The effect of rFVIIa on pro- and anti-inflammatory cytokines in serum and cerebrospinal fluid in a swine model of traumatic brain injury

Traumatic brain injury (TBI) is associated with significant infectious and inflammatory complications. Though increasing evidence suggests that rFVIIa administration may be efficacious for the pre-hospital treatment of TBI, the FVIIa-tissue factor complex has been shown to be immunologically active. To date the cytokine response to rFVIIa administration for the treatment of TBI has not been evaluated. Twenty anesthetized immature Yorkshire swine underwent fluid percussion TBI. At 15 min following injury, animals were randomized to receive either 90 μg/kg rFVIIa (rFVIIa) or nothing. Animals were observed for 6 h and then euthanized. Plasma and cerebrospinal (CSF) samples were collected at 0 min and 360 min, and ELISA analysis of TNF-α, IL-1β and IL-10 was performed. Survival in both groups was 100%. Baseline cytokine concentrations were not statistically different between rFVIIa and control animals in plasma or CSF. Animals in both groups did not have significant changes in plasma cytokine concentrations following TBI. Control animals did not demonstrate significant changes from baseline of CSF cytokine concentrations following TBI. The administration of rFVIIa however, resulted in significant increases in CSF TNF-α concentration (232.0 pg/ml ± 75.9 vs 36.4 pg/ml ± 10.4, p = 0.036) and IL-10 concentration (10.7 pg/ml ± 0.6 vs 8.8 pg/ml ± 0.1, p = 0.015). IL-1β concentrations were not significantly changed over the experimental time course. These results suggest that rFVIIa administration for the treatment of TBI is not immunologically inert, and is associated with increased CSF concentrations of TNF-α and IL-10.     

(S)-Carboxy-3-Hydroxyphenylglycine, an Antagonist of Metabotropic Glutamate Receptor (mGluR)1a and an Agonist of mGluR2, Protects Against Audiogenic Seizures in DBA/2 Mice

Abstract: The in vivo anticonvulsant effects and in vitro metabo-tropic glutamate receptor selectivity of ( S )-4-carboxy-3-hydroxy-phenylglycine [(S)-4C3HPG] were examined. Intracerebroventricular injection of (S)-4C3HPG dose-dependently antagonized audiogenic-induced clonic and tonic convulsions in DBA/2 mice with ED₆₀ values of 76 and 110-nmol per mouse, respectively. (S)-4C3HPG dose-dependently inhibited the spontaneously evoked epileptic spikes in a cingulate cortex-corpus callosum slice preparation. (SJ-4C3HPG displaced the binding of [³H]glutamate in membranes prepared from baby hamster kidney (BHK) cells expressing the metabotropic glutamate receptor mGluR1a with an EC₅₀ of 5 β 1 u M. ( S )-4C3HPG dose-dependently antagonized glutamate-stimulated phosphoinositide hydrolysis in BHK cells expressing mGluR 1a with an IC₅₀ of 15 β 3 μ M. ( S )-4C3HPG was, however, an agonist at mGluR2 with an EC₆₀ of 21 β 4 μ M for inhibition of forskolin-stimulated cyclic AMP formation in BHK cells expressing the mGluR2. ( S )-4C3HPG had no effects at mGluR4a. These data suggest that the anticonvulsant action of ( S )-4C3HPG is mediated by combined antagonism of mGluRIa and agonism of mGluR2. These results suggest the importance of mGluR1a and/or mGluR2 in the control of epileptic activity.     

Differential modulation of carbachol and trans-ACPD-stimulated phosphoinositide turnover following traumatic brain injury

In the fluid percussion model of traumatic brain injury (TBI), we examined muscarinic and metabotropic glutamate receptor-stimulated polyphosphoinositide (PPI) turnover in rat hippocampus. Moderate injury was obtained by displacement and deformation of the brain within the closed cranial cavity using a fluid percussion device. Carbachol and (±)-1-Aminocyclopentane-trans-1,3.-dicarboxylic acid (trans-ACPD)-stimulated PPI hydrolysis was assayed in hippocampus from injured and sham-injured controls at both 1 hour and 15 days following injury. At 1 hour after TBI, the response to carbachol was enhanced in injured rats by up to 200% but the response to trans-ACPD was diminished by as much as 28%. By contrast, at 15 days after TBI, the response to carbachol was enhanced by 25% and the response to trans-ACPD was enhanced by 73%. The ionotropic glutamate agonists N-methyl-D-aspartate (NMDA), and -amino-3 hydroxy-5-methyl-4-isoxazolepropionate (AMPA), did not increase PPI hydrolysis in either sham or injured rats and injury did not alter basal hydrolysis. Thus, hippocampal muscarinic and metabotropic receptors linked to phospholipase C are differentially altered by TBI.Abbreviations used TBI traumatic brain injury - EAA excitatory amino acids - PPI polyphosphoinositides - IP inositol phosphates - NMDA N-methyl-D-aspartate - AMPA -amino-3-hydroxy-5-methylisoxazole-4-propionate - trans-ACPD (±)-1-Aminocyclopentanetrans-1,3-dicarboxylic acid - LTP long term potentiation     

Propofol Administration Modulates AQP-4 Expression and Brain Edema After Traumatic Brain Injury

The increased intracranial pressure caused by brain edema following traumatic brain injury (TBI) always leads to poor patient prognosis. Aquaporin-4 (AQP-4) plays an important role in edema formation and resolution, which may provide a novel therapeutic target for edema treatment. In this present study, we found that propofol treatment, within a short time, after TBI significantly reduced brain edema in a controlled cortical injury rat model and suppressed in vivo expression of AQP-4. The ameliorating effect of propofol was associated with attenuated expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). In addition, the regulatory effect of propofol on AQP-4 expression was investigated in cultured astrocytes. Results showed that propofol could block the stimulatory effect of IL-1β and TNF-α on AQP-4 expression in cultured astrocytes. We also found that both NFκB and p38/MAPK pathways were involved in IL-1β and TNF-α-induced AQP-4 expression and that propofol functions as a dual inhibitor of NFκB and p38/MAPK pathways. In conclusion, treatment with propofol, within a short time, after TBI attenuates cerebral edema and reduces the expression of AQP-4. Propofol modulates acute AQP-4 expression by attenuating IL-1β and TNF-α expression and inhibiting IL-1β and TNF-α induced AQP-4 expression.     

NAAG peptidase inhibitor increases dialysate NAAG and reduces glutamate, aspartate and GABA levels in the dorsal hippocampus following fluid percussion injury in the rat

Traumatic brain injury (TBI) produces a rapid and excessive elevation in extracellular glutamate that induces excitotoxic brain cell death. The peptide neurotransmitter N-acetylaspartylglutamate (NAAG) is reported to suppress neurotransmitter release through selective activation of presynaptic group II metabotropic glutamate receptors. Therefore, strategies to elevate levels of NAAG following brain injury could reduce excessive glutamate release associated with TBI. We hypothesized that the NAAG peptidase inhibitor, ZJ-43 would elevate extracellular NAAG levels and reduce extracellular levels of amino acid neurotransmitters following TBI by a group II metabotropic glutamate receptor (mGluR)-mediated mechanism. Dialysate levels of NAAG, glutamate, aspartate and GABA from the dorsal hippocampus were elevated after TBI as measured by in vivo microdialysis. Dialysate levels of NAAG were higher and remained elevated in the ZJ-43 treated group (50 mg/kg, i.p.) compared with control. ZJ-43 treatment also reduced the rise of dialysate glutamate, aspartate, and GABA levels. Co-administration of the group II mGluR antagonist, LY341495 (1 mg/kg, i.p.) partially blocked the effects of ZJ-43 on dialysate glutamate and GABA, suggesting that NAAG effects are mediated through mGluR activation. The results are consistent with the hypothesis that inhibition of NAAG peptidase may reduce excitotoxic events associated with TBI.     

Carnitine Inhibits Hydrolysis of Inositol Phospholipids Induced by Activation of Metabotropic Receptors

We previously found that carnitine prevents glutamate neurotoxicity and that this effect is mediated by activation of metabotropic glutamate receptors. We show now that carnitine inhibits the hydrolysis of inositol phospholipids induced by different agonists of metabotropic glutamate receptors (tACPD; (±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid; DHPG, (R,S)-3,5-dyhydroxyphenylglycine or S4C3HPG, (S)-4-carboxy-3-hydroxyphenylglycine). The EC₅₀ was ca. 170 M and the inhibition was complete at 1 mM carnitine. Carnitine also inhibits completely hydrolysis of inositol phospholipids induced by arterenol (agonist of adrenoceptors) and only partially (ca. 50%) that induced by carbachol (agonist of muscarinic receptors). Carnitine did not inhibit phospholipase C activity but inhibits partially (43%) the hydrolysis of inositol phospholipids induced by direct activation of G proteins with AIP-₄. The results reported indicate that carnitine inhibits the hydrolysis of inositol phospholipids induced by activation of metabotropic receptors likely by interfering the function of some types of G proteins.     

PM2.5鼻腔滴注致小鼠海马组织损伤的炎性机制

目的: 探讨鼻腔滴注不同浓度的PM_2.5对小鼠海马组织损伤的炎性机制。方法: 30只C57BL/6J小鼠随机分为3组(n=10):对照组、低剂量组、高剂量组。采用鼻腔滴注方法进行染毒,每次染毒前测量体重,低剂量组和高剂量组PM_2.5染毒剂量分别为1.5 mg/kg BW和7.5 mg/kg BW,对照组给予等体积的生理盐水,隔天染毒一次,共12次。用ELISA法测定血清中肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)和白介素-6(IL-6)水平。HE染色和电镜观察肺和海马组织的病理变化及超微结构。用抗体芯片技术测定海马组织炎性细胞因子水平。结果: PM_2.5鼻腔滴注染毒对小鼠血清中TNF-α、IL-1β和IL-6水平无显著影响(P＞0.05),肺组织结构也无明显病理改变。而在海马组织中,低剂量和高剂量PM_2.5暴露均能导致海马CA3区神经元排列紊乱,并存在神经元细胞周围突触数量减少,小血管周围水肿等超微结构变化。利用抗体芯片检测海马组织炎性细胞因子表达变化,结果显示,与对照组比较,低剂量组海马组织中CX3CL1、CSF2和TECK等炎性细胞因子水平显著升高(P＜0.05),而MIG和sTNFR1显著降低(P＜0.05);高剂量组中炎性因子CX3CL1、CSF2和TCA-3等显著升高(P＜0.05),而Leptin、MIG和FASLG等显著降低(P＜0.05)。结论: PM_2.5鼻腔滴注可诱导小鼠海马组织结构损伤,其作用途径可能为嗅脑通路,引起海马损伤的炎性机制可能与TNF-α和IL-6等促炎因子的显著升高和sTNFR1 、FASLG等炎性疾病标志物的显著降低有关。     

Elevated Cerebral Cortical CD24 Levels in Patients and Mice with Traumatic Brain Injury: A Potential Negative Role in Nuclear Factor Kappa B/Inflammatory Factor Pathway

Increasing evidence indicates that sterile inflammatory response contributes to secondary brain injury following traumatic brain injury (TBI). However, the specific mechanisms remain largely unknown, as is whether CD24, known as an important regulator in the non-infectious inflammatory response, plays a role in secondary brain injury after TBI. Here, the expression of CD24 was detected in samples from patients with TBI by quantitative real-time polymerase chain reaction (PCR), western blotting, immunohistochemistry and immunofluorescence. RNA interference was used to investigate the effects of CD24 on inflammatory response in a mouse model of TBI. Nuclear factor kappa B (NF-κB) DNA-binding activity was measured by electrophoretic mobility shift assay, and the levels of downstream pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and Interleukin 1β (IL-1β) were detected by real-time PCR. The results indicated that both the mRNA and protein levels of CD24 were markedly elevated after TBI in humans and mice, showing a time-dependent expression. The expression of CD24 could be observed in neurons, astrocytes and microglia in both humans and mice. Meanwhile, downregulation of CD24 significantly induced an increase of NF-κB DNA-binding activity and mRNA levels of TNF-α and IL-1β. These findings indicated that CD24 expression could negatively regulate the NF-κB/inflammatory factor pathway after experimental TBI in mice, thus providing a novel target for therapeutic intervention of TBI.     

The role of metabotropic glutamate receptor (mGluR) ligands in parkinsonian muscle rigidity

Summary. It has been shown that the primary striatal dopaminergic hypofunction which is at the origin of Parkinson's disease, results in a secondary hyperactivity of glutamatergic neurotransmission. In the search for a therapy of Parkinson's disease, ionotropic, mainly NMDA, receptor antagonists were found to have moderately beneficial, yet also some undesirable side-effects. Therefore the present study was aimed at determining whether some metabotropic glutamate receptor (mGluR) ligands may have antiparkinsonian effects in the haloperidol-induced muscle rigidity. To this end three mGluR ligands were used: the potent and selective mGluR I antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA), the mixed group II agonist/group I antagonist (S)-4-carboxy-3-hydroxyphenyl-glycine ((S)-4-C3HPG), and the potent group II agonist (+)-2-aminobicyclo[3.1.0.]hexane-2,6,-dicarboxylic acid (LY354740). Only LY354740 penetrated the brain from the periphery; for this reason other drugs were injected bilaterally into the rostral striatum or nucleus accumbens. The muscle tone was recorded by a mechanomyographic/electromyographic (MMG/EMG) method which measured the resistance of a rat's hind foot and the EMG reflex response of its muscles to passive movements. (S)-4C3HPG (5 and 15 μg/0.5 μl) and LY354740 (5 and 10 mg/kg i.p.) diminished the muscle rigidity induced by haloperidol (1 mg/kg i.p.). AIDA (0.5–15 μg/0.5 μl) injected into the striatum was only slightly effective in the highest dose used. However, when injected into the nucleus accumbens AIDA (15 μg/0.5 μl) significantly and strongly counteracted the haloperidol-induced muscle rigidity. Our results suggest that stimulation of group II striatal mGluRs seems to play a major role in diminution of parkinsonian-like muscle rigidity. However, it seems that the antagonism of group I mGluRs located in the nucleus accumbens may also be of importance to the antiparkinsonian effect. Received August 31, 1999 Accepted September 3, 1999     

腺苷A2A受体在小鼠颅脑创伤与外周组织损伤模型中的作用差异

本文旨在探索腺苷A2A受体在颅脑创伤、皮肤创伤及放射损伤复合创伤中的作用差异.分别观察和检测野生型小鼠、A2A受体基因敲除小鼠以及给予A2A受体激动剂CGS21680治疗的小鼠在皮肤创伤、放射损伤复合创伤后的伤口愈合时间以及颅脑创伤后的神经功能缺损情况、伤侧皮层脑含水量、脑脊液中谷氨酸浓度.结果表明,CGS21680促进外周组织伤口愈合,却加重颅脑创伤模型的神经功能损害,这与其促进谷氨酸释放有关.相反,A2A受体基因敲除显著延迟小鼠皮肤创伤及放射损伤复合创伤模型的伤口愈合,而在颅脑创伤模型中通过抑制谷氨酸释放产生保护效应.本研究初步证实,A2A受体激活促进谷氨酸大量释放可能是其在中枢损伤与外周损伤产生作用差异的机理之一,这为将来临床应用A2A受体激动剂减轻外周损伤,而用A2A受体拈抗剂减轻颅脑损伤提供了一定的实验依据.     

Effect of honey on mRNA expression of TNF-α, IL-1β and IL-6 following acute toxoplasmosis in mice

This study analyzed the mRNA expression of tumor necrosis factor (TNF-α), interleukin 1 beta (IL-1β) and interleukin 6 (IL-6) in mice experimentally infected with T. gondii undergoing honey treatment. Thirty male mice were divided in groups: pre-treatment/infected (1), infected/non-treated (2), infected/treated (3), non-infected/treated (4) and control (5). Honey was applied for groups 1, 3, 4 by gavage and the mice in group 1–3 were infected by T. gondii tissue cysts. The parasite load and the level of mRNA expression of the aforementioned cytokines in the brains of mice were assessed by qPCR. The mean number of T. gondii tachyzoite in 1 mg brain tissue was 32, 73 and 59 in groups one, two and three, respectively. The mRNA expression of TNF-α increased in group 1, 2 and 3, about 49.1%, 307.3% and 63.2%, respectively but it was down-regulated by 53% in group 4. The mRNA expression of IL-1β and IL-6 was also up-regulated in all groups except group 2. The mRNA level of TNF-α was reduced by 2.7-fold and 1.18-fold in pre-treated/infected (group 1) and infected/treated (group 3) compared with infected/non-treated (group 2). The mRNA level of IL-1β and IL-6 were increased in these groups. The current study demonstrated that honey can stimulate or suppress the mRNA expression of some pro-inflammatory cytokines in mice brains. Furthermore, honey suppresses the TNF-α mRNA expression in the presence of T. gondii infection but it stimulates the IL-1β and IL-6 mRNA expression. Treatment of the mice with honey reduces parasite multiplication in the brain.     

Ghrelin attenuates brain injury after traumatic brain injury and uncontrolled hemorrhagic shock in rats

Traumatic brain injury (TBI) and hemorrhagic shock often occur concomitantly due to multiple injuries. Gastrointestinal dysfunction occurs frequently in patients with TBI. However, whether alterations in the gastrointestinal system are involved in modulating neuronal damage and recovery after TBI is largely neglected. Ghrelin is a "gut-brain" hormone with multiple functions including antiinflammation and antiapoptosis. The purpose of this study was to determine whether ghrelin attenuates brain injury in a rat model of TBI and uncontrolled hemorrhage (UH). To study this, brain injury was induced by dropping a 450-g weight from 1.5 m onto a steel helmet attached to the skull of male adult rats. Immediately after TBI, a midline laparotomy was performed and both lumbar veins were isolated and severed at the junction with the vena cava. At 45 min after TBI/UH, ghrelin (4, 8 or 16 nmol/rat) or 1 mL normal saline (vehicle) was intravenously administered. Brain levels of TNF-α and IL-6, and cleaved PARP-1 levels in the cortex were measured at 4 h after TBI/UH. Beam balance test, forelimb placing test and hindlimb placing test were used to assess sensorimotor and reflex function. In additional groups of animals, ghrelin (16 nmol/rat) or vehicle was subcutaneously (s.c.) administered daily for 10 d after TBI/UH. The animals were monitored for 28 d to record body weight changes, neurological severity scale and survival. Our results showed that ghrelin downregulated brain levels of TNF-α and IL-6, reduced cortical levels of cleaved PARP-1, improved sensorimotor and reflex functions, and decreased mortality after TBI/UH. Thus, ghrelin has a great potential to be further developed as an effective resuscitation approach for the trauma victims with brain injury and severe blood loss.     

Dimethyl fumarate treatment after traumatic brain injury prevents depletion of antioxidative brain glutathione and confers neuroprotection

Dimethyl fumarate (DMF) is an immunomodulatory compound to treat multiple sclerosis and psoriasis with neuroprotective potential. Its mechanism of action involves activation of the antioxidant pathway regulator Nuclear factor erythroid 2‐related factor 2 thereby increasing synthesis of the cellular antioxidant glutathione (GSH). The objective of this study was to investigate whether post‐traumatic DMF treatment is beneficial after experimental traumatic brain injury (TBI). Adult C57Bl/6 mice were subjected to controlled cortical impact followed by oral administration of DMF (80 mg/kg body weight) or vehicle at 3, 24, 48, and 72 h after the inflicted TBI. At 4 days after lesion (dal), DMF‐treated mice displayed less neurological deficits than vehicle‐treated mice and reduced histopathological brain damage. At the same time, the TBI‐evoked depletion of brain GSH was prevented by DMF treatment. However, nuclear factor erythroid 2‐related factor 2 target gene mRNA expression involved in antioxidant and detoxifying pathways was increased in both treatment groups at 4 dal. Blood brain barrier leakage, as assessed by immunoglobulin G extravasation, inflammatory marker mRNA expression, and CD45⁺ leukocyte infiltration into the perilesional brain tissue was induced by TBI but not significantly altered by DMF treatment. Collectively, our data demonstrate that post‐traumatic DMF treatment improves neurological outcome and reduces brain tissue loss in a clinically relevant model of TBI. Our findings suggest that DMF treatment confers neuroprotection after TBI via preservation of brain GSH levels rather than by modulating neuroinflammation.

     

Some metabotropic glutamate receptor ligands reduce kynurenate synthesis in rats by intracellular inhibition of kynurenine aminotransferase II

Some metabotropic glutamate receptor (mGluR) ligands, such as quisqualate, L-(+)-2-amino-4-phosphonobutyric acid (L-AP4), 4-carboxy-3-hydroxyphenylglycine (4C3HPG), and L-serine-O:-phosphate (L-SOP), reduced the formation of the endogenous excitatory amino acid receptor antagonist kynurenate in brain and liver slices. The use of novel, subtype-selective mGluR agonists and antagonists excluded a role for any known mGluR subtype in this effect. The reduction of kynurenate formation was no longer observed when slices were incubated with the active mGluR ligands in the absence of extracellular Na(+). trans-Pyrrolidine-2,4-dicarboxylate (trans-PDC), a broad-spectrum ligand of Na(+)-dependent glutamate transporters, was also able to reduce kynurenate formation. Quisqualate, 4C3HPG, L-AP4, and L-SOP did not further reduce kynurenate formation in the presence of trans-PDC, suggesting that the two classes of drugs may share the same mechanism of action. Hence, we hypothesized that the active mGluR ligands are transported inside the cell and act intracellularly to reduce kynurenate synthesis. We examined this possibility by assessing the direct effect of mGluR ligands on the activity of kynurenine aminotransferases (KATs) I and II, the enzymes that transaminate kynurenine to kynurenate. In brain tissue homogenates, KAT II (but not KAT I) activity was inhibited by quisqualate, 4C3HPG, L-AP4, L-SOP, and trans-PDC. Drugs that were unable to reduce kynurenate formation in tissue slices were inactive. We conclude that some mGluR ligands act intracellularly, inhibiting KAT II activity and therefore reducing kynurenate formation. This effect should be taken into consideration when novel mGluR ligands are developed for the treatment of neurological and psychiatric diseases.     

Oxidant/anti-oxidant dynamics in patients with advanced cervical cancer: correlation with treatment response

The present study was designed to investigate the effects of benzyloxicarbonyl-l-phenylalanyl-alanine-fluoromethylketone (Z-FA.FMK), an inhibitor of cathepsin B on lung injury that occurs concurrently with liver injury induced by d-galactosamine/tumor necrosis factor-alpha (d-GalN/TNF-α). Four groups of BALB/c male mice were treated as follows: Group 1—mice receiving intravenous (iv) injections of physiological saline; Group 2—administered with 8 mg/kg Z-FA.FMK by iv injection; Group 3—mice treated with 700 mg/kg d-GalN and 15 μg/kg TNF-α by sequential intraperitoneal (ip) injection; Group 4—treated with 700 mg/kg d-GalN and 15 μg/kg TNF-α by sequential ip injection 1 h after administration with 8 mg/kg Z-FA.FMK. Mice from Groups 3 and 4 were sacrificed 4 h after d-GalN/TNF-α injections. The mice treated with d-GalN/TNF-α showed lung damage; increased TNF receptor-associated factor immunoreactivity, lipid peroxidation, protein carbonyl content, and lactate dehydrogenase activity; decreased catalase, superoxide dismutase, and paraoxonase activities. Treatment with Z-FA.FMK resulted in an improvement of these alterations in d-GalN/TNF-α-administered mice. The apoptotic index of type-II pneumocytes was the almost same in the four study groups, but pneumocytes labeled with proliferating cell nuclear antigen antibody was more numerous in Group 4 mice. Our results show that d-GalN/TNF-α results in lung damage without induction of apoptosis. Treatment with Z-FA.FMK stimulates proliferation of type-II pneumocytes and improves degenerative alterations in injured lung occurred with liver injury induced by d-GalN/TNF-α.     

小胶质细胞在脂多糖引起的热高敏中的作用

目的探讨小胶质细胞在脂多糖引起的热高敏中的作用。方法清洁级雄性昆明小鼠,随机分成两组,每组5只,腹腔注射LPS组和注射PBS组,在注射前及后30、60、120、240 min测量小鼠足底的热痛阈;每组于注射前及后4h各处死5只取脑组织检测IL-1β、TNF-α;每组于腹腔注射4h时处死动物,免疫荧光确定脑组织中小胶质细胞的激活情况。然后分为四组,米诺环素+PBS组,米诺环素+LPS组,PBS+PBS组,PBS+LPS组,每组5只,连续三天腹腔注射米诺环素或PBS,第三天注射LPS或PBS,在注射前及后30、60、120、240 min测量小鼠足底的热痛阈;每组于注射前及后4h各处死5只取脑组织检测IL-1β、TNF-α。结果与注射PBS相比,注射LPS导致IL-1β、TNF-α分泌增加,注射60、120、240 min小鼠的热痛阈降低;与米诺环素+PBS组、米诺环素+LPS组、PBS+PBS组相比,PBS+LPS组导致IL-1β、TNF-α分泌增加,注射60、120、240 min小鼠的热痛阈降低。结论LPS激活小胶质细胞分泌促炎细胞因子导致热高敏。     

The depolarization-induced outflow of d-[H]aspartate from rat brain slices is modulated by metabotropic glutamate receptors

Rat brain slices were used to study the effects of different metabotropic glutamate receptor ligands on (i) the depolarization (30 mM KCl)-induced outflow of previously taken up d-[³H]aspartate; (ii) the inhibition of forskolin (30 μM)-induced cyclic AMP accumulation; and (iii) the hydrolysis of phosphoinositides. In addition, the localization of mRNAs coding for different metabotropic glutamate receptor subtypes was detected using in situ hybridization. (1S,3R)-1-Aminocyclopentane-1,3-dicarboxylic acid (30–300 μM), a non selective metabotropic glutamate receptor agonist, significantly increased the KCl-induced output of radioactivity from cortical slices, whereas it inhibited the output from striatal slices. Conversely, (1S,3S,4S)-carboxycyclopropylglycine (0.1–1 μM), a relatively selective agonist of the mGluR2 metabotropic glutamate receptor subtype, had an inhibitory effect on the output of d-[³H]aspartate from both cortical and striatal slices and proved to be the most potent metabotropic glutamate receptor agonist in inhibiting cyclic AMP accumulation, but not in stimulating phosphoinositide hydrolysis. Since 2-amino-4-phosphonobutyrate (a mGluR4, mGluR6 and mGluR7 agonist) was not active in any of the assays tested, we hypothesized that the mGluR2 subtype could be involved in these events. Accordingly, mGluR2 mRNA expression was abundant in cortical neurons projecting to the striatum. Our experiments suggest that the stimulation of metabotropic glutamate receptors may either decrease or increase transmitter release depending on the subtype that prevails in the region under study.     

Autophagy is increased in mice after traumatic brain injury and is detectable in human brain after trauma and critical illness

Autophagy is a homeostatic process for recycling of proteins and organelles, that increases during times of nutrient deprivation and is regulated by reactive oxygen species. We reported that autophagy can also be induced after traumatic brain injury (TBI) in mice.1 Specifically, autophagosomes and multilamellar bodies were frequently observed in cell processes and axons in injured brain regions by electron microscopy, and lipidated microtubule-associated protein light chain 3 (LC3-II), was increased after TBI vs. controls. To determine if antioxidants could reduce autophagy, separate mice were treated with the antioxidant ?-glutamylcysteinyl ethyl ester (GCEE). Treatment with GCEE preserved total antioxidant reserves, reduced LC3-II in injured brains, and improved both behavioral and histological outcome after TBI. Here we report that LC3-II and autophagosomes were detectable in brain tissue from humans after TBI. Taken together, we show that autophagy occurs after both experimental and clinical TBI, and that oxidative stress contributes to overall neuropathology after TBI in mice, at least in part by initiating or influencing autophagy.     

The effects of adrenomedullin in traumatic brain injury

Traumatic brain injury (TBI) is a common cause of death and disability throughout the world. A multifunctional peptide adrenomedullin (AM) has protective effects in the central nervous system. We evaluated AM in an animal model as a therapeutic agent that reduces brain damage after traumatic brain injury. A total of 36 rats was divided into 3 groups as sham, head trauma plus intraperitoneal (ip) saline, and head trauma plus adrenomedullin ip. The diffuse brain injury model of Marmarou et al. was used. Blood samples were taken from all groups at the 1st, 6th and 24th hours for analysis of TNF-α (tumor necrosis factor-α), IL-1β (interleukin-1β) and IL-6 (interleukin-6) levels. At the end of the study (at the 24th hour) a neurological examination was performed and half of the rats were decapitated to obtain blood and tissue samples, the other half were perfused transcardiacally for studying the histopathology of the brain tissue. There were no statistically significant changes in plasma levels of IL-1β, IL-6 and TNF-α relative to the sham group. Also, changes in tissue levels of malonedialdehyde, myeloperoxidase and glutathione were not statistically significant. However, neurological scores and histopathological examinations revealed healing. AM individually exerts neuroprotective effects in animal models of acute brain injury. But the mechanisms of action remain to be assessed.