次声作用后大鼠延髓星形胶质细胞和神经元反应的关系

目的 研究8Hz,90dB和130dB次声作用后不同时间点,大鼠延髓中星形胶质细胞和神经元的反应及其相互关系。方法 8Hz,90dB和130db次声作用于大鼠,2h/d,分别作用1、7、14、21、28天后采用免疫组织化学双标记方法,观察大鼠延髓中胶质源纤维酸性蛋白（GFAP）和Fos蛋白表达的情况。结果 8Hz,130dB次声作用1d后大鼠延髓中开始出现GFAP阳性星形胶质细胞和Fos阳性神经元,分布相同,关系密切,并随作用次数增加而增多,14天后逐渐减少。90dB组大鼠各时间点GFAP反应均比130dB组弱。结论 8Hz,90dB和130dB次声作用可以同时激活延髓星形胶质细胞和神经元。     

Effect of bucladesine,pentoxifylline, and H‐89 as cyclic adenosine monophosphate analog,phosphodiesterase, and protein kinase A inhibitor on acute pain

The aim of this study was to determine the effects of cyclic adenosine monophosphate (cAMP) and its dependent pathway on thermal nociception in a mouse model of acute pain. Here, we studied the effect of H‐89 (protein kinase A inhibitor), bucladesine (Db‐cAMP) (membrane‐permeable analog of cAMP), and pentoxifylline (PTX; nonspecific phosphodiesterase (PDE) inhibitor) on pain sensation. Different doses of H‐89 (0.05, 0.1, and 0.5 mg/100 g), PTX (5, 10, and 20 mg/100 g), and Db‐cAMP (50, 100, and 300 nm /mouse) were administered intraperitoneally (I.p.) 15 min before a tail‐flick test. In combination groups, we injected the first and the second compounds 30 and 15 min before the tail‐flick test, respectively. I.p. administration of H‐89 and PTX significantly decreased the thermal‐induced pain sensation in their low applied doses. Db‐cAMP, however, decreased the pain sensation in a dose‐dependent manner. The highest applied dose of H‐89 (0.5 mg/100 g) attenuated the antinociceptive effect of Db‐cAMP in doses of 50 and 100 nm /mouse. Surprisingly, Db‐cAMP decreased the antinociceptive effect of the lowest dose of H‐89 (0.05 mg/100 g). All applied doses of PTX reduced the effect of 0.05 mg/100 g H‐89 on pain sensation; however, the highest dose of H‐89 compromised the antinociceptive effect of 20 mg/100 g dose of PTX. Co‐administration of Db‐cAMP and PTX increased the antinociceptive effect of each compound on thermal‐induced pain. In conclusion, PTX, H‐89, and Db‐cAMP affect the thermal‐induced pain by probably interacting with intracellular cAMP and cGMP signaling pathways and cyclic nucleotide‐dependent protein kinases.     

Structure-affinity relationships of adenosine A2B receptor ligands

Many selective and high affinity agonists and antagonists have been developed for the adenosine A(1), A(2A), and A(3) receptors. Very recently such compounds have been identified for the adenosine A(2B) receptors. This review presents an overview of the structure-affinity relationships of antagonists and agonists for this receptor subtype as published in the scientific and patent literature. To date the most selective >370-fold, high affinity adenosine A(2B) receptor antagonist is the xanthine analog, compound 16 (8-(1-(3-phenyl-1,2,4-oxadiazol-5-yl)methyl)-1H-pyrazol-4-yl)-1,3-dipropyl-1H-purine-2,6(3H,7H)-dione). The pyrrolopyrimidine analog OSIP339391 (73) is slightly less selective, 70-fold, but has a higher affinity 0.41 nM compared to 1 nM for compound 16. Other promising classes of compounds with selectivities ranging from 10- to 160-fold and affinities ranging from 3 to 112 nM include triazolo, aminothiazole, quinazoline, and pyrimidin-2-amine analogs. Progress has also been achieved concerning the development of selective high affinity agonists for the adenosine A(2B) receptor. For years the most potent, albeit non-selective adenosine A(2B) receptor agonist was (S)PHPNECA (88). Last year, a new class of non-ribose ligands was reported. Several compounds displayed selectivity with respect to adenosine A(2A) and A(3) receptors. In addition, full and partial agonists for the adenosine A(2B) receptor were identified with EC(50) values of 10 nM (LUF5835, 103) and 9 nM (LUF5845, 105), respectively.     

抑制脊髓损伤后星形胶质细胞增殖和胶质瘢痕形成的研究进展

对星形胶质细胞（AS）的性质和功能、脊髓损伤后的AS病理变化和作用、抑制AS增殖和胶质瘢痕形成的实验方法等方面进行综述。认为,AS激活后的不同分化时期对脊髓损伤修复具有一定的积极作用;但成熟以后,AS可以分泌有害因子,形成化学性胶质屏障,严重影响神经再生和阻碍轴突延长。脊髓损伤后AS被激活,静止态、活化态和增殖态往往并存,形成原因复杂,目前采取单一的方法很难有效控制AS增殖和胶质瘢痕形成。     

Mirror-image pain is mediated by nerve growth factor produced from tumor necrosis factor alpha-activated satellite glia after peripheral nerve injury

Mirror-image pain is characterized by mechanical hypersensitivity on the uninjured mirror-image side. Recent reports favor central mechanisms, but whether peripheral mechanisms are involved remains unclear. We used unilateral spinal nerve ligation (SNL) to induce mirror-image pain in rats. On the mirror-image (contralateral) side, we found that satellite glia in the dorsal root ganglion (DRG) were activated, whereas macrophages/Schwann cells in the DRG and astrocytes/oligodendrocytes/microglia in the dorsal spinal cord were not. Subsequently, an increase in nerve growth factor (NGF) was detected in the contralateral DRG, and NGF immunoreactivity was concentrated in activated satellite glia. These phenomena were abolished if fluorocitrate (a glial inhibitor) was intrathecally injected before SNL. Electrophysiological recordings in cultured small DRG neurons showed that exogenous NGF enhanced nociceptor excitability. Intrathecal injection of NGF into naive rats induced long-lasting mechanical hypersensitivity, similar to SNL-evoked mirror-image pain. Anti-NGF effectively relieved SNL-evoked mirror-image pain. In the contralateral DRG, the SNL-evoked tumor necrosis factor alpha (TNF-α) increase, which started later than in the ipsilateral DRG and cerebrospinal fluid, occurred earlier than satellite glial activation and the NGF increase. Intrathecal injection of TNF-α into naive rats not only activated satellite glia to produce extra NGF in the DRG but also evoked mechanical hypersensitivity, which could be attenuated by anti-NGF injection. These results suggest that after SNL, satellite glia in the contralateral DRG are activated by TNF-α that diffuses from the injured side via cerebrospinal fluid, which then activates satellite glia to produce extra NGF to enhance nociceptor excitability, which induces mirror-image pain.     

经皮电刺激对大鼠脊髓损伤后神经胶质酸性蛋白和神经生长因子表达的影响

目的:探讨经皮电刺激(TES)对大鼠脊髓损伤(SCI)后神经胶质酸性蛋白(GFAP)和神经生长因子(NGF)表达的影响。方法:选用成年雄性SD大鼠72只,随机分为3组:正常组(A组)、TES组(B组)和模型组(C组)。A组8只,B、C组各32只。用Allen法,复制T9脊髓不完全损伤动物模型。B组损伤后给予损伤部位上2cm位置的皮肤及右下肢小腿位置的皮肤TES治疗7d。BBB评分后,运用免疫组织化学染色和蛋白质印迹来检测GFAP、NGF的表达变化。结果:BBB评分显示,B组与C组相比,评分增加幅度大(P<0.05),SCI各组BBB评分均明显小于A组(P<0.05)。免疫组化和Western印迹检测结果显示在实验观察的7d中,B组与C组相比,GFAP的表达减少,在第5天达到最低值(P<0.05);NGF的表达一直在增加(P<0.05)。结论:在SCI后1—7d内,TES能抑制GFAP的表达,促进内源性NGF的合成,可能创造有利于神经再生的微环境,减少胶质瘢痕的形成。     

Sigma-1 receptors regulate activity-induced spinal sensitization and neuropathic pain after peripheral nerve injury

Sigma-1 receptor (σ₁R) is expressed in key CNS areas involved in nociceptive processing but only limited information is available about its functional role. In the present study we investigated the relevance of σ₁R in modulating nerve injury-evoked pain. For this purpose, wild-type mice and mice lacking the σ₁R gene were exposed to partial sciatic nerve ligation and neuropathic pain-related behaviors were investigated. To explore underlying mechanisms, spinal processing of repetitive nociceptive stimulation and expression of extracellular signal-regulated kinase (ERK) were also investigated. Sensitivity to noxious heat of homozygous σ₁R knockout mice did not differ from wild-type mice. Baseline values obtained in σ₁R knockout mice before nerve injury in the plantar, cold-plate and von Frey tests were also indistinguishable from those obtained in wild-type mice. However, cold and mechanical allodynia did not develop in σ₁R null mice exposed to partial sciatic nerve injury. Using isolated spinal cords we found that mice lacking σ₁R showed reduced wind-up responses respect to wild-type mice, as evidenced by a reduced number of action potentials induced by trains of C-fiber intensity stimuli. In addition, in contrast to wild-type mice, σ₁R knockout mice did not show increased phosphorylation of ERK in the spinal cord after sciatic nerve injury. Both wind-up and ERK activation have been related to mechanisms of spinal cord sensitization. Our findings identify σ₁R as a constituent of the mechanisms modulating activity-induced sensitization in pain pathways and point to σ₁R as a new potential target for drugs designed to alleviate neuropathic pain.     

Peripherally acting mu-opioid receptor agonist attenuates neuropathic pain in rats after L5 spinal nerve injury

Studies in experimental models and controlled patient trials indicate that opioids are effective in managing neuropathic pain. However, side effects secondary to their central nervous system actions present barriers to their clinical use. Therefore, we examined whether activation of the peripheral mu-opioid receptors (MORs) could effectively alleviate neuropathic pain in rats after L5 spinal nerve ligation (SNL). Systemic loperamide hydrochloride (0.3–10 mg/kg, s.c.), a peripherally acting MOR-preferring agonist, dose-dependently reversed the mechanical allodynia at day 7 post-SNL. This anti-allodynic effect produced by systemic loperamide (1.5 mg/kg, s.c.) was blocked by systemic pretreatment with either naloxone hydrochloride (10 mg/kg, i.p.) or methyl-naltrexone (5 mg/kg, i.p.), a peripherally acting MOR-preferring antagonist. It was also blocked by ipsilateral intraplantar pretreatment with methyl-naltrexone (43.5 μg/50 μl) and the highly selective MOR antagonist CTAP (5.5 μg/50 μl). However, this anti-allodynic effect of systemic loperamide was not blocked by intraplantar pretreatment with the delta-opioid receptor antagonist naltrindole hydrochloride (45.1 μg/50 μl). The anti-allodynic potency of systemic loperamide varied with time after nerve injury, with similar potency at days 7, 28, and 42 post-SNL, but reduced potency at day 14 post-SNL. Ipsilateral intraplantar injection of loperamide also dose-dependently (10–100 μg/50 μl) reversed mechanical allodynia on day 7 post-SNL. We suggest that loperamide can effectively attenuate neuropathic pain, primarily through activation of peripheral MORs in local tissue. Therefore, peripherally acting MOR agonists may represent a promising therapeutic approach for alleviating neuropathic pain.     

A shed form of LDL receptor-related protein-1 regulates peripheral nerve injury and neuropathic pain in rodents

Injury to the peripheral nervous system (PNS) initiates a response controlled by multiple extracellular mediators, many of which contribute to the development of neuropathic pain. Schwann cells in an injured nerve demonstrate increased expression of LDL receptor-related protein-1 (LRP1), an endocytic receptor for diverse ligands and a cell survival factor. Here we report that a fragment of LRP1, in which a soluble or shed form of LRP1 with an intact alpha-chain (sLRP-alpha), was shed by Schwann cells in vitro and in the PNS after injury. Injection of purified sLRP-alpha into mouse sciatic nerves prior to chronic constriction injury (CCI) inhibited p38 MAPK activation (P-p38) and decreased expression of TNF-alpha and IL-1beta locally. sLRP-alpha also inhibited CCI-induced spontaneous neuropathic pain and decreased inflammatory cytokine expression in the spinal dorsal horn, where neuropathic pain processing occurs. In cultures of Schwann cells, astrocytes, and microglia, sLRP-alpha inhibited TNF-alpha-induced activation of p38 MAPK and ERK/MAPK. The activity of sLRP-alpha did not involve TNF-alpha binding, but rather glial cell preconditioning, so that the subsequent response to TNF-alpha was inhibited. Our results show that sLRP-alpha is biologically active and may attenuate neuropathic pain. In the PNS, the function of LRP1 may reflect the integrated activities of the membrane-anchored and shed forms of LRP1.     

Altered spinal arachidonic acid turnover after peripheral nerve injury regulates regional glutamate concentration and neuropathic pain behaviors in rats

Spinal glutamate transporters (GT) have been implicated in the mechanisms of neuropathic pain; however, how spinal GT uptake activity is regulated remains unclear. Here we show that alteration of spinal arachidonic acid (AA) turnover after peripheral nerve injury regulated regional GT uptake activity and glutamate homeostasis. Chronic constriction nerve injury (CCI) in rats significantly reduced spinal GT uptake activity ((3)H-glutamate uptake) with an associated increase in extracellular AA and glutamate concentration from spinal microdialysates on postoperative day 8. AACOCF3 (a cytosolic phospholipase A2 inhibitor, 30mug) given intrathecally twice a day for postoperative day 1-7 reversed this CCI-induced spinal AA production, prevented the reduced spinal GT uptake activity and increased extracellular glutamate concentration. Conversely, alteration of spinal AA metabolism by diclofenac (a cyclooxygenase 1/2 inhibitor, 200mug) further reduced spinal GT uptake activity and increased extracellular glutamate concentration in CCI rats. GT uptake activity was also attenuated when AA (10 or 100nM) was directly added into spinal samples of na?ve rats in an in vitro(3)H-glutamate uptake assay, indicating a direct inhibitory effect of AA on GT uptake activity. Consistent with these findings, AACOCF3 reduced the development of both thermal hyperalgesia and mechanical allodynia, whereas diclofenac exacerbated thermal hyperalgesia, in CCI rats. Thus, spinal AA turnover may serve as a regulator in CCI-induced changes in regional GT uptake activity, glutamate homeostasis, and neuropathic pain behaviors. These data suggest that regulating spinal AA turnover may be a useful approach to improving the clinical management of neuropathic pain.     

Blocking the A2B adenosine receptor alleviates myocardial damage by inhibiting spleen-derived MDSC mobilisation after acute myocardial infarction

BackgroundMyeloid-derived suppressor cell (MDSC) mobilisation is an important immune event in acute myocardial infarction (AMI). The A_2B adenosine receptor (A_2BAR) plays key role in regulating MDSC function, but its specific involvement in MDSC mobilisation in AMI remains unclear.MethodsIn AMI patients, the circulating MDSC ratio and A_2BAR mRNA expression were measured. A mouse AMI model was established by left anterior descending coronary artery (LADCA) ligation. MDSCs were analysed by FACS and immunofluorescence staining (of heart tissue). A_2BAR mRNA expression was assessed by qRT-PCR. Myocardial injury was detected by HE staining. Myocardial cell apoptosis was analysed by immunohistochemistry. Cardiac systolic function was evaluated by transthoracic echocardiography.ResultsIn AMI patients, the circulating MDSC ratio was increased and positively correlated with A_2BAR mRNA expression (r = 0.86, p < 0.01). In AMI model mice, the percentage of MDSCs was increased in the circulation and infarcted heart and decreased in the spleen. MRS-1754-mediated A_2BAR inhibition decreased the MDSC ratio in the circulation and infarcted heart and prevented the decrease in MDSC number in the spleens of mice with AMI. A_2BAR blockade inhibited myocardial cell apoptosis, alleviated myocardial inflammatory injury, and improved myocardial systolic function in the AMI mouse model. Similar results were found in mice after splenectomy. Additionally, spleen-derived MDSC injection increased the MDSC ratio in the infarcted heart, increased myocardial cell apoptosis, aggravated myocardial injury, and decreased cardiac systolic function in mice with AMI.ConclusionBlocking A_2BAR alleviates myocardial damage and improves myocardial systolic function through inhibition of spleen-derived MDSC mobilisation after AMI.

Key Messages

• Spleen-derived MDSC mobilisation aggravates myocardial inflammatory injury within 24 h of AMI.
• A_2BAR promotes spleen-derived MDSC mobilisation within 24 h of AMI.
• Blocking A_2BAR improves myocardial systolic function through inhibition of spleen-derived MDSC mobilisation.

     

Past, present and future of A(2A) adenosine receptor antagonists in the therapy of Parkinson's disease

Several selective antagonists for adenosine A_2A receptors (A_2AR) are currently under evaluation in clinical trials (phases I to III) to treat Parkinson's disease, and they will probably soon reach the market. The usefulness of these antagonists has been deduced from studies demonstrating functional interactions between dopamine D₂ and adenosine A_2A receptors in the basal ganglia. At present it is believed that A_2AR antagonists can be used in combination with the dopamine precursor L-DOPA to minimize the motor symptoms of Parkinson's patients. However, a considerable body of data indicates that in addition to ameliorating motor symptoms, adenosine A_2AR antagonists may also prevent neurodegeneration. Despite these promising indications, one further issue must be considered in order to develop fully optimized antiparkinsonian drug therapy, namely the existence of (hetero)dimers/oligomers of G protein-coupled receptors, a topic that is currently the focus of intense debate within the scientific community. Dopamine D₂ receptors (D₂Rs) expressed in the striatum are known to form heteromers with A_2A adenosine receptors. Thus, the development of heteromer-specific A_2A receptor antagonists represents a promising strategy for the identification of more selective and safer drugs.     

胶质纤维酸性蛋白及生长相关蛋白-43在低声压次声治疗颅脑外伤大鼠过程中的变化

目的:探讨低声压级次声对大鼠颅脑外伤后胶质纤维蛋白(GFAP)及生长相关蛋白-43(GAP-43)表达的影响。方法:采用Feeney法制作颅脑外伤模型。将30只SD大鼠随机分为假手术组、模型组、次声60min组、次声90min组和次声120min组共5组,其中次声3组分别予次声干预60min、90min和120min,连续7天;模型组干预过程中除不开机外,其余过程同次声组。假手术组只打开颅窗,不损伤脑组织,不进行次声干预。7天后处死前行改良神经功能缺损评分(m NSS),然后断头取脑、免疫组化观察损伤脑组织周围GFAP及GAP-43表达变化。结果:次声3组与模型组的m NSS评分均存在显著差异(P0.05),次声3组间的m NSS评分无显著差异(P0.05)。免疫组化结果:15组间的GFAP表达存在显著性差异(P0.05),3个次声组与模型组比较均存在显著差异(P0.05),3个次声组间GFAP表达无明显差异(P0.05);25组间的GAP-43表达存在显著性差异(P0.05),3个次声组与模型组比较均存在显著差异(P0.05),3个次声组间GAP-43表达无明显差异(P0.05)。结论:低声压级次声能提高大鼠脑外伤后脑组织GFAP及GAP-43的表达,改善脑外伤大鼠神经功能。     

Somatosensory function in patients with and without pain after traumatic peripheral nerve injury

Why traumatic injuries to the peripheral nervous system infrequently result in neuropathic pain is still unknown. The aim of this study was to examine the somatosensory system in patients with traumatic peripheral nerve injury with and without pain to try to unravel possible links to mechanisms underlying development and maintenance of pain. Eighteen patients with spontaneous ongoing pain and 16 patients without pain after unilateral partial peripheral traumatic nerve injury were studied. In the area of partial denervation and in the corresponding contralateral area perception thresholds to warmth, cold, light touch, pressure pain, cold‐ and heat pain were assessed as were pain intensities at suprathreshold heat pain stimulation. Comparing sides patients with pain reported allodynia to cold (p = 0.03) and pressure (p = 0.016) in conjunction with an increase in the perception threshold to non‐painful warmth (p = 0.024) on the injured side. Pain‐free patients reported hypoesthesia to light touch (p = 0.002), cold (p = 0.039) and warmth (p = 0.001) on the injured side. There were no side differences in stimulus–response functions using painful heat stimuli in any of the groups. In addition, no significant difference could be demonstrated in any sensory modality comparing side‐to‐side differences between the two groups. In conclusion, increased pain sensitivity to cold and pressure was found on the injured side in pain patients, pointing to hyperexcitability in the pain system, a finding not verified by a more challenging analysis of side‐to‐side differences between patients with and without pain.     

烧伤后慢性应激对大鼠海马微管相关蛋白-2和胶质纤维酸性蛋白表达的影响

目的:探讨烧伤后慢性应激大鼠海马神经元微管相关蛋白-2（MAP-2）和神经胶质细胞胶质纤维酸性蛋白（GFAP）表达的变化。方法：采用30%深Ⅱ度烫伤、孤养及慢性中度不定期应激联合建立烧伤后并发抑郁模型,采用旷场实验观察烧伤后并发抑郁大鼠行为反应,电镜和免疫组化观察不同区域海马MAP-2和GFAP的表达及神经元和神经胶质细胞超微结构的变化。结果：烧伤后并发抑郁大鼠活动潜伏期明显延长,行为反应明显降低（P<0.01）。烧伤后并发抑郁、烧伤、抑郁及正常组之间MAP-2和GFAP在CA1区变化不明显;烧伤后并发抑郁大鼠在CA3区MAP-2和GFAP阳性细胞计数和累积光密度(89.58±15.18,69162.63±7905.36;57.33±6.50,37918.42±2060.98)明显低于正常组(108.80±18.45,84607.07±13602.34;90.50±5.98,55616.67±3776.54;P＜0.05）;在齿状回烧伤并发抑郁大鼠MAP-2和GFAP阳性细胞计数和累积光密度(261.00±35.37,32199.93±1344.15;73.42±7.32,68465.21±15571.64)与正常组相比(293.00±24.47,40299.77±1155.97;113．10±6.72,108416.10±5128.89)也明显降低(P＜0.05）。电镜可见烧伤并发抑郁组神经元和神经胶质细胞胞浆肿胀,有的线粒体髓鞘样改变,线粒体肿胀、空泡化,内质网扩张等改变。结论：海马神经元和神经胶质细胞结构改变可能是烧伤后抑郁发生的重要病理生理基础。     

Activation of glia and microglial p38 MAPK in medullary dorsal horn contributes to tactile hypersensitivity following trigeminal sensory nerve injury

Glial activation is known to contribute to pain hypersensitivity following spinal sensory nerve injury. In this study, we investigated mechanisms by which glial cell activation in medullary dorsal horn (MDH) would contribute to tactile hypersensitivity following inferior alveolar nerve and mental nerve transection (IAMNT). Activation of microglia and astrocytes was monitored at 2 h, 1, 3, 7, 14, 28, and 60 days using immunohistochemical analysis with OX-42 and GFAP antibodies, respectively. Tactile hypersensitivity was significantly increased at 1 day, and this lasted for 28 days after IAMNT. Microglial activation, primarily observed in the superficial laminae of MDH, was initiated at 1 day, maximal at 3 days, and maintained until 14 days after IAMNT. Astrocytic activation was delayed compared to that of microglia, being more profound at 7 and 14 days than at 3 days after IAMNT. Both tactile hypersensitivity and glial activation appeared to gradually reduce and then return to the basal level by 60 days after IAMNT. There was no significant loss of trigeminal ganglion neurons by 28 days following IAMNT, suggesting that degenerative changes in central terminals of primary afferents might not contribute to glial activation. Minocycline, an inhibitor of microglial activation, reduced microglial activation, inhibited p38 mitogen-activated protein kinase (MAPK) activation in microglia, and significantly attenuated the development of pain hypersensitivity in this model. These results suggest that glial activation in MDH plays an important role in the development of neuropathic pain and activation of p38 MAPK in hyperactive microglia contributes to pain hypersensitivity in IAMNT model.     

腺苷受体A1与A2A相互作用对小鼠大脑中动脉缺血/再灌注损伤区谷氨酸转运体GLT-1表达的影响

目的 探讨在不同A1受体活性状态下,腺苷A2A受体缺失对脑缺血/再灌注区GLT-1D的影响,并探讨其产生的缺血性脑保护的可能机制.方法 将腺苷A2A受体基因敲除小鼠(A2A R/KO)与野生型小鼠(A2AR/WR)制作成大脑中动脉缺血2 h/再灌注22 h模型,分别给予腺苷A1受体激动剂CPA及拮抗剂DPCPX,采用免疫组化、Western - blot方法检测缺血/再灌注区(纹状体区)谷氨酸转运体(GLT -1)的表达情况,同时观察对脑梗死体积和神经功能缺损程度的影响.结果 缺血2h/再灌注22 h后,KO小鼠的神经功能缺损程度均明显轻于同样干预的WT小鼠(P＜0.05),使用A1受体拮抗剂后,小鼠的神经缺损程度较非干预组明显加重,而使用A1受体激动剂后神经功能缺损程度较非干预组明显减轻;KO小鼠的梗死体积均明显小于同样干顶的WT小鼠(P＜0.01),A2AR - KO/A1拮抗剂组小鼠梗死体积较非干预小鼠明显增大,而A2AR - KO/A1激动剂组小鼠的梗死体积则明显缩小.在缺血/再灌注区,A1R激动剂CPA使小鼠的GLT -1表达明显高于非干预组,其中A2AR/KO小鼠的增加更为明显;而使用A1R拮抗剂DPCPX后,局部GLT -1的表达与非干预组相比无明显差异.结论 初步证明A2AR缺失产生的神经保护作用与A1受体功能激活,进而促进缺血/再灌注区GLT-1的表达增加有关.抑制A2AR,同时激活A1R能加强缺血性脑保护作用.     

Upregulation and redistribution of ephrinB and EphB receptor in dorsal root ganglion and spinal dorsal horn neurons after peripheral nerve injury and dorsal rhizotomy

EphrinB–EphB receptor signaling plays diverse roles during development, but recently has been implicated in synaptic plasticity in the matured nervous system and in pain processes. The present study investigated the correlation between expression of ephrinB and EphB receptor proteins and chronic constriction injury (CCI) of the sciatic nerve and dorsal rhizotomy (DR) in dorsal root ganglion (DRG) and spinal cord (SC); and interaction of CCI and DR on expression of these signals. Adult, male Sprague–Dawley rats were employed and thermal sensitivity was determined in the sham operated CCI and DR rats. Western blot and immunobiochemistry analysis and immunofluorescence staining techniques were used to detect the expression and location of the ephrinB–EphB receptor proteins in DRG and SC. The results showed that expression of ephrinB1 and EphB1 receptor proteins was significantly upregulated in DRG and SC in a time‐dependent manner corresponding to the development of thermal hyperalgesia after CCI. The increased expression is predominately located in the medium‐ and small‐sized DRG neurons, the superficial layers of spinal dorsal horn (DH) neurons, and the IB4 positive nociceptive terminals. DR increases ephrinB1 in DRG, not SC and EphB receptor in SC, not DRG. DR suppressed CCI‐induced upregulation of ephrinB1 in SC and EphB1 receptor in DRG and SC. These findings indicate that ephrinB–EphB receptor activation and redistribution in DRG and DH neurons after nerve injury could contribute to neuropathic pain. This study may also provide a new mechanism underlying DR‐induced analgesia in clinic.