression of GAD67 and EAAC1. The results suggest an antiepileptic effect derived from SG DM26 point EA. The possible mechanism is most likely the increased production of the inhibitory neurotransmitter GABA, which is observed as an increase in the expression of both GAD67 and EAAC1, as well as the potential synergy between the neuromodulator effects of EA and PB.

Combination of Constraint-Induced Movement Therapy with Electroacupuncture Improves Functional Recovery following Neonatal Hypoxic-Ischemic Brain Injury in Rats

Aim

Neonatal hypoxic-ischemia (HI) due to insufficient oxygen supply and blood flow during the prenatal and postnatal periods can cause cerebral palsy, a serious developmental condition. The purpose of this study was to investigate the efficacy of combining constraint-induced movement therapy (CIMT) and electroacupuncture to treat rat neonatal HI brain injury.

Methods

The left common carotid arteries of postnatal day 7 rats were ligated to induce HI brain injury, and the neonates were kept in a hypoxia chamber containing 8% oxygen for 2 hrs. Electroacupuncture at Baihui (GV 20) and Zusanli (ST 36) was performed concurrently with CIMT 3 weeks after HI induction for 4 weeks.

Results

Motor asymmetry after HI was significantly improved in the CIMT and electroacupuncture combination group, but HI lesion size was not improved. The combination of CIMT and electroacupuncture after HI injury increases NeuN and decreases GFAP levels in the cerebral cortex, suggesting that this combination treatment inversely regulates neurons and astrocytes. In addition, the combination treatment group reduced the level of cleaved caspase-3, a crucial mediator of apoptosis, in the cortex.

Conclusions

Our findings indicate that a combination of CIMT and electroacupuncture is an effective method to treat hemiplegia due to neonatal HI brain injury.

Acupuncture and neuroregeneration in ischemic stroke

Acupuncture is potentially beneficial for post-stroke rehabilitation and is considered a promising preventive strategy for stroke. Electroacupuncture pretreatment or treatment after ischemic stroke by using appropriate electroacupuncture parameters generates neuroprotective and neuroregenerative effects that increase cerebral blood flow, regulate oxidative stress, attenuate glutamate excitotoxicity, maintain blood-brain barrier integrity, inhibit apoptosis, increase growth factor production, and induce cerebral ischemic tolerance.

Preclinical Studies and Translational Applications of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) which refers to bleeding in the brain is a very deleterious condition with high mortality and disability rate. Surgery or conservative therapy remains the treatment option. Various studies have divided the disease process of ICH into primary and secondary injury, for which knowledge into these processes has yielded many preclinical and clinical treatment options. The aim of this review is to highlight some of the new experimental drugs as well as other treatment options like stem cell therapy, rehabilitation, and nanomedicine and mention some translational clinical applications that have been done with these treatment options.

Evolution of blood-brain-barrier permeability after acute ischemic stroke

The dynamics of BBB permeability after AIS in humans are not well understood. In the present study we measured the evolution of BBB permeability after AIS in humans using MRI. Patients presenting to our institution with a diagnosis of AIS underwent a single dynamic contrast-enhanced MRI (DCE-MRI) sequence to measure BBB permeability during their initial workup. Forty-two patients were included in the final analysis. The patient sample underwent DCE-MRI at a mean time of 23.8hrs after the onset of AIS symptoms (range: 1.3–90.7hrs). At all time-points the BBB permeability within the infarct region of the brain as defined on DWI/ADC was higher compared to the homologous region of the contralateral hemisphere (p<0.005). BBB permeability, expressed as a ratio of infarct permeability to contralateral permeability, was greatest at 6-48hrs after the onset of AIS. Although the data was not acquired longitudinally, these findings suggest that the permeability of the BBB is continually elevated following AIS, which contradicts previous assertions that BBB permeability after AIS follows a biphasic course. Knowledge of BBB dynamics following AIS may provide insight into future treatments for AIS, especially BBB stabilizing agents.

Anti-Inflammation of Natural Components from Medicinal Plants at Low Concentrations in Brain via Inhibiting Neutrophil Infiltration after Stroke

Inflammation after stroke consists of activation of microglia/astrocytes in situ and infiltration of blood-borne leukocytes, resulting in brain damage and neurological deficits. Mounting data demonstrated that most natural components from medicinal plants had anti-inflammatory effects after ischemic stroke through inhibiting activation of resident microglia/astrocytes within ischemic area. However, it is speculated that this classical activity cannot account for the anti-inflammatory function of these natural components in the cerebral parenchyma, where they are detected at very low concentrations due to their poor membrane permeability and slight leakage of BBB. Could these drugs exert anti-inflammatory effects peripherally without being delivered across the BBB? Factually, ameliorating blood-borne neutrophil recruitment in peripheral circulatory system has been proved to reduce ischemic damage and improve outcomes. Thus, it is concluded that if drugs could achieve effective concentrations in the cerebral parenchyma, they can function via crippling resident microglia/astrocytes activation and inhibiting neutrophil infiltration, whereas the latter will be dominating when these drugs localize in the brain at a low concentration. In this review, the availability of some natural components crossing the BBB in stroke will be discussed, and how these drugs lead to improvements in stroke through inhibition of neutrophil rolling, adhesion, and transmigration will be illustrated.

Electroacupuncture prevents cognitive impairments by regulating the early changes after brain irradiation in rats

Cognitive impairments severely affect the quality of life of patients who undergo brain irradiation, and there are no effective preventive strategies. In this study, we examined the therapeutic potential of electroacupuncture (EA) administered immediately after brain irradiation in rats. We detected changes in cognitive function, neurogenesis, and synaptic density at different time points after irradiation, but found that EA could protect the blood-brain barrier (BBB), inhibit neuroinflammatory cytokine expression, upregulate angiogenic cytokine expression, and modulate the levels of neurotransmitter receptors and neuropeptides in the early phase. Moreover, EA protected spatial memory and recognition in the delayed phase. At the cellular/molecular level, the preventative effect of EA on cognitive dysfunction was not dependent on hippocampal neurogenesis; rather, it was related to synaptophysin expression. Our results suggest that EA applied immediately after brain irradiation can prevent cognitive impairments by protecting against the early changes induced by irradiation and may be a novel approach for preventing or ameliorating cognitive impairments in patients with brain tumors who require radiotherapy.

Electroacupuncture treatment improves neurological function associated with regulation of tight junction proteins in rats with cerebral ischemia reperfusion injury

Strategies to develop effective neuroprotective therapy to reduce brain damage and related behavioral deficits in stroke patients are of great significance. Electroacupuncture (EA), which derives from traditional Chinese medicine, may be effective as a complementary and alternative method for promoting recovery of neurological function and quality of life. Adult Sprague-Dawley rats were randomly divided into 3 groups: (1) sham, (2) middle cerebral artery occlusion (MCAO) model groups of 2 h MCAO followed by 1, 3, 5, or 7 d of reperfusion, and (3) EA groups of 2 h MCAO followed by 1, 3, 5, or 7 d of reperfusion. EA groups received EA therapy by needling at GV20 and left ST36. The results show that EA therapy improved the neurological function and reduced infarct volume, confirmed by modified neurological severity scores and TTC staining. Real-time PCR, immunohistochemistry, and western blot assay verified that EA upregulated the expression of tight junction (TJ) claudin-5, occludin, and zonula occluding-1 from 1 to 7 d after reperfusion. Our findings suggest that EA reduces brain damage and related behavioral deficits via upregulation of the TJ proteins.

The neuroprotective effect of electro-acupuncture against ischemic stroke in animal model: a review

BACKGROUND

It is well established that electro-acupuncture can exert neuroprotection in animal experiments. However, the exact mechanism of electro-acupuncture against ischemic stroke is not very clear.

MATERIALS AND METHODS

Literature retrieval was performed in four databases (OVID, PUBMED, EMBASE, and ISI Web of Science), from respective inception to July 2013.

RESULTS

Series of studies have demonstrated that electro-acupuncture might be a promising method in reducing brain damage after stroke and induce brain ischemic tolerance before stroke through the promotion of angiogenesis, alleviation of the inflammatory response, regulation of the blood brain barrier (BBB), inhibition of apoptosis, and so on. Through these mechanisms, electro-acupuncture may reduce the neural damages associated with stroke.

CONCLUSION

An awareness of the benefits of acupuncture might lead more patients into accepting acupuncture therapy for the management of patients with ischemic stroke and patients with high risk of ischemic stroke.

Post-ischemic blood-brain barrier leakage in rats: one-week follow-up by MRI

Blood-brain barrier (BBB) disruption following ischemia-reperfusion is associated with such devastating consequences as edema and hemorrhagic transformation. Although several earlier reports on BBB disruption after experimental focal cerebral ischemia-reperfusion pointed out a biphasic opening, discrepancies occurred among the results of these studies as to the second opening. Furthermore, rarely was any evaluation longitudinal. We therefore performed repeated dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to monitor BBB permeability to gadopentetate dimeglumine (Gd-DTPA) following 90 min of transient focal cerebral ischemia in a single group of rats (n=10). At five time-points after reperfusion (at 2, 24, 48, 72 h, and 1 week), we estimated the blood-to-brain transfer rate constant (K(i)) of gadolinium with the Patlak plot graphical approach, and calculated contrast enhancement magnitude based on signal intensities of pre- and postcontrast T1-weighted images. Both methods revealed a persistent permeability to gadolinium during the whole experiment. The magnitude of contrast enhancement appeared higher at 1 week than at any of the other time-points (p<0.001), whereas no difference appeared in K(i) estimations when we analyzed the enhancement areas as an entirety. Sub-region K(i) values in a limited cortical area showed a difference at 1 week (p=0.014). The present study confirms that following transient focal cerebral ischemia, BBB leakage to Gd-DTPA is continuous, and during 1 week postreperfusion no BBB closure occurs.

A narrow time-window for access to the brain by exogenous protein after immunological targeting of a blood-brain barrier antigen

The endothelial barrier antigen (EBA) is a membrane protein expressed by endothelial cells of the rat blood-brain barrier (BBB). A previous short-term non-recovery study demonstrated that immunological targeting of EBA by intravenous administration of a monoclonal antibody (anti-EBA) led to acute opening of the BBB to exogenous and endogenous tracers. The aims of the present study were to determine whether opening of the BBB was reversible and compatible with survival, and whether a "therapeutic window" existed. A single intravenous injection of one of three doses (high, medium and low) of anti-EBA was used. Animals were allowed to survive for periods ranging from 17 min to 4 days. The tracer horseradish peroxidase (HRP) was administered intravenously 10 min before perfusion fixation, and its distribution was assessed in Vibratome sections of the brain and spinal cord. Leakage of HRP into the central nervous system was dose- and time-dependent. The medium dose produced incipient HRP leakage at 17 min and widespread pronounced leakage at 30 min. Progressive reduction in HRP permeability occurred from 45 min to 2 h, with barrier restoration by 3 h. At all subsequent time intervals (6 h-4 days) the BBB remained impermeable to HRP. The low and high doses produced less and greater HRP leakage, respectively, but restoration of the barrier still occurred at 3 h. The high dose, however, produced a number of deaths. Animals treated with an isotype control antibody showed no HRP leakage at comparable time intervals. The results indicated that (1) this model was compatible with survival, (2) opening of the BBB was monophasic and transient, occurring during a narrow "time-window", and (3) the barrier, once reconstituted, maintained its integrity.