scholarly journals Role of Primary Afferents in Arthritis Induced Spinal Microglial Reactivity

2021 ◽  
Vol 12 ◽  
Author(s):  
Charlie H. T. Kwok ◽  
Yuta Kohro ◽  
Michael Mousseau ◽  
Melissa S. O’Brien ◽  
John R. Matyas ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Atp Release ◽  
Afferent Input ◽  
Female Rats ◽  
Male Rats ◽  
Joint Injury ◽  
Joint Afferents ◽  
Spinal Dorsal ◽  
Monosodium Iodoacetate

Increased afferent input resulting from painful injury augments the activity of central nociceptive circuits via both neuron-neuron and neuron-glia interactions. Microglia, resident immune cells of the central nervous system (CNS), play a crucial role in the pathogenesis of chronic pain. This study provides a framework for understanding how peripheral joint injury signals the CNS to engage spinal microglial responses. During the first week of monosodium iodoacetate (MIA)-induced knee joint injury in male rats, inflammatory and neuropathic pain were characterized by increased firing of peripheral joint afferents. This increased peripheral afferent activity was accompanied by increased Iba1 immunoreactivity within the spinal dorsal horn indicating microglial activation. Pharmacological silencing of C and A afferents with co-injections of QX-314 and bupivacaine, capsaicin, or flagellin prevented the development of mechanical allodynia and spinal microglial activity after MIA injection. Elevated levels of ATP in the cerebrospinal fluid (CSF) and increased expression of the ATP transporter vesicular nucleotide transporter (VNUT) in the ipsilateral spinal dorsal horn were also observed after MIA injections. Selective silencing of primary joint afferents subsequently inhibited ATP release into the CSF. Furthermore, increased spinal microglial reactivity, and alleviation of MIA-induced arthralgia with co-administration of QX-314 with bupivacaine were recapitulated in female rats. Our results demonstrate that early peripheral joint injury activates joint nociceptors, which triggers a central spinal microglial response. Elevation of ATP in the CSF, and spinal expression of VNUT suggest ATP signaling may modulate communication between sensory neurons and spinal microglia at 2 weeks of joint degeneration.

scholarly journals Spatial organization of activity evoked by focal stimulation within the rat spinal dorsal horn as visualized by voltage-sensitive dye imaging in the slice

2019 ◽  
Vol 122 (4) ◽  
pp. 1697-1707 ◽  
Author(s):  
Masaharu Mizuno ◽  
Go Kato ◽  
Andrew M. Strassman
Keyword(s):  
White Matter ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Spatial Organization ◽  
Male Rats ◽  
Voltage Sensitive Dye ◽  
Spinal Dorsal ◽  
Medial Dorsal ◽  
Synaptic Responses ◽  
Voltage Sensitive Dye Imaging

In a prior study using laser scanning photostimulation, we found a pronounced cell type-specific mediolateral asymmetry in the local synaptic connectivity in the superficial laminae of the spinal dorsal horn (Kosugi M, Kato G, Lukashov S, Pendse G, Puskar Z, Kozsurek M, Strassman AM. J Physiol 591: 1935–1949, 2013). To obtain information on dorsal horn organization that might complement findings from microelectrode studies, voltage-sensitive dye imaging was used in the present study to examine patterns of activity evoked by focal electrical stimulation, in the presence and absence of synaptic blocking agents, at different positions in transverse, parasagittal, and horizontal slices of the dorsal horn of 2- to 3-wk -old male rats. A pronounced difference in responsiveness was found between medial and lateral dorsal horn, in that medial sites in the superficial dorsal horn showed much larger synaptic responses to focal stimulation than lateral sites. This difference appeared to be a result of a difference in the intrinsic elements of the dorsal horn, rather than a difference in the inputs from the white matter, because the stimulus intensities were subthreshold for evoking synaptic responses from stimulation at sites in the white matter, although it is also possible that the greater responsiveness is due, at least in part, to activation of Aβ primary afferent fibers that pass through the medial dorsal horn. The results raise the possibility of differences between medial and dorsal horn that need to be taken into account in the interpretation of studies of dorsal horn organization. NEW & NOTEWORTHY We used voltage-sensitive dye imaging to obtain information on spatial aspects of dorsal horn organization that are difficult to examine with single-cell approaches because of the limitations of microelectrode sampling. The most noteworthy finding was a previously unreported, extreme difference between medial and lateral dorsal horn in responsiveness to focal stimulation that appears to result, at least in part, from a greater degree of excitability or local connectivity in medial dorsal horn.

scholarly journals Evans Blue Reduces Neuropathic Pain Behavior by Inhibiting Spinal ATP Release

2019 ◽  
Vol 20 (18) ◽  
pp. 4443 ◽  
Author(s):  
Yin ◽  
Hong ◽  
Phạm ◽  
Shin ◽  
Gwon ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Evans Blue ◽  
Spinal Dorsal Horn ◽  
Critical Role ◽  
Atp Release ◽  
Pain Behavior ◽  
Dependent Manner ◽  
Spinal Dorsal

Upon peripheral nerve injury, vesicular ATP is released from damaged primary afferent neurons. This extracellular ATP subsequently activates purinergic receptors of the spinal cord, which play a critical role in neuropathic pain. As an inhibitor of the vesicular nucleotide transporter (VNUT), Evans blue (EB) inhibits the vesicular storage and release of ATP in neurons. Thus, we tested whether EB could attenuate neuropathic pain behavior induced by spinal nerve ligation (SNL) in rats by targeting VNUT. An intrathecal injection of EB efficiently attenuated mechanical allodynia for five days in a dose-dependent manner and enhanced locomotive activity in an SNL rat model. Immunohistochemical analysis showed that EB was found in VNUT immunoreactivity on neurons in the dorsal root ganglion and the spinal dorsal horn. The level of ATP in cerebrospinal fluid in rats with SNL-induced neuropathic pain decreased upon administration of EB. Interestingly, EB blocked ATP release from neurons, but not glial cells in vitro. Eventually, the loss of ATP decreased microglial activity in the ipsilateral dorsal horn of the spinal cord, followed by a reduction in reactive oxygen species and proinflammatory mediators, such as interleukin (IL)-1β and IL-6. Finally, a similar analgesic effect of EB was demonstrated in rats with monoiodoacetate-induced osteoarthritis (OA) pain. Taken together, these data demonstrate that EB prevents ATP release in the spinal dorsal horn and reduces the ATP/purinergic receptor-induced activation of spinal microglia followed by a decline in algogenic substances, thereby relieving neuropathic pain in rats with SNL.

scholarly journals Proteomics Analysis of the Spinal Dorsal Horn in Diabetic Painful Neuropathy Rats With Electroacupuncture Treatment

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiangmei Yu ◽  
Xiaomei Chen ◽  
Weiting Liu ◽  
Menghong Jiang ◽  
Zhifu Wang ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Fasting Blood Glucose ◽  
Male Rats ◽  
Tandem Mass ◽  
Painful Neuropathy ◽  
Proteomics Analysis ◽  
Spinal Dorsal ◽  
Diabetic Painful Neuropathy

BackgroundClinical evidence demonstrates that electro-acupuncture (EA) of the Zu sanli (ST36) and Shen shu (BL23) acupoints is effective in relieving diabetic painful neuropathy (DPN); however, the underlying molecular mechanism requires further investigation, including the protein molecules associated with EA’s effects on DPN.MethodsSprague-Dawley adult male rats (n =36) were randomly assigned into control, DPN, and EA groups (n=12 each). After four weeks of EA treatment, response to mechanical pain and fasting blood glucose were analyzed. A tandem mass tag (TMT) labeling approach coupled with liquid chromatography with tandem mass spectrometry was used to identify potential biomarkers in the spinal dorsal horn. Further, proteomics analysis was used to quantify differentially expressed proteins (DEPs), and gene ontology, KEGG pathways, cluster, and string protein network interaction analyses conducted to explore the main protein targets of EA.ResultsCompared with the DPN model group, the mechanical pain threshold was significantly increased, while the fasting blood glucose levels were clearly decreased in EA group rats. Proteomics analysis was used to quantify 5393 proteins, and DEPs were chosen for further analyses, based on a threshold of 1.2-fold difference in expression level (P < 0.05) compared with control groups. Relative to the control group, 169 down-regulated and 474 up-regulated proteins were identified in the DPN group, while 107 and 328 proteins were up- and down-regulated in the EA treatment group compared with the DPN group. Bioinformatics analysis suggested that levels of proteins involved in oxidative stress injury regulation were dramatically altered during the EA effects on DPN.ConclusionsOur results provide the valuable protein biomarkers, which facilitates unique mechanistic insights into the DPN pathogenesis and EA analgesic, antioxidant stress and hypoglycemic effect.

Effects of Tetramethylpyrazine on Neuronal Apoptosis in the Superficial Dorsal Horn in a Rat Model of Neuropathic Pain

2012 ◽  
Vol 40 (06) ◽  
pp. 1229-1239 ◽  
Author(s):  
Yu-Fang Leng ◽  
Xiang-Mei Gao ◽  
Shu-Xiu Wang ◽  
Yan-Hong Xing
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Neuronal Apoptosis ◽  
Caspase 3 ◽  
Sham Group ◽  
Male Rats ◽  
Spinal Dorsal ◽  
Post Operation ◽  
The Right

The Bennett and Xie (1988) model of chronic constriction injury (CCI) investigated the effects of tetramethylpyrazine (TMP) on neuropathic pain-associated behaviors and neuronal apoptosis in the spinal dorsal horn. Fifty-four male rats were randomly divided into sham (group S), CCI (group C) and TMP groups (group T). Each group was divided into subgroups (n = 6 in each group) according the time of sacrifice: 3 d, 7 d and 14 d. Rat sciatic nerves were unligated (group S), or the right sciatic nerve was loosely ligated (groups C and T) to produce CCI. Mechanical withdrawal thresholds (MWTs) and thermal withdrawal latencies (TWLs) were measured, and the rats were sacrificed at different time points post-operation. The L4-L6 sections of the spinal cord were removed. Apoptotic changes were evaluated using the TUNEL method. Immunohistochemistry assessed Bcl-2 and caspase-3 expression. TMP treatment increased MWT and TWL values and Bcl-2 expression, but it reduced neuronal apoptosis and caspase-3 expression in laminae I–II of the spinal dorsal horn. These results suggested that the inhibition of neuronal apoptosis via the modulation of Bcl-2 and caspase-3 proteins in the rat spinal dorsal horn contributed to TMP-induced analgesia.

scholarly journals Spinal α2-Adrenoceptor-mediated Analgesia in Neuropathic Pain Reflects Brain-derived Nerve Growth Factor and Changes in Spinal Cholinergic Neuronal Function

2010 ◽  
Vol 113 (2) ◽  
pp. 406-412 ◽  
Author(s):  
Ken-ichiro Hayashida ◽  
James C. Eisenach
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Choline Acetyltransferase ◽  
Spinal Dorsal Horn ◽  
Acetylcholine Release ◽  
Cholinergic Neurons ◽  
Male Rats ◽  
Spinal Dorsal ◽  
Alpha2 Adrenoceptor

Introduction Spinal alpha2-adrenoceptor stimulation produces analgesia in neuropathic pain states, and this effect in animals is blocked by the inhibitors of brain-derived neurotrophic factor (BDNF) function. In rats, alpha2-adrenoceptor stimulation normally inhibits acetylcholine release, but it excites release after nerve injury. The authors examined the roles of BDNF and excitatory Gs-protein in this change. Methods Male rats underwent L5-L6 spinal nerve ligation (SNL), and their lumbar spinal dorsal horns with or without spinal BDNF infusion were used for either synaptosome preparation for acetylcholine release or immunostaining for choline acetyltransferase. Results SNL did not alter spontaneous release from synaptosomes or choline acetyltransferase immunoreactivity in the spinal dorsal horn, but it reduced KCl-evoked acetylcholine release. Dexmedetomidine inhibited KCl-evoked acetylcholine release in synaptosomes from normal rats, but it excited KCl-evoked release in synaptosomes from SNL rats, and both effects were blocked by the alpha2-adrenoceptor antagonist idazoxan. Spinal infusion of an antibody to BDNF reduced choline acetyltransferase immunoreactivity in the spinal dorsal horn in both normal and SNL rats and abolished facilitation of KCl-evoked acetylcholine release by dexmedetomidine in SNL rats. Dexmedetomidine facilitation of acetylcholine release was also blocked by the inhibitors of Gs function. Discussion The increased reliance of spinal alpha2 adrenoceptors on cholinergic stimulation to cause analgesia after nerve injury reflects in part a shift from direct inhibition to direct excitation of spinal cholinergic neurons. The authors' results suggest that this shift relies on an interaction with Gs-proteins and BDNF.

scholarly journals Neonatal Local Noxious Insult Affects Gene Expression in the Spinal Dorsal Horn of Adult Rats

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-27 ◽  
Author(s):  
Ke Ren ◽  
Svetlana I Novikova ◽  
Fang He ◽  
Ronald Dubner ◽  
Michael S Lidow
Keyword(s):  
Gene Expression ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Expression Profiles ◽  
Male Rats ◽  
Sensitive Period ◽  
Spinal Level ◽  
Spinal Dorsal ◽  
Genes Encoding

Neonatal noxious insult produces a long-term effect on pain processing in adults. Rats subjected to carrageenan (CAR) injection in one hindpaw within the sensitive period develop bilateral hypoalgesia as adults. In the same rats, inflammation of the hindpaw, which was the site of the neonatal injury, induces a localized enhanced hyperalgesia limited to this paw. To gain an insight into the long-term molecular changes involved in the above-described long-term nociceptive effects of neonatal noxious insult at the spinal level, we performed DNA microarray analysis (using microarrays containing oligo-probes for 205 genes encoding receptors and transporters for glutamate, GABA, and amine neurotransmitters, precursors and receptors for neuropeptides, and neurotrophins, cytokines and their receptors) to compare gene expression profiles in the lumbar spinal dorsal horn (LDH) of adult (P60) male rats that received neonatal CAR treatment within (at postnatal day 3; P3) and outside (at postnatal 12; P12) of the sensitive period. The data were obtained both without inflammation (at baseline) and during complete Freund's adjuvant induced inflammation of the neonatally injured paw. The observed changes were verified by real-time RT-PCR. This study revealed significant basal and inflammation-associated aberrations in the expression of multiple genes in the LDH of adult animals receiving CAR injection at P3 as compared to their expression levels in the LDH of animals receiving either no injections or CAR injection at P12. In particular, at baseline, twelve genes (representing GABA, serotonin, adenosine, neuropeptide Y, cholecystokinin, opioid, tachykinin and interleukin systems) were up-regulated in the bilateral LDH of the former animals. The baseline condition in these animals was also characterized by up-regulation of seven genes (encoding members of GABA, cholecystokinin, histamine, serotonin, and neurotensin systems) in the LDH ipsilateral to the neonatally-injured paw. The largest aberration in gene expression, however, was observed during inflammation of the neonatally injured hindpaws in the ipsilateral LDH, which included thirty-six genes (encoding numerous members of glutamate, serotonin, GABA, calcitonin gene-related peptide, neurotrophin, and interleukin systems). These findings suggest that changes in gene expression may be involved in the long-term nociceptive effects of neonatal noxious insult at the spinal level.

scholarly journals Preliminary Study on Pain Reduction of Monosodium Iodoacetate-Induced Knee Osteoarthritis in Rats by Carbon Dioxide Laser Moxibustion

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Fan Wu ◽  
Ruixing Zhang ◽  
Xueyong Shen ◽  
Lixing Lao
Keyword(s):  
Treatment Group ◽  
Knee Osteoarthritis ◽  
Dorsal Horn ◽  
Carbon Dioxide Laser ◽  
Spinal Dorsal Horn ◽  
Pain Reduction ◽  
Control Group ◽  
Blank Control Group ◽  
Spinal Dorsal ◽  
Monosodium Iodoacetate

In order to study the effects of CO2laser moxibustion on the pain and inflammatory cytokine expression in the spinal dorsal horn of rats with monosodium iodoacetate- (MIA-) induced knee osteoarthritis (KOA), we designed an experiment by randomly assigning 8 SD rats into 3 groups, namely, a CO2laser moxibustion group, a sham treatment group, and a blank control group. The treatment group received a laser moxibustion on acupoint Dubi (ST 35; 5 min/treatment, 1 treatment/day) for 8 days, and after treatment, the rats exhibited significantly increased interhindpaw differences compared with their preinduction values. Meanwhile, cytokine microarray analysis showed that one cytokine (TIMP-1) was significantly upregulated and two cytokines (Agrin and MMP-8) were significantly downregulated in treatment group. The present study suggested that CO2laser moxibustion created certain pain reduction in the rats with MIA-induced KOA and significantly inhibited the expression of most inflammatory cytokines in the ipsilateral spinal dorsal horn.

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