Ameliorative effects of Bacopa monniera on lead-induced oxidative stress in different regions of rat brain

Abstract

Bacopa monniera is a rejuvenating herb for brain cells enhancing learning and cognitive ability. In the present investigation, the ameliorative effects of Bacopa monniera were examined against lead-induced oxidative stress in different regions of rat brain. Male rats were divided into five groups: control (1000?ppm sodium acetate) and exposed (1000?ppm lead acetate) for 4 weeks; DMSA (Meso-2,3-Dimercaptosuccinic acid)-treated (90?mg/kg body weight/day); Bacopa monniera-treated (BM) (10?mg/kg body weight/day) and a combination of BM?+?DMSA for seven consecutive days after 4 weeks of lead exposure. After treatment, the whole brain was isolated by sacrificing rats and four regions were separated namely cerebellum, hippocampus, frontal cortex and brain stem. Results indicated a significant (p?<?0.05) increase in reactive oxygen species (ROS), lipid peroxidation products (LPP) and total protein carbonyl content (TPCC) in association with tissue metal content in all the four regions of brain for exposed group compared with their respective controls. However, the lead-induced ROS, LPP, TPCC and tissue metal content were lowered on treatment with Bacopa monniera, almost reaching the control group values in all the above brain regions compared to DMSA and a combination therapy. Results suggest that Bacopa monniera can mitigate the lead induced-oxidative stress tissue specifically by pharmacologic interventions which encompass both chelation as well as antioxidant functions.     

Therapeutic potential of Moringa oleifera extracts against acetaminophen-induced hepatotoxicity in rats

Context: Moringa oleifera Lam. (Moringaceae) is a rich source of essential minerals and antioxidants; it has been used in human and animal nutrition. The leaves and flowers are being used by the population with great dietary importance.

Objective: The present study was to investigate the therapeutic effects of the hydroethanolic extract of Moringa oleifera (MO) leaves and flowers against hepatotoxicity induced by acetaminophen (APAP) in rats.

Materials and methods: In the hepatoprotective study, either flowers or leaves of hydroethanolic extract (200 or 400?mg/kg bw through IP injection) were administered an hour after APAP administration. N-Acetylcysteine (NAC) was used as the positive control for this study. Liver and kidney function tests including lipid peroxidation levels were analyzed and histopathological changes of liver and kidney were also observed.

Results: Acetaminophen-induced hepatotoxicity increased the activities of liver marker enzymes. Histologically, the liver was observed to have inflammation and bridging necrosis. Liver marker enzymes were significantly reduced when treated with flower and leaf extracts of MO in animals with APAP induced toxicity. In addition, there were no significant changes observed in clinical markers of kidney function. Histological observation on liver tissue from the rats treated with MO flower and leaf extract showed reduction in the severity of the liver damage.

Discussion and conclusion: These results indicated the possible therapeutic action of flower and leaf extract from MO in protecting liver damage in rats given an over dosage of APAP.     

Artemisia pallens alleviates acetaminophen induced toxicity via modulation of endogenous biomarkers

Abstract

Context: Acetaminophen (APAP) leads to severe hepatic and renal necrosis and thus causes significant clinical problems. Artemisia pallens Walls ex D.C. (Asteraceae) possesses various pharmacological properties such as antidiabetic, antioxidant, analgesic, and anti-inflammatory activity.

Objective: The objective was to evaluate the protective effects of Artemisia pallens methanol extract (APME) in APAP-induced hepatic and nephro-toxicity.

Materials and methods: The methanolic extract of aerial parts of Artemisia pallens (APME) was prepared. Toxicity was induced in male Wistar rats (180–220?g) by administration of APAP (700?mg/kg, p.o., 14?d). APME (100, 200, and 400?mg/kg, p.o.) was administered to rats 2?h before APAP oral administration. Various biochemical and molecular parameters along with histopathological aberration were studied in the kidney and liver of rats.

Results: Pretreatment with APME (200 and 400?mg/kg, p.o.) significantly (p?<?0.01 and p?<?0.001) decreased aspartate transaminase (AST), alanine transaminase (ALT), bilirubin, blood urea nitrogen (BUN), and serum creatinine as compared with APAP-treated rat. Decreased level of serum albumin, serum uric acid, and HDL were significantly (p?<?0.01 and p?<?0.001) restored by APME (200 and 400?mg/kg, p.o.) pre-treatment. Administration of APME (200 and 400?mg/kg, p.o.) significantly (p?<?0.01 and p?<?0.001) reduced the elevated level of cholesterol, LDL, LDH, triglyceride, and VLDL. It also significantly (p?<?0.01 and p?<?0.001) restored the altered level of hepatic and renal antioxidant enzymes (superoxide dismutase (SOD) and glutathione (GSH)). The increased level of malondialdehyde (MDA) and nitric oxide (NO) in hepatic as well as renal tissue was significantly (p?<?0.01 and p?<?0.001) decreased by APME (200 and 400?mg/kg, p.o.) administration. Histological alternation induced by APAP in liver and kidney was also reduced by the APME (200 and 400?mg/kg, p.o.) pre-treatment.

Conclusion: It is concluded that the methanol extract of Artemisia pallens alleviates APAP induced in rats toxicity through its antioxidative and anti-inflammatory actions.     

氟伐他汀对高胆固醇血症患者血清NO及血管内皮功能的影响

目的　观察短期氟伐他汀治疗对高胆固醇血症患者一氧化氮和一氧化氮合酶血管内皮功能的影响。方法　 35例原发性高胆固醇血症患者每日口服氟伐他汀 4 0mg共 8wk ,服药前后测量患者血清的TC、TG、LDL C和HDL C以及NO和NOS值 ,及用彩色多普勒超声测定反应性充血时肱动脉内径的变化。并与对照组进行比较。结果　原发性高胆固醇血症患者经氟伐他汀 8wk治疗后 ,血清的TC、TG、LDL C明显下降 ,血清的HDL C以及NO和NOS值明显增加 ,反应性充血时肱动脉内径扩张程度明显增加 ,这些与治疗前相比有明显差异。结论　氟伐他汀短期治疗能使高胆固醇血症患者血脂改变 ,NO和NOS值增加 ,血管内皮功能改善。     

一氧化氮参与非诺贝特抗高糖高胰岛素诱导的心肌肥大

目的研究过氧化物酶体增殖物激活受体-α(peroxi-some proliferator-activated receptor-α,PPAR-α)特异性激动剂非诺贝特(fenofibrate,FF)在高糖高胰岛素(high glucose and insulin,HGI)所致心肌细胞肥大中的作用及其与一氧化氮(nitric oxide,NO)途径的关系。方法乳鼠心肌细胞培养,以细胞表面积、蛋白含量和心房利钠因子mRNA表达为心肌肥大反映指标,观察FF对HGI致肥大作用的影响。利用Real-time PCR和Western blot方法检测mRNA及蛋白水平的表达;比色法和硝酸还原法分别检测细胞培养液中一氧化氮合酶(nitric oxide synthase,NOS)的活性和NO的浓度。结果FF浓度依赖性地抑制HGI诱导的心肌细胞肥大(P<0.01);FF0.3μmol·L-1明显上调HGI导致的PPAR-α以及内皮型一氧化氮合酶(endothelial nitric oxide synthase,eNOS)mRNA和蛋白表达的降低(P<0.05);并增加HGI降低的NOS活性和NO浓度(P<0.01)。PPAR-α阻断剂MK886可完全取消FF的上述作用(P<0.05)。L-精氨酸的作用与FF相似(P<0.01)。结论FF可能通过激活PPAR-α,从而促进eNOS的表达及NO的释放,产生抗HGI诱导心肌肥大的作用。     

D-硝基精氨酸对小鼠肾损伤及氧化应激作用

目的研究D-硝基精氨酸(D-NNA)对小鼠的肾损伤及其氧化应激机制。方法 ICR小鼠ig给予D-NNA150,50和15 mg·kg-1,连续30 d。测定并计算肾系数;血液生化分析仪检测血清中肌酐(Crea)和尿素氮(BUN);分光光度法测定肾组织一氧化氮(NO),硫代巴比妥酸法测丙二醛(MDA)含量,比色法测定谷胱甘肽过氧化酶(GSH-Px)和超氧化物歧化酶(SOD)活性;观察肾病理组织学变化。结果与5%葡萄糖对照组相比,D-NNA 150,50和15 mg·kg-1组血清中BUN分别明显升高了83.6%,36.2%和27.4%(P<0.05),D-NNA150和50 mg·kg-1组血清中Crea分别明显升高了281.6%和10.6%(P<0.05);D-NNA150 mg·kg-1组肾系数和NO水平分别明显降低了5.6%和25.5%(P<0.05);D-NNA150和50 mg·kg-1组肾组织中MDA水平分别明显升高了69.0%和36.9%(P<0.01),SOD活性和GSH-Px活性分别明显下降了17.4%和17.7%,7.3%和13.7%(P<0.05);D-NNA150 mg·kg-1组病理检查可见肾小管损伤,嗜碱性变,萎缩或囊性扩张和间质炎性浸润,D-NNA50和15 mg·kg-1组出现炎症细胞浸润。结论 D-NNA对小鼠肾有一定的损伤作用,其作用机制可能与D-NNA的手性转化产物L-NNA导致NO合成减少,产生ROS有关。     

葛根素对高胰岛素环境下大鼠肝细胞一氧化氮合成的影响

目的：观察葛根素对高胰岛素环境下大鼠肝细胞一氧化氮（NO）合成的影响。方法：体外培养BRL大鼠肝细胞株,用高胰岛素诱导其形成胰岛素抵抗细胞模型,观察葛根素对肝细胞一氧化氮合成的影响。结果：葛根素可调节高胰岛素环境下大鼠肝细胞一氧化氮合酶（NOS）的活性,增加肝细胞NO的合成。结论：葛根素可通过适度调节肝细胞NO的产生,从而促进肝细胞对葡萄糖转化,改善肝细胞胰岛素抵抗的作用。     

Effects of opioid (tramadol) treatment on testicular functions in adult male rats: The role of nitric oxide and oxidative stress

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Investigation of the effect of intracolonic melatonin gel formulation on acetic acid-induced colitis

The aims of the present study were to develop a colon-specific gel formulation of melatonin with sodium alginate and to evaluate its in vitro characteristics and intracolonic performance on oxidative stress parameters, such as nitric oxide (NOx), malondialdehyde (MDA) and glutathione (GSH) levels in rats with acetic acid-induced colitis. The melatonin-alginate gel formulations were prepared and their physico-pharmaceutical properties were determined. Formulation M5, which contained 3% of sodium alginate and 20% polyethylene glycol, was used for in vivo studies. The in vivo studies were conducted in rats with acetic acid-induced colitis. NOx, MDA and GSH levels were determined and histological investigations were performed. It was found that formulation M5 was the most suitable formulation for the colon-specific melatonin gel, in terms of pH, viscosity, drug release and mucoadhesion properties. The MDA levels in the tissues of Group 2 (treated with an intracolonic gel formulation without melatonin) were found to be significantly higher than in Group 1 (the untreated group). NOx levels decreased with the intracolonic and systemic melatonin treatment in the colitis-induced rats. Neither intracolonic nor intra-peritoneal (IP) melatonin treatment affected GSH levels. The epitelization of the colon tissues in groups administered with intracolonic melatonin, IP melatonin, and the intracolonic gel formulation without melatonin was much better than that found in the untreated group. It was concluded that melatonin participated in various defense mechanisms against the colonic inflammatory process, and that the dose, route and formulation type were the most important parameters in the effectiveness of melatonin.     

The therapeutic potential of drugs targeting the arginase pathway in asthma

Arginine metabolism by arginases may be of importance in health and disease, either by competing with nitric oxide synthases for the common substrate or by the production of L-ornithine. L-Ornithine serves as a precursor for L-proline and polyamines, which may be involved in tissue remodelling by promoting collagen synthesis and cell proliferation. Arginase activity potentiates airway reactivity by reducing the production of bronchodilatory nitric oxide. Increased arginase activity has been implicated in the development of allergen-induced airway hyper-responsiveness in experimental asthma. In addition, reduced L-arginine availability to inducible nitric oxide synthase by arginase may lead to an increased production of peroxynitrite, contributing to increased airway smooth muscle contractility, airway inflammation and cell damage in this disease. Recent studies demonstrate that the upregulation of arginase by T helper type 2 cytokines in lung tissue as well as in cultured airway fibroblasts indicates a possible role of the enzyme in airway re-modelling. These findings, in conjunction with human studies showing a role for arginase in acute asthma, open a new horizon for the therapeutic potential of drugs targeting the arginase pathway in asthma.     

Protective effect of yellow tea extract on N-nitrosodiethylamine-induced liver carcinogenesis

Context Yellow tea containing the same catechins as other types of tea but in different proportions has been suggested to possess potent anticancer activities.

Objective This study investigates the chemopreventive effect of yellow tea aqueous extract against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis in rats by employing histological and biochemical methods.

Materials and methods Wistar rats were divided randomly into four groups: control (I), yellow tea (II), NDEA (III), and yellow tea?+?NDEA (IV). Groups II and IV were exposed via a diet to yellow tea extract in a concentration of 10?g/kg feed; groups III and IV received 0.01% NDEA in drinking water. The experiment lasted for 13 weeks.

Results Daily intake of yellow tea in an average dose of 800?mg/kg b.w. alleviated the carcinogenic effect of NDEA as evidenced by reversed histopathological changes towards normal hepatocellular architecture and decreased lipid peroxidation, protein carbonyl formation, and DNA degradation by 64%, 37% and 15%, respectively, as compared with values obtained in NDEA alone-treated rats. Treatment with yellow tea extract caused protection of superoxide dismutase (SOD) and catalase (CAT); their activity was recovered by 47% and 12%, respectively, as compared with the NDEA-treated rats. Moreover, the extract normalized the NDEA-induced activity of paraoxonase 1 (PON1) and glutathione peroxidase (GPx), while a further increase in the level of reduced glutathione (GSH) was noticed.

Conclusions On the basis of these findings, it can be concluded that treatment with yellow tea partially protected the livers of rats from NDEA-induced hepatocarcinogenesis and that its antioxidant activity contributed to this effect.     

五种二苯乙烯类化合物对一氧化氮介导的血管舒张反应的影响及构效关系

目的研究5种二苯乙烯类化合物(白藜芦醇,RES;己烯雌酚,DES;二苯乙烯苷,THSG;反式二苯乙烯,TS和二苯乙烯苷水加成产物,SWA)对一氧化氮(NO)介导的舒张血管反应的影响,并探讨其作用与化学结构的关系.方法采用血管张力记录法,观察药物对大鼠主动脉血管环张力的作用,并测定药物对NO含量和对一氧化氮合酶(NOS)活性的影响.结果RES、DES、THSG、TS和SWA(1、3、10、30、100μmol·L-1)能剂量依赖性地舒张苯肾上腺素(10μmol·L-1)诱发的血管收缩反应,其效价强度,依次为THSG＞DES＞RES＞SWA=TS;与二甲亚砜比较,TS和SWA的作用不明显.L-Arg(1μmol·L-1)可增强RES、DES、THSG的舒张血管作用,而亚甲蓝(1μmol·L-1)却可削弱之.另外,RES、DES、THSG(10μmol·L-1)可增加血管总NO含量及NOS活性,其增加NOS活性作用的强度,依次为THSG＞DES＞RES＞SWA＞TS.结论RES、DES、THSG具有剂量依赖性依内皮性舒张血管作用,此作用与增加NO含量及NOS活性有关.它们结构中的乙烯双键对发挥舒张血管作用是必需的,苯环上的羟基的数量及位置决定着其作用强度.     

Role of the NO/sGC/PKG signaling pathway of hippocampal CA1 in morphine-induced reward memory

Although evidence suggests that the nitric oxide(NO)/soluble guanylyl cyclase(sGC)/cGMP dependent protein kinase(PKG) signaling pathway in the hippocampal CA1 region plays a key role in memory processing,it remains unclear whether this signaling cascade is involved in drug-induced reward memory.In this study,we investigated the role of the NO/sGC/PKG signaling pathway in the CA1 on morphine-induced reward memory using a conditioned place preference(CPP) paradigm.We found that rats receiving an intraperitoneal(ip) injection of 4 mg·kg-1 morphine exhibited CPP,whereas rats treated with only 0.2 mg·kg-1 morphine failed to produce CPP.Intra-CA1 injection of the neuronal NO synthase(nNOS) inhibitor 7-NI,the sGC inhibitor ODQ or the PKG inhibitor Rp-8-Br-PET-cGMPS had no effect on the acquisition of CPP by 4 mg·kg-1 morphine.Intra-CA1 injection of 7-NI blocked the consolidation of CPP induced by 4 mg·kg-1 morphine,and this amnesic effect of 7-NI was mimicked by ODQ and Rp-8-Br-PET-cGMPS.Intra-CA1 injection of the NOS substrate L-arg or the sGC activator YC-1 with an ineffective dose of morphine(2 mg·kg-1,ip) elicited CPP.This response induced by L-arg or YC-1 was reversed by pre-microinjection of Rp-8-Br-PET-cGMPS in the CA1.These results indicated that the activation of the NO/sGC/PKG signaling pathway in the CA1 is necessary for the consolidation of morphine-related memory.     

AE3通过NO通路参与心肌细胞缺氧预适应的保护作用

目的从细胞水平探讨阴离子交换蛋白3(AE3)在心肌细胞缺氧预处理(APC)保护作用中的意义以及与NO通路的关系。方法以原代培养的SD新生乳鼠心肌细胞为研究对象,建立缺氧/复氧(A/R)损伤和缺氧预适应保护模型。心肌细胞随机分为4组,Control组、A/R组、APC组和NO合成酶抑制剂L-NAME组。RT-PCR和Western blot法分别测定AE3的mRNA和蛋白表达,MTT法检测细胞存活率,生化自动分析仪测定LDH、CPK活性。结果 A/R处理后,心肌细胞AE3 mRNA转录及蛋白表达较Control组略增加。APC组AE3 mRNA转录及蛋白表达不仅均较Control组转录明显上调,而且较A/R组也明显上调。但预先加入NO合成酶抑制剂L-NAME则可抑制APC处理时AE3的表达增强,并取消APC的心肌保护作用。结论 AE3可能通过NO通路参与了心肌细胞APC的保护作用。     

L-精氨酸、L-硝基精氨酸对红藻氨酸诱导大鼠癫痫及其海马结构中iNOS mRNA表达的影响

目的　观察诱导型一氧化氮合酶 (iNOS)在红藻氨酸(KA)癫痫大鼠海马内的表达及L 精氨酸 (L Arg)和L 硝基精氨酸 (L NNA)慢性干预的影响。方法　采用惊厥剂量的KA(1 0mg·kg- 1 )诱导大鼠癫痫发作 ,以NOS抑制剂L NNA(50mg·kg- 1 )和NO前体L Arg(40mg·kg- 1 )进行干预 ,对大鼠的癫痫发作行为及KA后不同时间点的海马内i NOSmRNA ,通过RT PCR观察其表达。结果　KA可使动物发生时间相关性癫痫发作 ,L NNA预处理后使KA诱导的癫痫发作明显加重 ,而L Arg预处理后使KA诱导的癫痫发作减弱。iNOSmRNA在KA处理后 3h开始有微弱的表达 ,且随着时间的延长逐渐增加 ,2 4h达到最高水平 ,2d及3d时未见表达 ,但 7d时又出现高表达 ;经L NNA预处理的动物 ,KA后 1h其海马结构中未出现iNOSmRNA ,但L Arg预处理后再给予KA后 1h ,可见微弱的iNOSmRNA表达。结论　红藻氨酸给药后一定时间 ,癫痫大鼠海马结构中可出现iNOSmRNA表达 ,L Arg慢性干预也有一定影响     

The effect of aprotinin on ischemia–reperfusion injury in the rabbit kidney

Tissue subjected to a period of ischemia undergoes functional and morphological damage that increases during the reperfusion phase. In this study, the protective effect of aprotinin, which is a protease inhibitor, was assessed in a rabbit unilateral renal ischemia–reperfusion (I/R) model. New Zealand rabbits, weighing 1.5–2 kg, were randomized to receive either aprotinin 30.000 KIU kg⁻¹and 10.000 KIU kg⁻¹h⁻¹i.v. infusion (group I, n= 7) or equivalent volumes of 0.09% sodium chloride (SF) (group II, control, n= 7) i.v. 15 minutes before a 45 minutes interruption of left renal artery blood flow and then 45 minutes of reperfusion. Blood samples were obtained before and after the ischemia–reperfusion period for measurement of nitric oxide serum (NO) levels with the nitrite/nitrate colorimetric method. Histological changes were evaluated by quantitative measurements using a numerical score (0–4) and immunohistochemical analysis of inducible nitric oxide synthase (iNOS) expression was determined. A Wilcoxon W -test was used for statistical analysis of biochemical measurements and mean values were expressed as ± . Histological examination revealed the distinctive pattern of ischemic renal tissue injury with obvious signs of epithelial necrosis. The intensity of epithelial necrosis was more extensive in the SF group. Immunohistochemical analysis showed that there was severe immunostaining in the tubular epithelium in both cortical and medullary regions and iNOS expression was more intense in SF-only cases. The staining results for aprotinin cases did not differ much from the non-ischemic kidney. Biochemical analysis revealed an increase in serum NO levels in both groups (P< 0.05), but this was more evident in the SF group (mean NO levels were 38.63 ± 19.03μ mol L⁻¹in group I, 50.63 ± 24.28 μ mol L⁻¹in group II). No statistically important difference was observed between the two groups. These resultssuggest that aprotinin may be beneficial in the prevention of systemic inflammation after transient renal ischemia.     

Bladder instillation of Escherichia coli lipopolysaccharide alters the muscle contractions in rat urinary bladder via a protein kinase C-related pathway

Uropathogenic Escherichia coli is a common cause of urinary tract infection. We determined the effects of intravesical instillation of E. coli lipopolysaccharide (LPS, endotoxin) on muscle contractions, protein kinase C (PKC) translocation, and inducible nitric oxide synthase (iNOS) expression in rat urinary bladder. The contractions of the isolated rat detrusor muscle evoked by electrical field stimulations were measured short-term (1 h) or long-term (24 h) after intravesical instillation of LPS. One hour after LPS intravesical instillation, bladder PKC-alpha translocation from cytosolic fraction to membrane fraction and endothelial (e)NOS protein was elevated, and detrusor muscle contractions were significantly increased. PKC inhibitors chelerythrine and Ro32-0432 inhibited this LPS-enhanced contractile response. Application of PKC activator beta-phorbol-12,13-dibutyrate enhanced the muscle contractions. Three hours after intravesical instillation of LPS, iNOS mRNA was detected in the bladder. Immunoblotting study also demonstrated that the induction of iNOS proteins is detected in bladder in which LPS was instilled. 24 h after intravesical instillation of LPS, PKC-alpha translocation was impaired in the bladder; LPS did not affect PKC-delta translocation. Muscle contractions were also decreased 24 h after LPS intravesical instillation. Aminoguanidine, a selective iNOS inhibitor, blocked the decrease in PKC-alpha translocation and detrusor contractions induced by LPS. These results indicate that there are different mechanisms involved in the alteration of urinary bladder contractions after short-term and long-term treatment of LPS; an iNOS-regulated PKC signaling may participate in causing the inhibition of muscle contractions in urinary bladder induced by long-term LPS treatment.     

The cannabinoid 1 receptor antagonist AM251 produces nocifensive behavior via activation of ERK signaling pathway

Intrathecal (i.t.) injection of AM251, a cannabinoid 1 (CB₁) receptor antagonist, into the spinal lumbar space of mice elicited a behavioral response consisting of biting and licking with a few scratchings. In this study, we investigated to determine whether i.t. AM251 could influence the activity of extracellular signal-regulated kinase-1 and -2 (ERK1/2), a mitogen-activated protein kinase (MAPK) in neuronal nitric oxide synthase (nNOS) and inducible NOS (iNOS) activation. The CB₁ receptor agonist ACEA, neurokinin 1 (NK₁) receptor antagonists and NMDA receptor antagonists, inhibited i.t. AM251-induced behavioral response in a dose-dependent manner. The CB₂ receptor agonist, JWH-133 gave no effect on response elicited by i.t. AM251. Both non-selective NOS inhibitors, l-NAME and 7-NI, and N^ω-propyl-l-arginine, a selective inhibitor of nNOS resulted in a dose-dependent inhibition of i.t. AM251-induced behavioral response. The selective iNOS inhibitor, 1400W, in relatively large doses, inhibited in a non dose-dependent manner. The i.t. injection of AM251 produced a definite activation of ERK1/2 in the lumbar dorsal spinal cord. Behavioral experiments showed that U0126, a MAPK/ERK kinase (MEK) inhibitor, dose-dependently attenuated the behavioral response to i.t. AM251. Spinal activation of ERK1/2 following i.t. AM251 was reduced clearly by N^ω-propyl-l-arginine and U0126, while 1400W gave a significant effect on only ERK1 activation. These findings suggest that the nNOS-ERK pathway in spinal cord neurones plays an important role in AM251-induced nocifensive behavior and its inhibition may provide significant anti-nociception.