Central Noradrenergic Agonists in the Treatment of Ischemic Stroke-an Overview

Neuroprotective actions of norepinephrine in neurological diseases

Precise control of norepinephrine (NE) levels and NE-receptor interaction is crucial for proper function of the brain. Much evidence for this view comes from experimental studies that indicate an important role for NE in the pathophysiology and treatment of various conditions, including cognitive dysfunction, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and sleep disorders. NE provides neuroprotection against several types of insults in multiple ways. It abrogates oxidative stress, attenuates neuroinflammatory responses in neurons and glial cells, reduces neuronal and glial cell activity, promotes autophagy, and ameliorates apoptotic responses to a variety of insults. It is beneficial for the treatment of neurodegenerative diseases because it improves the generation of neurotrophic factors, promotes neuronal survival, and plays an important role in the regulation of adult neurogenesis. This review aims to present the evidence supporting a principal role for NE in neuroprotection, and molecular mechanisms of neuroprotection.

Exploring the pathogenesis and treatment of PSD from the perspective of gut microbiota

Post-stroke depression (PSD) is a psychological disease that can occur following a stroke and is associated with serious consequences. Research on the pathogenesis and treatment of PSD is still in the infancy stage. Patients with PSD often exhibit gastrointestinal symptoms; therefore the role of gut microbiota in the pathophysiology and potential treatment effects of PSD has become a hot topic of research. In this review, describe the research on the pathogenesis and therapy of PSD. We also describe how the gut microbiota influences neurotransmitters, the endocrine system, energy metabolism, and the immune system. It was proposed that the gut microbiota is involved in the pathogenesis and treatment of PSD through the regulation of neurotransmitter levels, vagal signaling, hypothalamic-pituitary-adrenal axis activation and inhibition, hormone secretion and release, in addition to immunity and inflammation.

Transcutaneous vagus nerve stimulation: a bibliometric study on current research hotspots and status

Background

Transcutaneous Vagal Nerve Stimulation (tVNS) has been used as a promising noninvasive neuromodulation technique for the treatment of various systems.The aim of this study was to analyze the research hotspots and future directions of tVNS in the 21st century by using bibliometric methods.

Methods

The study object was the literature related to tVNS from the Web of Science database from 2000 to May 2024. In order to measure and analyze the number of literature issuance, institutions, authors, countries, keywords, co-citations, and journals of publication, we used VOSviewer, Citespace, Bibliometrix R-package, and Scimago Graphica software. A narrative review of the current research content of tVNS was conducted to gain a better understanding of the current state of the field.

Results

A total of 569 papers were included in the study. The results show that from 2000 to 2024, the number of publications shows an increasing trend year by year, involving a total of 326 research institutions. The United States, China, and Germany are the major research centers. The study identified 399 keywords, which roughly formed 11 natural clusters, revealing that the current hotspots of related research are mainly reflected in 3 areas: intervention efficacy on nervous system diseases, mechanism of action of tVNS, and stimulation mode of tVNS. The top 10 most cited references focus on research into the mechanism of action of tVNS.

Conclusion

The efficacy and safety of tVNS have been confirmed in previous studies, but a standardized tVNS treatment protocol has not yet been developed, and most clinical studies have small sample sizes and lack multicenter and multidisciplinary collaboration. Currently, tVNS is used in the treatment of neurological diseases, psychiatric diseases, cardiovascular diseases, and some autoimmune diseases. It is expected that future research in this field will continue to focus on the application of tVNS in central nervous system diseases and the exploration of related mechanisms, and at the same time, with the rise of non-invasive neuromodulation technology, the application of tVNS in other diseases also has great potential for development.

Decreased levels of hydrogen sulfide in the hypothalamic paraventricular nucleus contribute to sympathetic hyperactivity induced by cerebral infarction

Paroxysmal sympathetic hyperactivity (PSH) is a common clinical feature secondary to ischemic stroke (IS), but its mechanism is poorly understood. We aimed to investigate the role of H2S in the pathogenesis of PSH. IS patients were divided into malignant (MCI) and non-malignant cerebral infarction (NMCI) group. IS in rats was induced by the right middle cerebral artery occlusion (MCAO). H2S donor (NaHS) or inhibitor (aminooxy-acetic acid, AOAA) were microinjected into the hypothalamic paraventricular nucleus (PVN). Compared with the NMCI group, patients in the MCI group showed PSH, including tachycardia, hypertension, and more plasma norepinephrine (NE) that was positively correlated with levels of creatine kinase, glutamate transaminase, and creatinine respectively. The 1-year survival rate of patients with high plasma NE levels was lower. The hypothalamus of rats with MCAO showed increased activity, especially in the PVN region. The levels of H2S in PVN of the rats with MCAO were reduced, while the blood pressure and renal sympathetic discharge were increased, which could be ameliorated by NaHS and exacerbated by AOAA. NaHS completely reduced the disulfide bond of NMDAR1 in PC12 cells. The inhibition of NMDAR by MK-801 microinjected in PVN of rats with MCAO also could lower blood pressure and renal sympathetic discharge. In conclusion, PSH may be associated with disease progression and survival in patients with IS. Decreased levels of H2S in PVN were involved in regulating sympathetic efferent activity after cerebral infarction. Our results might provide a new strategy and target for the prevention and treatment of PSH.

Locus Coeruleus and Noradrenergic Pharmacology in Neurodegenerative Disease

Adrenoceptors (ARs) throughout the brain are stimulated by noradrenaline originating mostly from neurons of the locus coeruleus, a brainstem nucleus that is ostensibly the earliest to show detectable pathology in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The α1-AR, α2-AR, and β-AR subtypes expressed in target brain regions and on a range of cell populations define the physiological responses to noradrenaline, which includes activation of cognitive function in addition to modulation of neurometabolism, cerebral blood flow, and neuroinflammation. As these heterocellular functions are critical for maintaining brain homeostasis and neuronal health, combating the loss of noradrenergic tone from locus coeruleus degeneration may therefore be an effective treatment for both cognitive symptoms and disease modification in neurodegenerative indications. Two pharmacologic approaches are receiving attention in recent clinical studies: preserving noradrenaline levels (e.g., via reuptake inhibition) and direct activation of target adrenoceptors. Here, we review the expression and role of adrenoceptors in the brain, the preclinical studies which demonstrate that adrenergic stimulation can support cognitive function and cerebral health by reversing the effects of noradrenaline depletion, and the human data provided by pharmacoepidemiologic analyses and clinical trials which together identify adrenoceptors as promising targets for the treatment of neurodegenerative disease.

Alterations in expression of α1-adrenergic receptors possibly are involved in prevention of age-associated apoptosis in rat hippocampus by treadmill exercise

OBJECTIVES

Exercise is assumed to attenuate age-related neuronal apoptosis, but the detailed mechanism(s) is not fully understood. α1-Adrenergic receptors (ARs) can either trigger or suppress apoptosis, therefore, here we determined the impact of treadmill exercise on the expression of the apoptosis regulatory proteins as well as α1-AR subtypes α1A- and α1B-ARs, in order to elucidate a possible association between apoptosis and the hippocampal expression of α1-ARs in aged male rats.

METHODS

Twenty-one male Wistar rats were divided into 3 groups (n=7): young control, aged sedentary, and aged + exercise. Western blot for α1A- and α1B-ARs as well as pro-(Bax and p53) and anti-apoptotic (Bcl2) proteins was conducted. An 8-week regular moderate-intensity treadmill exercise intervention was carried out in exercise group.

RESULTS

In aged rats, α1A-AR expression in the hippocampus was significantly increased, and exercise markedly prevented this event. While α1B-AR expression was no altered with aging, a marked reduction in α1B-AR level was detected in exercise group when compared to aged group. Furthermore, pro-apoptotic protein levels of Bax and p53 were upregulated and anti-apoptotic protein Bcl2 was downregulated in the aging hippocampus, but could be reversed by treadmill exercise. In the present research, exercise-induced reduction in α1A- and α1B-ARs was associated with an obvious downregulation of Bax/Bcl2 ratio in aged rats, suggesting that exercise may inhibit apoptosis through regulating α1-ARs, particularly α1A-AR.

CONCLUSIONS

Our study suggests that manipulations attenuating α1-AR activity, including nonselective α1-adrenergic antagonists, may protect against hippocampal neurodegeneration in aging brains.

Effect of electrode configuration in electroacupuncture on ischemic stroke treatment in rats

Background and aim

This study investigated the effect of the electrode configuration on EA treating ischemic stroke.

Experimental procedure

An ischemic stroke rat model was established. In the EA-P group, the anodes of EA were placed on the BL7 and BL8 acupoints of the lesioned, and the cathodes were placed on the BL7 and BL8 acupoints of the nonlesioned hemispheres; by contrast, in the EA-N group.

Results

The difference in neurological deficit scores between the first and fourth days and the difference in Rotarod test time between the fourth and first days after reperfusion were greater in the EA-P and EA-N groups than in the sham group (all p < 0.001). In the lesioned hemisphere, neuronal nuclei (NeuN), γ-aminobutyric acid-A (GABA)-A, postsynaptic density 95 (PSD95), and astrocyte glutamate transporter 1 (GLT-1) expression and microtubule-associated protein 2 (MAP2)/glyceraldehyde 3-phosphate dehydrogenase (GADPH) ratios were greater and the glial fibrillary acid protein (GFAP)/GADPH ratios were smaller in the EA-P than in the sham group (all p < 0.05), but these ratios in the EA-N group were similar to those in the sham group (all p > 0.05); serum adrenaline and serotonin levels in the sham group were lower than those in the normal and EA-P groups (both p < 0.05), and cerebrospinal fluid (CSF) glutamate levels were higher in the EA-P group than in the sham group (p < 0.05).

Conclusion

EA improved neurological function through multiple pathways. However, placing the anode on the lesioned hemisphere can provide more neuroprotection.

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.

Circular RNA CircPDS5B impairs angiogenesis following ischemic stroke through its interaction with hnRNPL to inactivate VEGF-A

BACKGROUND

Ischemic stroke (IS) is the primary cause of mortality and disability worldwide. Circular RNAs (circRNAs) have been proposed as crucial regulators in IS. This study focused on the role of circPDS5B in IS and its underlying mechanism.

METHOD

Transient middle cerebral artery occlusion (tMCAO) mice and glucose deprivation/reoxygenation (OGD/R)-exposed human brain microvascular endothelial cells (BMECs) were used as IS models. Expression levels of circPDS5B, heterogenous nuclear ribonucleoprotein L (hnRNPL), runt-related transcription factor-1 (Runx1), and Zinc finger protein 24 (ZNF24) were quantified by qRT-PCR. MTT, wound healing, transwell and tube formation assays were employed to evaluate the cell proliferation, migration, and angiogenesis, respectively. Moreover, RNA pull-down, and RIP assay were performed to investigate the interaction among circPDS5B, hnRNPL and vascular endothelial growth factor-A (VEGFA).

RESULTS

circPDS5B was significantly up-regulated in IS patients and tMCAO mice. Deficiency of circPDS5B relieved brain infarction and neuronal injury of tMCAO mice. OGD/R-induced apoptosis, inhibition in viability, migration, and angiogenesis in BMECs were dramatically abrogated by circPDS5B knockdown. Mechanistically, circPDS5B stabilized Runx1 and ZNF24 via recruiting hnRNPL, thereby suppressing the transcription and expression of VEGFA. hnRNPL silencing strengthened circPDS5B knockdown-mediated beneficial effect on IS.

CONCLUSION

Altogether, our study showed that high expression of circPDS5B exacerbated IS through recruitment of hnRNP to stabilize Runx1/ZNF24 and subsequently inactivate VEGF-A. Our findings suggest circPDS5B may be a novel therapeutic target for IS.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Levels of Serum and Urine Catecholaminergic and Apelinergic System Members in Acute Ischemic Stroke Patients

Objective: To compare levels of catecholaminergic system members, renalase, cerebellin, and their substrates, epinephrine, norepinephrine, and dopamine, and apelinergic system members, apelin, elabela, and nitric oxide in the blood and urine of patients with acute ischemic stroke and healthy controls. Materials and Methods: 42 patients with acute ischemic stroke and 42 age and sex-matched healthy controls were included in the study. Blood and urine samples were collected simultaneously and within the first 24 hours after the onset of acute stroke clinical manifestations and were measured using an ELISA method. Results: The levels of serum and urine cerebellin, renalase, epinephrine, norepinephrine, dopamine, apelin, elebela, and nitric oxide were similar in ischemic stroke and in control groups (P>0.05). Strong correlations were found between renalase, cerebellin, and catecholamine levels in serum and urine (p

Probing the structure and function of locus coeruleus projections to CNS motor centers

The brainstem nucleus locus coeruleus (LC) sends projections to the forebrain, brainstem, cerebellum and spinal cord and is a source of the neurotransmitter norepinephrine (NE) in these areas. For more than 50 years, LC was considered to be homogeneous in structure and function such that NE would be released uniformly and act simultaneously on the cells and circuits that receive LC projections. However, recent studies have provided evidence that LC is modular in design, with segregated output channels and the potential for differential release and action of NE in its projection fields. These new findings have prompted a radical shift in our thinking about LC operations and demand revision of theoretical constructs regarding impact of the LC-NE system on behavioral outcomes in health and disease. Within this context, a major gap in our knowledge is the relationship between the LC-NE system and CNS motor control centers. While we know much about the organization of the LC-NE system with respect to sensory and cognitive circuitries and the impact of LC output on sensory guided behaviors and executive function, much less is known about the role of the LC-NE pathway in motor network operations and movement control. As a starting point for closing this gap in understanding, we propose using an intersectional recombinase-based viral-genetic strategy TrAC (Tracing Axon Collaterals) as well as established ex vivo electrophysiological assays to characterize efferent connectivity and physiological attributes of mouse LC-motor network projection neurons. The novel hypothesis to be tested is that LC cells with projections to CNS motor centers are scattered throughout the rostral-caudal extent of the nucleus but collectively display a common set of electrophysiological properties. Additionally, we expect to find these LC projection neurons maintain an organized network of axon collaterals capable of supporting selective, synchronous release of NE in motor circuitries for the purpose of coordinately regulating operations across networks that are responsible for balance and movement dynamics. Investigation of this hypothesis will advance our knowledge of the role of the LC-NE system in motor control and provide a basis for treating movement disorders resulting from disease, injury, or normal aging.

Systemic immune responses after ischemic stroke: From the center to the periphery

Ischemic stroke is a leading cause of disability and death. It imposes a heavy economic burden on individuals, families and society. The mortality rate of ischemic stroke has decreased with the help of thrombolytic drug therapy and intravascular intervention. However, the nerve damage caused by ischemia-reperfusion is long-lasting and followed by multiple organ dysfunction. In this process, the immune responses manifested by systemic inflammatory responses play an important role. It begins with neuroinflammation following ischemic stroke. The large number of inflammatory cells released after activation of immune cells in the lesion area, along with the deactivated neuroendocrine and autonomic nervous systems, link the center with the periphery. With the activation of systemic immunity and the emergence of immunosuppression, peripheral organs become the second “battlefield” of the immune response after ischemic stroke and gradually become dysfunctional and lead to an adverse prognosis. The purpose of this review was to describe the systemic immune responses after ischemic stroke. We hope to provide new ideas for future research and clinical treatments to improve patient outcomes and quality of life.

Autonomic nervous activity analysis based on visibility graph complex networks and skin sympathetic nerve activity

Background: Autonomic nerve system (ANS) plays an important role in regulating cardiovascular function and cerebrovascular function. Traditional heart rate variation (HRV) and emerging skin sympathetic nerve activity (SKNA) analyses from ultra-short-time (UST) data cannot fully reveal neural activity, thereby quantitatively reflect ANS intensity.

Methods: Electrocardiogram and SKNA from sixteen patients (seven cerebral hemorrhage (CH) patients and nine control group (CO) patients) were recorded using a portable device. Ten derived HRV (mean, standard deviation and root mean square difference of sinus RR intervals (NNmean, SDNN and RMSSD), ultra-low frequency (<0.003 Hz, uLF), very low frequency ([0.003 Hz, 0.04 Hz), vLF), low frequency ([0.04 Hz, 0.15 Hz), LF) and high frequency power ([0.15 Hz, 0.4 Hz), HF), ratio of LF to HF (LF/HF), the standard deviation of instantaneous beat-to-beat R-R interval variability (SD1), and approximate entropy (ApEn)) and ten visibility graph (VG) features (diameter (Dia), average node degree (aND), average shortest-path length (aSPL), clustering coefficient (CC), average closeness centrality (aCC), transitivity (Trans), average degree centrality (aDC), link density (LD), sMetric (sM) and graph energy (GE) of the constructed complex network) were compared on 5-min and UST segments to verify their validity and robustness in discriminating CH and CO under different data lengths. Besides, their potential for quantifying ANS-Load were also investigated.

Results: The validation results of HRV and VG features in discriminating CH from CO showed that VG features were more clearly distinguishable between the two groups than HRV features. For effectiveness evaluation of analyzing ANS on UST segment, the NNmean, SDNN, RMSSD, LF, HF and LF/HF in HRV features and the CC, Trans, Dia and GE of VG features remained stable in both activated and inactivated segments across all data lengths. The capability of HRV and VG features in quantifying ANS-Load were evaluated and compared under different ANS-Load, the results showed that most HRV features (SDNN, LFHF, RMSSD, vLF, LF and HF) and almost all VG features were correlated to sympathetic nerve activity intensity.

Conclusions: The proposed autonomic nervous activity analysis method based on VG and SKNA offers a new insight into ANS assessment in UST segments and ANS-Load quantification.

Longitudinal changes in the hypothalamic–pituitary–adrenal axis and sympathetic nervous system are related to the prognosis of stroke

Background and purpose

This study sought to improve methods to identify biomarkers in the neuroendocrine system related to stroke progression to improve the accuracy of traditional tools for evaluating stroke prognosis.

Methods

Seventy-four stroke patients and 237 healthy controls were prospectively included. We measured urinary epinephrine (E), noradrenaline (NE), dopamine (DA) and cortisol (F) on days 1, 3, and 5 after stroke onset and plasma F, adrenocorticotropic hormone (ACTH), thyrotropin (TSH), prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and growth hormone (GH). The correlation between these hormone levels and 90-day prognosis was analyzed, their value in assessing prognosis was compared with lesion volume and National Institutes of Health Stroke Scale (NIHSS) scores using receiver operating characteristic (ROC) curves, and their correlation with conventional clinical variables was assessed.

Results

Levels of F, 24-h urinary free cortisol(UFC), E, NE, DA, and GH on days 1, 3, and 5 were significantly higher in stroke patients than in controls (P &lt; 0.01), while ACTH and TSH decreased, gradually approaching normal within 5 days of onset. Levels of E, NE, F, and 24-h UFC were proportional to severity, and all gradually decreased within 5 days of onset in patients with a good prognosis and gradually increased or remained high in those with a poor prognosis. After adjustment for age, sex, NIHSS, or Glasgow Coma Scale (GCS) score, F &gt; 13.6 μg/dL, ACTH &gt; 22.02 pg/mL and NE &gt; 123.5 μg/ 24 h were identified as risk factors for a poor prognosis 90 days after stroke (P &lt; 0.05). The combination of F, ACTH, NE, white blood cell count (WBC), glucose (Glu), and hemoglobin (Hb) was significantly more accurate than lesion volume (AUC: 0.931 vs. 0.694 P = 0.019) and NIHSS score (AUC: 0.931 vs. 0.746 P = 0.034) in predicting poor prognosis of stroke 1 day after onset. Hormones and traditional clinical variables were correlated to varying degrees, with NE correlating most strongly with 24-h UFC (r = 0.54) and moderately positively with lesion volume (r = 0.40) and NIHSS score (r = 0.45).

Conclusions

Stroke causes significant time-phased dynamic changes in the hypothalamic–pituitary–adrenal axis and sympathetic nervous system, and plasma F, ACTH, and urinary NE levels can be used to assess stroke severity and prognosis.

Chinese clinical trial registry

Registration Number: ChiCTR1900024992. Registration Date: 2019/8/6.

Construction of a Joint Prediction Model for the Occurrence of Ischemic Stroke and Acute Myocardial Infarction Based on Bioinformatic Analysis

Ischemic stroke (IS) has imposed significant threat to both middle-aged and elderly people worldwide. Acute myocardial infarction (AMI) is a rare but serious complication following IS, which can further increase patient disability and mortality rates. With the development of intravenous thrombolysis and endovascular treatment, the prognosis of IS has been greatly improved. However, the pathogenesis of IS complicated with AMI is still unclear. To fill this gap, this work uses bioinformatic analysis, where IS and AMI datasets were combined for differential gene analysis, and then, a ROC prediction model for target gene analysis was constructed. It is found that OSM gene has the highest prediction accuracy (AUC = 0.793), followed by IL6ST, IL6, JAK1, IL6R, and JAK2 genes. Joint prediction model showed higher accuracy in predicting the outcome of control and case (AUC = 0.918). The etiology of ischemic stroke and acute myocardial infarction is complicated. Their cooccurring pathological mechanisms and the conversion between the two diseases could not be explained by a single gene. Therefore, the joint prediction model in this work can provide a better prediction accuracy for research purpose.

Toward Diverse or Standardized: A Systematic Review Identifying Transcutaneous Stimulation of Auricular Branch of the Vagus Nerve in Nomenclature

OBJECTIVES

After 20 years of development, there is confusion in the nomenclature of transcutaneous stimulation of the auricular branch of the vagus nerve (ABVN). We performed a systematic review of transcutaneous stimulation of ABVN in nomenclature.

MATERIALS AND METHODS

A systematic search of the literature was carried out, using the bibliographic search engine PubMed. The search covered articles published up until June 11, 2020. We recorded the full nomenclature and abbreviated nomenclature same or similar to transcutaneous stimulation of ABVN in the selected eligible studies, as well as the time and author information of this nomenclature.

RESULTS

From 261 studies, 67 full nomenclatures and 27 abbreviated nomenclatures were finally screened out, transcutaneous vagus nerve stimulation and tVNS are the most common nomenclature, accounting for 38.38% and 42.06%, respectively. In a total of 97 combinations of full nomenclatures and abbreviations, the most commonly used nomenclature for the combination of transcutaneous vagus nerve stimulation and tVNS, accounting for 30.28%. Interestingly, the combination of full nomenclatures and abbreviations is not always a one-to-one relationship, there are ten abbreviated nomenclatures corresponding to transcutaneous vagus nerve stimulation, and five full nomenclatures corresponding to tVNS. In addition, based on the analysis of the usage habits of nomenclature in 21 teams, it is found that only three teams have fixed habits, while other different teams or the same team do not always use the same nomenclature in their paper.

CONCLUSIONS

The phenomenon of confusion in the nomenclature of transcutaneous stimulation of ABVN is obvious and shows a trend of diversity. The nomenclature of transcutaneous stimulation of ABVN needs to become more standardized in the future.

The "Dialogue" Between Central and Peripheral Immunity After Ischemic Stroke: Focus on Spleen

The immune response generated by the body after the incidence of ischemic stroke, runs through the comprehensive process of aftermath. During this process of ischemic stroke, the central neuroinflammation and peripheral immune response seriously affect the prognosis of patients, which has been the focus of research in recent years. As this research scenario progressed, the "dialogue" between central nervous inflammation and peripheral immune response after ischemic stroke has become more closely related. It's worth noting that the spleen, as an important peripheral immune organ, plays a pivotal role in this dialogue. Multiple mechanisms have previously been reported for brain-spleen crosstalk after ischemic stroke. Further, neuroinflammation in the brain can affect the peripheral immune state by activating/inhibiting spleen function. However, the activation of the peripheral immune inflammatory response can work reversibly in the spleen. It further affects intracerebral neuroinflammation through the injured blood-brain barrier. Therefore, paying close attention to the role of spleen as the pivot between central and peripheral immunity in ischemic stroke may help to provide a new target for immune intervention in the treatment of ischemic stroke. In the present review, we reviewed the important role of spleen in central neuroinflammation and peripheral immune response after ischemic stroke. We summarized the relevant studies and reports on spleen as the target of immune intervention which can provide new ideas for the clinical treatment of ischemic stroke.

Reappearance of Neurological Deficits in Pathologic Brain: Are Sedatives and Opioids Culprits? A Systematic Review

Following a brain insult, focal neurological deficits may develop. Despite resolution of these deficits with time, the subsequent administration of sedative medications and opioids may lead to recrudescence of previous neurological deficits. Therefore, the present systematic review aims to explore the role of different sedatives and opioid analgesics at reproducing focal neurological deficits in patients with previous brain insults undergoing surgery. Our PRISMA compliant systematic review covering the literature from 1990 to 2020 showed a consistent reoccurrence of neurological deficits following administration of benzodiazepines and opioids across 12 studies. It appears that in all studies, the manifestations were transient and affected mostly middle-aged patients (45 to 67 y of age). In addition, benzodiazepines and opioid antagonism by naloxone and flumazenil reverses the unmasking of prior neurological deficits. In contrast, it is not clear based on our study whether the unmasking or worsening of neurological deficits occurs following recent injuries or an older brain insult, although for most patients it appears to be the former. Future studies are needed to elucidate the mechanisms involved in unmasking prior deficits and/or extension of prior injuries by sedative and opioid analgesics. This review will aid in developing prospective studies on individual sedative medications and their effects on unmasking neurological deficits in patients with multiple brain pathologies.

A narrative review of adjuvant therapy for glioma: hyperbaric oxygen therapy

Glioma is a kind of common malignant tumor in neurosurgery and has a high mortality and morbidity rate, which poses a serious threat to the health of people all over the world. Surgery is the preferred treatment for patients with glioma, radiotherapy or chemotherapy can be used after surgery. Although there are clear therapeutic protocols, the efficacy and safety of these protocols are clinically proven, a large number of patients are still dissatisfied with the treatment and the health of the patient remains unsatisfactory. Therefore, it is crucial to look for other treatments or complementary treatments. In the modern medical treatment, hyperbaric oxygen (HBO) therapy is widely used in various kinds of pathological state of adjuvant therapy, and existing studies confirm the efficacy of HBO therapy in combination with surgery, radiotherapy, chemotherapy, and photodynamic therapy. Studies have shown that HBO can inhibit the growth of tumor tissue as an adjunctive therapy. This provides novel insights into the clinical treatment of glioma patients. Although HBO is not licensed for use in cancer treatment, as a kind of adjuvant therapy, the treatment effect of HBO can be accepted by the patients and its cost lower, which could be regarded as an ideal safe treatment.

Central sympathetic nerve activation in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a life-threatening condition, and although its two main complications-cerebral vasospasm (CVS)/delayed cerebral ischemia (DCI) and early brain injury (EBI)-have been widely studied, prognosis has not improved over time. The sympathetic nerve (SN) system is important for the regulation of cardiovascular function and is closely associated with cerebral vessels and the regulation of cerebral blood flow and cerebrovascular function; thus, excessive SN activation leads to a rapid breakdown of homeostasis in the brain. In the hyperacute phase, patients with SAH can experience possibly lethal conditions that are thought to be associated with SN activation (catecholamine surge)-related arrhythmia, neurogenic pulmonary edema, and irreversible injury to the hypothalamus and brainstem. Although the role of the SN system in SAH has long been investigated and considerable evidence has been collected, the exact pathophysiology remains undetermined, mainly because the relationships between the SN system and SAH are complicated, and many SN-modulating factors are involved. Thus, research concerning these relationships needs to explore novel findings that correlate with the relevant concepts based on past reliable evidence. Here, we explore the role of the central SN (CSN) system in SAH pathophysiology and provide a comprehensive review of the functional CSN network; brain injury in hyperacute phase involving the CSN system; pathophysiological overlap between the CSN system and the two major SAH complications, CVS/DCI and EBI; CSN-modulating factors; and SAH-related extracerebral organ injury. Further studies are warranted to determine the specific roles of the CSN system in the brain injuries associated with SAH.

Pertussis toxin-induced inflammatory response exacerbates intracerebral haemorrhage and ischaemic stroke in mice

Background

Stroke is a devastating disease, including intracerebral haemorrhage (ICH) and ischaemic stroke. Emerging evidences indicate that systemic inflammatory cascades after stroke contribute to brain damage. However, the direct effects and features of systemic inflammation on brain injury, especially comparing between ischaemic and haemorrhagic stroke, are still obscure.

Methods

Pertussis toxin (PT) was used to build a pro-inflammatory milieu after ICH and ischaemic stroke in mouse model. The neurodeficits, stroke lesion, immune response and blood–brain barrier (BBB) destruction were assessed.

Results

In ICH mouse model, PT-induced systemic inflammation exacerbated neurological deficits, and enlarged haemorrhage lesion and perihaematomal oedema. We also found promoted leucocyte infiltration and inflammatory cytokine release into the brain after PT treatment. Moreover, the integrity of the BBB was further disrupted after receiving PT. Furthermore, we demonstrated that PT enhanced brain inflammation and aggravated stroke severity in middle cerebral artery occlusion mouse model.

Conclusions

Our results suggest that PT increases inflammatory response that exacerbates brain injury after ICH or ischaemic stroke in mouse model.

Norepinephrine Protects against Methamphetamine Toxicity through β2-Adrenergic Receptors Promoting LC3 Compartmentalization

Norepinephrine (NE) neurons and extracellular NE exert some protective effects against a variety of insults, including methamphetamine (Meth)-induced cell damage. The intimate mechanism of protection remains difficult to be analyzed in vivo. In fact, this may occur directly on target neurons or as the indirect consequence of NE-induced alterations in the activity of trans-synaptic loops. Therefore, to elude neuronal networks, which may contribute to these effects in vivo, the present study investigates whether NE still protects when directly applied to Meth-treated PC12 cells. Meth was selected based on its detrimental effects along various specific brain areas. The study shows that NE directly protects in vitro against Meth-induced cell damage. The present study indicates that such an effect fully depends on the activation of plasma membrane β2-adrenergic receptors (ARs). Evidence indicates that β2-ARs activation restores autophagy, which is impaired by Meth administration. This occurs via restoration of the autophagy flux and, as assessed by ultrastructural morphometry, by preventing the dissipation of microtubule-associated protein 1 light chain 3 (LC3) from autophagy vacuoles to the cytosol, which is produced instead during Meth toxicity. These findings may have an impact in a variety of degenerative conditions characterized by NE deficiency along with autophagy impairment.

Long Noncoding RNA SNHG14 Promotes Ischemic Brain Injury via Regulating miR-199b/AQP4 Axis

BACKGROUND

Ischemic stroke is the leading cause of disability worldwide. Long noncoding RNAs (lncRNAs) play important roles in the pathogenesis of cerebral ischemia. This study aimed to investigate the role and mechanism of lncRNA small nucleolar RNA host gene 14 (SNHG14) in ischemic brain injury.

METHODS

Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in mice. The expression of SNHG14 in MCAO mouse model was detected by quantitative real-time PCR (qRT-PCR). The levels of SNHG14, microRNA-199b (miR-199b) and aquaporin 4 (AQP4) in oxygen-glucose deprivation (OGD)-stimulated BV2 cells were determined by qRT-PCR or western blot assay. Cell proliferation and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The levels of pro-inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress markers were examined using commercial kits. The relationships among SNHG14, miR-199b and AQP4 were confirmed by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay.

RESULTS

SNHG14 was up-regulated in MCAO mouse model. Depletion of SNHG14 lessened cerebral ischemia in MCAO mouse model. SNHG14 silencing inhibited inflammation and oxidative stress in OGD-exposed BV2 cells. MiR-199b level was decreased, while AQP4 level was increased in OGD-treated BV2 cells. Knockdown of miR-199b reversed the effect of SNHG14 knockdown on ischemic damage in OGD-stimulated BV2 cells. Moreover, AQP4 overexpression abolished the effect of miR-199b on ischemic injury in OGD-treated BV2 cells. Furthermore, SNHG14 indirectly regulate AQP4 expression by sponging miR-199b.

CONCLUSIONS

Knockdown of SNHG14 attenuated ischemic brain injury by inhibiting inflammation and oxidative stress through the miR-199b/AQP4 axis.

Interleukin-17A promotes the differentiation of bone marrow mesenchymal stem cells into neuronal cells

Ischemia or hemorrhagic stroke is one of the leading causes of death and permanent disability in the worldwide population. As a consequence of the potential increasing in stroke, stem cell therapy is currently an area of intense focus. However, there are less data available regarding the promotion of healing efficacy after stroke. The present study aimed to investigate whether the cytokine interleukin-17A (IL-17A) could have a role in promoting the neuronal differentiation of mesenchymal stem cells (MSCs) and to investigate the associated molecular mechanism. Firstly, different concentration of IL-17A at range from 5-40 ng/mL was applied to stimulate bone marrow MSCs (BMSCs) during the course of neurogenic differentiation. Then reverse transcription-PCR, histological analyses and immunofluorescence assays were used to determine the optimum concentration of IL-17A in promoting the neuronal differentiation of BMSCs, which was 20 ng/mL. Mechanistically, Wnt signaling pathway was activated and Notch signaling pathway was suppressed. In addition, there were antergic effect of these two signaling pathways modulating the neurogenic differentiation of BMSCs induced by IL-17A. The present study demonstrated the potential role of IL-17A-based BMSCs strategy for promoting neuronal differentiation in vitro. However, the treatment efficacy could be considerably confirmed in animals with ischemia stroke. Therefore, a more sophisticated strategy that addresses the complicated treatment associated with stroke is needed.

A Step further-The Role of Trigeminocardiac Reflex in Therapeutic Implications: Hypothesis, Evidence, and Experimental Models

The trigeminocardiac reflex (TCR) is a well-recognized brainstem reflex that represents a unique interaction between the brain and the heart through the Vth and Xth cranial nerves and brainstem nuclei. The TCR has mainly been reported as an intraoperative phenomenon causing cardiovascular changes during skull-base surgeries. However, it is now appreciated that the TCR is implicated during non-neurosurgical procedures and in nonsurgical conditions, and its complex reflex pathways have been explored as potential therapeutic options in various neurological and cardiovascular diseases. This narrative review presents an in-depth overview of hypothetical and experimental models of the TCR phenomenon in relation to the Vth and Xth cranial nerves. In addition, primitive interactions between these 2 cranial nerves and their significance are highlighted. Finally, therapeutic models of the complex interactions of the TCR and areas for further research will be considered.

N-Methyl-D-Aspartate Receptor Signaling-Protein Kinases Crosstalk in Cerebral Ischemia

Although stroke is very often the cause of death worldwide, the burden of ischemic and hemorrhagic stroke varies between regions and over time regarding differences in prognosis, prevalence of risk factors, and treatment strategies. Excitotoxicity, oxidative stress, dysfunction of the blood-brain barrier, neuroinflammation, and lysosomal membrane permeabilization, sequentially lead to the progressive death of neurons. In this process, protein kinases-related checkpoints tightly regulate N-methyl-D-aspartate (NMDA) receptor signaling pathways. One of the major hallmarks of cerebral ischemia is excitotoxicity, characterized by overactivation of glutamate receptors leading to intracellular Ca²⁺ overload and ultimately neuronal death. Thus, reduced expression of postsynaptic density-95 protein and increased protein S-nitrosylation in neurons is responsible for neuronal vulnerability in cerebral ischemia. In this chapter death-associated protein kinases, cyclin-dependent kinase 5, endoplasmic reticulum stress-induced protein kinases, hyperhomocysteinemia-related NMDA receptor overactivation, ephrin-B-dependent amplification of NMDA-evoked neuronal excitotoxicity and lysosomocentric hypothesis have been discussed.Consequently, ample evidences have demonstrated that enhancing extrasynaptic NMDA receptor activity triggers cell death after stroke. In this context, considering the dual roles of NMDA receptors in both promoting neuronal survival and mediating neuronal damage, selective augmentation of NR2A-containing NMDA receptor activation in the presence of NR2B antagonist may constitute a promising therapy for stroke.

In vitro cultured calculus bovis attenuates cerebral ischaemia-reperfusion injury by inhibiting neuronal apoptosis and protecting mitochondrial function in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In vitro cultured calculus bovis (ICCB), which is produced based on the formation mechanism of bovine gallstones, is used to replace the natural bezoar. It has been used in the clinic to treat brain diseases, including stroke, Alzheimer's disease and depression.

AIM OF STUDY

ICCB is used to treat encephalopathy in the clinic. We explored the effects of ICCB on cerebral ischaemia-reperfusion injury (CIRI) and the potential associated mechanisms.

MATERIALS AND METHODS

Rats were subjected to middle cerebral artery occlusion for 90 min, followed by 24 h of reperfusion, after being given different concentrations of ICCB once a day for 3 days. Subsequently, the neurological scores, brain oedema and volume of cerebral infarction were measured, and the histopathological changes in the cortex neurons were observed by haematoxylin and eosin staining (H&E). Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL). Ultrastructural changes in the mitochondria of the cortex were assessed by transmission electron microscopy (TEM). The apoptosis-related proteins Bax, Bcl-2, caspase-9, caspase-3, Mito-Cyt C and Cyto-Cyt C were detected by Western blotting.

RESULTS

Compared with those in the control group, the neurological scores, the volumes of cerebral infarction, and the brain water contents were significantly decreased in the ICCB groups at doses of 50 and 100 mg/kg. The ICCB treatment effectively decreased the neuronal apoptosis resulting from the CIRI-induced neuron injury. In addition, the histopathological damage and the mitochondria ultrastructure injury were partially improved in the CIRI rats after ICCB treatment. Western blotting analysis indicated that ICCB significantly decreased the expression of Bax, caspase-9, caspase-3 and Cyto-Cyt C protein levels while increasing the expression of Bcl-2 and Mito-Cyt C protein levels.

CONCLUSION

The ICCB protected against CIRI by suppressing the mitochondria-mediated apoptotic signalling pathway.

Delayed Recanalization-How Late Is Not Too Late?

Stroke has become the second most prevalent cause of mortality in the world. Currently, the treatment of ischemic stroke is based on thrombolytic and thrombectomy therapy shortly after the ischemic event (≤ 4.5 h for thrombolytic strategies; ≤ 6 h for thrombectomy strategies). However, the majority of patients are unable to receive prompt treatment, particularly in undeveloped countries. Alternative solutions are lacking for those patients that miss the optimal window of opportunity for treatment. Recently, new developments in imaging techniques and intravascular interventional devices enable the expansion of the window of opportunity for treating stroke patients. Clinical studies have reported that delayed recanalization at 24 h, or even more than 1 month, was beneficial for some patients. However, the mechanisms of neuroprotection that underly the delayed recanalization in these ischemic stroke patients remain unclear. In this review, we will summarize the clinical studies of delayed recanalization, and organize them according to the duration of occlusion. Additionally, we will discuss the changing guidelines and possible mechanisms based on animal research, and attempt to draw conclusions and future perspectives.

Orexin-A protects against cerebral ischemia-reperfusion injury by inhibiting excessive autophagy through OX1R-mediated MAPK/ERK/mTOR pathway

Orexin A (OXA) is a neuroprotective peptide that exerts protective effects on multiple physiological and pathological processes. Activation of autophagy is linked to the occurrence of cerebral ischemia-reperfusion injury (CIRI); however, its function remains incompletely understood. In this study, OXA was sought to exert its neuroprotective role by regulating autophagy in oxygen and glucose deprivation and reoxygenation (OGD/R) model and middle cerebral artery occlusion (MCAO) model of rats, and to elucidate the underlying molecular mechanisms. Acridine orange (AO) staining was used to evaluate autophagic vacuoles. Cell viability was measured by CCK8. The levels of p-ERK_1/2, t-ERK_1/2, p-mTOR, LC3B, Beclin 1, and p62 were evaluated by western blotting. Apoptosis rate was detected by Hoechst 33342 staining and Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL). OXA treatment alleviated neuronal apoptosis and significantly inhibited autophagy activity. Mechanistically, OXA exerted its neuroprotective effects in vivo and in vitro by suppressing over-activated autophagy by modulating OX1R-mediated MAPK/ERK/mTOR pathway. The results of this study elucidate the roles of autophagy in CIRI and the mechanisms underlying the neuroprotective action of OXA. Our findings could facilitate the development of novel therapeutics for ischemic stroke.

Locus Coeruleus and neurovascular unit: From its role in physiology to its potential role in Alzheimer's disease pathogenesis

Locus coeruleus (LC) is the main noradrenergic (NA) nucleus of the central nervous system. LC degenerates early during Alzheimer's disease (AD) and NA loss might concur to AD pathogenesis. Aside from neurons, LC terminals provide dense innervation of brain intraparenchymal arterioles/capillaries, and NA modulates astrocyte functions. The term neurovascular unit (NVU) defines the strict anatomical/functional interaction occurring between neurons, glial cells, and brain vessels. NVU plays a fundamental role in coupling the energy demand of activated brain regions with regional cerebral blood flow, it includes the blood-brain barrier (BBB), plays an active role in neuroinflammation, and participates also to the glymphatic system. NVU alteration is involved in AD pathophysiology through several mechanisms, mainly related to a relative oligoemia in activated brain regions and impairment of structural and functional BBB integrity, which contributes also to the intracerebral accumulation of insoluble amyloid. We review the existing data on the morphological features of LC-NA innervation of the NVU, as well as its contribution to neurovascular coupling and BBB proper functioning. After introducing the main experimental data linking LC with AD, which have repeatedly shown a key role of neuroinflammation and increased amyloid plaque formation, we discuss the potential mechanisms by which the loss of NVU modulation by LC might contribute to AD pathogenesis. Surprisingly, thus far not so many studies have tested directly these mechanisms in models of AD in which LC has been lesioned experimentally. Clarifying the interaction of LC with NVU in AD pathogenesis may disclose potential therapeutic targets for AD.

Photic sneeze reflex: another variant of the trigeminocardiac reflex?

The photic sneeze reflex (PSR) is a condition of uncontrollable sneezing episodes in response to bright light. This reflex often manifests as a mild phenomenon but may cause devastating consequences in some situations (aeroplane pilots, car drivers, etc.). Its exact mechanism is poorly understood. Interestingly, the roles of the fifth and tenth cranial nerves, brainstem nuclei and inciting patterns closely mimic a well-known brainstem reflex, known as the trigeminocardiac reflex (TCR). In this critical review, we hypothesize that the PSR can be a variant of the TCR. This concept will lead to a better understanding of the PSR and sharpens the TCR characteristics and open the doors for new research possibilities.

The Involvement and Therapy Target of Immune Cells After Ischemic Stroke

After ischemic stroke, the integrity of the blood-brain barrier is compromised. Peripheral immune cells, including neutrophils, T cells, B cells, dendritic cells, and macrophages, infiltrate into the ischemic brain tissue and play an important role in regulating the progression of ischemic brain injury. In this review, we will discuss the role of different immune cells after stroke in the secondary inflammatory reaction and focus on the phenotypes and functions of macrophages in ischemic stroke, as well as briefly introduce the anti-ischemic stroke therapy targeting macrophages.