Electroacupuncture preconditioning attenuates ischemic brain injury by activation of the adenosine monophosphate-activated protein kinase signaling pathway

Electroacupuncture produces analgesic effects via cannabinoid CB1 receptor-mediated GABAergic neuronal inhibition in the rostral ventromedial medulla

OBJECTIVE

Electroacupuncture (EA) is commonly used for pain control in clinical practice, yet the precise mechanisms underlying its action are not fully understood. The rostral ventromedial medulla (RVM) plays a crucial role in the modulation of pain. GABAergic neurons in the RVM (GABARVM neurons) facilitate nociceptive transmission by inhibiting off-cells activity. This research examined the role of GABARVM neurons in the analgesic effects of EA.

METHODS

Nociceptive behavior was evaluated using inflammatory pain models induced by complete Freund's adjuvant (CFA) and neuropathic pain models induced by chronic constrictive injury (CCI). Also, in situ hybridization, chemogenetics, in vivo mouse calcium imaging, and in vivo electrophysiological recordings were used to determine neuronal activity and neural circuitry.

RESULTS

EA at the "Zusanli" (ST36) on the affected side produced a significant analgesic effect in both CFA and CCI models. CFA treatment and CCI elevated the calcium activity of GABARVM neurons. Also, EA reduced the calcium activity, neuronal firing rates, and c-Fos expression of GABARVM neurons in both pain models. Chemogenetic inhibition of GABARVM neurons increased nociceptive thresholds. Chemogenetic activation of GABARVM neurons caused increased pain sensitivity in control mice and negated the analgesic effects of EA in both pain models. Moreover, reducing cannabinoid CB1 receptors on GABARVM neurons counteracted the analgesic effects of EA in CFA and CCI-induced pain models.

CONCLUSIONS

The study indicates that the analgesic effect of EA in inflammatory and neuropathic pain is facilitated by CB1 receptor-mediated inhibition of GABARVM neurons.

Transcription Factor EB: A Promising Therapeutic Target for Ischemic Stroke

Transcription factor EB (TFEB) is an important endogenous defensive protein that responds to ischemic stimuli. Acute ischemic stroke is a growing concern due to its high morbidity and mortality. Most survivors suffer from disabilities such as numbness or weakness in an arm or leg, facial droop, difficulty speaking or understanding speech, confusion, impaired balance or coordination, or loss of vision. Although TFEB plays a neuroprotective role, its potential effect on ischemic stroke remains unclear. This article describes the basic structure, regulation of transcriptional activity, and biological roles of TFEB relevant to ischemic stroke. Additionally, we explore the effects of TFEB on the various pathological processes underlying ischemic stroke and current therapeutic approaches. The information compiled here may inform clinical and basic studies on TFEB, which may be an effective therapeutic drug target for ischemic stroke.

Adiponectin regulates electroacupuncture-produced analgesic effects in association with a crosstalk between the peripheral circulation and the spinal cord

Neurotransmitter-mediated acupuncture analgesia has been widely studied in nervous systems. It remains largely unclear if peripheral substances are involved the acupuncture analgesia. Adiponectin (APN), a circulating adipokine, shows analgesic effects. The study aimed to examine whether APN regulates analgesic effects of electroacupuncture (EA) in the complete Freund's adjuvant (CFA)-induced mouse model. APN wild type (WT) and knockout (KO) mouse were employed in the study. We found that EA attenuates the CFA-induced pain as demonstrated by the Hargreaves thermal test and the von Frey filament test. The deletion of APN significantly reduced the acupuncture analgesia in the CFA-treated APN KO mice while the intrathecal administration of APN mimicked the analgesic effects of EA. We further revealed that EA produced analgesic effects mainly via APN/AdipoR2-mediated AMPK pathway by the siRNA inhibitions of APN receptors (adipoR1/2) in the spinal cord. The immunofluorescence staining analysis showed that EA increased the APN accumulation in spinal cord through the blood circulation. In conclusion, the study indicates a novel mechanism that acupuncture produces analgesic effects at least partially via APN/AdipoR2-AMPK pathway in the spinal cord.

Electroacupuncture ameliorates cerebral ischemia/reperfusion injury by suppressing autophagy via the SIRT1-FOXO1 signaling pathway

Cerebral ischemia/reperfusion (CIR) injury occurs when blood flow is restored in the brain, causing secondary damage to the ischemic tissues. Previous studies have shown that electroacupuncture (EA) treatment contributes to brain protection against CIR injury through modulating autophagy. Studies indicated that SIRT1-FOXO1 plays a crucial role in regulating autophagy. Here we investigated the mechanisms underlying the neuroprotective effect of EA and its role in modulating autophagy via the SIRT1-FOXO1 signaling pathway in rats with CIR injury. EA pretreatment at "Baihui", "Quchi" and "Zusanli" acupoints (2/15Hz, 1mA, 30 min/day) was performed for 5 days before the rats were subjected to middle cerebral artery occlusion, and the results indicated that EA pretreatment substantially reduced the Longa score and infarct volume, increased the dendritic spine density and lessened autophagosomes in the peri-ischemic cortex of rats. Additionally, EA pretreatment also reduced the ratio of LC3-II/LC3-I, the levels of Ac-FOXO1 and Atg7, and the interaction of Ac-FOXO1 and Atg7, but increased the levels of p62, SIRT1, and FOXO1. The above effects were abrogated by the SIRT1 inhibitor EX527. Thus, we presume that EA pretreatment elicits a neuroprotective effect against CIR injury, potentially by suppressing autophagy via activating the SIRT1-FOXO1 signaling pathway.

Inhibition of Triple-Negative Breast Cancer Tumor Growth by Electroacupuncture with Encircled Needling and Its Mechanisms in a Mice Xenograft Model

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer without effective targeted drugs. While breast cancer patients often use acupuncture for the relief of cancer-induced pain or the side effects of chemo- or radiation therapy, little information is known regarding the direct effects of electroacupuncture on TNBC tumor and its potential mechanisms. Here, we created a mice model of TNBC and electroacupuncture with encircled needling around the tumors was given to the animals daily for 3 weeks at 15-20 Hz (3 min, each time). For sham electroacupuncture control, the skin was punctured to a depth of 5 mm and then the needle was quickly withdrawn without electrical stimulation or manual needle manipulation. We found that electroacupuncture significantly inhibited TNBC tumor growth and the inhibitory rate increased gradually overtime. Mechanistic analysis showed that electroacupuncture inhibited tumor angiogenesis by reducing the expression of vascular endothelial growth factor A (VEGF-A), its receptor VEGF-R and neuropilin 1 (NRP-1). Electroacupuncture also led to a significant decrease of matrix metalloproteinase-2 (MMP-2) expression and an increase of tissue inhibitor of MMP (TIMP-2) expression. Additionally, the expression of semaphorin 3A (Sema3A) and nerve growth factor receptor (NGFR) p75 in TNBC tissue was significantly upregulated in response to electroacupuncture. Furthermore, tumor necrosis factor (TNF)-alpha level in the serum was dramatically reduced after electroacupuncture. These results showed that electroacupuncture could directly inhibit TNBC tumor growth through the inhibition of proteins related to tumor angiogenesis and extracellular matrix, the suppression of TNBC-induced inflammation and the upregulation of nerve growth factor receptors.

Hydroxybutyrate promotes the recovery from cerebral infarction by activating Amp-activated protein kinase signaling

Recent studies have shown that hydroxybutyrate (GHB) is effective for protection against ischemia/brain damage in rat models. However, the specific underlying mechanism is poorly understood. In line with the previous studies, the present data showed that GHB improves cerebral blood flow (CBF) and physiological variables, including pH, pCO₂ and pO₂. Using CD31-immunofluorescence staining, a reduction of blood vessel density was indicated in the middle cerebral artery occlusion (MCAO) group; however, GHB treatment enhanced the cerebral vascular density in the ischemic area. In addition, GHB treatment increased the number of BrdU/lectin double-positive cells. Furthermore, the reduction of nestin-positive cells was identified in the brain of MCAO rats, while the number of nestin-positive cells was significantly increased after GHB administration. Compared with the sham group, the activation of Amp-activated protein kinase (AMPK) was identified in MCAO rats, suggesting stress-mediated AMPK activation after ischemia. Furthermore, the western blot assay showed that GHB treatment resulted in further activation of AMPK and endothelial nitric oxide synthase (eNOS), suggesting an enhanced energy supply. In summary, the present novel data indicates that GHB promotes the recovery from cerebral infarction mainly by activating AMPK and eNOS signaling, thereby enhancing angiogenesis and neuron regeneration.

AMPK: Potential Therapeutic Target for Ischemic Stroke

5'-AMP-activated protein kinase (AMPK), a member of the serine/threonine (Ser/Thr) kinase group, is universally distributed in various cells and organs. It is a significant endogenous defensive molecule that responds to harmful stimuli, such as cerebral ischemia, cerebral hemorrhage, and, neurodegenerative diseases (NDD). Cerebral ischemia, which results from insufficient blood flow or the blockage of blood vessels, is a major cause of ischemic stroke. Ischemic stroke has received increased attention due to its '3H' effects, namely high mortality, high morbidity, and high disability. Numerous studies have revealed that activation of AMPK plays a protective role in the brain, whereas its action in ischemic stroke remains elusive and poorly understood. Based on existing evidence, we introduce the basic structure, upstream regulators, and biological roles of AMPK. Second, we analyze the relationship between AMPK and the neurovascular unit (NVU). Third, the actions of AMPK in different phases of ischemia and current therapeutic methods are discussed. Finally, we evaluate existing controversy and provide a detailed analysis, followed by ethical issues, potential directions, and further prospects of AMPK. The information complied here may aid in clinical and basic research of AMPK, which may be a potent drug candidate for ischemic stroke treatment in the future.

Anti-Apoptotic Mechanisms of Acupuncture in Neurological Diseases: A Review

Apoptosis, known as programmed cell death, plays a significant role in the pathogenesis of neurological diseases. Most of these diseases can be obviously alleviated by means of acupuncture treatment. Current research studies have shown that the efficacy of acupuncture to these medical conditions is closely associated with the anti-apoptotic potentials. Mainly based on the acupuncture's anti-apoptotic efficacy in prevalent neurological disorders, including cerebral ischemia-reperfusion injury, Alzheimer's disease, depression or stress related-modes, spinal cord injuries, etc., this review comes to a conclusion that the anti-apoptotic effect of acupuncture treatment for neurological diseases, evidently reflected through Bcl-2, Bax or caspase expression change, results from regulating mitochondrial or autophagic dysfunction as well as reducing oxidative stress and inflammation. The possible mechanisms of acupuncture's anti-apoptotic effect are associated with a series of downstream signaling pathways and the up-regulated expression of neurotrophic factors. It is of great importance to illuminate the exact mechanisms of acupuncture treatment for neurological dysfunctions.

Electroacupuncture preconditioning protects against focal cerebral ischemia/reperfusion injury via suppression of dynamin-related protein 1

Electroacupuncture preconditioning at acupoint Baihui (GV20) can reduce focal cerebral ischemia/reperfusion injury. However, the precise protective mechanism remains unknown. Mitochondrial fission mediated by dynamin-related protein 1 (Drp1) can trigger neuronal apoptosis following cerebral ischemia/reperfusion injury. Herein, we examined the hypothesis that electroacupuncture pretreatment can regulate Drp1, and thus inhibit mitochondrial fission to provide cerebral protection. Rat models of focal cerebral ischemia/reperfusion injury were established by middle cerebral artery occlusion at 24 hours after 5 consecutive days of preconditioning with electroacupuncture at GV20 (depth 2 mm, intensity 1 mA, frequency 2/15 Hz, for 30 minutes, once a day). Neurological function was assessed using the Longa neurological deficit score. Pathological changes in the ischemic penumbra on the injury side were assessed by hematoxylin-eosin staining. Cellular apoptosis in the ischemic penumbra on the injury side was assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling staining. Mitochondrial ultrastructure in the ischemic penumbra on the injury side was assessed by transmission electron microscopy. Drp1 and cytochrome c expression in the ischemic penumbra on the injury side were assessed by western blot assay. Results showed that electroacupuncture preconditioning decreased expression of total and mitochondrial Drp1, decreased expression of total and cytosolic cytochrome c, maintained mitochondrial morphology and reduced the proportion of apoptotic cells in the ischemic penumbra on the injury side, with associated improvements in neurological function. These data suggest that electroacupuncture preconditioning-induced neuronal protection involves inhibition of the expression and translocation of Drp1.

Roles of electro-acupuncture in glucose metabolism as assessed by 18F-FDG/PET imaging and AMPKα phosphorylation in rats with ischemic stroke

Targeted energy metabolism balance contributes to neural survival during ischemic stroke. Herein, we tested the hypothesis that electro‑acupuncture (EA) can enhance cerebral glucose metabolism assessed by 18F‑fluorodeoxyglucose/positron emission tomography (18F‑FDG/PET) imaging to prevent propagation of tissue damage and improve neurological outcome in rats subjected to ischemia and reperfusion injury. Rats underwent middle cerebral artery occlusion (MCAO) and received EA treatment at the LI11 and ST36 acupoints or non‑acupoint treatment once a day for 7 days. After EA treatment, a significant reduction in the infarct volume was determined by T2‑weighted imaging, accompanied by the functional recovery in CatWalk and Rota-rod performance. Moreover, EA promoted higher glucose metabolism in the caudate putamen (CPu), motor cortex (MCTX), somatosensory cortex (SCTX) regions as assessed by animal 18F‑FDG/PET imaging, suggesting that three‑brain regional neural activity was enhanced by EA. In addition, the AMP‑activated protein kinase α (AMPKα) in the CPu, MCTX and SCTX regions was phosphorylated at threonine 172 (Thr172) after ischemic injury; however, phosphorylation of AMPK was further increased by EA. These results indicate that EA could promote AMPKα phosphorylation of the CPu, MCTX and SCTX regions to enhance neural activity and motor functional recovery after ischemic stroke.

Transcutaneous electrical acupoint stimulation alleviates adverse cardiac remodeling induced by overload training in rats

Electroacupuncture has been shown previously to alleviate cardiac ischemia-reperfusion injury. Overload training (OT) exercise can result in profound cardiac damage and remodeling. In this study, we aimed to examine whether transcutaneous electrical acupoint stimulation (TEAS), a novel noninvasive and low-risk alternative to electroacupuncture, could counteract short-term OT-induced cardiac remodeling, fibrosis, autophagy, and apoptosis. Sixty rats were randomly divided into eight groups (n = 7 or 8/group): control, regular exercise, OT, OT plus low-, moderate- or high-frequency TEAS preconditioning, OT plus moderate-frequency TEAS postconditioning, or transcutaneous electrical nonacupoint stimulation (TENAS) preconditioning. The cardiac weight index (heart weight/body weight) was determined. Left ventricular morphology was examined by hematoxylin and eosin staining. Cardiac fibrosis and apoptosis were determined by Masson's trichrome and TUNEL staining, respectively. The presence of autophagosomes was observed by transmission electron microcopy. The expressions of autophagic markers (LC3 II/I and Beclin-1) were determined by Western blot. The results showed that 1) OT induced adverse cardiac structure changes but did not affect the cardiac weight index; 2) OT increased cardiac fibrosis and apoptosis and induced autophagosome formation with upregulated LC3 II/I and Beclin-1 expression; 3) TEAS preconditioning effectively alleviated OT-induced cardiac structure changes, fibrosis, apoptosis, and autophagy; 4) TEAS preconditioning produced better protective effects than TEAS postconditioning or TENAS preconditioning. Our results demonstrate that TEAS preconditioning protects the heart from OT-induced cardiac injury/remodeling, probably by inhibition of fibrosis, autophagy, and apoptosis.