Possible mechanisms of auricular acupoint stimulation in the treatment of migraine by activating auricular vagus nerve. / 从耳迷走神经探讨耳穴治疗偏头痛的可能机制.

Under the guidance of traditional Chinese medicine theory, the clinical research of auricular acupoint stimulation in the treatment of migraine has gained a lot, and the curative efficacy is definite, but its mechanism remains unclear. In the present paper, we discussed the efficacy of auricular acupoint stimulation including "transcutaneous auricular vagus nerve stimulation" (taVNS) in the treatment of migraine in recent years. Through bibliometric analysis, we screened out top 10 auricular acupoints (Shenmenï¼»TF4ï¼½, Pizhixiaï¼»AT4ï¼½, Jiaoganï¼»AH6aï¼½, Ganï¼»CO12ï¼½, Yidanï¼»CO11ï¼½, Neifenmiï¼»CO18ï¼½, Shenï¼»CO10ï¼½, Nieï¼»AT2ï¼½, Zhenï¼»AT3ï¼½ and Eï¼»AT1ï¼½) which were the most frequently used for migraine. Majority of these auricular acupoints just distributed in the region innervated by auricular vagus nerve. Thus, we thought that the analgesic effect of needling these auricular acupoints for migraine was produced by triggering the auricular vagus nerve, and concluded that the central mechanism underlying induction of analgesic effect by activating auricular vagus nerve may be achieved by activating the descending pain regulation pathway of the locus coeruleus nucleus and dorsal raphe nucleus. In addition, taVNS-induced 1) regulation of the activities of brain's default network and pain matrix, 2) activation of the cortical descending pain regulation pathway, and 3) inhibition of the neuroinflammatory response may also contribute to its ameliorating effect of migraine. This paper may provide ideas for the future research on the mechanism of auricular acupoint treatment of migraine.

[Effect of transcutaneous auricular vagus nerve stimulation on the splenic α7nAchR/JAK2/STAT3 signaling pathway in LPS-induced depressive-like behavior rats].

OBJECTIVE: To observe the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the improvement of depressive-like behavior and the splenic α7 nicotinic acetylcholine receptor (α7nAchR) / Janus kinase 2 (JAK2 / signal transducer and activator of transcription 3 (STAT3) signaling pathway in lipopolysaccharide (LPS)-induced depressive-like behavior rats, so as to investigate the antidepressant mechanism of taVNS. METHODS: SD rats were randomly divided into SD control group, SD model group and SD taVNS group, and α7nAchR knockout rats were also randomly divided into α7 control group, α7 model group and α7 taVNS group, with 6 rats in each group. Rat model of depressive-like behavior was established by intraperitoneal injection of LPS (1 mg/kg). Rats in both SD taVNS and α7 taVNS groups received taVNS intervention once a day (2 Hz/15 Hz, 2 mA, 30 min) from 7 days before LPS injection to 2 days after LPS injection, respectively. The mean speed, activity time and side immobility time in the open field test were recorded after taVNS. The contents of interleukin 10 (IL-10) and chemokine (C-X-C motif) ligand 1 (CXCL1) in serum were detected by electrochemiluminescence multifactorial method. The splenic phosphorylated (p)-JAK2 and p-STAT3 protein expressions were detected by Western blot. RESULTS: Compared with their respective control groups, the mean speed and active time were reduced (P<0.01, P<0.05, P<0.001) and the side immobility time was increased (P<0.001) in the open field test, serum IL-10 and CXCL1 levels were up-regulated (P<0.01, P<0.05, P<0.001), and splenic p-JAK2 protein expressions were down-regulated (P<0.05, P<0.01) in SD and α7nAchR knockout rats, and splenic p-STAT3 protein expression were down-regulated (P<0.05) in SD rats after LPS injection. Following taVNS intervention and in comparison with the model group , the mean speed and active time were increased (P<0.01) and the side immobility time was decreased (P<0.001) in the open field test, serum IL-10 and CXCL1 levels down-regulated (P<0.05), while splenic p-JAK2 and p-STAT3 protein expressions were up-regulated (P<0.01, P<0.001) in the SD taVNS group rather than in the α7 taVNS group. Compared with SD taVNS group, the α7 taVNS group showed increased (P<0.001, P<0.05) side immobility time in the open field test and serum IL-10, decreased splenic p-JAK2 and p-STAT3 protein expressions (P<0.01, P<0.05). CONCLUSION: taVNS may exert anti-inflammatory effects through modulating the splenic α7nAchR/JAK2/STAT3 signaling pathway, thereby ameliorating LPS-induced depressive-like behavior in rats.

Electroacupuncture relieves hyperalgesia by regulating neuronal-glial interaction and glutamate transporters of spinal dorsal horns in rats with acute incisional neck pain.

Objective: Glial cells are involved in the analgesic effect of electroacupuncture (EA) in rats with chronic neurological pain. The objective of this study was to observe the role of neuronal-glial interaction and glutamate (Glu) transporters in EA-induced acute neck pain relief in rats. Materials and methods: Male rats were placed into the following five groups: control, model, EA Futu (LI18), EA Hegu (LI4)-Neiguan (PC6), and EA Zusanli (ST36)-Yanglingquan (GB34). The incisional neck pain model was established by making a longitudinal incision along the midline of the neck. The thermal pain threshold (TPT) was measured using a radiation heat detector. The immunoactivities of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), neurokinin-1 receptor (NK-1R), Glu aspartate transporter (GLAST), and Glu transporter-1 (GLT-1) in the dorsal horns (DHs) of the cervico-spinal cord (C2-C5) were detected using immunofluorescence histochemistry. The expression levels of GFAP, Iba-1, GLAST, and GLT-1 mRNAs were determined using quantitative real-time polymerase chain reaction (PCR). Results: The TPT and levels of mRNAs expression and immunoactivity of GLT-1 and GLAST were significantly decreased, and those of Iba-1 and GFAP were significantly increased in the model group than those of the control group (P < 0.05). The activated microgliacytes were gathered around the NK-1R positive neurons, and co-expression of NK-1R and astrocytes was observed in the model group. EA LI18 significantly increased the TPT and expression of GLAST and GLT-1 mRNAs (P < 0.05) and notably decreased the number of Iba-1 positive cells and Iba-l mRNA expression (P < 0.05), whereas GLAST and GLT-1 antagonists inhibited the analgesic effect of EA LI18. However, these effects, except for the downregulation of Iba-1 mRNA, were not observed in the EA ST36-GB34 group. Fewer NK-1R-positive neurons were visible in the spinal DHs in the EA LI18 group, and the co-expression of NK-1R and astrocytes was also lower than that in the three EA groups. Conclusion: Electroacupuncture of LI18 had an analgesic effect in rats with neck incisions, which may be related to its functions in suppressing the neuronal-glial cell interaction through NK-1R and upregulating the expression of GLAST and GLT-1 in the spinal DHs.

[κ-opioid receptor is involved in electroacupuncture analgesia via inhibition of spinal microglial Toll-like receptor 4 in neuropathic pain rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on the expression of lumbar spinal κ-opioid receptor (KOR) and Toll-like receptor 4(TLR4) in microglia in neuropathic pain rats, so as to explore the role of cross-talk between KOR and TLK4 in EA-induced alleviation of chronic neuropathic pain. METHODS: Wistar male rats were randomized into control, model, EA and EA plus KOR inhibitor (EA+inhibitor) groups (n=18 in each group). The neuropathic pain model was established in rats by ligature of the right sciatic nerve. EA was applied at bilateral "Zusanli"(ST36) and "Yanglingquan"(GB34) for 30 min, once daily for 5 days. JDTic dihydrochloride (a KOR inhibitor) was administrated by intraperitoneal injection before EA intervention. The difference value of paw withdrawal thermal latency (PWLD) of the bilateral hind-limbs was used as the thermal pain reaction level. At the end of experiments, the rat's lumbar spinal cord (L2-L4) was taken for detecting the expression of CD68 mRNA (a marker of the activated microglia) and Iba-1 (a marker for the activated and resting microglia) immunoactivity, and dynorphin content, and KOR mRNA and TLR4 protein (in immunomagnetic microbead method separated microglia) by using fluorescence quantitative PCR, immunofluorescence, radioimmunoassay and Western blot, separately. RESULTS: Compared with the control group, a strong thermal hyperalgesia was induced, the expression levels of Iba-1 and CD68 mRNA in the spinal cord, TLR4 protein of the spinal microglia were significantly increased(P<0.01) in the model group. The microglia were characterized by somatic hypertrophy and thickened branches in the model group. After EA intervention, the PWLD, the expression of Iba-1, CD68 mRNA and TLR4 protein of the microglia were significantly decreased(P<0.05), while the content of spinal dynorphin and the expression of KOR mRNA of the microglia increased in the EA group relative to the model group(P<0.05). The hypertrophic microglia shrinked slightly in the EA group. After injection of KOR inhibitor, the PWLD and expression levels of Iba-1, CD68 mRNA and TLR4 protein were significantly increased(P<0.05), and the expression of KOR mRNA was significantly decreased(P<0.05) in the EA+inhibitor group in comparison with the EA group. CONCLUSION: The analgesia effect of EA may partly mediated by spinal microglial KOR and the activation of KOR of microglia may be a target for inhibition of microglial TLR4-induced pro-inflammatory signaling.

Auricular Vagus Nerve Stimulation Ameliorates Functional Dyspepsia with Depressive-Like Behavior and Inhibits the Hypothalamus-Pituitary-Adrenal Axis in a Rat Model.

BACKGROUND: The hypothalamus-pituitary-adrenal axis is the most important endocrine system to control irritability response. Functional dyspepsia (FD) is closely related to irritability. This study aimed to preliminarily explore the corticotropin-releasing factor (CRF) mechanism of auricular vagus nerve stimulation (aVNS) for FD model rats. METHODS: Sprague-Dawley adult male rats were randomly divided into normal group, model group, aVNS group, and sham-aVNS group. Except for the normal rats, all other rats were induced into the FD model through tail-clamping stimulation for 3 weeks. Once the rat model was developed successfully, rats in the aVNS group and sham-aVNS group were intervened with aVNS or sham-aVNS for 2 weeks. No intervention was given to rats in the normal and model groups. The effect of aVNS was assessed. The expressions of hippocampal corticotropin-releasing hormone receptor 1 (CRHR1), hypothalamus CRF, adrenocorticotropic hormone (ACTH), and corticosterone in serum were assessed. RESULTS: 1. Compared with normal rats, model-developing rats showed FD-like behavior. 2. Compared with model rats, rats in the aVNS group showed an improved general condition score and gastric motility, and increased horizontal and vertical motion scores. 3. The release of corticosterone, ACTH in serum, and CRF in the hypothalamus all increased in model rats but decreased with aVNS instead of sham-aVNS. 4. The expression of hippocampus CRHR1 was lower in model rats but higher in the aVNS group. CONCLUSION: aVNS ameliorates gastric motility and improves the mental state in the FD-like rat, probably via inhibiting the CRF pathway.

[Spinal cord Toll like receptor 4 and its co-stimulatory molecule heat shock protein 90 may parti-cipate in electroacupuncture analgesia in rats with chronic neuropathic pain].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on the expression of Toll like receptor 4(TLR4)and heat shock protein 90(HSP90) in the spinal cord of rats with chronic constriction injury (CCI) of sciatic nerve, so as to explore the mechanism of spinal cord TLR4 and HSP90 in alleviating chronic neuropathic pain by EA. METHODS: Male Wistar rats were randomized into control, model, EA, HSP90 inhibitor (inhibitor) and EA+ inhibitor groups (n=10 in each group). The neuropathic pain model was established by ligature of the right sciatic nerve to induce CCI. EA (1 mA，2 Hz/15 Hz)was applied at bilateral "Zusanli"(ST36) and "Yanglingquan"(GB34) for 30 min, once daily for 5 days. Rats of the inhibitor and EA+inhibitor groups were given a subcutaneous injection of HSP90 inhibitor geldanamycin (50 µg/kg) at the neck before daily EA. The paw withdrawal latency (PWL) of the bilateral hind-limbs was detected by using an algesia-detector. The contents of interleukin 1ß (IL-1ß) and tumor necrosis factor α (TNF-α) in the lumbar spinal cord (L2-L4) tissue were detected by enzyme-linked immunosorbent assay. The relative expression levels of HSP90 and TLR4 proteins in the lumbar spinal cord (L2-L4) were detected using Western blot and immunofluorescence double labeling, respectively. RESULTS: Following CCI, a strong thermal hyperalgesia, an apparent up-regulation of expression of HSP90 and TLR4 proteins and TLR4 in microglia, and increasing levels of IL-1ß and TNF-α in the spinal cord were induced in the model group relevant to the control group (P<0.01，P<0.05). Five sessions of EA intervention or inhibitor injection significantly attenuated hyperalgesia, reversed the increase of IL-1ß and TNF-α, and down-regulated the expression of TLR4 in microglia (P<0.05). Compared with the model group, the expression of HSP90 was further increased (P<0.05), and those of TLR4 in microglia and neurons were significantly decreased and increased, respectively in the EA group (P<0.05). Compared with the EA group, the levels of PWLD,TLR4 and HSP90 expression, and the proportions of neuronal nuclei antigen（NeuN） and TLR4, and ionized calcium binding adapter molecule （Iba1） and TLR4 co-expressed cells were significantly decreased in the inhibitor group and EA+inhibitor group (P<0.05). The proportion of NeuN and TLR4 co-expression cells in the EA+inhibitor group was significantly higher than that of the inhibitor group (P<0.05). CONCLUSION: EA stimulation of ST36 and GB34 can alleviate thermal hyperalgesia in CCI rats, which is closely associated with its effect in regulating the expression of TLR4 in the spinal cord neurons and microglia. HSP90 in the spinal cord may be a co-stimulatory molecule for EA induced relief of neuropathic pain by regulating TLR4.

[Effects of transcutaneous auricular vagus nerve stimulation on autonomic nervous function in rats with functional dyspepsia].

OBJECTIVE: To observe the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the autonomic nerve function in a rat model of functional dyspepsia (FD), so as to explore the mechanism of taVNS underlying regulation of FD. METHODS: SD rats were randomly divided into normal control group(n=8) and FD model group(n=26).The FD model was replicated with iodoacetamide gavage. The FD model rats were randomly divided into model, taVNS, sham-taVNS and Zusanli(ST36) groups, with 6 rats in each group. Rats in the taVNS group received electrical stimulation of auricular concha,while the sham-taVNS group received no electrical stimulation and rats in the ST36 group received stimulation at ST36 for 30 min once daily for 14 consecutive days. Cervical trapezius electromyography score and abdominal withdrawal reflex (AWR) score were used to evaluate gastric sensitivity. Histopathological changes of the gastric antrum tissue were observed under microscope after H.E. staining. Autonomic nerve function in rats was recorded and assessed by heart rate variability(HRV). The content of acetylcholine (Ach) and the expression of Ach receptor M3R in gastric antrum was detect by ELISA and Western blot, separately. RESULTS: Compared with the normal control group, the cervical trapezius electromyography and AWR scores of the model group increased (P<0.01, P<0.001), and there was no erosion in the gastric antral mucosa and muscle layer. The high-frequency power (HF) in HRV decreased (P<0.05), the ratio of low-frequency power/high-frequency power (LF/HF) increased (P<0.001), and the Ach content and its receptor M3R expression in gastric antrum tissue decreased (P<0.05). Following interventions, the cervical trapezius electromyography and AWR scores decreased (P<0.01,P<0.001, P<0.05), HF in HRV increased and LF/HF decreased(P<0.01，P<0.05,P<0.001), and the content of Ach in gastric antrum tissue and the expression of its receptor M3R increased (P<0.01, P<0.05) in both taVNS and ST36 groups relevant to the model group. CONCLUSION: taVNS can increase the activity of the vagus nerve and regulate the balance of the autonomic nerve function, which may be one of the mechanisms of taVNS in reducing the gastric sensitivity of rats with FD. In regulating the vagus nerve function, taVNS and acupuncture at ST36 acupoint have the similar effects.

[Application prospect of common viral tracers in study on brain effect of acupuncture].

The feasibility and prospect of viral tracers and mediating functional components are explored in study on brain effect of acupuncture. In the paper, proceeding with viral tracers, the viral tracers used to analyze the structure of specific neural circuits are introduced, as well as their mediated probes, optical/chemical genetics techniques, Cre-LoxP systems, etc. The viral tracers and their functional components can not only mark specifically nerve cells or neural circuits, but also interfere with the function of specific types of neurons or nuclei. They solve some disadvantage of traditional nerve tracing method that only describes the morphology of neurons of one brain region and the simple projection among brain regions, and the indirect and non-specific absorption. The viral tracers and their functional components play the important approach to decoding the mechanism on brain effect of acupuncture when introduced in experimental acupuncture so as to provide an in vivo, real-time and intuitive novel method for a further analysis of neurobiological mechanism on brain effect of acupuncture.

Transcutaneous Auricular Vagus Nerve Stimulation: From Concept to Application.

Whether in the West or the East, the connection between the ear and the rest of the body has been explored for a long time. Especially in the past century or more, the relevant theoretical and applied research on the ear has greatly promoted the development of ear therapy, and finally the concept of transcutaneous auricular vagus nerve stimulation (taVNS) has been proposed. The purpose of taVNS is to treat a disease non-invasively by applying electrical current to the cutaneous receptive field formed by the auricular branch of the vagus nerve in the outer ear. In the past two decades, taVNS has been a topic of basic, clinical, and transformation research. It has been applied as an alternative to drug treatment for a variety of diseases. Based on the rapid understanding of the application of taVNS to human health and disease, some limitations in the development of this field have also been gradually exposed. Here, we comprehensively review the origin and research status of the field.

[Effect of transcutaneous auricular vagus nerve stimulation on hyperglycemia and insulin receptors expression in impaired glucose tolerance rats].

OBJECTIVE: To explore the effect of transcutaneous auricular vagus nerve stimulation (taVNS) on blood glucose regulation and the expression of insulin receptors (INR) of hypothalamus, liver and skeletal muscle tissues in impaired glucose tolerance (IGT) rats, so as to reveal its mechanisms underlying improvement of IGT. METHODS: Thirty-six male Wistar rats were randomly divided into control, model, transcutaneous auricular none-vagus nerve stimulation (tnVNS), and taVNS groups (n=9 in each group). The IGT model was established by feeding the rats with high-fat and high-sugar diet for 5 weeks, and subsequent intraperitoneal injection of a dose of streptozotocin (20 mg/kg). Transcutaneous electrostimulation (2 mA, 2 Hz/15 Hz) was applied to auricular concha (taVNS) or auricular margin (tnVNS), respectively. The treatment was conducted for 30 min once daily for 4 weeks. The body weight, fasting plasma glucose (FPG), 2 h plasma glucose (2 h PG) were recorded every week. The contents of plasma insulin (INS), glucagon (GC), glycosylated hemoglobin (GHbA1c) were detected by using enzyme linked immunosorbent assay (ELISA). The expression levels of INR in hypothalamus, liver and skeletal muscle tissues were detected by Western blot. RESULTS: After modeling, the rats' body weight, the contents of FPG, 2 h PG, GC and GHbA1c were significantly up-regulated (P<0.001, P<0.05, P<0.01), and the content of INS and expression of INR in hypothalamus, liver and skeletal muscle tissues were significantly down-regulated in the model group compared with the control group (P<0.001, P<0.01, P<0.05). Following the treatment, the increased FPG, 2 h PG, GC, and the decreased INS and INR expression of hypothalamus, liver and skeletal muscle tissues were apparently reversed in the taVNS group relevant to the model group (P<0.001, P<0.01, P<0.05). Compared with the tnVNS group, the FPG and 2 h PG contents were considerable decreased, and the content of INS and INR expression of hypothalamus and liver were obviously increased in the taVNS group (P<0.001, P<0.05, P<0.01). CONCLUSION: taVNS can improve the blood glucose and insulin sensitivity in IGT rats, which may contribute to its effectiveness in up-regulating the expression of INR in hypothalamus, liver and skeletal muscle tissues.

GABAergic Inhibition of Spinal Cord Dorsal Horns Contributes to Analgesic Effect of Electroacupuncture in Incisional Neck Pain Rats.

BACKGROUND: Acupuncture has shown to be effective in relieving post-surgical pain. Nonetheless, its underlying mechanisms remain largely unknown. In the present study, we investigated the effect of electroacupuncture (EA) on the expression of GABA, GABA-A receptor (R) and GABA-BR in the spinal cord dorsal horns (DHs), and the involved neural cells in rats with incisional neck pain. MATERIALS AND METHODS: Male SD rats were randomly divided into control, model, Futu (LI18), Hegu-Neiguan (LI4-PC6), and Zusanli-Yanglingquan (ST36-GB34) groups. The incisional neck pain model was established by making a longitudinal incision and repeated mechanical separation along the thyroid gland region. EA (2Hz/100Hz, 1mA) was applied to LI18, LI4-PC6, ST36-GB34 separately for 30min, once at 4, 24 and 48h after incision. The local thermal pain threshold (TPT) of the focus was measured and the expression of GABA, and GABAR proteins and mRNAs detected by immunofluorescence stain and quantitative RT-PCR, respectively. RESULTS: The analgesic effect of LI18 and LI4-PC6 was superior to that of ST36-GB34 in incisional neck pain rats. Moreover, the EA stimulation of LI18 or LI4-PC6 increased the expression of GABA and GABA-Aα2 and GABA-Aß3, GABA-B1, and GABA-B2 mRNAs in spinal DHs 4h after surgery, while GABA-A and GABA-B antagonists inhibited the analgesic effect of LI18. Immunofluorescence double staining showed that GABA was expressed on astrocytes and neurons, and GABA-B expressed only on neurons. CONCLUSION: EA of both LI18 and LI4-PC6 has a good analgesic effect in incisional neck pain rats, which is closely related to their effects in upregulating the expression of GABA and its receptors in spinal DHs. The effects of LI18 and LI4-PC6 EA are obviously better that those of ST36-GB34 EA, and GABA is expressed on neurons and astrocytes.

[Instant adjustive effect of auricular electroacupuncture on brain default model network of patients with primary insomnia].

OBJECTIVE: To investigate the immediate brain effect of auricular electroacupuncture (EA) in the treatment of primary insomnia (PI). METHODS: In this study, 15 subjects with PI who were diagnosed according to Pitsburgh Sleep Quality Index (PSQI), and other 15 age- and gender-matched subjects without insomnia were recruited in the present study. The PI patients received EA (4 Hz/20 Hz, a tolerable electrical current strength) of auricular concha for 30 min, and their resting state functional magnetic resonance imaging (fMRI) data before and after treatment were collected. The healthy subjects received no any treatment and their resting state fMRI data were collected. The diffe-rence of default mode network functional connectivity between the patients and healthy subjects, and changes of the patient's brain functional connectivity after EA treatment were estimated by using seed-point-based analysis (SPBA). RESULTS: Analysis by taking the posterior cingulate gyrus as the seed-point showed that compared with the healthy participants before treatment, the patient's brain functional connectivity between the posterior cingulate gyrus and the right insula, or the inferior frontal gyrus of the right opercularis region, or the right rolandic operculum was increased. After 30 minutes' EA treatment, the functional connectivity between the posterior cingulate gyrus and the precuneus, the left angular gyrus, the left frontal superior gyrus, the left frontal middle cortex, the right temporalis inferior gyrus, the right temporalis middle gyrus or the left medial orbitofrontal cortex was decreased, while the functional connectivity between the posterior cingulate gyrus and the right lingual gyrus, or the cortex surrounding the right calcarine fissure was increased. CONCLUSION: EA of auricular concha has an instant effect in modulating the brain default mode network in PI patients, which may be its brain mechanism underlying improvement of PI.

[A modified device for transcutaneous electrical auricular concha stimulation in rats].

In the present paper, we introduce a newly modified device named "transcutaneous electrical auricular concha stimulator (TEACS)" for rats. It concludes a main unit (power and control buttons) with newly designed specific output electrodes. Each of the output electrode is made up of two pieces of iron sheet containing magnet and can be firmly attached to the auricular concha and the corresponding site of dorsal auricle, respectively. The two iron sheets are separately connected to each of the output terminal of the main unit via two pieces of wire. This newly modified output electrode replaces the original wire clip, and solves the problems of easy loosening and easy injury of the original spring clip due to repeated usage, being simple, flexible and convenient in application.

[Electroacupuncture alleviated incisional neck pain possibly by suppressing TNF-α expression and increasing IL-4/IL-4 receptor signaling in cervical dorsal part of spinal cord in incisio-nal neck pain rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on incisional pain and expression of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) and interleukin-4 (IL-4) of cervical dorsal part of spinal cord in rats with incisional neck pain, so as to explore its analgesic mechanisms. METHODS: Eighty-four male SD rats were randomly divided into normal control, model, EA-Futu(LI18) and EA-Zusanli(ST36)-Yanglingquan(GB34, EA-ST36-GB34) groups (n=21 in each group). The incisional neck pain model was established by making a longitudinal incision along the bilateral cervical thyroid regions and repeated mechanical separation stimulation. For rats of the EA groups, EA (2 Hz/100 Hz, 1 mA) was applied to bilateral LI18 or ST36-GB34 for 30 min/ time during the surgery, and 20 and 44 h after surgery, respectively. The thermal pain threshold (TPT) of the incisional region was detected. The immunoactivity of TNF-α and IL-10 of the dorsal portion of the cervical spinal cord (C2-C5) was detected by immunofluorescence, and the expression of TNF-α, IL-10, IL-4 and IL-4 receptor (IL-4R) mRNAs was determined by quantitative real-time PCR. RESULTS: Compared with the normal group, the TPT of the incisional area was significantly decreased at 4, 24 and 48 h after neck-incision (P<0.05), the levels of TNF-α mRNA, IL-10 mRNA and TNF-α IL-10 immunoactivity at 24 h were remarkably increased (P<0.05), and the expression of IL-4R mRNA was considerably decreased at 24 h in the model group (P<0.05). Following EA intervention, the TPT, and expression levels of IL-4 mRNA and IL-4R mRNA were significantly increased at 24 h after surgery in the EA-LI18 group relevant to the model group (P<0.05), while the expression level of TNF-α(coexpressed with microgliacytes) in the EA-LI18 group, and TNF-α mRNA expression at 24 h in both EA-LI18 and EA-ST36-GB34 groups, as well as the expression of IL-10 and IL-10 mRNA at 24 h in both EA-LI18 and EA-ST36-GB34 groups were significantly decreased (P<0.05). The effect of EA LI18 was significantly superior to that of EA ST36-GB34 in up-regulating TPT and expression of IL-4 mRNA and IL-4R mRNA at 24 h (P<0.05). CONCLUSION: EA of LI18 has an analgesic effect in incisional neck pain rats, which may be related to its effect in down-regulating the expression of TNF-α, IL-10 and promoting IL-4 /IL-4R signaling in dorsal portions of the cervical spinal cord. The analgesic effect of EA LI18 is better than that of EA ST36-GB34.

[Auricular electroacupuncture improves depression possibly by promoting hippocampal Raf/ERK/RSK/CREB signaling in chronic unpredictable mild stress induced depression rats].

OBJECTIVE: To observe the effect of auricular electroacupuncture (EA) on intracellular Raf/ extracellular signal-regulated kinase (ERK)/ ribosomal S6 kinase (RSK)/ cAMP response element-binding protein (CREB) signal pathway in the hippocampus of depression model rats, so as to explore its anti-depressive mechanism. METHODS: A total of 60 male SD rats were randomly divided into control, model, auricular EA, PD98059(ERK inhibitor), DMSO (Dimethylsulfoxide), PD98059+EA groups (n=10 in each group). The rats in the control group were fed with normal diet without any treatment. The depression model was induced by chronic unpredictable mild stress (CUMS) for consecutive 21 days. EA (20 Hz, 2 mA) was applied to bilateral auricular "Xin"(Heart) and "Shenmen" for 30 min, once daily for 28 days. Rats of the PD98059, DMSO and PD98059+EA groups received intracerebroventricular injection of PD98059(100 µmol/L), DMSO and PD98059 (dissolved by DMSO) solutions (5 µL/d), respectively, once daily for 28 days. Sucrose preference test (sucrose consumption) was conducted at the baseline, before and after the intervention. The expression of hippocampal Raf, phosphorylated (p)-Raf, ERK, p-ERK, RSK, CREB and p-CREB proteins were detected by Western blot after EA intervention. RESULTS: Following modeling, the sucrose consumption volume, and the expression levels of hippocampal Raf, p-Raf, ERK, p-ERK, RSK, CREB, p-CREB proteins were significantly lower in the model group than those in the control group (P<0.01). Following the treatment, the sucrose consumption and the expression levels of Raf, p-Raf, ERK, p-ERK, RSK, CREB, p-CREB in the auricular EA group and those of p-Raf, ERK and CREB in the PD98059+EA group were obviously increased in comparison with the model group (P<0.05, P<0.01), the expression level of p-ERK in the PD98059 group was obviously decreased in comparison with the model group (P<0.05), suggesting an improvement of depression after auricular EA. Compared with auricular EA group, the expression level of p-ERK, p-CREB and RSK in the PD98059+EA group were significantly decreased (P<0.05). CONCLUSION: EA of auricular "Xin" and "Shenmen" is able to improve depression in depression rats, which is probably related to its effect in promoting activities of hippocampal Raf/ERK/RSK/CREB signaling.

[High Mobility Group Box 1/ CD 24 Receptor/ß-EP Signaling in "Zusanli" (ST 36) Region Contributes to Electroacupuncture Analgesia in Rats with Neuropathic Pain].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on the expression of high mobility group box 1 (HMGB 1) and its receptor CD 24 proteins and ß-endorphin (ß-EP) content in "Zusanli" (ST 36) region in rats with chronic constriction injury (CCI), so as to explore its mechanisms underlying pain relief. METHODS: Thirty male Wistar rats were rando-mized into control, CCI model and EA groups (n＝ 10 rats in each). The neuropathic pain model was established by ligature of the left sciatic nerve to induce CCI in the model and EA groups, and sham operation was performed in rats of the control group. Paw with drawal latency (PWL, thermal pain threshold) of the bilateral hind-limbs was detected by using an algesia-detector. Eight days after CCI operation, EA was applied to bilateral "Zusanli" (ST 36) and "Yanglingquan" (GB 34) for 30 min, once daily for 5 days. The acetylated-HMGB 1 expression was determined by immunoprecipitation, and the expression of HMGB 1 and toll like receptor 4 (TLR 4) proteins and CD 24 mRNA were detected using Western blot and fluorescent quantitative real time-PCR, respectively, and the content of ß-EP in the acupoint region was assayed by enzyme linked immunosorbent assay (ELISA). Anti-CD 24 neutralizing antibody (200 µL, 100 µg/mL) was injected into ST 36 region once daily for 3 days for verifying the involvement of HMGB 1/CD 24 signaling in EA analgesia. RESULTS: Compared with the control group, the bilateral PWL difference values in the other two groups were significantly increased (P<0.05), meaning an occurrence of hyperalgesia after CCI. In comparison with the CCI model group, the hyperalgesia in the EA group was obviously decreased (P<0.05). After CCI, the expression levels of HMGB 1 and TLR 4 proteins were considerably increased compared with those in the control group (P<0.05). After 5-times' EA, the acetylated-HMGB 1, the expression of CD 24 mRNA, and the content of ß-EP were notably up-regulated (P<0.05), and there were no obvious changes in the expression levels of HMGB 1 and TLR 4 proteins (P>0.05). After local injection of anti-CD 24 antibody, EA-induced increases of ß-EP content and reduction of thermal pain threshold were significantly suppressed (P<0.05). CONCLUSION: EA of ST 36 and GB 34 can alleviate neuropathic pain in CCI rats, which is associated with its effects in up-regulating ß-EP content, and HMGB 1 protein and CD 24 mRNA expression levels in ST 36 region. The activated HMGB 1/CD 24/ß-EP signaling contributes to EA-ST 36 induced analgesia.

Repeated electroacupuncture treatment attenuated hyperalgesia through suppression of spinal glial activation in chronic neuropathic pain rats.

BACKGROUND: Cumulated evidence reveals that glial cells in the spinal cord play an important role in the development of chronic neuropathic pain and are also complicated in the analgesic effect of EA intervention. But the roles of microgliacytes and astrocytes of spinal cord in the process of EA analgesia remain unknown. METHODS: A total of 120 male Wistar rats were used in the present study. The neuropathic pain model was established by chronic constrictive injury (CCI) of the sciatic nerve. The rats were randomly divided into sham group, CCI group, and sham CCI + EA group, and CCI + EA group. EA was applied to bilateral Zusanli (ST36)-Yanlingquan (GB34). The mechanical (both time and force responses) and thermal pain thresholds (PTs) of the bilateral hind-paws were measured. The number of microgliacytes and activity of astrocytes in the dorsal horns (DHs) of lumbar spinal cord (L4-5) were examined by immunofluorescence staining, and the expression of glial fibrillary acidic protein (GFAP) protein was detected by western blot. RESULTS: Following CCI, both mechanical and thermal PTs of the ipsilateral hind-paw were significantly decreased beginning from the 3rd day after surgery (P < 0.05), and the mechanical PT of the contralateral hind-paw was considerably decreased from the 6th day on after surgery (P < 0.05). CCI also significantly upregulated the number of Iba-1 labeled microgliacytes and the fluorescence intensity of glial fibrillary acidic protein (GFAP) -labeled astrocyte in the superficial laminae of DHs on bilateral sides (P < 0.05). After repeated EA, the mechanical and thermal PTs at bilateral hind-paws were significantly relieved (P < 0.05). The increased of number of microgliacytes was markedly suppressed by 2 days' EA intervention, and the average fluorescence intensity was suppressed by 2 weeks' EA. The expression of GFAP protein were down-regulated by 1 and 2 weeks' EA treatment, respectively (P < 0.05). CONCLUSIONS: Repeated EA can relieve neuropathic pain and mirror-image pain in chronic neuropathic pain rats, which is probably associated with its effect in downregulating glial cell activation of the lumbar spinal cord, the microgliacyte first and astrocyte later.

[Effect of Electroacupuncture Intervention on Expression of Synaptic Plasticity-related Molecules in Amygdala in Chronic Pain-negative Affection Rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on expression of synaptic plasticity-related glutamate N-methyl-D-aspartate (NMDA) receptor subunit NR 1, gamma-aminobutyric acid (GABA) receptor subunits (Aß 2, B 1), etc. in the amygdala in chronic neuropathic pain negative affection (CNPPNA) rats, so as to reveal its mechanism underlying pain relief. METHODS: Male Wistar rats were randomized into normal control, CNPPNA model, EA, and anesthesia+EA (AEA)groups (n=14 in each group, 8 for quantitative RT-PCR and 6 for immunofluorescence staining). The CNPPNA model was established by ligation of the left sciatic nerve and repeated electrical stimulation of the hindpaw plantar skin in the pain-paired compartment. EA was applied to bilateral "Zusanli"(ST 36)and "Yanglingquan"(GB 34)for 30 min, once daily for 7 days.Thermal pain threshold (paw withdrawal latency, PWL)of the bilateral paws was measured by using a Tail-Flick Unit. The conditioned place aversion (CPA) was determined by using a CPA-paired compartment. The expression levels of GABAAß 2, GABAB 1, NMDA receptor subunit NR 1, postsynaptic density-95 protein(PSD-95), Piccolo genes in the right amygdala area were determined using quantitative RT-PCR, and the immunoactivity of metabotropic glutamate receptor subunit 1 (mGluR 1) and GABAB 2 in the basolateral amygdala (BLA) nucleus was detected using immunofluorescence staining. RESULTS: After modeling, PWL difference (PWLD) values of the model group were significantly increased (P<0.001),and the time spent in the CPA-paired compartment was considerably decreased compared with the control group (P<0.001).After EA intervention for 3 and 7 days, the PWLD levels of both EA and AEA groups were apparently decreased(P<0.05),and the time spent in the CPA-paired compartment was apparently increased in the EA and AEA groups(P<0.05),suggesting a pain relief and an improvement of the negative affection after EA intervention. Additionally, following EA, the apparently-decreased expression levels of GABAAß 2,GABAB 1,PSD-95,Piccolo genes and the reduced numbers of GABAB 2 positive cells and NMDA-NR 1 mRNA as well as mGluR 1 positive fiber numbers were remarkably increased in the EA group (P<0.05, P<0.001).The expression levels of Piccolo gene, GABAB 2 and mGluR 1 positive cells/fiber numbers were apparently lower in the AEA group than in the EA group (P<0.001). No significant differences were found between the EA and AEA groups in the PWLD, time spent in the CPA-paired compartment, and the expression levels of NMDA-NR 1, GABAAß 2, GABAB 1 and PSD-95 genes (P>0.05). CONCLUSIONS: Repeated EA stimulation of ST 36-GB 34 has a role in relieving both sensory and affection dimensions of chronic pain in CNPPNA rats, which Feb be respectively related to its effects in up-regulating the expression of GABAAß 2, GABAB 1, NMDA-NR 1, PSD-95 and Piccolo genes, and in promoting the expression of mGluR 1 and GABAB 2 proteins and Piccolo gene in the amygdala.

Black Phosphorus Quantum Dot Induced Oxidative Stress and Toxicity in Living Cells and Mice.

Black phosphorus (BP), as an emerging successor to layered two-dimensional materials, has attracted extensive interest in cancer therapy. Toxicological studies on BP are of great importance for potential biomedical applications, yet not systemically explored. Herein, toxicity and oxidative stress of BP quantum dots (BPQDs) at cellular, tissue, and whole-body levels are evaluated by performing the systemic in vivo and in vitro experiments. In vitro investigations show that BPQDs at high concentration (200 µg/mL) exhibit significant apoptotic effects on HeLa cells. In vivo investigations indicate that oxidative stress, including lipid peroxidation, reduction of catalase activity, DNA breaks, and bone marrow nucleated cells (BMNC) damage, can be induced by BPQDs transiently but recovered gradually to healthy levels. No apparent pathological damages are observed in all organs, especially in the spleen and kidneys, during the 30-day period. This work clearly shows that BPQDs can cause acute toxicities by oxidative stress responses, but the inflammatory reactions can be recovered gradually with time for up to 30 days. Thus, BPQDs do not give rise to long-term appreciable toxicological responses.

Activation of hippocampal MEK1 contributes to the cumulative antinociceptive effect of electroacupuncture in neuropathic pain rats.

BACKGROUND: Electroacupuncture (EA) intervention can relieve a variety of pain; however, optimal EA protocols have not been clearly determined. In addition, although central mitogen-activated protein kinase kinase (MEK) signaling has been shown to be involved in the antinociceptive effect of acupuncture stimulation, its characteristics at different time-points of EA intervention have not been fully elucidated. Therefore, the present study investigated the relationship between the effects of different numbers of EA intervention sessions and the activation of MEK1 in the hippocampus and hypothalamus in a rat model of neuropathic pain. METHODS: After ligation of the left sciatic nerve, which induces chronic constriction injury (CCI), the acupoints Zusanli (ST36) and Yanglingquan (GB34) were applied. The thermal withdrawal latency of the hind paw was used to evaluate the effect of EA on pain thresholds. Intra-hippocampus microinjection of PD98059, a MEK inhibitor, was performed to validate the involvement of MEK in EA analgesia. The hippocampus and hypothalamus were harvested to examine the phosphorylation levels of MEK (pMEK) by western blotting. RESULTS: In CCI rats, the thermal pain threshold of the affected hind paw decreased significantly relative to the control. Following subsequent daily EA interventions, CCI-induced ipsilateral hyperalgesia was markedly improved from day 4 and the analgesic effect of EA lasted 3 days after cessation of EA. Four sessions of EA markedly suppressed CCI-induced decrease of hippocampal pMEK1 (normalized to the total MEK level). In contrast, successive sessions of EA intervention gradually down-regulated the CCI-induced up-regulation of hypothalamic pMEK1 along with the increase numbers of EA intervention. However, EA did not exert the same analgesic effect after microinjection of PD98059 into the contralateral hippocampus during the first 3 days of EA intervention. CONCLUSIONS: EA intervention can induce time-dependent cumulative analgesia in neuropathic pain rats after 4 successive sessions of daily EA intervention, which is at least in part related to the activation of hippocampal MEK1.