Mechanism of Shikonin on spinal cord injury in rats based on TNFR/RIPK1 pathway / 中国骨伤

OBJECTIVE@#To explore the effect of shikonin on the recovery of nerve function after acute spinal cord injury(SCI) in rats.@*METHODS@#96 male Sprague-Dawley(SD)rats were divided into 4 groups randomly:sham operation group (Group A), sham operation+shikonin group (Group B), SCI+ DMSO(Group C), SCI+shikonin group (Group D).The acute SCI model of rats was made by clamp method in groups C and D . After subdural catheterization, no drug was given in group A. rats in groups B and D were injected with 100 mg·kg-1 of shikonin through catheter 30 min after modeling, and rats in group C were given with the same amount of DMSO, once a day until the time point of collection tissue. Basso-Beattie-Bresnahan(BBB) scores were performed on 8 rats in each group at 6, 12, and 3 d after moneling, and oblique plate tests were performed on 1, 3, 7 and 14 d after modeling, and then spinal cord tissues were collected. Eight rats were intraperitoneally injected with propidine iodide(PI) 1 h before sacrificed to detection PI positive cells at 24 h in each group. Eight rats were sacrificed in each group at 24 h after modeling, the spinal cord injury was observed by HE staining.The Nissl staining was used to observe survivor number of nerve cells. Western-blot technique was used to detect the expression levels of Bcl-2 protein and apoptosis related protein RIPK1.@*RESULTS@#After modeling, BBB scores were normal in group A and B, but in group C and D were significantly higher than those in group A and B. And the scores in group D were higher than those in group C in each time point (P<0.05). At 12 h after modeling, the PI red stained cells in group D were significantly reduced compared with that in group C, and the disintegration of neurons was alleviated(P<0.05). HE and Nissl staining showed nerve cells with normal morphology in group A and B at 24h after operation. The degree of SCI and the number of neuronal survival in group D were better than those in group C, the difference was statistically significant at 24h (P<0.05). The expression of Bcl-2 and RIPK1 proteins was very low in group A and B;The expression of RIPK1 was significantly increased in Group C and decreased in Group D, with a statistically significant difference (P<0.05);The expression of Bcl-2 protein in group D was significantly higher than that in group C (P<0.05).@*CONCLUSION@#Shikonin can alleviate the pathological changes after acute SCI in rats, improve the behavioral score, and promote the recovery of spinal nerve function. The specific mechanism may be related to the inhibition of TNFR/RIPK1 signaling pathway mediated necrotic apoptosis.

Microglial Depletion does not Affect the Laterality of Mechanical Allodynia in Mice / 神经科学通报·英文版

Mechanical allodynia (MA), including punctate and dynamic forms, is a common and debilitating symptom suffered by millions of chronic pain patients. Some peripheral injuries result in the development of bilateral MA, while most injuries usually led to unilateral MA. To date, the control of such laterality remains poorly understood. Here, to study the role of microglia in the control of MA laterality, we used genetic strategies to deplete microglia and tested both dynamic and punctate forms of MA in mice. Surprisingly, the depletion of central microglia did not prevent the induction of bilateral dynamic and punctate MA. Moreover, in dorsal root ganglion-dorsal root-sagittal spinal cord slice preparations we recorded the low-threshold Aβ-fiber stimulation-evoked inputs and outputs of superficial dorsal horn neurons. Consistent with behavioral results, microglial depletion did not prevent the opening of bilateral gates for Aβ pathways in the superficial dorsal horn. This study challenges the role of microglia in the control of MA laterality in mice. Future studies are needed to further understand whether the role of microglia in the control of MA laterality is etiology-or species-specific.

Mechanism of Mongolian drug Naru-3 in initiation of neuroinflammation of neuropathic pain from MMP9/IL-1β signaling pathway / 中国中药杂志

Neuropathic pain(NP) has similar phenotypes but different sequential neuroinflammatory mechanisms in the pathological process. It is of great significance to inhibit the initiation of neuroinflammation, which has become a new direction of NP treatment and drug development in recent years. Mongolian drug Naru-3 is clinically effective in the treatment of trigeminal neuralgia, sciatica, and other NPs in a short time, but its pharmacodynamic characteristics and mechanism of analgesia are still unclear. In this study, a spinal nerve ligation(SNL) model simulating clinical peripheral nerve injury was established and the efficacy and mechanism of Naru-3 in the treatment of NPs was discussed by means of behavioral detection, side effect evaluation, network analysis, and experimental verification. Pharmacodynamic results showed that Naru-3 increased the basic pain sensitivity threshold(mechanical hyperalgesia and thermal radiation hyperalgesia) in the initiation of SNL in animals and relieved spontaneous pain, however, there was no significant effect on the basic pain sensitivity threshold and motor coordination function of normal animals under physiological and pathological conditions. Meanwhile, the results of primary screening of target tissues showed that Naru-3 inhibited the second phase of injury-induced nociceptive response of formalin test in mice and reduced the expression of inflammatory factors in the spinal cord. Network analysis discovered that Naru-3 had synergy in the treatment of NP, and its mechanism was associated with core targets such as matrix metalloproteinase-9(MMP9) and interleukin-1β(IL-1β). The experiment further took the dorsal root ganglion(DRG) and the stage of patho-logical spinal cord as the research objects, focusing on the core targets of inducing microglial neuroinflammation. By means of Western blot, immunofluorescence, agonists, antagonists, behavior, etc., the mechanism of Naru-3 in exerting NP analgesia may be related to the negative regulation of the MMP9/IL-1β signaling pathway-mediated microglia p38/IL-1β inflammatory loop in the activation phase. The relevant research enriches the biological connotation of Naru-3 in the treatment of NP and provides references for clinical rational drug use.

Neuroprotective effect of tetramethylpyrazine on mice after spinal cord injury / 中国中药杂志

This study aims to investigate the neuroprotective effect of tetramethylpyrazine on mice after spinal cord injury and its mechanism. Seventy-five female C57BL/6 mice were randomly divided into 5 groups, namely, a sham operation group, a model group, a tetramethylpyrazine low-dose group(25 mg·kg~(-1)), a tetramethylpyrazine medium-dose group(50 mg·kg~(-1)), and a tetramethylpyrazine high-dose group(100 mg·kg~(-1)), with 15 mice in each group. Modified Rivlin method was used to establish the mouse model of acute spinal cord injury. After 14 d of tetramethylpyrazine intervention, the motor function of hind limbs of mice was evaluated by basso mouse scale(BMS) and inclined plate test. The levels of inflammatory cytokines tumor necrosis factor-α(TNF-α), interleukin-6(IL-6), and interleukin-1β(IL-1β) in the spinal cord homogenate were determined by enzyme-linked immunosorbent assay(ELISA). Hematoxylin-eosin(HE) staining was used to observe the histology of the spinal cord, and Nissl's staining was used to observe the changes in the number of neurons. Western blot and immunofluorescence method were used to detect the expression of glial fibrillary acidic protein(GFAP) and C3 protein. Tetramethylpyrazine significantly improved the motor function of the hind limbs of mice after spinal cord injury, and the BMS score and inclined plate test score of the tetramethylpyrazine high-dose group were significantly higher than those of the model group(P<0.01). The levels of TNF-α, IL-6, and IL-1β in spinal cord homogenate of the tetramethylpyrazine high-dose group were significantly decreased(P<0.01). After tetramethylpyrazine treatment, the spinal cord morphology recovered, the number of Nissl bodies increased obviously with regular shape, and the loss of neurons decreased. As compared with the model group, the expression of GFAP and C3 protein was significantly decreased(P<0.05,P<0.01) in tetramethylpyrazine high-dose group. In conclusion, tetramethylpyrazine can promote the improvement of motor function and play a neuroprotective role in mice after spinal cord injury, and its mechanism may be related to inhibiting inflammatory response and improving the hyperplasia of glial scar.

Effects of intrathecal injection of ropivacaine on spinal cord in rats based on genomics / 中南大学学报(医学版)

OBJECTIVES@#There are clinical reports of nerve injury caused by ropivacaine. The mechanism for nerve injury induced by ropivacaine has not been fully clarified. This study aims to investigate the changes of pain threshold and L3 spinal cord genomics at 6 h and 24 h after intrathecal injection of 0.5% and 1.0% ropivacaine, and to explore the underlying mechanisms for nerve injury caused by ropivacaine.@*METHODS@#A total of 30 male Sprague Dawley rats weighing 220-260 g were successfully implanted with microspinal catheter. The rats were randomly divided into 5 groups (each n=6): a control group (given saline), a ropivacaine group 1 and a ropivacaine group 2 (both given 1% ropivacaine), a ropivacaine group 3 and a ropivacaine group 4 (both given 0.5% ropivacaine). The rats received continuous intrathecal injection of corresponding drugs at 8.3 μL/h for 24 h via an implanted intrathecal catheter followed by 24 h-pause of injection for the ropivacaine group 2, the ropivacaine group 4 and the control group, 6 h-pause of injection for the ropivacaine group 1 and the ropivacaine group 3. For each group, the observation of behavioral change and the paw withdrawal mechanical threshold (PWMT) was conducted immediately after the injection and again after the pause of injection. After the PWMT observation, the rats were dissected to acquire L3 spinal cords. Illumina sequencing was applied to construct gene libraries. Then the statistical methods were used to find out differentially expressed genes between the groups. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis were conducted for those genes. Real-time RT-PCR was used to determine different expressions of some of those genes.@*RESULTS@#Compared with control group, the PWMT got higher in the ropivacaine group 1-4 and was positively correlated with concentration, negatively correlated with discontinuation duration. Compared with control group, the ropivacaine group 1 had 488 differentially expressed genes, of which 456 were up-regulated and 32 were down-regulated; the ropivacaine group 2 had 1 194 differentially expressed genes, of which 1 092 were up-regulated and 102 were down-regulated; the ropivacaine group 3 had 518 differentially expressed genes, of which 384 were up-regulated and 134 were down-regulated; and the ropivacaine group 4 had 68 differentially expressed genes, of which 46 were up-regulated and 22 were down-regulated. GO enrichment analysis and KEGG signaling pathway analysis showed that most of these differentially expressed genes were related to signaling pathways of inflammatory response.@*CONCLUSIONS@#After intrathecal injection of 0.5% ropivacaine and 1.0% ropivacaine for 24 h, the differentially expressed genes in L3 spinal cord of rats are mainly related to signaling pathways of inflammatory response.

Research progress of Notch signaling pathway in spinal cord injury / 中国骨伤

Spinal cord injury is a severe central nervous system disease, which will cause a series of complex pathophysiological changes and activate a variety of signaling pathways including Notch signaling. Studies have evidenced that activation of the Notch signaling pathway is not conducive to nerve repair and symptom improvement after spinal cord injury. Its mechanisms include inhibiting neuronal differentiation and axon regeneration, promoting reactive astrocyte proliferation, promoting M1 macrophage polarization and the release of proinflammatory factors, and inhibiting angiogenesis. Therefore, it has become a promising therapeutic strategy to inhibit Notch signal as a target in the treatment of spinal cord injury. In recent years, some researchers have used drugs, cell transplantation or genetic modification to regulate Notch signaling, which can promote the recovery of nerve function after spinal cord injury, thereby providing new treatment strategies for the treatment of spinal cord injury. This article will summarize the mechanism of Notch signaling pathway in spinal cord injury, and at the same time review the research progress in the treatment of spinal cord injury by modulating Notch signaling pathway in recent years, so as to provide new research ideas for further exploring new strategies for spinal cord injury.

Tetrahydropalmatine alleviated diabetic neuropathic pain by inhibiting activation of microglia via p38 MAPK signaling pathway / 中国中药杂志

Neuropathic pain is one of the common complications of diabetes. Tetrahydropalmatine(THP) is a main active component of Corydalis Rhizoma with excellent anti-inflammatory and pain-alleviating properties. This study aims to investigate the therapeutic effect of THP on diabetic neuropathic pain(DNP) and the underlying mechanism. High-fat and high-sugar diet(4 weeks) and streptozotocin(STZ, 35 mg·kg~(-1), single intraperitoneal injection) were employed to induce type-2 DNP in rats. Moreover, lipopolysaccharide(LPS) was used to induce the activation of BV2 microglia in vitro to establish an inflammatory cellular model. Fasting blood glucose(FBG) was measured by a blood glucose meter. Mechanical withdrawal threshold(MWT) was assessed with von Frey filaments, and thermal withdrawal latency(TWL) with hot plate apparatus. The protein expression levels of OX42, inducible nitric oxide synthase(iNOS), CD206, p38, and p-p38 were determined by Western blot, the fluorescence expression levels of OX42 and p-p38 in the dorsal horn of the rat spinal cord by immunofluorescence, the mRNA content of p38 and OX42 in rat spinal cord tissue by qRT-PCR, and levels of nitric oxide(NO), interleukin-1β(IL-1β), interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), interleukin-10(IL-10), and serum fasting insulin(FINS) by enzyme-linked immunosorbent assay(ELISA). RESULTS:: showed that the mo-del group demonstrated significant decrease in MWT and TWL, with pain symptoms. THP significantly improved the MWT and TWL of DNP rats, inhibited the activation of microglia and p38 MAPK signaling pathway in rat spinal cord, and ameliorated its inflammatory response. Meanwhile, THP promoted the change of LPS-induced BV2 microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, suppressed the activation of the p38 MAPK signaling pathway, decreased the expression levels of inflammatory factors NO, IL-1β, IL-6, and TNF-α, and increased the expression level of anti-inflammatory factor IL-10. The findings suggested that THP can significantly ameliorate the pain symptoms of DNP rats possibly by inhibiting the inflammatory response caused by M1 polarization of microglia via the p38 MAPK pathway.

Mechanism of Chuanxiong Rhizoma intervention on central sensitization of Panx1-Src-NMDAR-2B signaling pathway in neuropathic pain model rats / 中国中药杂志

Excitatory toxicity(ET) is an important factor of neuropathic pain(NPP) induced by central sensitization(CS), and the association of pannexin-1(Panx1)-Src-N-methyl-D-aspartate receptor subunit 2 B(NMDAR-2 B) is an important new pathway for ET to initiate CS. The present study confirmed whether the central analgesic effect of Chuanxiong Rhizoma extract(CRE) was achieved through the synchronous regulation of the brain and spinal pathways of Panx1-Src-NMDAR-2 B. In this study, dynamic and simulta-neo-us microdialysis of the brain and spinal cord in vivo combined with behavioristics, high performance liquid chromatography(HPLC)-fluorescence detection, microdialysis analysis(ISCUS~(flex)), ultrasensitive multifactorial electrochemiluminescence immunoassay, ELISA, and Western blot was employed to investigate the protein expression of NMDAR-2 B, Src, and Panx1, extracellular excitatory amino acids, cytokines, energy metabolites, and substance P in spinal dorsal horn(SDH) and anterior cingulate cortex(ACC) after CRE intervention with the rat model of spared sciatic nerve injury(SNI) as the experimental tool. Compared with the sham group, the SNI group exhibited diminished mechanical withdrawal threshold(MWT)(P<0.01), increased cold spray scores(P<0.01), glutamate(Glu), D-serine(D-Ser), and glycine(Gly) in extracellular fluids of ACC, and Glu, D-Ser, interleukin-1β(IL-1β), and lactic acid(Lac) in extracellular fluids of SDH(P<0.05), dwindled tumor necrosis factor(TNF-α)(P<0.05), and elevated protein levels of NMDAR-2 B, Src, and Panx1 in ACC(P<0.05). Compared with the SNI model rats, high-and medium-dose CRE(CRE-H/M) could potentiate the analgesic activity as revealed by the MWT test(P<0.05) and CRE-M enabled the decrease in cold spray scores(P<0.05). CRE-H/M could inhibit the levels of Glu, D-Ser and Gly in the extracellular fluids of ACC(P<0.05), and the levels of Glu in the extracellular fluids of SDH(P<0.05) in SNI rats. CRE-M significantly increased the levels of glucose(Gluc), Lac, interferon-gamma(IFN-γ), keratinocyte chemoattractant/human growth-regulated oncogenes(KC/GRO), and IL-4 in extracellular fluids of SDH in SNI rats(P<0.05). CRE-H/M/L could also inhibit the levels of NMDAR-2 B, Src and Panx1 in ACC and SDH in SNI rats(P<0.05). The central analgesic effect of CRE is presumedly related to the inhibited release of excitatory amino acid transmitters(Glu, D-Ser and Gly) in ACC and SDH of SNI rats, decreased protein expression of NMDAR-2 B, Src and Panx1 in the two regions, and the regulation of the Panx1-Src-NMDAR-2 B pathway in the spinal cord and brain. The above findings partially clarified the scientific basis of clinical analgesic effect of Chuanxiong Rhizoma.

Expression of Pax6 and Pax7 proteins during the central nervous system development in human embryos / Expresión de proteínas Pax6 y Pax7 durante el desarrollo del sistema central nervioso en embriones humanos

The family of paired box (Pax) genes encodes the transcription factors that have been emphasized for the particular importance to embryonic development of the CNS, with the evidence obtained from various animal models. Human embryos have rarely been available for the detection of the expression of Pax family members. In this study 32 human embryos of Carnegie (CS) stages 10-20 were investigated to find the differences in the expression of Pax6 and Pax7 proteins in different regions of the neural tube and the caudal spinal cord. The expression of Pax6 and Pax7, as determined by immunohistochemistry, showed a tendency to increase in the later stages of the development both in the spinal cord and the brain. Significantly weaker expression of Pax6 and Pax7 was observed at CS 10 as compared to the later stages. At CS 10-12 weak expression of Pax6 was noticed in both dorsal and ventral parts of the developing spinal cord, while the expression of Pax7 was restricted to the cells in the roof plate and the dorsal part of the spinal cord. At CS 14-20 in the developing spinal cord Pax6 and Pax7 were detected mostly in the neuroepithelial cells of the ventricular layer, while only weak expression characterized the mantle and the marginal layers. At the same stages in the developing brain Pax6 and Pax7 were expressed in the different regions of the forebrain, the midbrain and the hindbrain suggesting for their involvement in the differentiation of neurons in specific parts of the developing brain.

La familia de genes Pax del inglés (Paired box) codifica los factores de transcripción debido a la particular importancia en el desarrollo embrionario del SNC, con la evidencia obtenida de varios modelos animales. Rara vez han estado disponibles embriones humanos para la detección de la expresión de genes de la familia Pax. En este estudio, se investigaron 32 embriones humanos de Carnegie (CS) etapas 10-20 para encontrar las diferencias en la expresión de las proteínas Pax6 y Pax7 en diferentes regiones del tubo neural y la médula espinal caudal. La expresión de Pax6 y Pax7, según la inmunohistoquímica, se observó una tendencia a aumentar en las etapas posteriores del desarrollo, tanto en la médula espinal como en el cerebro. Se observó una expresión significativamente más débil de Pax6 y Pax7 en CS 10 en comparación con las etapas posteriores. En CS 10-12 se notó una expresión débil de Pax6 en las partes dorsal y ventral de la médula espinal en desarrollo, mientras que la expresión de Pax7 se limitó a células en la placa del techo y dorsal de la médula espinal. En CS 14-20 en la médula espinal en desarrollo, Pax6 y Pax7 se observó principalmente en las células neuroepiteliales de la capa ventricular, mientras que expresión débil se caracterizó en las capas marginales. En las mismas etapas en el cerebro en desarrollo, Pax6 y Pax7 se expresaron en las diferentes áreas del prosencéfalo, el mesencéfalo y el mesencéfalo, lo que sugiere su participación en la diferenciación de las neuronas en partes específicas del cerebro en desarrollo.

Spinal protein kinase A and phosphorylated extracellular signal-regulated kinase signaling are involved in the antinociceptive effect of phytohormone abscisic acid in rats / A proteína quinase A da medula espinhal e a sinalização da quinase fosforilada regulada por sinal extracelular estão envolvidas no efeito antinociceptivo do ácido fito-hormônio abscísico em ratos

Abstract Objective: The phytohormone abscisic acid (ABA) as a signaling molecule exists in various types of organisms from early multicellular to animal cells and tissues. It has been demonstrated that ABA has an antinociceptive effect in rodents. The present study was designed to assess the possible role of PKA and phosphorylated ERK (p-ERK) on the antinociceptive effects of intrathecal (i.t.) ABA in male Wistar rats. Methods: The animals were cannulated intrathecally and divided into different experimental groups (n=6‒7): Control (no surgery), vehicle (received ABA vehicle), ABA-treated groups (received ABA in doses of 10 or 20 µg/rat), ABA plus H.89 (PKA inhibitor)-treated group which received the inhibitor 15 min prior to the ABA injection. Tail-flick and hot-plate tests were used as acute nociceptive stimulators to assess ABA analgesic effects. p-ERK was evaluated in the dorsal portion of the spinal cord using immunoblotting. Results: Data showed that a microinjection of ABA (10 and 20 µg/rat, i.t.) significantly increased the nociceptive threshold in tail flick and hot plate tests. The application of PKA inhibitor (H.89, 100 nM/rat) significantly inhibited ABA-induced analgesic effects. Expression of p-ERK was significantly decreased in ABA-injected animals, which were not observed in the ABA+H.89-treated group. Conclusions: Overall, i.t. administration of ABA (10 µg/rat) induced analgesia and p-ERK down-expression likely by involving the PKA-dependent mechanism.

Resumo Objetivo: O ácido fito-hormônio abscísico (ABA) existe como molécula sinalizadora em vários tipos de organismos, de multicelulares a células e tecidos animais. Foi demonstrado que o ABA tem efeito antinociceptivo em roedores. O presente estudo foi desenhado para avaliar o possível papel da PKA e da ERK fosforilada (p-ERK) nos efeitos antinociceptivos do ABA intratecal (i.t.) em ratos Wistar machos. Métodos: Os animais foram canulados por via i.t. e divididos em diferentes grupos experimentais (n=6‒7): controle (sem cirurgia), veículo (veículo ABA recebido), grupos tratados com ABA (recebeu ABA em doses de 10 ou 20 µg/rato), grupo tratado com ABA mais H.89 (inibidor de PKA) que recebeu o inibidor 15 minutos antes da injeção de ABA. Os testes de movimento da cauda e placa quente foram utilizados como estimuladores nociceptivos agudos para avaliar os efeitos analgésicos da ABA. A p-ERK foi avaliada na porção dorsal da medula espinhal por imunotransferência. Resultados: A microinjeção de ABA (10 e 20 µg/rato, i.t.) aumentou significativamente o limiar nociceptivo nos testes de movimento da cauda e placa quente. A aplicação de inibidor de PKA (H.89, 100 nM/rato) inibiu significativamente os efeitos analgésicos induzidos por ABA. A expressão de p-ERK diminuiu significativamente em animais injetados com ABA que não foram observados no grupo tratado com ABA+H.89. Conclusões: No geral, a administração i.t. de ABA (10 µg/rato) induziu a analgesia e expressão negativa de p-ERK provavelmente envolvendo mecanismo dependente de PKA.

Effects of oxidative stress on liver, brain and spinal cord of rats using L-NAME and treated with hydroxyurea. A model of sickle cell complication

Abstract Purpose: To analyze the serum levels of nitric oxide and correlate them with the levels of thiobarbituric acid reactive substances (TBARS) in liver, brain and spinal cord of animals using L-NAME and treated with hydroxyurea. Methods: Eighteen male albino Wistar rats were divided into three groups. NG-nitro-L-arginine methyl ester (L-NAME) was intraperitoneally administered to induce oxidative stress. TBARS and plasma nitric oxide levels were analyzed in all groups. Histopathology of the liver and vascular tissue was performed. Results: Statistically significant differences were seen in liver, brain and spinal cord TBARS levels. Conclusions: Following the use of L-NAME, hepatic tissue increased the number of Kupffer cells as oxidative stress and inflammatory response increased. The use of L-NAME caused an increase in lipid peroxidation products and, consequently, in oxidative stress in animals. Hydroxyurea doses of 35 mg / kg / day reduced TBARS values in liver, brain and spinal cord.

Age-related changes and effects of regular low-intensity exercise on gait, balance, and oxidative biomarkers in the spinal cord of Wistar rats

The present study aimed to analyze age-related changes to motor coordination, balance, spinal cord oxidative biomarkers in 3-, 6-, 18-, 24-, and 30-month-old rats. The effects of low-intensity exercise on these parameters were also analyzed in 6-, 18-, and 24-month-old rats. Body weight, blood glucose, total cholesterol, and high-density lipoprotein (HDL) cholesterol were assessed for all rats. The soleus muscle weight/body weight ratio was used to estimate skeletal muscle mass loss. Body weight increased until 24 months; only 30-month-old rats exhibited decreased blood glucose and increased total cholesterol and HDL cholesterol. The soleus muscle weight/body weight ratio increased until 18 months, followed by a small decrease in old rats. Exercise did not change any of these parameters. Stride length and step length increased from adult to middle age, but decreased at old age. Stride width increased while the sciatic functional index decreased in old rats. Performance in the balance beam test declined with age. While gait did not change, balance improved after exercise. Aging increased superoxide anion generation, hydrogen peroxide levels, total antioxidant capacity, and superoxide dismutase activity while total thiol decreased and lipid hydroperoxides did not change. Exercise did not significantly change this scenario. Thus, aging increased oxidative stress in the spinal cord, which may be associated with age-induced changes in gait and balance. Regular low-intensity exercise is a good alternative for improving age-induced changes in balance, while beneficial effects on gait and spinal cord oxidative biomarkers cannot be ruled out because of the small number of rats investigated (n=5 or 6/group).

Involvement of adenosine A1 receptor in electroacupuncture-mediated inhibition of astrocyte activation during neuropathic pain / Envolvimento do receptor de adenosina A1 na inibição da ativação de astrócitos mediada por eletroacupuntura durante a dor neuropática

ABSTRACT Neuropathic pain is a chronic pain condition caused by damage or dysfunction of the central or peripheral nervous system. Electroacupuncture (EA) has an antinociceptive effect on neuropathic pain, which is partially due to inhibiting astrocyte activation in the spinal cord. We found that an intrathecal injection of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist, reversed the antinociceptive effects of EA in a chronic constriction injury-induced neuropathic pain model. The expression of GFAP in L4-L6 spinal cord was significantly upgraded, while DPCPX suppressed the effect of the EA-mediating inhibition of astrocyte activation, as well as wiping out the EA-induced suppression of cytokine content (TNF-α). These results indicated that the adenosine A1 receptor is involved in EA actions during neuropathic pain through suppressing astrocyte activation as well as TNF-α upregulation of EA, giving enlightenment to the mechanisms of acupuncture analgesia and development of therapeutic targets for neuropathic pain.

RESUMO A dor neuropática é uma condição de dor crônica causada por dano ou disfunção do sistema nervoso central ou periférico. A eletroacupuntura (EA) tem um efeito antinociceptivo durante a dor neuropática, que é parcialmente devido à inibição da ativação de astrócitos na medula espinhal. Descobrimos que a injeção intratecal de 8-ciclopentil-1,3-dipropilxantina (DPCPX), um antagonista seletivo do receptor de adenosina A1, reverteu os efeitos antinociceptivos da EA no modelo de dor neuropática induzida por lesão por constrição crônica (CCI). A expressão da GFAP na medula espinal L4-L6 foi significativamente melhorada, enquanto a DPCPX suprimiu o efeito da inibição mediadora da EA na ativação de astrócitos, bem como eliminou a supressão induzida pela EA do conteúdo de citocina (TNF-α). Esses resultados indicam que o receptor de adenosina A1 está envolvido nas ações da EA durante a dor neuropática, suprimindo a ativação astrocitária, bem como o aumento da TNF-α na EA, fornecendo esclarecimentos sobre os mecanismos de analgesia da acupuntura e o desenvolvimento de alvos terapêuticos para dor neuropática.

Treatment with ascorbic acid and alpha-tocopherol modulates oxidative-stress markers in the spinal cord of rats with neuropathic pain

Vitamin E (vit. E) and vitamin C (vit. C) are antioxidants that inhibit nociception. The effect of these vitamins on oxidative-stress markers in the spinal cord of rats with chronic constriction injury (CCI) of the sciatic nerve is unknown. This study investigated the effect of intraperitoneal administration of vit. E (15 mg·kg-1·day-1) and vit. C (30 mg·kg-1·day-1), given alone or in combination, on spinal cord oxidative-stress markers in CCI rats. Adult male Wistar rats weighing 200-250 g were divided equally into the following groups: Naive (rats did not undergo surgical manipulation); Sham (rats in which all surgical procedures involved in CCI were used except the ligature), and CCI (rats in which four ligatures were tied loosely around the right common sciatic nerve), which received injections of vitamins or vehicle (saline containing 1% Tween 80) for 3 or 10 days (n=6/each group). The vitamins prevented the reduction in total thiol content and the increase in superoxide-anion generation that were found in vehicle-treated CCI rats. While nitric-oxide metabolites increased in vehicle-treated CCI rats 3 days after surgery, these metabolites did not show significant changes in vitamin-treated CCI rats. In all rats, total antioxidant capacity and hydrogen-peroxide levels did not change significantly. Lipid hydroperoxides increased 25% only in vehicle-treated CCI rats. These changes may contribute to vit. C- and vit. E-induced antinociception, because scavenging reactive oxygen species seems to help normalize the spinal cord oxidative status altered by pain.

Exogenous neuregulin-1 attenuates STZ-induced diabetic peripheral neuropathic pain in rats

Abstract Purpose: To investigate whether modulating NRG1 could attenuate diabetic neuropathic pain and analyze the underlying mechanism. Methods: Male SD rats were randomly divided into control group, diabetic group, NRG1 intervention group. After STZ-induced 2 weeks, NRG1 intervention daily for consecutive 7 days. 4 weeks after NRG1 intervention, both the mechanical withdrawal threshold and the morphological changes of the dorsal root ganglion and sural nerve were observed. Meanwhile, the expression of NGF, IL-1β, TNF-α in spinal cord were determined. Results: Compared with the diabetic group, NRG1 treatment improved the mechanical withdrawal threshold in diabetic rats, pathological changes of dorsal root ganglion and sural nerve were alleviated by NRG1 treatment with electron microscopy imagine. Moreover, compared with the control group, the expression of NGF was significantly decreased and the production of IL-1β, TNF-α were markedly induced in diabetic group. Furthermore, NRG1 treatment could normalized the above effect as compared to diabetic group. Conclusion: NRG1 exerted positive effects on the behavioral and pathological changes of rats with STZ-induced diabetic neuropathic pain, the underlying mechanism might be related to the promotion of NGF excretion and the inhibition of inflammatory cytokines excretion.

Effects of N-acetylcysteine on spinal cord oxidative stress biomarkers in rats with neuropathic pain

N-acetylcysteine (NAC) inhibits nociceptive transmission. This effect has been associated partly with its antioxidant properties. However, the effect of NAC on the levels of lipid hydroperoxides (a pro-oxidant marker), content of ascorbic acid (a key antioxidant molecule of nervous tissue) and total antioxidant capacity (TAC) is unknown. Thus, our study assessed these parameters in the lumbosacral spinal cord of rats with chronic constriction injury (CCI) of the sciatic nerve, one of the most commonly employed animal models of neuropathic pain. Thirty-six male Wistar rats weighing 200-300 g were equally divided into the following groups: Naive (rats did not undergo surgical manipulation); Sham (rats in which all surgical procedures involved in CCI were used except the ligature), and CCI (rats in which four ligatures were tied loosely around the right common sciatic nerve). All rats received intraperitoneal injections of NAC (150 mg·kg−1·day−1) or saline for 1, 3, or 7 days. Rats were killed 1, 3, and 7 days after surgery. NAC treatment prevented the CCI-induced increase in lipid hydroperoxide levels only at day 1, although the amount was higher than that found in naive rats. NAC treatment also prevented the CCI-induced increase in ascorbic acid content, which occurred at days 1, 3, and 7. No significant change was found in TAC with NAC treatment. The changes observed here may be related to the antinociceptive effect of NAC because modulation of oxidative-stress parameters seemed to help normalize the spinal cord oxidative status altered by pain.

N-acetylcysteine downregulates phosphorylated p-38 expression but does not reverse the increased superoxide anion levels in the spinal cord of rats with neuropathic pain

We determined the effect of N-acetylcysteine (NAC) on the expression of the phosphorylated p38 (p-p38) protein and superoxide anion generation (SAG), two important players in the processing of neuropathic pain, in the lumbosacral spinal cord of rats with chronic constriction injury (CCI)-induced neuropathic pain. The sciatic functional index (SFI) was also measured to assess the functional recovery post-nerve lesion. Thirty-six male Wistar rats were divided equally into the following groups: Naive (rats did not undergo surgical manipulation); Sham (rats in which all surgical procedures involved in CCI were used except the ligature), and CCI (rats in which four ligatures were tied loosely around the right common sciatic nerve), which received 2, 4, or 8 intraperitoneal injections of NAC (150 mg·kg-1·day-1) or saline beginning 4 h after CCI. Rats were sacrificed 1, 3, and 7 days after CCI. The SFI was measured on these days and the lumbosacral spinal cord was used for analysis of p-p38 expression and SAG. CCI induced a decrease in SFI as well as an increase in p-p38 expression and SAG in the spinal cord. The SFI showed a partial recovery at day 7 in saline-treated CCI rats, but recovery was improved in NAC-treated CCI rats. NAC induced a downregulation in p-p38 expression at all time-points evaluated, but did not reverse the increased SAG induced by CCI. Since p-p38 is a mediator in neuropathic pain and/or nerve regeneration, modulation of this protein may play a role in NAC-induced effects in CCI rats.

Effectiveness of hip muscle strengthening in patellofemoral pain syndrome patients: a systematic review

Introduction: Patellofemoral pain syndrome (PFPS) is characterized by anterior knee pain, which may limit the performance of functional activities. The influence of hip joint motion on the development of this syndrome has already been documented in the literature. In this regard, studies have investigated the effectiveness of hip muscle strengthening in patients with PFPS. Objectives: The aims of this systematic review were (1) to summarize the literature related to the effects of hip muscle strengthening on pain intensity, muscle strength, and function in individuals with PFPS and (2) to evaluate the methodological quality of the selected studies. Method: A search for randomized controlled clinical trials was conducted using the following databases: Google Scholar, MEDLINE, PEDro, LILACS, and SciELO. The selected studies had to distinguish the effects of hip muscle strengthening in a group of patients with PFPS, as compared to non-intervention or other kinds of intervention, and had to investigate the following outcomes: pain, muscle strength, and function. The methodological quality of the selected studies was analyzed by means of the PEDro scale. Results: Seven studies were selected. These studies demonstrated that hip muscle strengthening was effective in reducing pain. However, the studies disagreed regarding the treatments' ability to improve muscle strength. Improvement in functional capabilities after hip muscle strengthening was found in five studies. Conclusion: Hip muscle strengthening is effective in reducing the intensity of pain and improving functional capabilities in patients with PFPS, despite the lack of evidence for its ability to increase muscle strength. .

Consumption and expenditure on food prepared away from home among Mexican adults in 2006 / Consumo y gasto en alimentos preparados fuera de casa en adultos mexicanos en 2006

Objective. To describe food expenditure and consumption of foods prepared away from home among Mexican adults. Materials and methods. Data were from 45 241 adult participants in the National Health and Nutrition Survey 2006, a nationally-representative, cross-sectional survey of Mexican households. Descriptive statistics and multivariable linear and logistic regression were used to assess the relationship between location of residence, educational attainment, socioeconomic status and the following: 1) expenditure on all food and at restaurants, and 2) frequency of consumption of comida corrida or restaurant food and street food. Results. Food expenditure and consumption of food prepared away from home were positively associated with socioeconomic status, educational attainment, and urban vs. rural residence (p<0.001 for all relationships in bivariate analyses). Conclusions. Consumption of food prepared outside home may be an important part of the diet among urban Mexican adults and those with high socioeconomic status and educational attainment.

Objetivo. Describir los gastos en alimentos y el consumo de alimentos preparados fuera de casa en población mexicana. Material y métodos. Los datos fueron de 45 241 adultos mexicanos en la Encuesta Nacional de Salud y Nutrición de 2006, representativa al nivel nacional. Se utilizaron estadísticas descriptivas y regresión linear y logística para estimar la relación entre el lugar de residencia, el nivel educativo y el nivel socioeconómico, con el gasto en todos los alimentos y en restaurantes, y con la frecuencia de consumo de comida corrida, en restaurantes y de la calle. Resultados. El gasto en alimentos y el consumo de alimentos preparados se asociaron positivamente con el nivel socioeconómico, el nivel educativo y la residencia rural (p<0,001 para todas las relaciones). Conclusiones. El consumo de alimentos preparados puede ser una parte importante de la dieta de los adultos urbanos y de aquéllos con altos niveles socioeconómicos y educativos.

Effects of sciatic nerve transection on glucose uptake in the presence and absence of lactate in the frog dorsal root ganglia and spinal cord / Efeito da secção do nervo isquiático sobre a captação de glicose na presença e ausência de lactato em gânglio da raiz dorsal e medula espinhal de rãs

Frogs have been used as an alternative model to study pain mechanisms because the simplicity of their nervous tissue and the phylogenetic aspect of this question. One of these models is the sciatic nerve transection (SNT), which mimics the clinical symptoms of “phantom limb”, a condition that arises in humans after amputation or transverse spinal lesions. In mammals, the SNT increases glucose metabolism in the central nervous system, and the lactate generated appears to serve as an energy source for nerve cells. An answerable question is whether there is elevated glucose uptake in the dorsal root ganglia (DRG) after peripheral axotomy. As glucose is the major energy substrate for frog nervous tissue, and these animals accumulate lactic acid under some conditions, bullfrogs Lithobates catesbeianus were used to demonstrate the effect of SNT on DRG and spinal cord 1-[14C] 2-deoxy-D-glucose (14C-2-DG) uptake in the presence and absence of lactate. We also investigated the effect of this condition on the formation of 14CO2 from 14C-glucose and 14C-L-lactate, and plasmatic glucose and lactate levels. The 3-O-[14C] methyl-D-glucose (14C-3-OMG) uptake was used to demonstrate the steady-state tissue/medium glucose distribution ratio under these conditions. Three days after SNT, 14C-2-DG uptake increased, but 14C-3-OMG uptake remained steady. The increase in 14C-2-DG uptake was lower when lactate was added to the incubation medium. No change was found in glucose and lactate oxidation after SNT, but lactate and glucose levels in the blood were reduced. Thus, our results showed that SNT increased the glucose metabolism in the frog DRG and spinal cord. The effect of lactate on this uptake suggests that glucose is used in glycolytic pathways after SNT.

As rãs são usadas como modelos experimentais alternativos no estudo da nocicepção, tanto pela simplicidade do seu tecido nervoso como por permitirem uma abordagem filogenética sobre o tema. Um desses modelos é a secção do nervo isquiático (SNI), o qual simula os sintomas clínicos do “membro fantasma”, uma condição que ocorre nos humanos após amputação ou secção completa da medula espinal. Em mamíferos, a SNI aumenta o metabolismo da glicose no sistema nervoso central, e o lactato é uma fonte energética para as células nervosas. Porém é desconhecido se essa é a situação em gânglio da raiz dorsal (GRD). Como a glicose é o principal substrato energético para o tecido nervoso de rãs, e a concentração plasmática de lactato está aumentada nesses animais em distintas situações, a rã-touro Lithobates catesbeianus foi usada para demonstrar os efeitos da SNI sobre a captação de 1-[14C] 2-deoxi-D-glicose (14C-2-DG), na presença e ausência de lactato, em GRD e medula espinal. Foram demonstrados ainda os efeitos dessa condição experimental sobre a formação de 14CO2 a partir de 14C-glicose e 14C-L-lactato, e a concentração plasmática de glicose e lactato. A captação de 3-O-[14C] metil-D-glicose (14C-3-OMG) foi usada para demonstrar a relação tecido/meio estável da glicose nessas condições. A captação de 14C-2-DG aumentou três dias após a SNI, sem qualquer alteração na captação de 14C-3-OMG. O aumento foi reduzido quando o lactato foi acrescentado ao meio de incubação. A taxa de oxidação da glicose e do lactato não modificou após SNI, mas houve redução na concentração plasmática de glicose e lactato. Assim, a SNI aumenta o metabolismo da glicose no GRD e medula espinal de rãs. Os efeitos do lactato sobre essa captação sugerem o uso da glicose na via glicolítica após a SNI.