Association Between the Diabetic Foot Ulcer and the Bacterial Colony of the Skin Based on 16S rRNA Gene Sequencing: An Observational Study.

Objective: Microorganisms have been the main cause of refractory and high recurrence of diabetic foot ulcer (DFU). This study attempted to observe the skin bacterial colony in healthy skin, diabetic skin and DFU skin. Methods: Forty-eight diabetes patients were recruited at Panyu Central Hospital from March 2021 to March 2022 and divided into DFU group (T group, n = 22), diabetes without foot ulcer group (TW group, n = 26). Besides, a healthy control group (H group, n = 10) was recruited at the same time. The swab samples of foot skin in the same position in the three groups were collected. The microorganisms obtained from the skin were analyzed by 16S rRNA gene sequencing. The composition of the skin microorganisms was determined, and the species diversity of the skin microbiota was analyzed by α and ß diversity. The species differences in the skin microbiota and the relative abundance of different operational taxonomic units (OUTs) with the most significant abundance were analyzed by linear discriminant analysis effect size (LEfSe). Results: Significant changes were found in the composition of the skin microbiota in the T and TW groups relative to the H group. However, the species diversity of the skin microbiota was significantly reduced in the T and TW groups, with the lowest one in the T group. The composition of microbial diversity in the T group was significantly different from that of the TW and H groups. Among the skin bacterial colonies, the abundance of Staphylococcus, Enhydrobacter, and Corynebacterium_1 was obviously reduced, while that of Escherichia coli and Pseudomonas was significantly increased. Conclusion: Changes in the abundance of Staphylococcus, Enhydrobacter, Corynebacterium_1, Escherichia coli and Pseudomonas in the skin bacterial colonies can be the main causative factors for DFU. This study indicates that altering the microbiota composition of wounds may help the treatment of DFU.

Frequent DYSF rare variants/mutations in 152 Han Chinese samples with ovarian endometriosis.

PURPOSE: Endometriosis is a common chronic gynecological disease greatly affecting women health. Prior studies have implicated that dysferlin (DYSF) aberration might be involved in the pathogenesis of ovarian endometriosis. In the present study, we explore the potential presence of DYSF mutations in a total of 152 Han Chinese samples with ovarian endometriosis. METHODS: We analyze the potential presence of DYSF mutations by direct DNA sequencing. RESULTS: A total of seven rare variants/mutations in the DYSF gene in 10 out of 152 samples (6.6%) were identified, including 5 rare variants and 2 novel mutations. For the 5 rare variants, p.R334W and p.G941S existed in 2 samples, p.R865W, p.R1173H and p.G1531S existed in single sample, respectively; for the two novel mutations, p.W352* and p.I1642F, they were identified in three patients. These rare variants/mutations were absent or existed at extremely low frequency either in our 1006 local control women without endometriosis, or in the China Metabolic Analytics Project (ChinaMAP) and Genome Aggregation Database (gnomAD) databases. Evolutionary conservation analysis results suggested that all of these rare variants/mutations were evolutionarily conserved among 11 vertebrate species from Human to Fox. Furthermore, in silico analysis results suggested these rare variants/mutations were disease-causing. Nevertheless, we find no significant association between DYSF rare variants/mutations and the clinical features in our patients. To our knowledge, this is the first report revealing frequent DYSF mutations in ovarian endometriosis. CONCLUSION: We identified a high frequency of DYSF rare variants/mutations in ovarian endometriosis for the first time. This study suggests a new correlation between DYSF rare variants/mutations and ovarian endometriosis, implicating DYSF rare variants/mutations might be positively involved in the pathogenesis of ovarian endometriosis.

Estrogen receptor 1 mutations in 260 cervical cancer samples from Chinese patients.

Cervical cancer is one of the leading causes of cancer-associated mortality among females; however, the underlying molecular mechanisms of its carcinogenesis remain largely unclear. Previous comprehensive genomic studies have revealed prevalent estrogen receptor 1 (ESR1) mutations in breast cancer, which are rare in certain other types of cancer. To the best of our knowledge, it is unknown whether ESR1 mutations also exist in cervical cancer. Considering the evidence that cervical cancer shares certain genetic aberrations with breast cancer, and that the progression of both breast and cervical cancers can be affected by estrogen, it is possible that cervical cancer may also harbor ESR1 mutations. In the present study, a total of 260 Chinese cervical cancer samples with distinct subtypes were tested for the presence of ESR1 mutations. A total of three heterozygous missense ESR1 mutations, p.K303R (c.908A>G), p.T311M (c.932C>T) and p.Y537C (c.1610A>G), were identified in 3/207 (1.4%) cervical squamous cell carcinoma samples, which were absent in 27 adenosquamous carcinomas and 26 adenocarcinomas samples. Of the three individuals with an ESR1mutation, 1 patient was also diagnosed with ovarian endometriosis and the other 2 patients were diagnosed with a uterine fibroid. A bioinformatics analysis suggested that these ESR1 mutations may be pathogenic by promoting the development of cervical cancer. Furthermore, a previous comprehensive study confirmed that individuals with cervical squamous cell carcinoma possessed ESR1 mutations. These combined studies indicate that ESR1 mutations may participate in the carcinogenesis of cervical squamous cell carcinoma, albeit at a low frequency. In conclusion, the present study identified three potentially pathogenic ESR1 mutations in Chinese cervical squamous cell carcinoma samples, but not in other subtypes.

The effect of pre- and after-treatment of sevoflurane on central ischemia tolerance and the underlying mechanisms.

In recent years, with continuous research efforts targeted at studying the effects of pre- and after-treatment of inhaled anesthetics, significant progress has been made regarding the common clinical use of low concentrations of inhaled sevoflurane and its effect on induced central ischemia tolerance by pre- and post-treatment. In this study, we collected, analyzed, classified, and summarized recent literature regarding the effect of sevoflurane on central ischemia tolerance and its related mechanisms. In addition, we provide a theoretical basis for the clinical application of sevoflurane to protect the central nervous system and other important organs against ischemic injury.

Cause analysis, prevention, and treatment of postoperative restlessness after general anesthesia in children with cleft palate.

Cleft palate is one of the most common congenital malformations of the oral and maxillofacial region, with an incidence rate of around 0.1%. Early surgical repair is the only method for treatment of a cleft lip and palate. However, because of the use of inhalation anesthesia in children and the physiological characteristics of the cleft palate itself combined with the particularities of cleft palate surgery, the incidence rate of postoperative emergence agitation (EA) in cleft palate surgery is significantly higher than in other types of interventions. The exact mechanism of EA is still unclear. Although restlessness after general anesthesia in children with cleft palate is self-limiting, its effects should be considered by clinicians. In this paper, the related literature on restlessness after surgery involving general anesthesia in recent years is summarized. This paper focuses on induction factors as well as prevention and treatment of postoperative restlessness in children with cleft palate after general anesthesia. The corresponding countermeasures to guide clinical practice are also presented in this paper.

PirB Overexpression Exacerbates Neuronal Apoptosis by Inhibiting TrkB and mTOR Phosphorylation After Oxygen and Glucose Deprivation Injury.

Previous studies have proven that paired immunoglobulin-like receptor B (PirB) plays a crucial suppressant role in neurite outgrowth and neuronal plasticity after central nervous system injury. However, the role of PirB in neuronal survival after cerebral ischemic injury and its mechanisms remains unclear. In the present study, the role of PirB is investigated in the survival and apoptosis of cerebral cortical neurons in cultured primary after oxygen and glucose deprivation (OGD)-induced injury. The results have shown that rebarbative PirB exacerbates early neuron apoptosis and survival. PirB gene silencing remarkably decreases early apoptosis and promotes neuronal survival after OGD. The expression of bcl-2 markedly increased and the expression of bax significantly decreased in PirB RNAi-treated neurons, as compared with the control- and control RNAi-treated ones. Further, phosphorylated TrkB and mTOR levels are significantly downregulated in the damaged neurons. However, the PirB silencing markedly upregulates phosphorylated TrkB and mTOR levels in the neurons after the OGD. Taken together, the overexpression of PirB inhibits the neuronal survival through increased neuron apoptosis. Importantly, the inhibition of the phosphorylation of TrkB and mTOR may be one of its mechanisms.

Neuroprotective effects of sevoflurane against electromagnetic pulse-induced brain injury through inhibition of neuronal oxidative stress and apoptosis.

Electromagnetic pulse (EMP) causes central nervous system damage and neurobehavioral disorders, and sevoflurane protects the brain from ischemic injury. We investigated the effects of sevoflurane on EMP-induced brain injury. Rats were exposed to EMP and immediately treated with sevoflurane. The protective effects of sevoflurane were assessed by Nissl staining, Fluoro-Jade C staining and electron microscopy. The neurobehavioral effects were assessed using the open-field test and the Morris water maze. Finally, primary cerebral cortical neurons were exposed to EMP and incubated with different concentration of sevoflurane. The cellular viability, lactate dehydrogenase (LDH) release, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were assayed. TUNEL staining was performed, and the expression of apoptotic markers was determined. The cerebral cortexes of EMP-exposed rats presented neuronal abnormalities. Sevoflurane alleviated these effects, as well as the learning and memory deficits caused by EMP exposure. In vitro, cell viability was reduced and LDH release was increased after EMP exposure; treatment with sevoflurane ameliorated these effects. Additionally, sevoflurane increased SOD activity, decreased MDA levels and alleviated neuronal apoptosis by regulating the expression of cleaved caspase-3, Bax and Bcl-2. These findings demonstrate that Sevoflurane conferred neuroprotective effects against EMP radiation-induced brain damage by inhibiting neuronal oxidative stress and apoptosis.

Two monoclonal antibodies recognising aa 634-668 and aa 1026-1055 of NogoA enhance axon extension and branching in cultured neurons.

In a previous study, we generated two monoclonal antibodies (mAbs) in mice, aNogoA-N and aNogo-66 mAb, which were raised against recombinant N-terminal fragments of rat NogoA and Nogo-66, respectively. When compared with the commercial rabbit anti-rat NogoA polyclonal antibody (pAb), which can specifically recognise NogoA, the two mAbs were also specific for the NogoA antigen in immunofluorescence histochemical (IHC) staining and Western blot (WB) analysis. Serial truncations of NogoA covering the N-terminal region of NogoA (aa 570-691) and Nogo-66 (aa 1026-1091) were expressed in E. coli. The epitopes recognised by aNogoA-N and aNogo-66 are located in the aa 634-668 and aa 1026-1055 regions of NogoA, respectively. Both mAbs remarkably enhanced the axon growth and branching of cultured hippocampal neurons in vitro. These results suggest that the antibodies that bind to aa 634-668 and aa 1026-1055 of NogoA may have stimulatory effects on axon growth and branching. Additionally, the two mAbs that we generated are specific for NogoA and significantly block NogoA function. In conclusion, two sites in NogoA located within aa 634-668 and aa 1026-1055 are recognised by our two antibodies and are novel and potentially promising targets for repair after central nervous system (CNS) injury.

Depressing interleukin-1ß contributed to the synergistic effects of tramadol and minocycline on spinal nerve ligation-induced neuropathic pain.

Our previous study indicated that coadministration of tramadol and minocycline exerted synergistic effects on spinal nerve ligation (SNL)-induced neuropathic mechanical allodynia. However, the underlying mechanisms are still unclear. Recent reports indicated that spinal proinflammatory factor interleukin-1ß (IL-1ß) contributed to the development of neuropathic pain and the positive feedback communication between neuron and glia. Therefore, the present research is to confirm whether spinal IL-1ß-related pathway response contributes to the synergistic effects of tramadol and minocycline on SNL-induced neuropathic pain. Real-time RT-PCR demonstrated IL-1ß up-expression in the ipsilateral spinal dorsal horn 3 days after lesion, which could be significantly decreased by tramadol and minocycline coadministration. Immunofluorescence and Western blot indicated that SNL-induced microglial phosphorylated p38 (p-p38) upregulation was also inhibited by tramadol and minocycline coapplication. Meanwhile, intrathecal administration of p38 inhibitor SB203580 markedly alleviated mechanical allodynia whilst reducing IL-1ß and Fos expression induced by SNL. Moreover, intrathecal neutralized antibody of IL-1ß could depress SNL-induced mechanical allodynia and Fos expression. These results suggest that depressing SNL-induced aberrant activation of the spinal dorsal horn IL-1ß-related pathway contributes to the underlying mechanism of the synergistic effects of tramadol and minocycline coadministration on SNL-induced neuropathic mechanical allodynia.

Tramadol and propentofylline coadministration exerted synergistic effects on rat spinal nerve ligation-induced neuropathic pain.

Neuropathic pain is an intractable clinical problem. Drug treatments such as tramadol have been reported to effectively decrease neuropathic pain by inhibiting the activity of nociceptive neurons. It has also been reported that modulating glial activation could also prevent or reverse neuropathic pain via the administration of a glial modulator or inhibitor, such as propentofylline. Thus far, there has been no clinical strategy incorporating both neuronal and glial participation for treating neuropathic pain. Therefore, the present research study was designed to assess whether coadministration of tramadol and propentofylline, as neuronal and glial activation inhibitors, respectively, would exert a synergistic effect on the reduction of rat spinal nerve ligation (SNL)-induced neuropathic pain. Rats underwent SNL surgery to induce neuropathic pain. Pain behavioral tests were conducted to ascertain the effect of drugs on SNL-induced mechanical allodynia with von-Frey hairs. Proinflammatory factor interleukin-1ß (IL-1ß) expression was also detected by Real-time RT-PCR. Intrathecal tramadol and propentofylline administered alone relieved SNL-induced mechanical allodynia in a dose-dependent manner. Tramadol and propentofylline coadministration exerted a more potent effect in a synergistic and dose dependent manner than the intrathecal administration of either drug alone. Real-time RT-PCR demonstrated IL-1ß up-expression in the ipsilateral spinal dorsal horn after the lesion, which was significantly decreased by tramadol and propentofylline coadministration. Inhibiting proinflammatory factor IL-1ß contributed to the synergistic effects of tramadol and propentofylline coadministration on rat peripheral nerve injury-induced neuropathic pain. Thus, our study provided a rationale for utilizing a novel strategy for treating neuropathic pain by blocking the proinflammatory factor related pathways in the central nervous system.

Combination of tramadol with minocycline exerted synergistic effects on a rat model of nerve injury-induced neuropathic pain.

Neuropathic pain is a refractory clinical problem. Certain drugs, such as tramadol, proved useful for the treatment of neuropathic pain by inhibiting the activity of nociceptive neurons. Moreover, studies indicated that suppression or modulation of glial activation could prevent or reverse neuropathic pain, for example with the microglia inhibitor minocycline. However, few present clinical therapeutics focused on both neuronal and glial participation when treating neuropathic pain. Therefore, the present study hypothesized that combination of tramadol with minocycline as neuronal and glial activation inhibitor may exert some synergistic effects on spinal nerve ligation (SNL)-induced neuropathic pain. Intrathecal tramadol or minocycline relieved SNL-induced mechanical allodynia in a dose-dependent manner. SNL-induced spinal dorsal horn Fos or OX42 expression was downregulated by intrathecal tramadol or minocycline. Combination of tramadol with minocycline exerted powerful and synergistic effects on SNL-induced neuropathic pain also in a dose-dependent manner. Moreover, the drug combination enhanced the suppression effects on SNL-induced spinal dorsal horn Fos and OX42 expression, compared to either drug administered alone. These results indicated that combination of tramadol with minocycline could exert synergistic effects on peripheral nerve injury-induced neuropathic pain; thus, a new strategy for treating neuropathic pain by breaking the interaction between neurons and glia bilaterally was also proposed.

Effects of starch nanospheres solution on hemodynamic values in rats with hemorrhagic shock: a preliminary study in hemorrhagic shock resuscitation.

BACKGROUND: The objective of the present study was to explore the resuscitation effects of starch nanospheres solution on hemodynamics in rats with hemorrhagic shock. METHODS: A total of 20 Sprague-Dawley rats were randomly divided into 2 groups: resuscitation group 1 (infusion with Ringer's solution) and resuscitation group 2 (infusion with starch nanospheres solution) with 10 rats per group. The rats in resuscitation groups 1 and 2 were subjected to hemorrhagic shock, and resuscitation was performed with Ringer's solution and starch nanospheres solution. The changes in the hemodynamic values of the rats in both groups were observed and recorded. RESULTS: The hemodynamic values included the systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, heart rate, and respiratory rate. After resuscitation, the systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate in resuscitation group 2 had reverted back to the base values (P > 0.05). The systolic blood pressure, diastolic blood pressure, and mean arterial pressure were lower at all points in resuscitation group 1 than in resuscitation group 2 (P < 0.05). The respiratory rate was more rapid after resuscitation at 30 and 60 min in resuscitation group 1 than in resuscitation group 2 (P < 0.05). CONCLUSIONS: Starch nanospheres solution expands the circulating blood volume and improves the hemodynamics. It also increases the effective circulating blood volume and improves the shock symptoms of effective hypovolemia.

Triptolide prevents and attenuates neuropathic pain via inhibiting central immune response.

BACKGROUND: Current treatments for neuropathic pain are far from satisfactory. Considering the essential contribution of central immune factors to the pathogenesis of neuropathic pain, targeting inflammatory response is well accepted as an effective strategy for treating neuropathic pain. Triptolide has a long history in traditional Chinese medicine for treating inflammatory diseases and has been proven to inhibit cytokines released from glial cells. OBJECTIVE: In the present study, we tested whether systemic treatment with triptolide could prevent or attenuate nocifensive behaviors associated with neuropathic pain. We further tried to explore the underlying mechanism of the potential anti-allodynia effect of triptolide. STUDY DESIGN: A randomized, double blind, controlled animal trial. METHODS: Triptolide was administered systemically in a rat model of neuropathic pain induced by spinal nerve ligation (SNL) in the single bolus and repeated treatment manners. In the single bolus treatment experiment, triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) or vehicle was given to SNL and sham-operated rats once on day 1 or on day 10 after surgery (n = 6 each). In the repeated treatment study, prophylactic treatment with triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) was given to rats during the period of day -3 (3 days prior to SNL) to day 7 (7 days post-SNL) inclusively (n = 6 each). Another set of SNL and sham rats on postoperative day 10 received treatment with triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) or vehicle during the period of days 11-20 inclusively (n = 6 each), to assess potential reversal of established pain behavior. Mechanical allodynia of the rats was tested with von Frey filaments. Astrocytic and microglial activation in the spinal dorsal horn was evaluated with immunofluorescent histochemistry. Phosphorylation of mitogen-activated protein kinases (MAPKs), and expression of inflammatory cytokines (interleukin-6, interleukin-1beta, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) were examined with Western blot analysis and real-time reverse transcription polymerase chain reaction study. RESULTS: A single bolus treatment with triptolide could neither prevent the induction nor reverse the maintenance of SNL-induced mechanical allodynia. However, repeated administration of triptolide dose-dependently inhibited neuropathic pain behavior in both preventative and interventional paradigms. Triptolide hampered SNL-induced activation of glial cells (astrocytes and microglia) in the spinal dorsal horn without influencing neurons. In addition, SNL-induced phosphorylation of MAPKs could be inhibited by triptolide. Furthermore, up-regulated expression of inflammatory cytokines in neuropathic pain states could be remarkably blocked by triptolide. LIMITATIONS: The direct target site (such as a specific receptor) of triptolide is still to be determined. In addition, triptolide could not completely block the SNL-induced mechanical allodynia. CONCLUSIONS: Our data suggest that triptolide may be a potential novel treatment for neuropathic pain through modulating immune response in the spinal dorsal horn.

The Inhibition of Spinal Astrocytic JAK2-STAT3 Pathway Activation Correlates with the Analgesic Effects of Triptolide in the Rat Neuropathic Pain Model.

Neuropathic pain (NP) is an intractable clinical problem without satisfactory treatments. However, certain natural products have been revealed as effective therapeutic agents for the management of pain states. In this study, we used the spinal nerve ligation (SNL) pain model to investigate the antinociceptive effect of triptolide (T10), a major active component of the traditional Chinese herb Tripterygium wilfordii Hook F. Intrathecal T10 inhibited the mechanical nociceptive response induced by SNL without interfering with motor performance. Additionally, the anti-nociceptive effect of T10 was associated with the inhibition of the activation of spinal astrocytes. Furthermore, intrathecal administration of T10 attenuated SNL-induced janus kinase (JAK) signal transducers and activators of transcription 3 (STAT3) signalling pathway activation and inhibited the upregulation of proinflammatory cytokines, such as interleukin-6, interleukin-1 beta, and tumour necrosis factor-α, in dorsal horn astrocytes. Moreover, NR2B-containing spinal N-methyl D-aspartate receptor (NMDAR) was subsequently inhibited. Above all, T10 can alleviate SNL-induced NP via inhibiting the neuroinflammation in the spinal dorsal horn. The anti-inflammation effect of T10 may be related with the suppression of spinal astrocytic JAK-STAT3 activation. Our results suggest that T10 may be a promising drug for the treatment of NP.

Biomechanical optimisation of the length ratio of the two endosseous portions in distraction implants: a three-dimensional finite element analysis.

Insufficient alveolar height is one of the most common problems in oral implantation, and it may preclude placement of an implant or compromise the final aesthetic outcome of the restoration. To solve this problem, distraction implants (DIs) have been introduced because they can fulfill the functions of bony augmentation and implantation simultaneously and facilitate the operation, minimise the trauma, and shorten the duration of treatment. However, the high risk of complications such as device fracture from uneven distribution of stress or transport bone resorption from insufficient blood supply, has impeded their clinical use. As the cortical transport portion of the DI is more important for bearing occlusal force than the apical support portion, and the length of the transport portion is normally the height of the transport bone segment, lengthening the transport portion may help to obtain a rational distribution of stress and increase the blood supply to the transport bone. For those cases in which alveolar height is limited, the dimension of the DI must be minimised to be applicable, so it is important to find an optimised balance between the lengths of the transport and support portions for a better performance. We have made a finite element analysis to optimise the length ratio of transport:support portions. The effects of the length ratios on the stress distribution in the jawbones were evaluated. A ratio of 8:2 showed the minimum stress and most resistance to displacement. These results provide a valuable reference for further improvement of designs of DI and help to promote its clinical application.

Surgical treatment of a giant neurofibroma.

Neurofibromatosis type 1, an autosomal dominant inherited disease, presents pathologic symptoms of multiple systems, including neurofibromatosis, skeletal dysplasia, café-au-lait spots in skins, and so on. A 45-year-old man with neurofibromatosis type 1 was reported in this article. The patient presented a giant neurofibroma in his head and neck, dysplasia of skull, facial bones and spinal columns, and multiple café-au-lait spots in systematic skins. Satisfactory curative effects were obtained in this case after tumor resection and prosthesis implantation.

Spinal astrocytic activation is involved in a virally-induced rat model of neuropathic pain.

Postherpetic neuralgia (PHN), the most common complication of herpes zoster (HZ), plays a major role in decreased life quality of HZ patients. However, the neural mechanisms underlying PHN remain unclear. Here, using a PHN rat model at 2 weeks after varicella zoster virus infection, we found that spinal astrocytes were dramatically activated. The mechanical allodynia and spinal central sensitization were significantly attenuated by intrathecally injected L-α-aminoadipate (astrocytic specific inhibitor) whereas minocycline (microglial specific inhibitor) had no effect, which indicated that spinal astrocyte but not microglia contributed to the chronic pain in PHN rat. Further study was taken to investigate the molecular mechanism of astrocyte-incudced allodynia in PHN rat at post-infection 2 weeks. Results showed that nitric oxide (NO) produced by inducible nitric oxide synthase mediated the development of spinal astrocytic activation, and activated astrocytes dramatically increased interleukin-1ß expression which induced N-methyl-D-aspartic acid receptor (NMDAR) phosphorylation in spinal dorsal horn neurons to strengthen pain transmission. Taken together, these results suggest that spinal activated astrocytes may be one of the most important factors in the pathophysiology of PHN and "NO-Astrocyte-Cytokine-NMDAR-Neuron" pathway may be the detailed neural mechanisms underlying PHN. Thus, inhibiting spinal astrocytic activation may represent a novel therapeutic strategy for clinical management of PHN.

Neuronal NR2B-containing NMDA receptor mediates spinal astrocytic c-Jun N-terminal kinase activation in a rat model of neuropathic pain.

Spinal N-methyl d-aspartate receptor (NMDAR) plays a pivotal role in nerve injury-induced central sensitization. Recent studies suggest that NMDAR also contributes to neuron-astrocyte signaling. c-Jun N-terminal kinase (JNK) is persistently and specifically activated (indicated by phosphorylation) in spinal cord astrocytes after nerve injury and thus it is considered as a dependable indicator of pain-related astrocytic activation. NMDAR-mediated JNK activation in spinal dorsal horn might be an important form of neuron-astrocyte signaling in neuropathic pain. In the present study, we observed that intrathecal injection of MK-801, a noncompetitive NMDA receptor antagonist, or Ro25-6981 and ifenprodil, which are selective antagonists of NR2B-containing NMDAR each significantly reduced nerve injury-induced JNK activation. Double immunostaining showed that NR2B was highly expressed in neurons, indicating the effect of NMDAR antagonists on JNK activation was indirect. We further observed that intrathecal injection of NMDA (twice a day for 3 days) significantly increased spinal JNK phosphorylation. Besides, NMDAR-related JNK activation could be blocked by a neuronal nitric oxide synthase (nNOS) selective inhibitor (7-nitroindazole sodium salt) but not by a nNOS sensitive guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Finally, real-time RT-PCR and immunostaining showed that nerve injury-induced interleukin-1beta expression was dependent on astrocytic JNK activation. Treatments targeting NMDAR-nNOS pathway also influenced interleukin-1beta expression, which further confirmed our hypothesis. Taken together, our results suggest that neuronal NMDAR-nNOS pathway could activate astrocytic JNK pathway. Excitatory neuronal transmission initiates astrocytic activation-induced neuroinflammation in this way, which contributes to nerve injury-induced neuropathic pain.

Post-injury administration of minocycline: an effective treatment for nerve-injury induced neuropathic pain.

Neuropathic pain is an intractable clinical problem, affecting millions of people worldwide. Preemptive administration of minocycline has been confirmed useful for treating neuropathic pain by inhibiting spinal microglia activation and consequently lowering proinflammatory cytokine expression. However, most patients with neuropathic pain have no chance to receive preemptive treatment and it remains unclear whether there is a therapeutic time window for post treatment with minocycline. The present study is to confirm the effect and the therapeutic time window of intrathecal minocycline on spinal nerve ligation (SNL)-induced neuropathic pain after lesion. Behavioral test and immunohistochemistry are utilized to determine the variation of mechanical allodynia and microglia phosphorylated-p38 (p-p38) expression respectively after intrathecal minocycline. Results showed that post-injury intrathecal minocycline attenuated mechanical allodynia effectively together with inhibiting spinal microglia p-p38 expression on post operative day (POD) 1, POD 3 and POD 7. Additionally, results from POD 10 and POD 21 showed that intrathecal minocycline suppressed spinal microglia p-p38 expression but without any effects on reversing mechanical allodynia. It is concluded that post-injury intrathecal minocycline is an effective therapeutic intervention for treating SNL-induced neuropathic pain by inhibiting spinal microglia activation. Accordingly, there is indeed a therapeutic time window for post-injury intrathecal minocycline, which is the initiation stage of neuropathic pain development.

Ketamine depresses toll-like receptor 3 signaling in spinal microglia in a rat model of neuropathic pain.

Reports suggest that microglia play a key role in spinal nerve ligation (SNL)-induced neuropathic pain, and toll-like receptor 3 (TLR3) has a substantial role in the activation of spinal microglia and the development of tactile allodynia after nerve injury. In addition, ketamine application could suppress microglial activation in vitro, and ketamine could inhibit proinflammatory gene expression possibly by suppressing TLR-mediated signal transduction. Therefore, the present study was designed to disclose whether intrathecal ketamine could suppress SNL-induced spinal microglial activation and exert some antiallodynic effects on neuropathic pain by suppressing TLR3 activation. Behavioral results showed that intrathecal ketamine attenuated SNL-induced mechanical allodynia, as well as spinal microglial activation, in a dose-dependent manner. Furthermore, Western blot analysis displayed that ketamine application downregulated SNL-induced phosphorylated-p38 (p-p38) expression, which was specifically expressed in spinal microglia but not in astrocytes or neurons. Besides, ketamine could reverse TLR3 agonist (polyinosine-polycytidylic acid)-induced mechanical allodynia and spinal microglia activation. It was concluded that intrathecal ketamine depresses TLR3-induced spinal microglial p-p38 mitogen-activated protein kinase pathway activation after SNL, probably contributing to the antiallodynic effect of ketamine on SNL-induced neuropathic pain.