绞股蓝总皂甙（GPS）对大鼠脾脏淋巴细胞增殖功能的影响及其与去甲肾上腺素

本文以神经内分泌免疫调节网络学说及祖国医学的整体观为指导思想，研究观察了我国民间常用草药绞股蓝的活性成分-绞股蓝总皂甙（GPS）对大鼠脾脏淋巴细胞增殖功能的影响及其与下丘脑，脾脏去甲肾上腺素（NE）以及血浆皮质酮的相互关系，结果表明，大鼠ipGPS,10及20mg.kg^-1。d^-1共7d，其脾细胞对丝裂原ConA诱导的增殖反应明显增强，以10mg.kg^-1.d^-1剂量组更为显著，同时，以高效液相色谱电化学检测器测定单胺类神经递质的结果表明，下丘脑NE含量下降脾脏NE亦明显降低，与脾细胞增殖反应呈负相关，此外，血浆皮质酮水平下降，结果提示，GPS对免疫反应的影响，与作用于神经内分泌免疫调节网络，进而发挥免疫增强作用具有密切关系。     

吗啡对淋巴细胞反应性的影响

本文探讨小鼠或大鼠一次性sc吗啡对分裂原诱导的淋巴细胞增殖反应的影响。结果,吗啡抑制Con A诱导的小鼠或大鼠全血淋巴细胞增殖反应,作用呈浓度依赖关系;但脾淋巴细胞反应性并未明显受损,即使吗啡给药浓度增至50 mg·kg~(-1)。如分离大鼠全血单个核细胞,再观察其对Con A的反应性,则吗啡的抑制活性依然存在,提示全血中的血浆成分不是全血和脾淋巴细胞对吗啡作用敏感性不同的原因。进一步实验发现,纳洛酮10 mg·kg~(-1)预处理可完全拮抗吗啡25 mg·kg~(-1)所致小鼠和大鼠全血淋巴细胞反应性下降,使其恢复至正常水平;而单独给予纳洛酮,对脾和全血淋巴细胞增殖皆无影响。结果表明,吗啡整体给药的免疫调节作用与药物剂量及淋巴细胞的组织来源有关,且其效应通过阿片受体介导。     

松果体和褪黑激素对大鼠脾淋巴细胞增殖和地诺前列酮产生的影响(英文)

目的:研究松果体和褪黑激素对大鼠脾淋巴细胞增殖及地诺前列酮产生的影响.方法:采用松果体切除术,淋巴细胞增殖反应测定及地诺前列酮放射免疫检定法.结果:大鼠脾淋巴细胞增殖反应存在昼夜节律.松果体切除后,此昼夜节律消失,脾淋巴细胞增殖反应降低,而脾脏地诺前列酮增加.16:00ip褪黑激素(Mel)10 μg·kg~(-1)·d~(-1)连续7 d能恢复之,且促进正常大鼠脾淋巴细胞增殖反应,抑制脾地诺前列酮的产生.结论:松果体Mel促进大鼠脾淋巴细胞增殖反应与抑制脾脏地诺前列酮的产生有关系。     

白芍总甙对大鼠佐剂性关节炎及其免疫功能的影响

本文研究了白芍总甙(TGP)对大鼠佐剂性关节炎(AA)的治疗作用及其机理。TGP 50 mg·kg~1·d~1 ig,连续11d对大鼠多发性关节炎有明显的防治作用,同时可使AA大鼠腹腔巨噬细胞升高的H_2O_2和白细胞介素(IL-1)水平下降,并可使AA大鼠低下的胸腺细胞有丝分裂原反应及脾淋巴细胞产生IL-2能力恢复正常。表明TGP对AA大鼠有抗炎和机能依赖性的免疫调节作用。     

去胸腺对大鼠糖代谢的影响及地黄寡糖对其的调节作用

目的　观察去胸腺 (Tx)大鼠血糖、血浆胰岛素水平及肝糖原的变化及地黄寡糖 (ROS)对去胸腺大鼠糖代谢的调节作用。方法　① 4wk龄Wistar大鼠手术摘除胸腺 ,测定大鼠去胸腺 3、4、8、15mon后血浆葡萄糖、肝糖原含量、血浆胰岛素水平 ;②观察ROS(2 5 0mg·kg-1,po,× 6 0d)给予去胸腺术 7月后对大鼠脾淋巴细胞增殖、血糖、肝糖原、血浆胰岛素及皮质酮水平的影响。结果　①大鼠去胸腺术后 3～ 15mon血糖无明显变化 ,但从 8mon起肝糖原含量及胰岛素水平均升高 ;②ROS可基本逆转去胸腺大鼠糖代谢变化 ,使之向正常发展 :使肝糖原由高向正常转化 ;血浆胰岛素水平在Tx大鼠有升高趋势 ,ROS可使之恢复正常 ;血浆皮质酮水平在Tx大鼠有下降 ,ROS可使之恢复上升 ;ROS可逆转因去胸腺引起之脾淋巴细胞增殖下降。结论　大鼠去胸腺可引起糖代谢的某些变化 ,ROS可以大部分逆转这种变化     

糖皮质激素对美沙酮抑制海洛因依赖大鼠戒断反应的影响

目的··:探讨海洛因依赖大鼠催促戒断反应强度与应激反应程度的关系和糖皮质激素对美沙酮抑制海洛因依赖大鼠催促戒断反应的影响。方法··:用海洛因建立大鼠身体依赖模型,以体重下降百分率、戒断症状评分为成瘾强度指标并分别测定给药前及给药后不同时间的血浆ACTH和血清皮质酮作为应激程度指标。结果··:在戒断反应程度随用药时间延长而增强的同时,血中与应激有关的主要激素ACTH、皮质酮也呈渐增趋势,提示戒断反应出现时伴有应激反应并与之呈正相关;美沙酮20mg·kg-1加地塞米松10mg·kg-1控制大鼠催促戒断症状的效果不仅优于单用美沙酮20mg·kg-1或地塞米松10mg·kg-1(P<0.05),而且与大剂量美沙酮30mg·kg-1疗效相近(P>0.05)。结论··:糖皮质激素有协同美沙酮抑制海洛因依赖大鼠催促戒断反应的作用,可提高美沙酮的脱毒治疗效果。     

白芍总甙的免疫调节作用及机理

本文报道TGP的免疫调节作用,并探讨其作用机理。TGP 5 mg·kg~(-1)·d~(-1) ip 5～8 d对Cy诱导的小鼠DTH反应增高或降低呈反向调节,也可拮抗Cy诱导的小鼠溶血素生成量下降,表现出双向调节特征。TGP本身无有丝分裂原样作用,但终浓度45和450 ng/ml可促进ConA诱导小鼠脾淋巴细胞的增殖;同样浓度还可促进NDV诱导的人脐血白细胞产生IFNα,TGP的这种免疫增强作用可能是其体内向上恢复免疫功能的机理之一。TGP 5～10 mg·kg~(-1)·d~(-1) ip 4～8 d对DXM抑制小鼠溶血素的生成及DTH反应无明显拮抗作用,同时TGP还可使正常小鼠和DXM处理的SRBC致敏小鼠血浆CS水平下降。     

金属硫蛋白对大鼠硝酸甘油耐药性的影响(英文)

目的:评价金属硫蛋白(metallothionein, Met)在体内是否能改善硝酸甘油耐药的发生。方法:大鼠给予硝酸甘油(nitroglycerin, Nit)贴剂治疗两天(0.05 mg·h~(-1))以产生耐药。于耐药大鼠预先给予ZnCl_2以诱导内源性Met的合成及给予外源性Met15 mg·kg~(-1)·d~(-1)连续2 d。结果:Nit ZnCl_2组大鼠肝脏、血浆Met明显高于对照组(C组)。Nit组大鼠离体主动脉环的舒张反应最低。Nit ZnCl_2组大鼠及Nit Met组大鼠对SNP的降压反应明显强于Nit组。结论:外源性Met或内源性诱导合成的Met可以改善大鼠Nit耐药的发生。     

孕酮对大鼠吗啡奖赏效应及下丘脑和纹状体内单胺递质水平的影响

目的:观察孕酮对于吗啡所致奖赏效应及下丘脑、纹状体内单胺类神经递质水平的影响。方法:采用大鼠条件性位置偏爱(CPP)模型,建立离体电化学检测技术高效液相色谱法测定大鼠下丘脑及纹状体内去甲肾上腺素(NE)、多巴胺(DA)和5-羟色胺(5-HT)的含量。结果:吗啡(5mg·kg-1)可诱导大鼠产生稳定的CPP效应;孕酮(5mg·kg-1及20mg·kg-1)本身不产生CPP效应,但能抑制吗啡诱导的CPP效应。与对照组比较,吗啡诱导CPP形成时,下丘脑内NE水平明显升高(P<0.05),纹状体内NE、DA和HT的水平明显升高(P<0.05,P<0.01)。与吗啡组比较,合用20mg·kg-1孕酮使纹状体内DA水平显著下降(P<0.01)。结论:孕酮对吗啡的CPP效应具有一定的抑制作用,其机制可能与降低纹状体内DA水平有关。     

硒对大鼠钴心肌病的保护作用

用氯化钴(Co5 m g/kg·d~(-1)×7 ip)引起大鼠钴心肌病,探讨硒的保护作用。预先给硒(Se50μg/kg·d~(-1)×14iP)可防止钴所致心肌损害,表现为血浆CPK和GOT活性下降以及心肌不出现组织病理学改变。给硒可提高心肌硒水平和谷胱甘肽过氧化物酶活性,但对心肌脂质过氧化物含量无影响。与钴组大鼠相比,硒加钴组大鼠心肌琥珀酸脱氢酶(SDH)染色反应增强、脂质染色和游离脂肪酸水平降至正常,说明硒的保护作用机理可能在于:防止钴所致心肌SDH活性的抑制和脂代谢障碍。     

尼美舒利诱导人鼻咽癌CNE2细胞凋亡作用

目的观察尼美舒利（NIM）诱导人鼻咽癌CNE2细胞凋亡作用。方法0,0.05,0.1,0.2,0.4,0.8 mmol&#8226;L－1NIM作用于体外培养的CNE2细胞株,光学显微镜观察细胞形态和数量变化,透射电子显微镜观察细胞形态和结构变化,噻唑蓝（MTT）法检测细胞悬液吸光度值,流式细胞术（FCM）检测细胞周期分布和凋亡率,蛋白免疫印迹反应（Western Blot）检测细胞环氧化酶2（COX 2）蛋白表达情况。结果不同浓度NIM作用3 d后,CNE2细胞皱缩,数量减少,与药物浓度呈正相关;透射电镜下,细胞形态结构随NIM浓度增加而出现不同程度破坏和死亡征象;相同作用时间下,NIM浓度越高,吸光度值越低;FCM结果显示,NIM各剂量组均在G0/G1峰前出现一个亚二倍体峰（凋亡峰）,随着NIM浓度增高,G0/G1期细胞所占比例逐渐下降,G2/M期细胞比例升高,凋亡率逐渐增高;Western Blot结果显示,随着NIM浓度增加,COX 2蛋白表达量逐渐减少。上述结果均与NIM浓度相关,经统计学处理,与对照组和相邻前一浓度组比较,均差异有统计学意义（P＜0.05）。结论NIM能诱导人鼻咽癌CNE2细胞凋亡,且呈剂量依赖性,该作用与抑制COX 2有关。     

尼美舒利与阿霉素联合应用对肝癌HepG_2细胞增殖及凋亡的影响

目的探讨尼美舒利(n im esu lide,NIM)联合阿霉素(adriamyc in,ADM)对人肝癌细胞株HepG2的增殖抑制及诱导凋亡作用。方法采用MTT比色法检测药物的生长抑制作用,应用金正均法判断两药的相互作用,吖啶橙荧光染色观察细胞的形态学改变,流式细胞仪(flow cytom etry,FCM)检测细胞凋亡率。结果MTT结果显示NIM(25、50、100μmol.L-1)与ADM(0.156,0.313,0.625 mg.L-1)联合应用对人肝癌细胞株HepG2的增殖抑制均有不同程度的协同作用(q>1.15),联合用药组与ADM各单药组相比差异有显著性(P<0.01)。吖啶橙荧光染色可见典型的凋亡形态学特征。FCM检测凋亡显示NIM 100μmol.L-1和ADM2.5 mg.L-1单独及联合应用48 h后DNA直方图上均出现典型的亚二倍体“凋亡峰”,联合用药组凋亡率(19.6%)明显高于各单独用药组(2.48%和10.6%)。结论NIM与ADM联合应用具有协同抑制人肝癌细胞株HepG2细胞增殖与诱导其凋亡作用。     

Active fraction combination from Liuwei Dihuang decoction(LW-AFC) ameliorates corticosterone-induced long-term potentiation impairment in mice in vivo

Liuwei Dihuang decoction(LW), a classic formula in traditional Chinese medicine(TCM), has been used for nearly one thousand years for various diseases with characteristic features of kidney yin deficiency. LW consists of 6herbs including Dihuang[prepared root of Rehmannia glutinosa(Gaertn) DC], Shanyao(rhizome of Dioscorea polystachya Turcz), Shanzhuyu(fruit of Cornus officinalis Siebold Zucc), Mudanpi(root bark of Paeonia × suffruticosa Andrews),Zexie(rhizome of Alisma plantago-aquatica L) and Fuling[scleorotia of Wolfiporia extensa(Peck) Ginns]. LW-active fraction combination(LW-AFC) is extracted from LW, it is effective for the treatment of kidney yin deficiency in many animal models. There are 3 fractions in LW-AFC, a polysaccharide fraction(LWB-B), a glycoside fraction(LWD-b) and an oligosaccharide fraction(CA-30). Our previous results indicate that LW-AFC has similar pharmacological effects to LW, modulating the balance of the NIM network. LW-AFC has positive effects in many animal models of kidney deficiency or disturbance of the NIM network. LW-AFC could improve the cognitive ability in Alzheimer′s disease(AD) animal models(APP/PS1, SAMP8), where modulating immune function and balancing the NIM network may play an important role in its cognition improving effects. Our study also showed that LW-AFC had protective effects on stress-induced disturbances of the NIM network. However, the underlying mechanisms remain elusive and need further investigation. OBJECTIVE This study evaluated the effects of LW-AFC and the active fractions(polysaccharide, LWB-B; glycoside, LWD-b; oligosaccharide,CA-30) on corticosterone(Cort)-induced long-term potentiation(LTP) impairment in vivo. METHODS LTP was used to evaluate the synaptic plasticity. LW-AFC was orally administered for seven days. The active fractions were given by either chronic administration(ig, ip, 7 d) or single administration(icv, ig, ip). Cort was injected subcutaneously 1 h before the high-frequency stimulation(HFS) to induce LTP impairment. Moreover, in order to research on the possible effective pathways, an antibiotic cocktail and an immunosuppressant were also used. RESULTS Chronic administration(ig) of LW-AFC and its three active fractions could ameliorate Cort-induced LTP impairment. Single administration(icv, ig, ip) of any of the active fractions had no effect on Cort-induced LTP impairment, while chronic administration(ig, ip) of LWB-B or LWD-b showed positive effects against Cort. Interestingly, CA-30 only showed protective effects via ig administration,and there was little effect when CA-30 was administered ip In addition, when the intestinal microbiota was disrupted by application of the antibiotic cocktail, CA-30 showed little protective effects against Cort. The effects of LW-AFC were also abolished when the immune function was inhibited. In the hippocampal tissue, Cort treatment increased corticosterone and glutamate, and LW-AFC could inhibit the Cort-induced elevation of corticosterone and glutamate; there was little change in D-serine in Cort-treated animals, but LW-AFC could increase the D-serine levels. CONCLUSION LW-AFC and its three active fractions could ameliorate Cort-induced LTP impairment. Their protective effects are unlikely by a direct way, and immune modulation might be the common pathway. CA-30 could protect LTP from impairment via modulating the intestinal microbiota. Decreasing corticosterone and glutamate and increasing D-serine in the Cort-treated animals' hippocampal tissue might be one of the mechanisms for the neural protective effects of LW-AFC. Further study is needed to understand the underlying mechanisms.     

Nimesulide interaction with membrane model systems: Are membrane physical effects involved in nimesulide mitochondrial toxicity?

Nimesulide (NIM), a widely used nonsteroidal anti-inflammatory drug (NSAID), is known to interfere with mitochondrial physiology and to cause idiosyncratic hepatotoxicity. In this study, we characterized the effects of NIM on the physical properties of membrane models containing the main phospholipid classes of the inner mitochondrial membrane: phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL). NIM binding/incorporation was observed with the mitochondrial membrane mimicking model composed of dioleoyl PC (DOPC), dioleoyl PE (DOPE) and tetraoleoyl CL (TOCL) at a 1:1:1 M ratio, as well as an increase of membrane permeability, monitored by calcein release, and an increase of lipid disorder, evaluated by fluorescence anisotropy of DPH-PA. Consistently, DSC thermograms of dipalmitoyl PC (DPPC) and a mixture of dipalmitoyl PE (DPPE) and TOCL (7:3 M ratio) showed a NIM-induced decrease of the cooperativity of the phase transition and a shift of the DPPC endotherm to lower temperatures. On the other hand, ³¹P NMR studies with the ternary lipid model indicated a stabilizing effect of NIM on the lipid bilayer structure. Quenching of the fluorescent probes DPH and DPH-PA revealed a peripheral insertion of NIM in the hydrophobic portion of the bilayer. Our data indicate that NIM may influence mitochondria physiological processes by interfering with membrane structure and dynamics. The relevance of these findings will be discussed in terms of the reported NIM effects on mitochondria transmembrane potential, protonophoresis, and induction of the permeability transition pore.     

Inhibition of the mitochondrial permeability transition by the nonimmunosuppressive cyclosporin derivative NIM811

Cyclosporin A (CsA) shows cytoprotective properties in many cellular and in vivo models that may depend on interference of the interaction of cyclophilin A with calcineurin or of cyclophilin D with the mitochondrial permeability transition (PT) pore. The nonimmunosuppressive cyclosporin derivative N-methyl-4-valine-cyclosporin (PKF220-384) inhibits the mitochondrial permeability transition (MPT) like CsA but without calcineurin inactivation. PKF220-384 has been used to discriminate between PT pore- and calcineurin mediated effects but is no longer available. Here, we evaluated the effects of another nonimmunosuppressive cyclosporin derivative, N-methyl-4-isoleucine-cyclosporin (NIM811) on the MPT. Using two newly developed microtiter plate assays, one measuring mitochondrial swelling from absorbance and the other measuring mitochondrial membrane potential from changes in safranin fluorescence, we show that NIM811 blocks the MPT induced by calcium and inorganic phosphate, alone or in combination with the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, the complex I inhibitor rotenone, and the prooxidant t-butylhydroperoxide. NIM811 was equipotent to CsA and half as potent as PKF220-384. Additionally, we show that NIM811 blocks cell killing and prevents in situ mitochondrial inner membrane permeabilization and depolarization during tumor necrosis factor-alpha-induced apoptosis to cultured rat hepatocytes. NIM811 inhibition of apoptosis was equipotent with CsA except at higher concentrations: CsA lost efficacy but NIM 811 did not. We conclude that NIM811 is a useful alternative to PKF220-384 to investigate the role of the mitochondrial permeability transition in apoptotic and necrotic cell death.     

Effect of nimodipine on drinking behavior measured in the runway: comparison and interaction with (+/-)-amphetamine

The aim of the present study was to evaluate the ability of the calcium channel blocker (CCE), nimodipine (NIM), to interact with (+/-)-amphetamine (AMPH) in modifying ingestive behavior. Rats performed in a water-reinforced runway paradigm with multiple trials. Water was available in sufficient quantity to produce satiety under control conditions as measured by a decline in response rate over the session. NIM and AMPH, given alone, did not produce significant effects on performance but produced behavioral changes when administered in combination. In particular, the combination of the highest doses (13 mg/kg i.p. NIM plus 0.56 mg/kg i.p. AMPH) initially depressed both running and drinking, whereas in later trials it increased running rate, without producing a parallel increase in water intake. These results suggest that NIM enhances AMPH-produced inhibition of drinking, whereas it first depresses and then enhances the AMPH-mediated runway performance, suggesting the rate dependency of this latter effect.     

Effects of nimesulide,a cyclooxygenase-2 selective inhibitor,on colitis induced tumors

Cyclooxygenase-2 (COX-2) is known to suppress sporadic colorectal cancer, but effect of selective COX-2 inhibitor in UC-associated neoplasia is still unknown. This study investigated effect of a selective COX-2 inhibitor on colorectal carcinogenesis in experimental murine UC. Chronic colitis was induced in mice by four cycles of administration of dextran sulfate sodium (DSS) (i. e., 5 % DSS for 7 days and distilled water for the following 14 days), and the mice were sacrificed 120 days after the end of the fourth cycle. The mice were divided into the following five groups: Group A, served as a disease control; Group B, received a diet mixed with 400 ppm of nimesulide (NIM), a selective COX-2 inhibitor, during the whole period; Group C, received NIM during the four cycles of DSS administration; Group D, received NIM for 120 days from the end of the fourth cycle; Group E, served as a normal control. In Group D, NIM significantly suppressed the occurrence of dysplasia and/or cancer. The results show that NIM inhibited both dysplasia and cancer in DSS-treated mice, thus showing that NIM has preventive effects on the remission phase of carcinogenesis. Received 20 July 2006; revised 21 August 2006; accepted 4 September 2006     

内皮素放射免疫分析在药理中的应用

通过结扎大鼠双侧颈总动脉建立脑缺血再灌注损伤动物模型,采用放射免疫分析技术检测其体内的内皮素（ET）水平,来研究甘糖酯（PGMS）和尼莫地平（NIM）对缺血再灌注损伤大鼠脑实质的影响,实验结果表明,PGMS和NIM都能降低缺血再灌注损伤大鼠血浆及脑组织中ET的含量,保护缺血引起的神经元损伤,为临床治疗脑血管疾病提供了新的思路。     

Effects of nimodipine and nifedipine upon behavior and regional brain monoamines in the rat

The effects of single and repeated (9 times) administration of two dihydropyridines (DHPs), nimodipine (NIM) and nifedipine (NIF) (5 mg/kg per 12 h and 2.5 mg/kg per 12 h, IP), on the behavior of male adult rats in the holeboard and in the plus-maze, were investigated. Besides, the effects of repeated administration of the drugs on the levels of dopamine (DA), serotonin (5-HT), and their respective major metabolites in several regions of the central nervous system (CNS) were also assessed. The effects of single and repeated administration of the drugs were similar. Both DHPs caused a significant decrease in general motor activity which was evident in both tests and more marked with the higher doses. The two exploratory parameters measured in the holeboard, i.e. head-dipping frequency and duration, were dissociated under pharmacological treatment. The drug-treated animals did not show an increased emotionality in the holeboard. However, in the plus-maze, NIF (5 mg/kg) and to a lesser extent NIM, appeared to induce some anxiety-related responses which may be secondary, at least in part, to the depressing effect on activity and exploration. Repeated administration of NIM and NIF caused an increase in striatal DA and DOPAC levels, whilst no effects were found on serotonergic system in any of the regions of the CNS analyzed.     

Alternative transcripts of the GABA(A) receptor epsilon subunit in human and rat

The effect of 1,4-dihydropyridine (DHP) calcium channel blockers (CCBs), nimodipine (NIM) and lercanidipine (LDP) on the analgesic response of selective kappa-opioid receptor agonists, U50,488H, PD117,302 and U69,593 was determined in male Sprague-Dawley rats using the tail-flick test. The effect of NIM on development of tolerance to U50,488H-induced analgesia and the status of brain DHP-sensitive Ca(2+) channel (L-type) binding sites in both U50,488H-naive and tolerant rats was determined using the highly selective DHP radioligand, [(3)H]PN200-110. Tolerance was induced by injecting U50,488H (25 mg/kg, i.p.) twice daily for 4 days. Intraperitoneal (i.p.) injection of kappa-opioid receptor agonists produced a dose-dependent acute analgesic response. NIM (1 mg/kg; i.p.) and LDP (0.3 mg/kg; i.p.) used in the study produced no tail-flick analgesia. Administration of NIM and LDP (15 min prior) significantly potentiated the analgesia produced by three kappa-opioid receptor agonists. Tolerance developed completely to the analgesic effect induced by U50,488H (25 mg/kg, i.p.) administered on the 5th day. NIM (1 mg/kg, i.p.) twice daily for 4 days not only completely inhibited the development of tolerance to analgesic response but also significantly potentiated it (supersensitivity). There was a significant up-regulation of DHP binding sites (B(max): +41%) in whole brain membranes of tolerant rats when compared to vehicle treated naive rats, implicating increased influx of Ca(2+) through L-type channels in kappa-opioid tolerance. U50,488H (25 mg/kg, i.p.) and NIM (1 mg/kg, i.p.) twice daily for 4 days also resulted in an equivalent up-regulation of DHP binding sites (+36%) as that of U50,488H alone. These results strongly suggest a functional role of L-type Ca(2+) channels in the regulation of pain sensitivity, mechanism of kappa-opioid analgesia and expression of tolerance.