Curcumin inhibits the increase of glutamate, hydroxyl radicals and PGE2 in the hypothalamus and reduces fever during LPS-induced systemic inflammation in rabbits

Evidence has accumulated to suggest that systemic administration of lipopolysaccharide (LPS), in addition to elevating tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) as well as fever, induces overproduction of glutamate, hydroxyl radicals and prostaglandin E(2) (PGE(2)) in the rabbit's hypothalamus. Current study was attempted to assess whether Curcumin exerts its antipyresis by reducing circulating pro-inflammatory cytokines and hypothalamic glutamate, hydroxyl radicals and PGE(2) in rabbits. The microdialysis probes were stereotaxically and chronically implanted into the preoptic anterior hypothalamus of rabbit brain for determination of glutamate, hydroxyl radicals, and PGE(2) in situ. It was found that systemic administration of LPS (2 microg/kg) induced increased levels of both core temperature and hypothalamic levels of both glutamate and hydroxyl radicals accompanied by increased plasma levels of TNF-alpha, IL-1beta, and IL-6. The rise in both the core temperature and hypothalamic glutamate and hydroxyl radicals could also be induced by direct injection of TNF-alpha, IL-1beta, or IL-6 into the lateral ventricle of rabbit brain. Pretreatment with Curcumin (5-40 mg/kg, i.p.) 1 h before an i.v. dose of LPS significantly reduced the LPS-induced overproduction of circulating TNF-alpha, IL-1beta, and IL-6, and brain glutamate, PGE(2), and hydroxyl radicals. Both the febrile response and overproduction of both glutamate and hydroxyl radicals in the hypothalamus caused by central administration of TNF-alpha, IL-1beta, or IL-6 could be suppressed by Curcumin. These results indicate that systemic injection of Curcumin may exert its antipyresis by inhibiting the glutamate-hydroxyl radicals-PGE(2) pathways in the hypothalamus and circulating TNF-alpha, IL-1beta, and IL-6 accumulation during LPS fever.     

Hypothalamic somatostatin may mediate endotoxin-induced fever in the rat

Summary (1) The changes in rectal temperature produced by an injection of a bacterial endotoxin piromen (10–40 ng in 1.0 l) or somatostatin-14 (SS-14; 0.1–0.3 pg in 1.0 l) into the preoptic anterior hypothalamic area were assessed and compared in control rats, in rats with hypothalamic SS depletion, and in rats with hypothalamic SS receptor blockade. (2) Intrahypothalamic injection of either piromen or SS-14 produced a dose-related rise in rectal temperature in intact, control rats. The fever induced by intrahypothalamic injection of piromen or SS-14, as well as that induced by intraperitoneal injection of piromen, was antagonized by pretreatment of the hypothalamus with a SS-14 receptor antagonist (0.1 ng in 1.0 l) in rats. (3) On the other hand, intraperitoneal administration of cysteamine (30–100 mg/kg), in addition to producing a dose-related fall in rectal temperature, also caused a dose-related fall in hypothalamic SS-levels in rats. Furthermore, the fever induced by intrahypothalamic injection of piromen, but not SS-14, was antagonized by depletion of hypothalamic SS levels with an intraperitoneal dose of cysteamine (30 mg/kg). (4) The results indicate that a somatostatinergic pathway in the hypothalamus may mediate endotoxin-induced fever in the rat.This study was supported by grants from the National Science Council of the Republic of China Send offprint requests to Mao-Tsun Lin at the above address     

Aspirin may exert its antipyresis by inhibiting the N-methyl-D-aspartate receptor-dependent hydroxyl radical pathways in the hypothalamus

Recent findings have suggested that the N-methyl-D-aspartate (NMDA) receptor-dependent hydroxyl radical pathway in the hypothalamus of rabbit brain may mediate the fever induced by lipopolysaccharide (LPS). The aim of this study was to investigate whether aspirin exerts its antipyresis by suppressing hypothalamic glutamate and hydroxyl radicals in rabbits. The microdialysis probes were stereotaxically and chronically implanted into the preoptic anterior hypothalamus of rabbit brain for determination of both glutamate and hydroxyl radicals in situ. It was found that intravenous (i.v.) injection of LPS, in addition to inducing fever, caused increased levels of both glutamate and hydroxyl radicals in the hypothalamus. Pretreatment with aspirin (10 - 60 mg/kg, i.v.) one hour before an i.v. dose of LPS significantly reduced the febrile response and attenuated the LPS-induced increased levels of both glutamate and hydroxyl radicals in the hypothalamus. The increased levels of prostaglandin E(2) (PGE(2)) in the hypothalamus induced by LPS could be suppressed by aspirin pretreatment. The data indicate that systemic administration of aspirin, in addition to suppressing PGE(2) production, may exert its antipyresis by inhibiting the NMDA receptor-dependent hydroxyl radical pathways in the hypothalamus during LPS fever.     

The effect of caffeine on MDMA-induced hydroxyl radical production in the mouse striatum

BackgroundThe psychostimulant 3,4-methylenedioxymethamphetamine (MDMA) with a strong addictive potential is widely used as a recreational drug. Neurotoxicity of MDMA is related with the generation of highly reactive free radicals.MethodsMDMA was given in doses of 20 and 40 mg/kg ip alone or in combination with caffeine (CAF) 10 mg/kg ip. Extracellular concentration of hydroxyl radical was measured using microdialysis in freely moving mice and was assayed by HPLC with electrochemical detection.ResultsMDMA dose-dependently increased production of hydroxyl radical in the mouse striatum and its effect was reversed by caffeine.ConclusionsThe data show that caffeine may have neuroprotective properties as it decreased oxidative stress induced by MDMA.     

Central interleukin-10 attenuated lipopolysaccharide-induced changes in core temperature and hypothalamic glutamate, hydroxyl radicals and prostaglandin-E(2)

It has been documented that intravenous lipopolysaccharide (LPS) in rabbits causes fever accompanied by increased levels of extracellular glutamate, hydroxyl radicals, and prostaglandin E₂ (PGE₂) in the hypothalamus and circulating tumor necrosis factor-alpha (TNF-α). This investigation was to determine whether central interleukin-10 (IL-10) exerted its antipyresis by reducing changes in circulating TNF-α and extracellular glutamate, hydroxyl radicals and PGE₂ in the hypothalamus. The microdialysis probes were stereotaxically and chronically implanted into the preoptic anterior hypothalamus of rabbit brain for determinating extracellular glutamate, hydroxyl radicals, and PGE₂ in situ. It was found that systemically injected LPS (2 μg/kg, intravenously) increased the levels of core temperature, and extracellular glutamate, hydroxyl radicals, and PGE₂ in the hypothalamus accompanied by increased plasma levels of TNF-α. Pretreatment with IL-10 (10–100 ng, intracerebroventricularly) 1 h before intravenous LPS significantly reduced the LPS-induced changes in extracellular glutamate, hydroxyl radicals, and PGE₂ in the hypothalamus and fever, but not the increased levels of TNF-α in rabbits. These findings suggested that directly injected IL-10 into the lateral cerebral ventricle 1 h before intravenous LPS exerted its antipyresis by inhibiting the changes in extracellular glutamate, hydroxyl radicals and PGE₂ in the hypothalamus during LPS fever in rabbits.     

Taurine reduces ammonia- and N-methyl-D-aspartate-induced accumulation of cyclic GMP and hydroxyl radicals in microdialysates of the rat striatum

Acute ammonia neurotoxicity caused by intraperitoneal administration of ammonium salts is mediated by overactivation of N-methyl-D-aspartate (NMDA) receptors, with ensuing generation of free radicals and extracellular accumulation of cyclic GMP (cGMP) arising from stimulation of nitric oxide (NO) synthesis. In this study, infusion of ammonium chloride or NMDA into the striata of rats via microdialysis probes increased the contents of cyclic GMP and hydroxyl radicals in the microdialysates. Co-infusion of taurine virtually abolished both the ammonia- and NMDA-induced accumulation of cGMP. Taurine also attenuated accumulation of hydroxyl radicals evoked by either treatment. This result is the first evidence of a potential of taurine to attenuate the effects of NMDA receptor overactivation by ammonia in vivo and points to the inhibition of the NMDA receptor-mediated NO synthesis as a possible mechanism of its neuroprotective action. Taurine or its blood-brain barrier penetrating analogues may be applicable in treatment of ammonia-induced neurological deficits.     

灿烂绿褪色法测Fenton体系羟自由基含量

目的利用羟自由基可使灿烂绿褪色的原理．间接检测羟自由基含量。方法以单因素法通过测量吸光度确定Fenton体系产生控自由基使灿烂绿褪色的各实验条件;并通过用姜黄素、葛根素、槲皮苷3种物质来验证方法的有效性。结果通过实验得到实验最佳条件为ED．TA．Fe2＋（0．945mmol·L-1）1mL、H2O2（3％）2．5mL、灿烂绿（0．2mmol·L-1）1mL在37℃水浴70min;根据该体系3种药物清除羟自由基活性：姜黄素〉葛根素〉槲皮苷。结论灿烂绿褪色法有较好的稳定性;并且能区分姜黄素、葛根素以及槲皮苷的羟自由基清除活性。     

The antipyretic effects of baicalin in lipopolysaccharide-evoked fever in rabbits

Evidence has accumulated to indicate that systemic administration of lipopolysaccharide (LPS), in addition to elevating tumor necrosis factor-alpha (TNF-alpha) as well as fever, induces overproduction of both glutamate and hydroxyl radicals in the rabbit's hypothalamus. Current investigation was attempted to determine whether baicalin exerts its antipyresis by suppressing overproduction of circulating TNF-alpha and hypothalamic glutamate and hydroxyl radicals in rabbits. The microdialysis probes were stereotaxically and chronically implanted into the preoptic anterior hypothalamus of rabbit brain for determination of both glutamate and hydroxyl radicals in situ. It was found that systemic administration of LPS (0.5-10 microg/kg) induced dose-related increased levels of both core temperature and hypothalamic levels of both glutamate and hydroxyl radicals accompanied by increased plasma levels of TNF-alpha. The rise in both the core temperature and hypothalamic glutamate and hydroxyl radicals could also be induced by direct injection of TNF-alpha (1-20 ng) into the lateral ventricle of rabbit brain. Pretreatment with baicalin (2-20 mg/kg, i.v.) one hour before an i.v. dose of LPS significantly reduced the LPS-induced overproduction of circulating TNF-alpha and brain glutamate and hydroxyl radicals. Both the febrile response and overproduction of both glutamate and hydroxyl radicals in the hypothalamus caused by central administration of TNF-alpha could be suppressed by baicalin. These findings suggest that systemic administration of baicalin may exert its antipyresis by inhibiting the N-methyl-D-aspartate receptor-dependent hydroxyl radicals pathways in the hypothalamus and circulating TNF-alpha accumulation during LPS-fever.     

珠芽蓼清除羟自由基作用研究

目的为了解珠芽蓼根茎作为蝙蝠蛾幼虫食物的生理作用,研究它的提取物对羟自由基的清除能力。方法采用邻二氮菲—Fe2+氧化法检测珠芽蓼根茎的提取物对H2O2/Fe2+体系产生的羟自由基的清除作用。结果珠芽蓼根茎蒸馏水提取物和丙酮提取物均对羟自由基有清除作用,其中丙酮提取物的作用最强。结论珠芽蓼根茎具有明显的清除羟自由基作用,其活性主要来自丙酮提取物部分。     

Investigations concerning the correlation of COX-1 inhibitory and hydroxyl radical scavenging activity

The aim was to study the COX-1 inhibiting efficacy in context with hydroxyl radical scavenging properties of compounds bearing a carboxylic acid and ester function, respectively. In general, the acids are more potent radical scavengers than the corresponding esters but there is no clear correlation with their COX-1 inhibiting potencies. A feasible scavenging mechanism of carboxylic acids is discussed.     

The hydroxyl radical generation and oxidative stress for the earthworm Eisenia fetida exposed to tetrabromobisphenol A

Biochemical effects of tetrabromobisphenol A (TBBPA) on the earthworm Eisenia fetida, including superoxide dismutase, catalase, glutathione-S-transferase, reduced glutathione, oxidized glutathione, GSH/GSSG ratio and malondialdehyde (MDA) level, were measured to assess ecological toxicity of TBBPA. With OECD standard filter-paper contact test method, earthworms were exposed to TBBPA of a range of concentrations (0.00, 0.01, 0.05, 0.1, 0.5 and 1.0 mg L⁻¹). According to the electron paramagnetic resonance spectrum, reactive oxygen species (ROS) generated in the earthworm was identified as the hydroxyl radical (^•OH) which was significantly induced at all TBBPA concentrations. With the increasing of TBBPA concentration, the antioxidant enzymes, glutathione and MDA levels varied significantly. The results showed that TBBPA exerts its toxic effects on E. fetida by inducing the generation of ROS and resulting in oxidative damage. The results show that the ^•OH production leads to oxidative stress in the tissues of the earthworm E. fetida.     

枳椇子各部位清除羟自由基作用的比较

目的比较枳木具子不同提取部位对羟自由基的清除作用。方法采用邻二氮菲氧化法,检测枳子不同提取部位对体系产生的羟自由基的清除作用。结果枳木具子乙酸乙酯部位的羟自由基清除率为11.7%,总提取物的羟自由基清除率为13.6%,剩余物的羟自由基清除率为-6.5%。结论枳子清除羟自由的有效部位集中在乙酸乙酯部位。     

NMDA receptor activation antagonizes the NMDA antagonist-induced antianxiety effect in the elevated plus-maze test in mice

BackgroundThe purpose of this study was to determine how the activation of different regulatory domains of the NMDAcomplex affects the antianxiety effect of antagonists acting at its distinct binding sites.MethodsThe anxiolytic-like activity was assessed by the elevated plus-maze test in mice.ResultsThe anxiolytic activity of CGP 37849 (a competitive NMDAreceptor antagonist) and L-701,324 (an antagonist at glycine site) was confirmed, but effects of both were significantly reduced by N-methyl-D-aspartic acid (NMDA) or by D-serine agonists at glutamate and glycine site of the NMDA receptor complex, respectively.ConclusionThe obtained data suggest that stimulation of the glutamate or glycine recognition site of the NMDAreceptor complex significantly decreases the antianxiety properties of antagonists of either site.     

NMDA receptor and NO mediate ET-1-induced behavioral and cardiovascular effects in periaqueductal gray matter of rats

Endothelin-1 (ET-1), a novel and potent vasoconstrictor in blood vessel, is known to have some functions in the rat central nervous system (CNS). In order to investigate the central functions of ET-1, ET-1 was administered to the periaqueductal gray area (PAG) of anesthetized rats to induce barrel rolling and increase the arterial blood pressure (ABP). ET-1 had a modulatory effect on central cardiovascular and behavioral control. The selective N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (3 micromol/kg, i.p.) blocked the ET-1 induced responses, and both the nitric oxide synthase (NOS) inhibitor L-NAME (N-nitro-L-arginine methylester 1 mmol/rat) and the nitric oxide (NO) scavenger hemoglobin (15 nmol/rat) had similar effects in reducing the ET-1 (10 pmol/rat)-induced behavioral changes and ABP elevation. However, NO donor sodium nitroprusside (SNP 10 microg, 1 microg/rat) decreased the ET-1 induced ABP elevation, and recovered the ET-1-induced barrel rolling effect that was reduced by MK-801. These results suggest that ET-1 might have neuromodulatory functions such as ABP elevation and barrel rolling induction in the PAG of the rats via the NMDA receptor and NO.     

Evidence that the reactions of cadmium in the presence of metallothionein can produce hydroxyl radicals

A variety of Cu reconstituted metallothioneins (MTs) containing different amounts of copper ions together with Cd₇-MT free of copper were prepared and used in spin trapping experiments designed to show cadmium is not a Fenton active metal. A significant increase of the DMPO/·OH adduct was observed, with increased concentrations of the copper containing MTs, H₂O₂ enhanced DMPO/·OH adduct formation, catalase and the Cu (I) specific chelating agent bathocuproine, reduced DMPO/·OH adduct formation. These results suggest that Cu (I) and H₂O₂ both have important roles in the production of active species in these systems and cause DMPO/·OH formation. However, Cd₇-MT showed no ability to cause generation of DMPO adducts with H₂O₂ seeming to indicate cadmium is not a Fenton metal. To test this hypothesis further trapping studies were run with added sulphite and lipid peroxide using both commercial MT and Cd₇-MT since cadmium causes peroxidation in vivo. Commercial MT generates radicals with added sulphite and peroxide, Cd₇-MT does not, demonstrating that cadmium is not a Fenton metal. These results help to explain the oxidative damage to DNA observed in the presence of MT and cadmium in vitro. Received: 3 February 1998 / Accepted: 24 July 1998     

Enhanced NMDA receptor NR1 phosphorylation and neuronal activity in the arcuate nucleus of hypothalamus following peripheral inflammation

AbstractAim:To investigate the role of glutamate and N-methyl-D-aspartate (NMDA) receptors in central sensitization following peripheral inflammation in the arcuate nucleus (ARC) of the mediobasal hypothalamus.Methods:Mediobasal hypothalamic slices were prepared from rats undergoing peripheral inflammation, which was induced by a unilateral injection of complete Freund's adjuvant (CFA) into hind paw. Neuronal activation levels in the ARC were monitored by recording extracellular unit discharges. The NMDA receptor NR1 subunit (NR1) was measured using Western blot analysis.Results:Enhanced NR1 phosphorylation was observed in the ARC of CFA-inflamed rats. Compared with the control rats, the firing rate of spontaneous discharges in ARC neurons of inflamed rats was significantly higher, and it was significantly reduced both by an NMDA receptor antagonist (MK-801, 300 μmol/L) and by a non-NMDA receptor antagonist (CNQX, 30 μmol/L). Application of exogenous glutamate (200 μmol/L) or NMDA (25 μmol/L) resulted in increased neuronal discharges for ARC neurons, which was enhanced to a greater extent in inflamed rats than in control rats.Conclusion:Glutamate receptor activation in the hypothalamic ARC plays a crucial role in central sensitization associated with peripheral inflammation.     

姜黄素对羟自由基及红细胞氧化性溶血的影响

目：探讨姜黄素（Ｃurcumin,Cur)清除羟自由基及防御脂质过氧化的能力。方法;利用Ｆenton反应生成羟自由基（OH）,由AAPH诱发红细胞氧化性溶血。结果：姜黄素对羟自由基有较强的清除作用（SC50为58．8μmol/L),其作用超过OH的特异性清除剂甘露醇（SC50为2．3μmol/L）;姜黄素（120μmol/L)能有效地抑制由AAPH诱发的红细胞氧化性溶血（抑制2h以上）,显示了较强的防御脂质过氧化的能力。结论：姜黄素对癌症及炎症等的治疗作用可能与其清除自由基及防御脂质过氧化的能力有关。     

Hitting The Right Spot: NMDA Receptors in the Auditory Thalamus May Hold the Key to Understanding Schizophrenia

In this issue, Wang and colleagues solve an important puzzle in the understanding of schizophrenia. Previous work has linked N-methyl-D-aspartate (NMDA) receptor hypofunction to schizophrenia and shown that individuals with schizophrenia have a suppressed steady-state cortical response to 40-Hz repetitive auditory stimulation. However, systemic application of NMDA antagonists paradoxically increases this cortical response in rodents. Here, by specifically applying NMDA receptor blockade in the auditory thalamus while simultaneously measuring the acoustically driven response in 2 cortical regions, Wang and colleagues found the drop in the steady-state response that is seen in schizophrenia. These findings solve an important paradox in the field and suggest that specific thalamic neurochemical alterations may occur in the brain of individuals with schizophrenia. In addition, this work suggests that suppression of NMDA receptors in the thalamus may serve as a potential animal model for the disease.     

In vivo release by histamine agonists and antagonists of endogenous catecholamines in the cat hypothalamus

Summary The posterior hypothalamus of anaesthetized cats was superfused through a push-pull cannula with histamine agonists and antagonists and the release of endogenous catecholamines was determined in the superfusate. Hypothalamic superfusion with histamine, 2-methylhistamine (H₁-agonist), dimaprit (H₂-agonist) or metiamide (H₂-antagonist) enhanced the release of the catecholamines dopamine, noradrenaline and adrenaline. The releasing effects of these substances depended on the presence of calcium ions. Superfusion with 2-pyridylethylamine (H₁-agonist) was virtually ineffective, while superfusion with 2-thiazolethylamine (H₁-agonist) enhanced the rate of release of noradrenaline and adrenaline without influencing the release of dopamine. Superfusion with mepyramine (H₁-antagonist) inhibited the release of noradrenaline and adrenaline without affecting the release of dopamine. Hypothalamic superfusion with a concentration of procaine which was equi-anaesthetic to that of mepyramine was ineffective. Ranitidine (H₂-antagonist) did not alter the rates of release of the catecholamines. The releasing effect of histamine was inhibited on hypothalamic superfusion with mepyramine and ranitidine. Ranitidine also inhibited the releasing effects of dimaprit and 2-methylhistamine thus indicating that the releasing action of the latter compound was mainly due to stimulation of H₂-receptors. These data suggest that blockade of H₁-receptors of the posterior hypothalamus reduces the release of noradrenaline and adrenaline, while stimulation of H₁-receptors seems to increase the rates of release of these two catecholamines. Stimulation of H₂-receptors enhances the release of all three catecholamines. Thus, dopaminergic neurones of the hypothalamus seem to possess H₂-receptors, while noradrenergic and adrenergic neurones possess H₁- and H₂-receptors.This work was supported by the Deutsche Forschungsgemeinschaft     

急性阿片耐受大鼠脊髓NMDA受体NR2A及NR2B亚基表达的改变

目的：了解大鼠短期多次应用芬太尼能否发生急性阿片耐受以及急性阿片耐受大鼠脊髓NMDA受体NR2A和NR2B亚基表达的改变。方法：24只体重为200-220g的雄性SD大鼠随机分为3组（n=8）：对照组（C）,生理盐水组（S）及芬太尼组（F）。F组大鼠给予皮下注射芬太尼30μg/kg,共4次,每两次注射之间间隔15min,S组大鼠以生理盐水代替芬太尼,C组大鼠未给药。给药前及给药结束后每30min以Von-Frey仪测定各组大鼠的机械刺激缩足阈值（paw withdrawal threshold,PWT）。当F组大鼠的PWT恢复到给药前基础水平时,各组大鼠均给予腹腔注射吗啡5mg/kg。随后仍每30min测定各组大鼠的PWT,直至F组大鼠的PWT再次回到基础水平。对各组大鼠不同时间点的PWT进行组内和组间比较。另24只体重为2000-220g的雄性SD大鼠分组及给药方法同前（分为C^＊、S^＊及F^＊组）,当F＊组大鼠的PWT首次恢复到基础值时,不给予吗啡,处死各组大鼠,取脊髓,以Western blotting方法测定NMDA受体NR2A及NR2B亚基的蛋白表达水平。结果：连续4次皮下注射芬太尼（F组）后大鼠首先表现为PWT较基础值显著升高,随后PWT降低到基础值以下,然后逐渐恢复至基础值水平,此时皮下注射吗啡后,吗啡的镇痛效果显著低于其他两组大鼠（S组,C组）。F^＊组大鼠脊髓的NR2B亚基表达水平显著高于C^＊组及S^＊组,各组大鼠脊髓的NR2A亚基表达水平的差异无统计学意义。结论：短期应用芬太尼可导致大鼠发生急性阿片耐受。急性阿片耐受大鼠的脊髓NMDA受体NR2B亚基表达水平显著升高,NR2A亚基表达水平无明显变化。