两面针结晶8的解痉和镇痛作用研究

结晶-8,是从两面针提出的一种单体。当浓度为1×10^-6～1×10^-4g/ml对正常离体豚鼠回肠活动无影响,但对乙酰胆硷、匹鲁卡品、氯化钡及组织胺所致肠肌收缩有明显的松弛作用;结晶-8腹腔注射10 mg/kg有明显抑制小鼠扭体反应;8～20 mg/kg明显提高家兔及大鼠痛阈,200μg/kg脑室注射亦有明显提高大鼠痛阈。其镇痛作用不被丙烯吗啡(5 mg/kg)所拮抗,而被利血平(4 mg/kg)所对抗。表明结晶-8的解痉作用直接作用于肠平滑肌。而镇痛作用具有中枢性,与吗啡受体无直接关系,但与脑内单胺类介质有关。     

N-酰基-N′-(2-吲哚甲酰基)肼的合成及其生理活性

2-吲哚甲酰肼与取代基为H,CH₃,ClCH₂,C₂H₅,CH₃(CH₂)₃,4-Br-C₆H₄和3-吡啶基的甲酰氯在DMF中反应时均得双酰肼化合物。但在乙腈中与乙酰氯或丙酰氯反应时,分别得到两种失水产物,经¹³C核磁共振仪分析表明其为吲哚2位(口恶)二唑取代的化合物,其余仍为双酰肼化合物。体外试验显示;N-甲酰基,N-氯代乙酰基-2-吲哚甲酰肼(Ⅰ,Ⅲ)和2-[2-(5-乙基)-1,3,4-(口恶)二唑]-吲哚(Ⅸ)对强毒人型结核菌H₃₇RV有抑制作用。     

家兔隔区和伏核内钙、镁离子对抗电针镇痛与吗啡镇痛

本文通过脑内慢性埋植套管向家兔一侧隔区或伏核内注射微量(10 nmol)CaCl₂或MgCl₂,可显著对抗吗啡镇痛和电针镇痛。注入核外则无效。家兔一侧隔区或伏核内注入阳离子螯合剂CDTA(20 nmol)加强吗啡镇痛和电针镇痛。文中就Ca²⁺,Mg²⁺作用的相似性,电针镇痛与吗啡镇痛机理的相似性,以及伏核和隔区在上述镇痛中的重要性进行了讨论。     

可乐定镇痛与中枢Ca2+的关系

用大鼠甩尾法和放射配基结合实验,探讨了可乐定镇痛与中枢Ca²⁺的关系。CaCl₂(1μmol/rat,icv)和EGTA(0.2μmol/rat,icv)分别拮抗和增强可乐定(1mg/kg,sc)的镇痛。戊脉安(0.1μmol/rat,icy)对可乐定(1 mg/kg,sc)镇痛无明显影响,但可部分翻转CaCl₂对可乐定镇痛的拮抗。CaCl₂(1×10^-3mol)对[³H]-可乐定结合无明显抑制。结果表明可乐定镇痛与脑室周围组织中Ca²⁺浓度变化密切相关,Ca²⁺至少部分需经对戊脉安敏感的钙通道进入细胞内方可拮抗可乐定镇痛。推沦:可乐定镇痛与神经元内Ca²⁺有关。     

疟疾防治药物的研究——Ⅹ.2,4-二氨基-6-N1,N2-二取代肼基-喹唑啉类衍生物的合成及其抗疟作用

本文报道了2,4-二氨基-6-N¹,N²-二取代肼基-喹唑啉类衍生物的合成及其抗疟活性的研究。这类化合物的合成是以2,4-二氨基6-取代苄基氨基-喹唑啉为原料经亚硝化、还原成为2,4-二氨基6-(N¹-取代苄基)—肼基喹唑啉,再与相应的醛缩合而成。此类化合物经伯氏鼠疟原虫抑制性治疗初筛表明有少数具有一定的效果。有11个化合物经约氏鼠疟原虫—斯氏按蚊系统病因性初筛有效。其中化合物Ⅱ_1,7,8,11,15和Ⅲ₁口服2.5mg/kg,连续3天,可使受试小鼠全部得到保护。     

3-甲基芬太尼衍生物构效关系及受体结合特征研究

对3-甲基芬太尼的1-苯乙基、4-N-丙酰基进行了结构改造、测定了所合成化合物的镇痛活性及部分化合物的镇痛作用持续时间、阿片受体亲和力和对阿片受体亚型的选择性。结果表明,大部分化合物均有较强的吗啡样镇痛活性,强度约为吗啡的2～180倍。所试化合物的镇痛作用持续时间比芬太尼延长6～10倍。化合物1～4的受体亲和力(IC₅₀)约为10^-7～10^-3mol。化合物13对阿片μ-受体有较高的选择性,对大鼠脑膜的λ/δ比值大于700,对小鼠脑膜的μ/δ比值为1000。     

7-甲氧基-4′-羟基-3′-二乙胺甲基异黄酮(MHDF)对大鼠血流动力学和主动脉的作用

本实验观察了MHDF对整体大鼠血流动力学和离体大鼠胸主动脉的作用。结果表明iv MHDF(3～12.8 mg/kg)能降低大鼠左心室±dp/dt_max,V_max,V_pm和LVSP,延长T-dp/dt_max,减慢心率。MHDF还能舒张大鼠胸主动脉,ED₅₀为6.5×10^-6mol/L;非竞争拮抗NA和CaCl₂致主脉收缩,pD₂′为3.11±0.21和3.73±0.07;抑制高K⁺致主动脉收缩,IC₅₀为1.76×10^-5mol/L。提示MHDF对血管的作用与α受体阻断剂不同,而可能与钙拮抗有关。     

具有柔性亲电侧链的蒂巴因和奥利文衍生物的合成和生物活性

本文报道了三个新的阿片受体亲和标记配基的合成和初步药理实验的结果,其中化合物7α-双(2-氯乙基)胺基甲基-6,14-内亚乙烯基-四氢奥利文(3),简称α-CMO,在豚鼠回肠纵行肌(GPT),小鼠输精管(MVD)及大鼠脑(去小脑)P₂膜制品中均为阿片受体不可逆结合的激动剂。镇痛试验表明它的活性为吗啡的18倍,镇痛作用持续时间达二天之久。     

紫草素抗炎及对白三烯B4生物合成的抑制作用

皮下注射紫草素(shikonin)10mg.kg^-1对小鼠巴豆油耳炎症和大鼠酵母性足肿有明显抑制作用;在白细胞体外温孵系统中,紫草素在10^-4～10^-7mol·L^-1浓度范围内可浓度依赖性地抑制LTB₄和5-HETE生物合成,其50%抑制浓度(IC₅₀)分别为6.2×10^-7mol.L^-1和2.6×1O^-7mol·L^-1。此外,还报道紫草素几个天然衍生物对LTB₄生物合成的影响。     

双氢杨梅树皮素对兔胸主动脉条平滑肌收缩反应的影响

用兔胸主动脉条研究双氢杨梅树皮素对去甲肾上腺素(NE)、KCl和CaCl₂所致兔胸主动脉条收缩反应量效曲线的影响。双氢杨梅树皮素能显著地抑制NP、KCl和CaCl₂所致兔胸主动脉杂的收缩,量效曲线右移,最大反应降低,对高K⁺所致兔胸主动脉条收缩的抑制作用明显大于NE所致兔胸主动脉条收缩的抑制作用。双氢杨梅树皮素对NE引起的依赖内Ca²⁺释放的收缩有明显抑制作用,而对NE依赖细胞外Ca²⁺性收缩区在较高浓度时才显示抑制作用,提示双氢杨梅树皮素可能对电压依赖性钙通道(PDC)有选择性阻滞作用。     

维生素K3中枢镇痛效应的探讨

经由大鼠、小鼠甩尾及兔甩头法测痛,证实k₃具有剂量依赖的镇痛作用。兔侧脑室微量注射k₃亦有显著镇痛效应。k₃的镇痛作用可被阿片拮抗剂纳络酮所拮抗。实验观察到k₃与吗啡的镇痛效应间存在交叉耐受现象。一定浓度的k₃可抑制电场刺激所致豚鼠回肠纵肌标本的收缩,这一效应亦可被纳络酮部分逆转。小鼠经k₃预处理后对k₃的镇痛产生耐受;连续k₃大剂量预处理后纳络酮激发不产生跳跃。     

Morphine induced changes in ethanol-and water-intake are attenuated by the 5-HT3/4 antagonist tropisetron (ICS 205-930)

The opiate agonist morphine has been shown to increase ethanol intake and mesolimbic dopamine (DA) levels. Conversely, the 5-HT_3/4 antagonist tropisetron has been shown to decrease ethanol intake and morphine-induced increases in mesolimbic DA levels. This study was designed to test the effects of acutely administered tropisetron on morphine-induced changes in ethanol (6% v/v) and water intake in a two-bottle test procedure. Ten water restricted male rats were injected with combinations of morphine (0.0, 0.56, 1.0, 1.5, 10.0, and 17.0 mg/kg, SC) and tropisetron (0.0, 1.0, 10.0, and 17.0 mg/kg, SC) prior to test sessions. Morphine (1.0 and 1.5 mg/kg) significantly increased absolute (g/kg) and relative ethanol intake (ethanol/total fluid). Tropisetron alone did not affect ethanol or water intake. When tropisetron (10.0 and 17.0 mg/kg) was administered in combination with morphine (1.5 mg/kg), the increase in ethanol intake induced by morphine was attenuated. Tropisetron (1.0 mg/kg) reversed a decrease in ethanol intake induced by morphine (17.0 mg/kg). The two highest doses of tropisetron partially attenuated a significant decrease in water intake produced by morphine (17.0 mg/kg). These data suggest that opiate and 5-HT₃ mechanisms could interact in the regulation of ethanol intake. However, the doses of tropisetron tested were high and, therefore, the potential involvement of 5-HT₄ receptors or other neurotransmitter systems in regulating ethanol intake is discussed.     

Conditioned place preference: no tolerance to the rewarding properties of morphine

The effect of repeated morphine administration on conditioned place preference (CPP) using a novel treatment schedule, i.e., drug treatment was always contingent with the conditioned environmental stimuli, was investigated. We also examined whether changes in the μ- and κ-opioid receptor binding occurred in the brain of morphine-treated animals. Intraperitoneal (i.p.) administration of morphine (2 and 10 mg/kg) induced a place preference after 8 daily conditioning trials (4 morphine injections on alternate trials), the level of preference being the same with the two doses of the opiate. No change in place preference was observed in the morphine-treated rats at 2 mg/kg, when animals were further trained up to a total of 32 conditioning trials (16 morphine injections). Conversely, after 20 conditioning trials (10 morphine injections), a stronger CPP response developed in the morphine-treated rats at 10 mg/kg. Signs of morphine withdrawal were never detected in morphine-treated rats during the experiment. Loss of body weight (index of opiate dependence) was not observed either 24 h or 48 h after the last morphine administration. μ- and κ-opioid receptor density and affinity were not affected by repeated morphine administrations at either dose. The results demonstrate that no tolerance develops to the rewarding properties of morphine. Indeed, a sensitisation effect may occur at increasing doses of the opiate. Furthermore, changes in the rewarding effect of morphine are not dependent upon alterations in opioid receptors involved in the reinforcing mechanisms. Received: 31 October 1996 / Accepted: 7 February 1997     

Naloxone prevention of morphine LDR curve flattening associated with high-dose tolerance

Male wistar rats, previously made tolerant to morphine by at least 3 weeks of daily intraperitoneal (IP) injections of 20 mg/kg morphine-SO₄ (MS), were then given 200 mg/kg MS daily for 4 or 5 days. Tail immersion tests of antinociception, carried out before and after the 200 mg/kg MS treatment, indicated that the additional morphine treatment was followed by a large further decrease in opiate sensitivity, characterized by decreased slope of the log-dose/response curve (LDR curve flattening). The further decrease in opiate sensitivity was substantially reduced by naloxone-HCl (IP) in a dose of 10 mg/kg given 30 min before and 8 h after the 200 mg/kg MS injections, or a dose of 4 mg/kg given 45 min after the MS. It was concluded that LDR curve flattening produced by high doses of MS is mediated by specific opiate receptors, and is a true expression of a high degree of opiate tolerance in the intact rat.     

Interactive role of adenosine and dopamine in the opiate withdrawal syndrome

Adenosine reduces opioid withdrawal symptoms by activating A₁ adenosine receptors, probably by inhibiting excitatory amino acid release. Since blockade of A_2A adenosine receptors seems to enhance dopaminergic striatopallidal transmission, we evaluated the role of the purinergic system in the opiate withdrawal syndrome by using two A₁ receptor agonists [N⁶-cyclohexyladenosine, CHA and 2-chloro-N⁶-cyclopentyladenosine, CCPA], and two A_2A receptor antagonists (SCH 58261 and 8-(3-chlorostyryl)caffeine, CSC).Male adult rats received increasing doses of morphine sulphate suspended in 5 ml/kg of a sustained release preparation (40–100 mg/kg s.c.) daily for 4 days and 20 h after the last administration, the withdrawal syndrome was evoked by naloxone (5 mg/kg i.p.). Animals were observed for 30 min for signs of opiate withdrawal. Other groups of rats were implanted with concentric probes for microdialysis and dopamine levels were measured in the nucleus accumbens. CHA and CCPA (0.05, 0.1 or 0.5 mg/kg i.p.) significantly reduced "wet-dog" shakes, diarrhoea, teeth chattering, jumping and writhing. SCH 58261 and CSC (0.1, 0.5 or 1 mg/kg i.p.), given 10 min before naloxone, also reduced signs of opiate withdrawal. CHA plus SCH 58261 and CCPA plus CSC greatly enhanced the reduction of withdrawal signs observed with CHA and CCPA or CSC and SCH 58261 alone. In vivo microdialysis showed that naloxone significantly decreased DA release; this effect was prevented by pretreatment with systemic SCH 58261 and CSC, but not with CHA and CCPA. Our results demonstrate that A₁ and A_2A adenosine receptors mediate the effect induced by adenosine in opiate withdrawal syndrome and suggest that adenosine A₁ agonists and adenosine A_2A antagonists may be beneficial in the treatment of this syndrome.L. Stella and V. de Novellis share first authorship     

Effects of NMDA receptor channel blockers, dizocilpine and memantine, on the development of opiate analgesic tolerance induced by repeated morphine exposures or social defeats in mice

Development of tolerance to opiates involves various neurochemically and pharmacologically distinct processes. For instance, the diversity of opiate tolerance has been suggested by experiments comparing the establishment of diminished response to different effects of opiate agonists. Antagonists acting at N-methyl-d-aspartate (NMDA) receptors has become a very useful tool for studying opiate tolerance mechanisms since these drugs have been shown to retard the development of tolerance to analgesic properties of opiates. The present study compared the ability of two NMDA receptor channel blockers, dizocilpine and memantine, to affect the development of tolerance to morphine analgesia induced by repeated social defeat or by repeated morphine administrations. Male BALB/c mice were assessed for the tail-flick response before and after the defeat in five social confrontations, or before and after repeated morphine injections (20 mg/kg, s.c., once daily for 8 days). Repeated morphine injections were explicitly paired with environmental cues. Socially-defeated as well as morphine-treated mice developed significant tolerance to morphine analgesia. Separate groups of mice were exposed to repeated social confrontations or injections of morphine with each defeat or morphine injection followed by administration of either dizocilpine (0.03–0.3 mg/kg, i.p.) or low-affinity channel blocker memantine (3–30 mg/kg, i.p.). Both dizocilpine and memantine were effective in preventing the development of repeated morphine-induced tolerance to acute morphine analgesia. Treatments with NMDA receptor antagonists that retarded development of non-associative tolerance also suppressed the establishment of associative tolerance significantly. Social defeat-induced tolerance was prevented by dizocilpine but not by memantine. Our results suggest some degree of similarity in the mechanisms of morphine analgesic tolerance induced by pharmacological, contextual and social stimuli. Received: 13 December 1997 / Accepted: 15 April 1998     

Inhibitory effects of MPEP,an mGluR5 antagonist,and memantine,an <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="SmallCaps">D</Emphasis>-aspartate receptor antagonist,on morphine antinociceptive tolerance in mice

Abstract Rationale. Inhibition of N-methyl-D-aspartate (NMDA) receptors by memantine, an NMDA-receptor antagonist, and other antagonists of ionotropic receptors for glutamate inhibit the development of opiate antinociceptive tolerance. The role of metabotropic receptors for glutamate (mGluR) in opiate tolerance is less known. Objective. In the present study, we examined the effect of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), the mGluR type-I (subtype mGluR5) antagonist, as well as the effect of co-administration of low doses of memantine and MPEP on morphine antinociceptive tolerance in mice. Methods. Morphine antinociceptive activity was tested twice, before and after chronic morphine administration, in the tail-flick test using a cumulative dose–response protocol. Tolerance was induced by six consecutive days of b.i.d. administration of morphine (10 mg/kg, s.c.). Saline, memantine (7.5 mg/kg and 2.5 mg/kg, s.c.), MPEP (30 mg/kg and 10 mg/kg, i.p.) and the combination of both antagonists at low doses was given 30 min prior to each morphine injection during its chronic administration. A separate experiment assessed the effects of memantine, MPEP and their combination on acute morphine antinociception using a tail-flick test. Results. MPEP (30 mg/kg but not 10 mg/kg) as well as memantine (7.5 mg/kg but not 2.5 mg/kg) attenuated the development of tolerance to morphine-induced antinociception. When given together, the low doses of MPEP (10 mg/kg) and memantine (2.5 mg/kg) also significantly attenuated opiate tolerance. None of the treatments with glutamate antagonists produced antinociceptive effects or significantly affected morphine-induced antinociception. Conclusions. The data suggest that both mGluR5 and NMDA receptors may be involved in the development of morphine antinociceptive tolerance. Electronic Publication     

Adenosine receptor agonists attenuate and adenosine receptor antagonists exacerbate opiate withdrawal signs

Previous studies have demonstrated a role for adenosine in mediating opiate effects. Adenosine receptors and their functions have been shown to be regulated by chronic opiate treatment. This study examines the role of adenosine receptors in the expression of opiate withdrawal behaviors. The effects of single doses of parenterally administered adenosine receptor subtype-selective agonists and antagonists on opiate withdrawal signs in morphine-dependent mice were measured. Mice received subcutaneous morphine pellet treatment for 72 h and then underwent naloxone-precipitated withdrawal after pretreatment with adenosinergic agents. Adenosine agonists attenuated different opiate withdrawal signs. The A₁ agonistR-N ⁶(phenylisopropyl)adenosine (0, 0.01, 0.02 mg/kg, IP) significantly reduced wet dog shakes and withdrawal diarrhea, while the A_2a-selective agonist 2-p-(2-carboxethyl) phenylethylamino-5'-N-ethylcarboxamidoadenosine or CGS 21680 (0, 0.01, 0.05 mg/kg, IP) significantly inhibited teeth chattering and forepaw treads. Adenosine receptor antagonists enhanced different opiate withdrawal signs. The adenosine A₁ antagonist 1,3-dipropyl-8-cyclopentylxanthine (0, 1, 10 mg/kg, IP) significantly increased weight loss and the A₂ antagonist, 3,7-dimethyl-1-propargylxanthine (0, 1 and 10 mg/kg, IP) enhanced wet dog shakes and withdrawal diarrhea. Treatment effects of adenosinergic agents were not due to nonspecific motor effects, as demonstrated by activity monitoring studies. These results support a role for adenosine receptors in the expression of opiate withdrawal and suggest the potential utility of adenosine agonists in its treatment.Abstracts were presented at meetings of the Fifth International Symposium on Adenosine and Adenine Nucleotides in Philadelphia, Pa, May 9–13, 1994 and Society for Neuroscience in Miami Beach, FLa., November 13–18, 1994     

Effects of morphine on EEG in rats and their possible relations to hypo- and hyperkinesia

It was previously shown in rats that administration of cocaine ord-amphetamine in moderate doses produced alterations in EEG characteristic for activation of D₁ dopamine receptors, whereas large doses induced alterations resembling activation of D₂ dopamine receptors. Since morphine, among other effects, enhances the dopaminergic transmission, it was investigated whether this effect might be apparent in the EEG which was recorded telemetrically in awake, not restrained rats. In a moderate dose (3 mg/kg IP), morphine produced a desynchronisation and a general decrease of power in all of the frequency bands except beta-2. This effect was antagonized by naloxone (0.5 mg/kg IP) but only in part by the blocker of D₁ receptors SCH 23390 (0.2 mg/kg IP) and not by haloperidol in a dose which mainly blocks D₂ receptors (0.1 mg/kg IP). The dose of morphine used (3 mg/kg IP) produced only slight signs of behavioural activation. The results suggest that the decrease in power observed after this dose of morphine was only in part due to an activation of dopaminergic mechanisms via D₁ receptors and partly must be explained by other actions of morphine. A large dose of morphine (15 mg/kg IP) at the beginning produced catalepsy and muscular rigidity and subsequent behavioural activation; in the EEG during both behavioural phases a general increase in power in all of the frequency bands was observed which was most pronounced in the alpha-2 band (9.75–12.50 Hz). After repeated administration of this dose (14 times during a period of 21 days) a test dose of 15 mg/kg morphine led to a reversal of these effects resulting in behavioural activation and a decrease in power in most of the frequency bands. Accordingly, most but not all experimental conditions used led to consistent correlations between behavioural signs and EEG alterations after administration of morphine.     

In vivo apparent pA2 analysis in rats treated with either clocinnamox or morphine

Experiments tested the hypothesis that loss of agonist potency or effectiveness following irreversible antagonist or chronic agonist treatment may result from affinity changes at opioid receptors. Apparent affinity of naltrexone or nalbuphine for opioid receptors was measured in vivo in rats treated with either a single dose of the irreversible antagonist clocinnamox or repeated doses of morphine. Apparent affinity of each antagonist was estimated from its potency as an antagonist of discriminative stimulus or rate-decreasing effects of morphine in rats trained to discriminate 3.2 mg/kg morphine and saline. In control rats, apparent pA₂ values for naltrexone and nalbuphine were 7.5–7.6 and 5.3, respectively. In clocinnamox-treated rats, apparent pA₂ values for naltrexone were 7.2–7.7, suggesting that clocinnamox treatment did not alter affinity of naltrexone for sites through which morphine exerts behavioral effects. In rats treated repeatedly with morphine, apparent pA₂ values for nalbuphine were 5.1–5.3, suggesting that repeated morphine treatment did not alter affinity of nalbuphine for these sites. The observation that neither clocinnamox nor repeated morphine treatment altered in vivo affinity estimates for naltrexone or nalbuphine, respectively, suggests that the reductions in agonist potency produced by these treatments do not result from changes in affinity at opioid receptors.This work was supported by US Public Health Service Grant DA03796 and NIDA Research Scientist Development Award K02 DA00132 to A.M. Young. A portion of this work is presented in abstract form [Walker EA, Richardson TM, Young AM (1995) Apparent affinity estimates for opioid antagonists in rats treated with clocinnamox or chronic morphine. In: Harris LS (ed) NIDA Res Monogr 153: 450]