Extracellular signal‐regulated kinase (ERK) is involved in LPS‐induced disturbances in intestinal motility

Background Lipopolysaccharide (LPS) is a causative agent of sepsis. A relationship has been described between LPS, free radicals, and cyclooxygenase‐2 (COX‐2). Here, we investigate the role of extracellular signal‐regulated kinase (ERK) mitogen‐activated protein kinases (MAPK) in the effect of LPS on intestinal motility, oxidative stress status, and COX‐2 expression. Methods Rabbits were injected with (i) saline, (ii) LPS, (iii) U0126, an ERK MAPK inhibitor, or (iv) U0126+LPS. Duodenal contractility was studied in an organ bath with acetylcholine, prostaglandin E₂, and KCl added. Neuromuscular function was assessed by electrical field stimulation (EFS). Neurotransmitter blockers were used to study the EFS‐elicited contractile response. The formation of products of oxidative damage to proteins (carbonyls), lipids, [malondialdehyde (MDA), and 4‐hydroxyalkenals (4‐HDA)] was quantified in plasma and intestine. The protein expression of phospho‐ERK (p‐ERK), total ERK, and COX‐2 in the intestine was measured by western blot, and p‐ERK was localized by immunohistochemistry. Key Results Acetylcholine, prostaglandin E₂, and KCl‐induced contractions decreased with LPS. Electrical field stimulation induced a neurogenic contraction that was reduced by LPS. Lipopolysaccharide increased p‐ERK and COX‐2 expression and the levels of carbonyls and MDA+4‐HDA. U0126 blocked the effect of LPS on acetylcholine, prostaglandin E₂, KCl, and EFS‐induced contractions, the levels of carbonyls and MDA+4‐HDA and p‐ERK and COX‐2 expression. Phospho‐ERK was detected mostly in the neurons of the myenteric and submucosal ganglia. Conclusions & Inferences We can suggest that ERK is involved in the mechanism of action of LPS in the intestine.     

The effects of prenatal stress on expression of p38 MAPK in offspring hippocampus

The hippocampus, which has the highest density of GC receptors in the brain, is involved in the regulation of the HPA and the behavioral responses to stress. Overexposure to corticosteroid hormones is harmful to hippocampal neuron integrity. Our purpose is to investigate the effects of prenatal stress (PNS) on expression of p38 mitogen-activated protein kinase (p38 MAPK) in offspring hippocampal neurons using Western blotting and Immunohistochemistry. The prenatal restraint stress induces significant increase in the expression of p-p38 MAPK and total p38 MAPK in female offspring hippocampus. The level of p-p38 MAPK in PNS female offspring rats was significantly increased (126.41+/-3.937, n=6) compared with that in the control female offspring rats (101.35+/-3.468, n=6, P<0.01). Immunoblot analysis revealed there was significant difference in the level of total p38 MAPK between the female control and prenatal restraint stress offspring rats (101.70+/-3.162 vs. 128.111+/-2.724, respectively, P<0.01). Immunodensity of p38 MAPK was significantly increased above female control in PNS female offspring hippocampal CA3 and CA4 fields (P<0.001 vs. control group, CON). The data suggest that exposure of animals to a period of stressful experience during a critical phase could impose lasting effects on the offspring hippocampal neurons cellular signalling of offspring hippocampus.     

p38MAPK activation and DUSP10 expression in meningiomas

The mitogen activated protein kinase (MAPK) p38MAPK has been implicated in regulation of cell proliferation and apoptosis. However, expression, activation and regulation has not been studied in meningiomas, to our knowledge. p38MAPK is regulated, in part, by dual specificity phosphatases (DUSP) that inactivate signaling by dephosphorylation. DUSP10 is also a likely participant in regulating meningioma proliferation. Five fetal and an adult human leptomeninges and 37 meningioma cultures (MC) were evaluated for DUSP10 as well as phosphorylation of its substrates p38MAPK and p44/42MAPK by western blot and DUSP10 expression by polymerase chain reaction. Platelet derived growth factor-BB (PDGF-BB), transforming growth factor B1 (TGFB1) and cerebrospinal fluid effects on DUSP10 and signaling were also studied in vitro. DUSP10 and phospho-p38MAPK and phospho-p44/42MAPK were detected in all six leptomeninges. DUSP10 was detected in 13 of 17 World Health Organization grade I, 11 of 14 grade II and four of six grade III meningiomas. Phospho-p38MAPK was detected in nine of 17 grade I, two of six grade II, and four of six grade III meningiomas. In the majority of meningiomas DUSP10 expression correlated inversely with phosphorylation of p38MAPK. PDGF-BB increased DUSP10 in MC2 and MC4 and weakly in MC3. TGFB1 increased phosphorylation of p38MAPK and caspase 3 activation. Thus p38MAPK and DUSP10 likely participate in the pathogenesis of meningiomas.     

转染热休克蛋白70对p38MAPK信号通路的影响

目的：探讨热休克蛋白（HSP70）在人胶质瘤细胞BT-325p38MAPK信号通路中的作用。方法：用脂质体介导法将hsp70基因导入人胶质瘤细胞BT-325中，倒置显微镜观察转染细胞的形态学及粘附性变化，紫外线照射30min后，采用免疫组化和Western-blot方法测定转染前后HSP70的表达水平及照射前后p38MAPK表达情况。结果：免疫组化和Western-blot证实hsp70基因成功转染入BT-325中，转染细胞受到紫外线照射后p38MAPK表达减弱。结论：体外转染hsp70基因可抑制紫外线照射后BT-325细胞p38MAPK的表达。     

实验性大鼠尾壳核脑出血后p38MAPK、ICAM-1的动态表达

目的探讨脑出血后血肿周围组织p38丝裂原活化蛋白激酶(p38M APK)和细胞间粘附分子-1(I-CAM-1)的动态变化。方法健康雄性W istar大鼠42只,将动物随机分成假手术组和脑出血组,采用免疫组织化学方法观察术后不同时间点p38M APK和ICAM-1的动态变化。结果脑出血组各时间点血肿周围组织均有不同程度磷酸化p38M APK阳性细胞表达,脑出血后3h周围组织即有表达,于6h出现广泛性表达,24h时达最高峰,持续至5d仍有表达。ICAM-1的表达在48h达高峰,随后渐下降。结论脑出血后脑组织损伤诱导p38M APK和ICAM-1的表达,二者可能参与了脑出血后脑组织损伤的病理机制。     

p38MAPK对耐苯妥英钠和卡马西平癫痫模型大鼠电生理和行为的影响

目的 观察p38丝裂原活化蛋白激酶(p38 mitogen-activated protein kinase,p38MAPK)信号通路抑制剂SB202190对耐苯妥英钠和卡马西平大鼠电生理指标和行为学的影响.方法 建立慢性杏仁核点燃癫痫模型,筛选出耐药大鼠,通过侧脑室注射SB202190,对照组注射生理盐水.观察其对各组大鼠后放电阈值(after discharge threshold,ADT)和行为学的影响.结果 相对于对照组,耐药组大鼠在给予SB202190后,ADT明显高于对照组(P＜0.05);Racine行为分级明显下降(P＜0.05).结论 阻断p38MAPK信号通路可以协助AEDs改善耐药大鼠的电生理活动,降低点燃后发作分级,提示p38MAPK信号通路参与了难治性癫痫的耐药.     

p38MAPK基因对胶质瘤细胞C6生长周期的影响

目的 研究p38MAPK基因对大鼠胶质瘤细胞C6生长周期的影响。方法 利用脂质体将p38MAPK基因导入C6细胞中，用免疫细胞化学染色检测其在转染前后的表达，用HE染色、流式细胞仪、TUNEL等研究其对细胞形态、粘着状况和生长周期的影响。结果 pCMV5-p38MAPK组P38MAPK蛋白表达阳性，细胞形态发生变化，贴壁性降低，G1期百分比增加，而S期和G2期百分比减低，并出现凋亡峰。结论 p38MAPK基因可影响C6细胞的生长周期，并诱导C6细胞凋亡。     

Inhibition of p38 MAP kinase activity enhances axonal regeneration

Tumor necrosis factor alpha (TNF)-induced cellular signaling through the p38 mitogen-activated protein kinase (p38 MAPK) pathway plays a critical role in Wallerian degeneration and subsequent regeneration, processes that depend on Schwann cell (SC) activity. TNF dose-dependently induces Schwann cell and macrophage activation in vivo and apoptosis in primary SC cultures in vitro, while inhibition of p38 MAPK is thought to block these cellular processes. We show with Western blots that after sciatic nerve crush injury, phosphorylated p38 (p-p38) MAPK is significantly increased (P < 0.01) in distal nerve segments. In tissue sections, p38 co-localized immunohistochemically with activated Schwann cells (GFAP) and to a lesser degree with macrophages (ED-1). In other experiments, animals were gavaged with Scios SD-169 (10 or 30 mg/kg) or excipient (PEG300) 1 day before and daily after crush injury to the sciatic nerve. SD-169 is a proprietary oral inhibitor of p38 MAPK activity. The rate of axonal regeneration was determined by the functional pinch test and was significantly increased in treated animals 8 days after crush injury (P < 0.05; 30 mg/kg dose). In SD-169-treated animals with nerve transection, nerve fibers regenerating through a silicone chamber were morphologically more mature than untreated nerves when observed 28 days after transection. TNF immunofluorescence of distal nerve segments after crush injury suggested that SD-169 reduced SC TNF protein. In support of these findings, SD-169 significantly reduced (P < 0.05) TNF-mediated primary SC death in culture experiments. We conclude that inhibition of p38 activity promotes axonal regeneration through interactions with SC signaling and TNF activity.     

Activation of p38 MAPK participates in brain ischemic tolerance induced by limb ischemic preconditioning by up-regulating HSP 70

This study investigates whether activation of p38 MAPK by the up-regulation of HSP 70 participates in the induction of brain ischemic tolerance by limb ischemic preconditioning (LIP). Western blot and immunohistochemical assays indicated that p38 MAPK activation occurred earlier than HSP 70 induction in the CA1 region of the hippocampus after LIP. P-p38 MAPK expression was up-regulated at 6 h and reached its peak 12 h after LIP, while HSP 70 expression was not significantly increased until 1 day and peaked 2 days after LIP. Neuropathological evaluation by thionin staining showed that quercetin (4 ml/kg, 50 mg/kg, intraperitoneal injection), an inhibitor of HSP 70, blocked the protective effect of LIP against delayed neuronal death that is normally induced by lethal brain ischemic insult, indicating that HSP 70 participates in the induction of brain ischemic tolerance by LIP. Furthermore, SB 203580, an inhibitor of HSP 70, inhibited HSP 70 activation in the CA1 region of the hippocampus induced by LIP either with or without the presence of subsequent brain ischemic insult. Based on the above results, it can be concluded that activation of p38 MAPK participates in the brain ischemic tolerance induced by LIP at least partly by the up-regulation of HSP 70 expression.     

NOS、p38MAPK、Caspase-3介导大鼠脑缺血神经细胞凋亡可能通路的实验研究

目的探讨脑缺血后细胞凋亡发生的可能机制以及神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)、诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)、p38丝裂原活化蛋白激酶(mitogen activated proteinkinasep38,p38MAPK)和半光氨酸蛋白酶-3(caspase-3)在脑缺血后神经细胞凋亡中的共同作用机制。方法采用线栓法闭塞大鼠大脑中动脉(middle cerebral artery occlusion,MACO)建立脑缺血SD大鼠模型,应用透射电镜观察脑缺血对脑组织超微结构的影响,流式细胞仪方法(FCM)分别定量检测细胞凋亡率,半定量RT-PCR检测nNOS、iNOS,p38MAPK和Caspase-3mRNA表达水平。结果透视电镜下脑缺血6h出现核固缩,缺血12h出现细胞核分裂,缺血24h出现凋亡小体;FCM检测细胞凋亡百分率随着缺血时间延长而增加,缺血72h达到高峰,约70.37%;RT-PCR产物的琼脂糖凝胶电泳显示nNOS、iNOS、p38MAPK和Caspase-3mRNA的特异性片段大小分别为501、342、250和342bp,但mRNA表达量不一致,nNOS mRNA主要在缺血早期表达,iNOS、p38MAPK和Caspase-3mRNA在缺血中晚期表达,并在缺血3~5d,后三种基因的表达量达到高峰。结论脑缺血区域发生典型的神经细胞凋亡现象,nNOS来源的NOS在缺血早期发挥神经毒性作用,iNOS来源的NOS在缺血晚期发挥神经毒性作用;NOS,p38MAPK和Caspase-3三种基因的相互关系可能构成介导缺血神经细胞凋亡的通路之一。     

Administration of the p38 MAPK inhibitor SB203580 affords brain protection with a wide therapeutic window against focal ischemic insult

We have reported previously the delayed and differential induction of p38alpha and p38beta mitogen-activated protein kinases (MAPKs) in microglia and astrocytes, respectively, in brain after transient global ischemia. We report here the sustained induction and activation of p38alpha MAPK in activating microglia in rat brain after transient middle cerebral artery occlusion (MCAO). The intraventricular administration of SB203580, a p38 MAPK inhibitor, 30 min before MCAO reduced the infarct volume to 50% of the control, which was accompanied by the significant improvement of neurological deficits. More interestingly, the infarct volume was reduced to 72% and 77% when SB203580 was administered 6 hr and 12 hr after MCAO, respectively. The induction of various factors involved in inflammatory processes, such as inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and cyclooxygenase-2 (COX-2), was suppressed by the administration of SB203580 at 6 hr after MCAO. These results suggest that sustained activation of p38 MAPK pathway and p38 MAPK-associated inflammatory processes play a crucial role in postischemic brain.     

Role of p38 MAPK and pro-inflammatory cytokines expression in glutamate-induced neuronal death of neonatal rats

Pro-inflammatory cytokines TNF-, IL-1β and IL-6 rises significantly during neuronal damage and activate the signaling p38 MAPK pathway, which is involved in the apoptotic (AP) neuronal death. Systemic administration of glutamate as monosodium salt (MSG) to newborn animals induces neuronal death, however whether neurons die by AP or necrosis through MAPK p38 pathway activation it is unknown. In this study, TNF-, IL-1β and IL-6 expression levels, AP neuronal death and cellular type that produces TNF- was also identified in the cerebral cortex (CC) and striatum (St) of rats at 8, 10, and 14 days of age after neonatal exposure to MSG. TNF- production and AP neuronal death was significantly increased in the CC at PD8–10, and in the St in all ages studied by excitotoxicity effect induced with MSG. This effect was completely inhibited by SB203580 (p38 inhibitor) in both regions studied. TNF-, IL-1β and IL-6 RNAm increased after MSG administration, whereas SB203580 did not modify their expression. These data indicates that neuronal death induced by excitotoxicity appears to be mediated through p38 signaling pathway activated by TNF- and their inhibition may have an important neuroprotective role as part of anti-inflammatory therapeutic strategy.     

Dynamic expression of p38beta MAPK in neurons and astrocytes after transient focal ischemia

Here we report the dynamically regulated expression of p38beta MAPK isoform in specific subsets of cells in postischemic brain. The activity of p38beta MAPK in the postischemic brain revealed biphasic induction at 30 min and 4 days after 1 h MCAO. During the early surge period, p38beta MAPK was preferentially localized in the nucleus and dendrites of neurons in the future infarction area, while during the delayed surge p38beta MAPK was heavily induced in reactive astrocytes in penumbra. The temporally and spatially regulated pattern of p38beta MAPK expression in the postischemic brain suggests distinct roles of p38beta MAPK in neuronal death and in the astrocyte activation.     

Ginkgolide B inhibits platelet release by blocking Syk and p38 MAPK phosphorylation in thrombin-stimulated platelets

Introduction

Atherosclerosis is a chronic vascular inflammatory disease. Platelets play a critic role in the initiation of vascular inflammation in atherosclerosis. In the present study, we investigated the effects of ginkgolide B on the inhibition of platelet release and the potential mechanisms.

Methods

Experiments were performed in freshly human platelets. Platelet aggregation and ATP release were measured with a Lumi-aggregometer. Thrombin (0.5 U/ml) was used to induce platelet activation. Protein expression and phosphorylation was examined by Western blotting.

Results

The results showed that ginkgolide B significantly suppressed ATP release by 50.8% in thrombin-activated platelets. Ginkgolide B completely abolished the expression of platelet factor 4 (PF4) and CD40 Ligand (CD40L). Moreover, ginkgolide B fully attenuated the phosphorylation of Syk and p38MAPK. Similarly, R788 (a syk inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited the expression PF4 and CD40L, respectively. Furthermore, the combination of low concentrations of ginkgolide B and R788 or SB203580 has synergistic inhibition on the expression of PF4 and CD40L. Ginkgolide B partially reduced calcium efflux by 52.7% in thrombin-stimulated platelets.

Conclusion

Ginkgolide B potently inhibited the expression of PF4 and CD40L in thrombin-activated platelets. Ginkgolide B partially decreased ATP release and Ca^2 + efflux. The mechanism might be associated with the inhibition of Syk and p38 MAPK phosphorylation. These results demonstrated that ginkgolide B might be a promising drug on inhibiting platelet function and reducing inflammation in atherosclerosis.     

p38MAPK对MMPs介导的EAN模型动物免疫损伤调控的研究进展

急性炎症性脱髓鞘性多发性神经根神经炎即吉兰-巴雷综合征(GBS)是以周围神经和脊神经根,脱髓鞘和小血管周围淋巴细胞及巨噬细胞的炎性反应为病理特点的自身免疫性疾病,通常也会累及脑神经,主要临床表现为四肢对称性弛缓性瘫痪.     

L-DOPA-induced activation of striatal p38MAPK and CREB in neonatal dopaminergic denervated rat: relevance to self-injurious behavior

The destruction of nigrostriatal dopaminergic neurons with 6-hydroxydopamine (6OHDA) during the neonatal period results in dopamine (DA) loss and susceptibility for self-injurious behavior (SIB) when challenged with L-dihydroxyphenylalanine (L-DOPA), via a supersensitive D1 receptor-mediated mechanism. However, there are no changes in D1 receptor binding or mRNA levels, suggesting a potential postreceptor signaling mechanism(s). Here, we examined whether L-DOPA-induced SIB is associated with altered MAPK signaling (p38MAPK, ERK1/2, and JNK) and their nuclear target, CREB. Neonatal dopaminergic lesioned animals were challenged, as adults, with L-DOPA, observed for SIB for 6 hr, and then sacrificed. The data were grouped as follows: control, lesioned rats without SIB (SIB(-)), and lesioned rats that were positive for SIB (SIB(+)). HPLC analysis of striatal extracts revealed a more significant loss of DA and an increase of serotonin in the SIB(+) than in the SIB(-) group. The striatal levels of TH protein were severely decreased, but D1 receptor levels were unaltered in the lesioned groups. These results confirm and extend previous studies indicating that SIB is associated with a near-total loss of DA and TH, an increase in serotonin, and no change in D1 receptor levels. The present studies further revealed that the levels of active phosphorylated forms of p38MAPK and CREB were significantly higher in the SIB(+) group than in the SIB(-) group in the striatum, but not in cortex or olfactory tubercle. The results indicate an induction of striatal p38MAPK and an activation of its nuclear target, CREB, as additional mechanisms in the genesis of L-DOPA-induced SIB.     

Forced retraction of spinal root injury enhances activation of p38 MAPK cascade in infiltrating macrophages

Root‐rupture injury is a type of preganglionic brachial plexus injury resulting from traction force, where a small section of the spinal root is usually left behind. We have established experimental models of both root‐rupture injury with traction force and rhizotomy without traction force in rats and we examined the activation of microglia/macrophages in both conditions. LGP107 and LGP96, which are rat homologs of lysosome‐associated membrane proteins, were most useful as immunohistochemical markers of mononuclear phagocytes. The metabolic activation of macrophages was analyzed by immunohistochemistry with a series of antibodies against tumor necrosis factor‐alpha (TNF‐alpha), cathepsin B, p38 mitogen‐activated protein kinase (MAPK), and mitogen‐activated kinase kinase 3 (MKK3). Both root‐rupture injury and rhizotomy rapidly induced the aggregation of numerous macrophages from the injured dorsal root to the dorsal funiculus and TNF‐alpha was highly expressed by the macrophages in the injured dorsal root at 48 h. Activation of p38 MAPK was preferentially observed in the macrophages at the ruptured dorsal root; however, only slight activation of p38 MAPK was observed at the rhizotomized dorsal root. These findings suggest that traction injury of the spinal root might induce activation of the p38 MAPK cascade and production of TNF‐alpha in the infiltrating macrophages, both of which might participate in aggravation of the root injury.     

Paeonol alleviates neuropathic pain by modulating microglial M1 and M2 polarization via the RhoA/p38MAPK signaling pathway

Background

This study aimed to investigate the potential mechanism of paeonol in the treatment of neuropathic pain.

Methods

Relevant mechanisms were explored through microglial pseudotime analysis and the use of specific inhibitors in cell experiments. In animal experiments, 32 SD rats were randomly divided into the sham operation group, the chronic constrictive injury (CCI) group, the ibuprofen group, and the paeonol group. We performed behavioral testing, ELISA, PCR, Western blotting, immunohistochemistry, and immunofluorescence analysis.

Results

The pseudotime analysis of microglia found that RhoA, Rock1, and p38MAPK were highly expressed in activated microglia, and the expression patterns of these genes were consistent with the expression trends of the M1 markers CD32 and CD86. Paeonol decreased the levels of M1 markers (IL1β, iNOS, CD32, IL6) and increased the levels of M2 markers (IL10, CD206, ARG-1) in LPS-induced microglia. The expression of iNOS, IL1β, RhoA, and Rock1 was significantly increased in LPS-treated microglia, while paeonol decreased the expression of these proteins. Thermal hyperalgesia occurred after CCI surgery, and paeonol provided relief. In addition, paeonol decreased the levels of IL1β and IL8 and increased the levels of IL4 and TGF-β in the serum of CCI rats. Paeonol decreased expression levels of M1 markers and increased expression levels of M2 markers in the spinal cord. Paeonol decreased IBA-1, IL1β, RhoA, RhoA-GTP, COX2, Rock1, and p-p38MAPK levels in the spinal dorsal horn.

Conclusion

Paeonol relieves neuropathic pain by modulating microglial M1 and M2 phenotypes through the RhoA/p38 MAPK pathway.