High-frequency spinal cord stimulation produces longlasting analgesic effects by restoring lysosomal function and autophagic flux in the spinal dorsal horn

High-frequency spinal cord stimulation(HF-SCS) has been established as an effective therapy for neuropathic pain. However, the analgesic mechanisms involved in HF-SCS remain to be clarified. In our study, adult rat neuropathic pain was induced by spinal nerve ligation. Two days after modeling, the rats were subjected to 4 hours of HF-SCS(motor threshold 50%, frequency 10,000 Hz, and pulse width 0.024 ms) in the dorsal horn of the spinal cord. The results revealed that the tactile allodynia of spinal nerve-injured rats was markedly alleviated by HFSCS, and the effects were sustained for 3 hours after the stimulation had ceased. HF-SCS restored lysosomal function, increased the levels of lysosome-associated membrane protein 2(LAMP2) and the mature form of cathepsin D(matu-CTSD), and alleviated the abnormally elevated levels of microtubule-associated protein 1 A/B-light chain 3(LC3)-II and sequestosome 1(P62) in spinal nerve-injured rats. HF-SCS also mostly restored the immunoreactivity of LAMP2, which was localized in neurons in the superficial layers of the spinal dorsal horn in spinal nerve-injured rats. In addition, intraperitoneal administration of 15 mg/kg chloroquine for 60 minutes reversed the expression of the aforementioned proteins and shortened the timing of the analgesic effects of HF-SCS. These findings suggest that HF-SCS may exhibit longlasting analgesic effects on neuropathic pain in rats through improving lysosomal dysfunction and alleviating autophagic flux. This study was approved by the Laboratory Animal Ethics Committee of China Medical University, Shenyang, China(approval No. 2017 PS196 K) on March 1, 2017.

“Three Methods and Three Points” regulates p38 mitogen-activated protein kinase in the dorsal horn of the spinal cord in a rat model of sciatic nerve injury

Tuina is a traditional Chinese treatment for sensory disturbances caused by peripheral nerve injury and related diseases. Our previous studies showed that tuina regulates relevant regions and indices of the spinal dorsal horn using the Dian, Bo, and Rou method in Yinmen（BL37）, Yanglingquan（GB34）, and Weizhong（BL40）. Treatment prevents muscle atrophy, protects spinal cord neurons, and promotes sciatic nerve repair. The mechanisms of action of tuina for treating peripheral nerve injury remain poorly understood. This study established rat models of sciatic nerve injury using the crushing method. Rats received Chinese tuina in accordance with the principle of ＂Three Methods and Three Points,＂ once daily for 20 days. Tuina intervention reduced paw withdrawal latency and improved wet weight of the gastrocnemius muscle, as well as promoting morphological recovery of sciatic nerve fibers, Schwann cells, and axons. The protein expression levels of phospho-p38 mitogen-activated protein kinase, tumor necrosis factor-α, and interleukin-1β also decreased. These findings indicate that ＂Three Methods and Three Points＂ promoted morphological recovery and improved behavior of rats with peripheral nerve injury.

Effect of propofol on glutamate-induced activation and related inflammatory cytokines of astrocytes from spinal cord dorsal horn

BACKGROUND： Astrocytes participate in central nervous system-mediated physiological or pathological processes, such as pain. Activated dorsal horn astrocytes from the spinal cord produce nerve active substances and proinflammatory cytokines, such as interleukin-lbeta （IL-1 β ）, IL-6, and tumor necrosis factor- α （TNF-α ）, which play important roles in pain transduction and regulation. OBJECTIVE： To investigate the effects of different doses of propofol on activation of cultured spinal cord dorsal horn astrocytes induced by glutamate, as well as changes in IL-1β, IL-6, and TNF- α, and 1L-10 （anti-inflammatory cytokine） expression in rats, and to explore the dose relationship of propofol. DESIGN, TIME AND SETTING： The cellular and molecular biology experiment was performed at the Central Laboratory of Yunyang Medical College between March 2006 and December 2007. MATERIALS： Forty healthy, Wistar rats, aged 2-3 days, were selected. Propofol was provided by Zeneca, UK; glutamate by Sigma, USA; EPICS XL flow cytometry by Beckman culture, USA; rabbit-anti-mouse glial fibrillary acidic protein （GFAP） antibody kit and inflammatory cytokine detection kit were provided by Zhongshan Biotechnology Company Ltd., Beijing; multimedia color pathologic image analysis system was a product of Nikon, Japan. METHODS： Astrocytes were harvested from T11- L6 spinal cord dorsal horn of Wistar rats and incubated for 3 weeks. The cells were divided into seven groups, according to various treatment conditions： control group was cells cultured in Hank＇s buffered saline solution; intralipid group was cells cultured in intralipid （0.2 mL/L）; glutamate group was cells cultured with 100 u mol/L glutamate; propofol group was cells cultured with 250 u mol/L propofol; three glutamate plus propofol groups were cultured in 100 11 mol/L of glutamate, followed by 5, 25, and 250 u mol/L of propofol 10 minutes later. MAIN OUTCOME MEASURES： GFAP-labeled astrocytes were analyzed using a multimedia pathology imaging analysis system to detect area density （AD） and average optical density （AOD） of positive cells. The supernatant concentrations of IL-1β, TNF- α, IL-6, and IL-10 were determined using radioimmune assays. RESULTS： Compared with the control group, cells in the glutamate plus low-dose propofol group were activated and hypertrophic, and AD and AOD were significantly increased （P 〈 0.01 ）. Concentrations of IL-1β, TNF- α, and IL-6 were also significantly increased （P 〈 0.01）, while IL-10 levels remained unchanged （P 〉 0.05）, but still higher than the control and glutamate groups （P 〉 0.05）. Compared with the glutamate group, astrocyte activation was inhibited by moderate and high-dose propotol. In addition, with moderate and high-dose propofol, AD, AOD, IL-1β, TNF- α, and IL-6 concentrations were significantly decreased （P 〈 0.05-0.01）, and IL-10 levels were increased （P 〈 0.01 ）. CONCLUSION： Propofol can effectively inhibit glutamate-induced astrocyte activation in the spinal cord dorsal horn, significantly inhibit production of IL-1 β, TNF- α, and IL-6, and increase IL-10 synthesis and release in a dose-dependent manner.

The Double Projecting Neuron of the Cat Spinal Dorsal Horn——A Study with Double Retrograde Fluorescent Tracing Technique

The new double projecting neurons were found in the cat spinal dorsal horn by the double retrograde fluorescent tracing technique.Fast Blue(FB)was injected into unilateral dorsal column nucleus(DCN)of adult cats anesthetized with pentobarbital.Nuclear Yellow(NY)was injected ipsilaterally into the lateral cervical nucleus(LCN)8-9 days later.After an additional 18-30 hrs.

The mechanisms underlying long-term potentiation of C-fiber evoked field potentials in spinal dorsal horn

Long-term potentiation(LTP) of C-fiber evoked field potentials in spinal dorsal horn is first reported in 1995.Since then,the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary afferent C-fibers and neurons in spinal dorsal horn have been investigated by different laboratories.In this article,the related data were summarized and discussed.

Differential effects of glutamate receptor antagonists on dorsal horn neurons responding to colorectal distension in a neonatal colon irritation rat model

AIM: To investigate and compare the effects of spinal D-(-)-2-amino-7-phosphonoheptanoic acid (AP-7) and 6-cyano-7-nitroquinoxaline-2,3-dione disodium (CNQX),two glutamate receptor antagonists, on the responses of dorsal horn neurons to colorectal distension (CRD) in adult rats exposed to neonatal colon irritation (CI).METHODS: Hypersensitive SD rats were generated by CI during postnatal days 8, 10 and 12. Experiments on adult rats were performed using extracellular single-unit recording. The effects of spinal application of AP-7 (0.001,0.01, 0.1, 1 mmoL) were tested on the CRD-evoked neuronal responses in 16 controls and 17 CI rats. The effects of CNQX (0.2, 2, 5, 10 μmoL) were also tested on the CRD-evoked responses of 17 controls and 18 CI neurons.RESULTS: (1) The average responses of lumbosacral neurons to all intensities of CRD in CI rats were significantly higher than those in control rats; (2) In control rats, AP-7 (0.01 mmoL) had no significant effect on the neuronal response to all intensities of CRD (20,40, 60, 80 mmHg); while AP-7 (0.1 mmoL) inhibited the neuronal response to 80-mmHg CRD. By contrast, in CI rats, AP-7 (0.01-1 mmoL) attenuated the CRD-evoked neuronal responses to all distention pressures in a dosedependent manner; (3) In control rats, CNQX (2 μmoL)had no significantly effect on the neuronal response to all intensities of CRD; however, CNQX (5 μmoL) significantly attenuated the responses to CRD in the 40-80 mmHg range. By contrast, CNQX (2-10 μmoL)significantly decreased the neuronal responses in CI rats to non-noxious and noxious CRD in a dose-dependent manner.CONCLUSION: Our results suggest that spinal N-methyl-D-aspartate (NMDA) and non-NMDA receptors may contribute to the processing of central sensitivity in a neonatal CI rat model, but they may play different roles in it.

Changes in response properties of nociceptive dorsal horn neurons in a murine model of cancer pain

Pain associated with cancer that metastasizes to bone is often severe and debilitating.A better understanding of the neural mechanisms that mediate cancer pain is needed for the development of more effective treatments.In this study,we used an established model of cancer pain to characterize changes in response properties of dorsal horn neurons.Fibrosarcoma cells were implanted into and around the calcaneus bone in mice and extracellular electrophysiological recordings were made from wide dynamic range(WDR) and high threshold(HT) dorsal horn neurons.Responses of WDR and HT neurons evoked by mechanical,heat,and cold stimuli applied to the plantar surface of the hind paw were compared between tumor bearing mice and control mice.Mice exhibited hyperalgesia to mechanical and heat stimuli applied to their tumor-bearing hind paw.WDR neurons in tumor-bearing mice exhibited an increase in spontaneous activity,and enhanced responses to mechanical,heat,and cold stimuli as compared to controls.Our findings show that sensitization of WDR neurons,but not HT neurons,contributes to tumor-evoked hyperalgesia.

Chinese Tuina remodels the synaptic structure in neuropathic pain rats by downregulating the expression of N-methyl D-aspartate receptor subtype 2B and postsynaptic density protein-95 in the spinal cord dorsal horn

OBJECTIVE:To investigate whether the Chinese massage system,Tuina,exerts analgesic effects in a rat model of chronic constriction injury(CCI)by remodeling the synaptic structure in the spinal cord dorsal horn(SCDH).METHODS:Sixty-nine male Sprague–Dawley rats were randomly and evenly divided into the normal group,sham group,CCI group,CCI+Tuina group,CCI+MK-801[an N-methyl D-aspartate receptor subtype 2B(NR2B)antagonist]group,and CCI+MK-801+Tuina group.The neuropathic pain model was established using CCI with right sciatic nerve ligation.Tuina was administered 4 d after CCI surgery,using pressing manipulation for 10 min,once daily.Motor function was observed with the inclined plate test,and pain behaviors were observed by the Von Frey test and acetone spray test.At 19 d after surgery,the L3-L5 spinal cord segments were removed.Glutamate,interleukin 1β(IL-1β),and tumor necrosis factor-α(TNF-α)levels were detected by enzyme-linked immunosorbent assay.The protein expression levels of NR2B and postsynaptic density protein-95(PSD-95)were detected by Western blot,and the synaptic structure was observed by transmission electron microscopy(TEM).RESULTS:CCI reduced motor function and caused mechanical and cold allodynia in rats,increased glutamate concentration and TNF-αand IL-1βlevels,and increased expression of synapse-related proteins NR2B and PSD-95 in the SCDH.TEM revealed that the synaptic structure of SCDH neurons was altered.Most of these disease-induced changes were reversed by Tuina and intrathecal injection of MK-801(P<0.05 or<0.01).For the majority of experiments,no significant differences were found between the CCI+MK-801 and CCI+MK-801+Tuina groups.CONCLUSIONS:Chinese Tuina can alleviate pain by remodeling the synaptic structure,and NR2B and PSD-95 receptors in the SCDH may be among its targets.

Effect of pre-electroacupuncture on p38 and c-Fos expression in the spinal dorsal horn of rats suffering from visceral pain

Background Acupuncture is an effective way to relieve pain, but the mechanism by which electroacupuncture （EA） decreases the visceral pain state still remains unclear. This study aimed to evaluate the effects of pre-electroacupuncture on pain behaviors, p38 phosphorylation, and c-Fos protein and mRNA expression in both the colonic wall and spinal dorsal horn of rats suffering from visceral pain. This study also investigated the probable signaling regulatory mechanism of the analgesic effect induced by electroacupuncture. Methods All rats were randomized into the control （Con） group, the Con＋EA group, the visceral pain （VP） group, and VP＋EA group （n=8 for all groups）. The visceral pain model was established using 40 ul of 5% formalin solution injected into the colon of rats. EA was applied to the bilateral Jiaji acupoints for 20 minutes before application of visceral pain. Parameters for EA were set at a continuous wave （20 Hz） and intensity where the rats shook their whiskers but did not scrabble （≤1 mA）. The visceral pain score was recorded and the expressions of p38 and c-Fos protein were detected using Western blotting. Real-time quantitative PCR was also used to determine the expression of c-Fos mRNA. Results Rats in the VP group immediately presented with obvious visceral pain behaviors after being injected with formalin. p38 activity and c-Fos protein and mRNA expression in both the colonic wall and spinal dorsal horn were higher in the VP group than in the Con group （P 〈0.05）. By contrast, visceral pain behaviors were delayed in rats from the VP＋EA group. p38 activity and c-Fos protein and mRNA expression were lower in the VP＋EA group than that in the VP group （P〈0.01）. Conclusions Pre-electroacupuncture of the Jiaji acupoint has prophylactic analgesic effects on rats suffering from visceral pain. The p38 signal transduction pathway may be partly involved in the regulatory mechanism of this analgesic effect.

AMPA receptor trafficking in inflammation-induced dorsal horn central sensitization

Activity-dependent postsynaptic receptor trafficking is critical for long-term synaptic plasticity in the brain, but it is unclear whether this mechanism actually mediates the spinal cord dorsal hom central sensitization （a specific form of synaptic plasticity） that is associated with persistent pain. Recent studies have shown that peripheral inflammation drives changes in ct-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor （AMPAR） subunit trafficking in the dorsal horn and that such changes contribute to the hypersensitivity that underlies persistent pain. Here, we review current evi- dence to illustrate how spinal cord AMPARs participate in the dorsal hom central sensitization associated with persistent pain. Understanding these mechanisms may allow the development of novel therapeutic strategies for treating persistent pain.

Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats

Objective: To study the effects of electroacupuncture(EA) in chronic constrictive injury(CCI) rat model and the expression of N-methyl-D-aspartate receptor type 2B(NR2B) in ipsilateral spinal dorsal horn in rats to explore the analgesic mechanisms of EA. Methods: According to the random number table, totally 180 rats were evenly divided into a sham group, a CCI group, and an EA group. CCI model was conducted with four4–0 chromic gut ligatures loosely ligated around the left sciatic nerve 1 cm above the trifurcation. Rats in the EA group received 2 Hz EA therapy bilaterally at acupoints of Zusanli(ST 36) and Sanyinjiao(SP 6) once daily(30 min/d) for 30 days after surgery. Paw withdrawal thresholds(PWTs) were measured on 0(baseline), 1, 3, 7, 15,30 days after surgery. Rats were sacri?ced on 0, 1, 3, 7, 15 and 30 days after surgery, and the L4–5 segments of spinal cord were removed to detect the expression of NR2B by immunohistochemistry and quantitative polymerase chain reaction. Results: PWTs in the CCI group were signi?cantly lower than the sham group at Day1–30 after surgery, and reached its lowest at Day 1(P<0.01). After EA treatment, the PWTs recovered rapidly and were signi?cantly higher than those in the CCI group on 3, 7, 15 and 30 days after surgery(P<0.01). The numbers of NR2B-immunoreactive cells of the CCI group signi?cantly increased after CCI surgery compared with the sham group(P<0.01). Compared with the CCI group, stimulation of EA markedly decreased the numbers of NR2B-immunoreactive cells at Day 3, 7, 15 and 30(P<0.05). In the sham group, NR2B mRNA was expressed at a low level. It increased after CCI surgery, which increased rapidly at Day 7(P<0.01) and reached its peak value at Day 15(P<0.01). After EA stimulation, relative quantity of NR2B mRNA expression was less than that in the CCI group at Day 15 and 30(P<0.05). Conclusions: Low frequency of EA had antinociceptive effect in CCI rat model. The analgesic effects of EA might be through the inhibition of NR2B.

MODULATION OF A δ－AND C－FIBER EVOKED RESPONSES OF NOCICEPTIVE NEURONS IN THE SUPERFICIAL AND THE DEEPER DORSAL HORN OF THE ME

The present study was designed to investigate the effects of intravenously administered agonists and antagonists at μ(DAMGO, naloxone,)δ1 (DPDPE,BNTX)andδ2(DELT, NTB)opioid receptors on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla.Extracellular single unit recording were made from 70 nociceptive neurons(28 NS,42 WDR) in the superficial dorsal horn and 37 nociceptive neurons(4 NS,33 WDR)in the deeper dorsal horn.All these neurons had an ipsilateral orofacial mechanoreceptive field and majority of these neurons had no spontaneous activity. The latencies for the C fiber evoked responses ranged from 34～105 msec whereas for Aδfiber-evoked responses it ranged from 3～22msec. A clear separation was observed between early and late responses of evoked by Cand Aδ-fiber.Application of DPDPE,DELT and DAMGO produced inhibitory effects on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and thedeeper dorsal horn.By comparison,the inhibition was more pronounced on the C-fiber evoked response than on the Aδ-fiber evoked response,and DAMGO produced a stronger inhibitory action than both DELT and DPDPE. Additionally,DPDPE produced facilitation, or inhibition followed by facilitation on the Aδ-and C-response and the effect had longer latency and longer time course.DPDPE also induced completely oppsite effects on the Aδ-and C-fiber evoked responses.Although the facilitation was observed,the effect was not dose-dependent. Application of BNTX (0.4～1mg/kg),a δ1 receptor antagonist,produced antagonism of DPDPE in 88%(7/8) neurons. Application of the doses (0.7～1mg/kg) of BTB,δ2-receptor antagonist,resulted in antagonism of both DELT and DPDPE. The inhibition of DELT on Aδ-response was antagonized by doses (0.3～1mg/kg)of NTB in 100% (14/14)neurons while the antagonism on C-response was in 79%(11/14) neurons.The effect produced by DPDPE was antagonized by the doses (0.7～1mg/kg) of NTB in 100%(4/4) neurons. However,a smaller dose of NTB(0.3mg/kg)which and antagonize the effect of DELT,did not antagonize the effect of DPEPE in 100%(4/4) neurons. The inhibitory action of DAMGO on Aδ-and C-fiber evoked responses was completely antagonized by naloxone(0. 2mg/kg) in 100% (6/6) neurons. These results suggest that:①μ-and δ-opioid receptors play an important role in modulating Aδ-and Cfiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla; ② The inhibitory action produced by DPDPE, DELT and DAMGO was more pronounced on the C-fiber evoked excitation and indicates that the agonists produce more predominant inhibition on the responses of dorsal horn neurons to noxious stimuli; ③ activation of either δ1-orδ2-opioid receptors produces inhibitory actions on Aδ- and C-response of nociceptive neurons in the superficial and the deeper dorsal horn of the medullal;DPDPE and DELT act at different δ-opioid receptor subtypes in the rat rnedulla; ⑤i.v.-administered NTB can distinguish δ-opioid receptor subtypes in a limited dose range.When administered i. v., 0. 3mg/kg of NTB is selective for δ2-opioid receptor.

THE PROJECTION LINKAGE BETWEEN THE SPINAL DORSAL HORN NEURONS AND BOTH THE SOLITARY TRACT AND DORSAL COLUMN NUCLEI

Electrical stimulation of the solitary tract nucleus (SN) and dorsal column nuclei (DCN)as well as microelectrode recording from the lumbal spinal dorsal horn have been used tofind and identify the axonal projection of and the afferent innervation on the spinal neuronsof pentobarbital- anesthetized rats. A total of 92 neurons was recorded and identified mainly in laminae Ⅲ-Ⅴ of the lumbarspinal dorsal horn. Of them, 38 neurons were activated antidromically from stimulation ofboth the SN and DCN. The other 54 neurons responded synaptically to both the SN andDCN stimulations. The initial antidromic responses of 8 neurons in the first group werefollowed by one or more responses synaptically driven from the SN and/or DCN stimulation.Conduction velocities were in the range of A delta fibers, but faster in the antidromicresponses and slower in the synaptic responses. These results indicate that (i) some spinal neurons issue branched axons of larger-sizedA delta fibers and double project to both the SN and

The Functional Linkage Among the "ZSL"-Spinal Dorsal Horn-SN

Electrical stimulation of the Zusanli point (ZSL) and solitary tract nucleus (SN) as well as microelectrode recording from the laminae Ⅲ-Ⅴ of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 57 spinal neurons responding to the stimulations of both ZSL and SN. Among them, 34 responded antidromically to SN; the others responded orthodromically to SN. Among them, the lowthreshold mechano-receptive(LTM) neurons and wide-dynamic-range (WDR) neurons were 50 percent respectively. The results indicate that (ⅰ) a single spinal dorsal horn neuron receives somatic afferent input and then conveys it to the visceral sensory nucleus-SN; (ⅱ) some spinal dorsal horn neurons receive, in turn, innervation from the SN; (ⅲ) the convergence and integration between somatic and visceral sensory inputs might occur in the spinal dorsal horn neurons and/or SN.

CONNECTION BETWEEN SPINAL CORD DORSAL HORN NEURONS AND THE SOLITARY TRACT NUCLEUS OF RAT——A PHYSIOLOGICAL STUDY

The solitary tract nucleus (STN) is a primary visceral sensory nucleus to which neuroanatomists and neurophysiologists have devoted much attention for years. Little is known, however, to the projection connection between the STN and spinal cord. Loewy morphologically described the descending projection from STN to the spinal cord in the

Reduction of GABA-and substance P-immunoreactivities in spinal dorsal horn by capsaicin

γ-aminobutyric acid (GABA)-containing neurons are densely located in laminae Ⅰ—Ⅱ of the spinal cord where substance P (SP)-containing primary afferent C fibers terminate. By the antibody microprobe technique, we found that capsaicin, a chemical irritant selectively activating C fibers, significantly produced the release of SP in lamina Ⅱ.

Effects of Electroacupuncture on Expression of COX-2 in the Dorsal Horn of Spinal Cord of Arthritic Rats

目的:本工作试图通过观察慢性炎症痛大鼠脊髓背角环氧合酶(COX-2)蛋白表达的变化,探讨脊髓背角 COX-2是否与电针镇痛的作用机制有关。方法:在佐剂性关节炎大鼠的模型上,采用行为学和免疫组化技术两种方法,观察电针治疗后不同时相关节炎大鼠的痛敏评分及脊髓背角 COX-2蛋白的表达,并与正常组、模型组和药物组加以对照。结果:电针能明显减小关节炎大鼠痛敏评分的绝对值。多次电针具有显著的累积效应;并且随着电针治疗次数的增加,大鼠脊髓背角 COX-2免疫阳性细胞数显著下降。结论:电针阳陵泉和昆仑两穴对佐剂性关节炎大鼠有明显的镇痛作用,并同时抑制其脊髓背角 COX-2蛋白的表达。

THE PROPERTY OF PERIPHERAL INPUT OF PROJECTION NEURONS IN THE SPINAL CORD DORSAL HORN

Antidromic and orthodromic responses of the projection neurons in the dorsal horn ofthe spinal cord have been recorded by a glass microelectrode in anesthetized and paralyz-ed cats. Furthermore, the effect of cervical segment antidromic stimulation to orthodromicresponse of the projection neurons has been observed by way of conditioning-test stimulation. Among all the spinocervical tract neurons (SCT), the dorsal column postsynaptic neu-rons (DCPS) and the spinocervical tract-dorsal column postsynaptic neurons (SCT-DCPS),which were identified by cervical segment antidromic stimulation, 46% are low-thresholdmechanoreceptive (LTM) and 54% are wide-dynamic-range (WDR) neurons. Most LTMneurons can evoke the same response to both 10 times (10 T) and 50 times (50 T) the thresh-old stimulation on the peroneal nerve. Most WDR neurons to 50 T intensity stimulation arestronger than the 10 T stimulation. Under the antidromic-cervical segment conditioningstimulation, the amount of orthodromic-discharging in most

In vivo imaging of the neuronal response to spinal cord injury:a narrative review

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury(SCI).However,this subject has been neglected in part because appropriate tools are lacking.Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease.This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques,and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI.We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations.Finally,we identify the challenges and possible solutions for spinal cord neuron imaging.

基于SP/NK1R/βARRS通路电针缓解神经性疼痛的实验研究

目的观察针刺对坐骨神经慢性缩窄模型(chronic constriction injury,CCI)大鼠疼痛行为及脊髓背角P物质(substance P,SP)含量和神经激肽1受体(neurokinin 1 receptor,NK1R)、β-抑制蛋白1抗体(β-arrestin 1,βARR1)蛋白水平的影响。方法将36只雄性Sprague-Dawley(SD)大鼠随机分为假手术组、模型组、电针组和手针组,每组9只。暴露模型组、电针组和手针组大鼠左侧股骨中段坐骨神经并进行结扎,建立坐骨神经慢性缩窄模型;假手术组暴露坐骨神经但不结扎。造模后第8天开始,电针组和手针组分别对环跳和阳陵泉穴进行干预。测定4组大鼠造模后第0、7、13、21、29天的机械痛阈、热痛阈及后肢负重分布。采用酶联免疫吸附法(enzyme-linked immunosorbent assay,ELISA)检测4组大鼠L4~L6腰膨大脊髓背角组织中SP含量;用蛋白质印迹法(Western blotting)检测4组大鼠L4~L6腰膨大脊髓背角组织中NK1R和βARR1蛋白表达。结果造模后第7天,模型组、电针组和手针组大鼠机械痛阈和热痛阈较假手术组降低(P<0.05),两后肢负重分布差异较假手术组增加(P<0.05)。针刺干预后,造模后第13、21、29天,手针组和电针组大鼠机械痛阈和热痛阈高于模型组(P<0.05),两后肢负重分布差异小于模型组(P<0.05);造模后第29天,电针组机械痛阈和热痛阈均高于手针组(P<0.05);造模后第21天,电针组两后肢负重分布差异小于手针组(P<0.05)。针刺干预全部结束后,模型组脊髓背角组织SP含量低于假手术组(P<0.05),手针组和电针组SP含量高于模型组(P<0.05)。针刺干预全部结束后,模型组脊髓背角组织NK1R和βARR1蛋白表达高于假手术组(P<0.05),电针组和手针组NK1R和βARR1蛋白表达低于模型组(P<0.05)。结论针刺可能通过调控脊髓背角SP水平及NK1R和βARR1蛋白表达对神经病理性疼痛起到镇痛效应。