强啡肽A（1—17）所致大鼠运动障碍及对脊髓组织AC—cAMP水平的…

大鼠蛛网膜下腔注射强啡肽Ａ（１－１７），观察其所引起的行为变化及对脊髓组织ＡＣ－ｃＡＭＰ系统的影响。提示к型阿片受体和Ｌ型Ｃａ＾２＋通道参与了强啡肽Ａ（１－１７）所引起的大鼠运动障碍及对脊髓组织ＡＣ、ｃＡＭＰ水平的调控。     

强啡肽A（1－17）对大鼠脊髓组织钙调蛋白含量和磷酸二酯酶活性的影响

观察强啡肽Ａ（１－１７）经大鼠蛛网膜下腔注射后对胞内Ｃａ２＋受体钙调蛋白（ＣａＭ）含量及其依赖于Ｃａ２＋／ＣａＭ的磷酸二酯酶（ＰＤＥ）活性的影响。结果表明：强啡肽Ａ（１－１７）１０、２０ｎｍｏｌ给药１０ｍｉｎ可使脊髓组织ＣａＭ含量和ＰＤＥ活性明显下降，呈量效依赖关系，２ｈ后均有不同程度的恢复。选择性ｋ型阿片受体拮抗剂ｎｏｒ－ＢＮＩ３０ｎｍｏｌ、兴奋性氨基酸ＮＭＤＡ受体特异性拮抗剂ＡＰＶ１０ｎｍｏｌ可显著对抗强啡肽Ａ（１－１７）２０ｎｍｏｌ降低脊髓组织ＣａＭ含量的作用并完全阻断强啡肽Ａ（１－１７）对ＰＤＥ活性的抑制；Ｌ型Ｃａ２＋通道阻断剂异搏定１００ｎｍｏｌ亦可部分阻断强啡肽Ａ（１－１７）２０ｎｍｏｌ对脊髓组织ＣａＭ含量和ＰＤＥ活性的影响。     

强啡肽A－（1－13）类似物的合成及生物活性

用固相多肽合成方法，合成了强啡肽Ａ－（１－１３）（Ｉ）及其类似物［Ａｌａ８，Ｄ－Ｐｒｏ１０］－ＤＹＮＡ－（１－１３）－ＮＨ２（ＩＩ）和［Ｄ－Ａｌａ２，Ａｌａ８，Ｄ－Ｐｒｏ１０］－ＤＹＮＡ－（１－１３）－ＮＨ２（ＩＩＩ），并对其进行了镇痛活性试验和ＭＶＤ及ＲＶＤ试验。结果表明，合成产物均有镇痛活性，其中类似物ＩＩＩ的镇痛活性是１的３．６倍，ＲＶＤ试验活性比１强１３５倍，比已知的ｋ－受体强激动剂Ｕ５００４８８强１１倍。     

强啡肽A（1－17）致大鼠脊髓损伤

为研究脊髓损伤及继发性损伤的发病机理及其治疗方法，建立了蛛网膜下腔注射强啡肽Ａ（ＤｙｎＡ）致大鼠脊髓损伤动物模型。发现内源性ＤｙｎＡ（１－１７）的氨基端酪氨酸与竣基端的氨基酸残基在致脊髓损伤中都是重要的：Ｎ－甲基－Ｄ－天冬氨酸受体拮抗剂ＤＬ－２－氨基－５－胯酰戊酸（ＡＰＶ），犬尿氨酸及ＭＫ－８０１在对抗ＤｙｎＡ的损伤中均有一定的疗效。但ＡＰＶ和ＭＫ－８０１本身有一定毒性。而犬尿酸氨是一种内源性物质，主要作用于甘氨酸Ｂ变构调节位点，对整体生理功能影响较小。钙拮抗剂维拉帕米对抗强啡肽的致脊髓损伤作用迅速而完全。在所用剂量（５０ｎｍｏｌ）下无毒副作用。     

强啡肽A（1－17）致大鼠脊髓损伤

为研究脊髓损伤及继发性损伤的发病机理及其治疗方法，建立了蛛网膜下腔注射强啡肽Ａ（ＤｙｎＡ）致大鼠脊髓损伤动物模型。发现内源性ＤｙｎＡ（１－１７）的氨基端酪氨酸与竣基端的氨基酸残基在致脊髓损伤中都是重要的：Ｎ－甲基－Ｄ－天冬氨酸受体拮抗剂ＤＬ－２－氨基－５－胯酰戊酸（ＡＰＶ），犬尿氨酸及ＭＫ－８０１在对抗ＤｙｎＡ的损伤中均有一定的疗效。但ＡＰＶ和ＭＫ－８０１本身有一定毒性。而犬尿酸氨是一种内源性物质，主要作用于甘氨酸Ｂ变构调节位点，对整体生理功能影响较小。钙拮抗剂维拉帕米对抗强啡肽的致脊髓损伤作用迅速而完全。在所用剂量（５０ｎｍｏｌ）下无毒副作用。     

（Sp）－8－氯腺苷－3＇，5＇－环磷酸辛酯对人白血病HL－60细胞的诱导分化作用

（Ｓｐ）－８－氯腺苷－３＇，５＇－环磷酸辛酯（Ｓｐ－ｏｃｔｙｌ８－ｃｈｌｏｒｏａｄｅｎｏｓｉｎｅ３＇，５＇－ｃｙｃｌｏｐｈｏｓｐｈａｔｅ，ＯＣＣ）对人白血病ＨＬ－６０细胞有生长抑制和分化诱导作用，该作用与ＯＣＣ浓度和处理时间呈正相关，为不可逆性。流式细胞光度术发现，ＯＣＣ阻断ＨＬ－６０细胞周期于Ｇ１期。参入实验证实，ＯＣＣ对ＨＬ－６０细胞ＤＮＡ合成有显著抑制作用，但不影响ＲＮＡ和蛋白质合成。ＯＣＣ能直接激活ＨＬ－６０细胞浆中提取的蛋白激酶Ａ（ＰＫＡ），并抑制它与ｃＡＭＰ的结合。经ＯＣＣ处理的ＨＬ－６０细胞浆中ＰＫＡ活性明显升高，说明ＯＣＣ能与ｃＡＭＰ竞争ＰＫＡ的结合并激活ＰＫＡ。     

强啡肽A(1-17)在脊髓的致瘫作用及其与神经毒作用的相关性

在以行为学为观察指标(甩尾镇痛和斜板实验)的基础上,用组织学方法探讨大剂量强啡肽A在脊髓水平的致瘫作用与其神经毒作用的关系。结果表明,给大鼠蛛网膜下腔(it)注射强啡肽A(1-17)20nmol·L^-1,共10μl,给药后5～10min即引起大鼠后肢不可逆性瘫痪、甩尾反射被抑制长达40h以上。大鼠脊髓组织学检查发现,腰、骶段脊髓前角运动神经元大量坏死或严重变性、以腰段损伤最为显著(运动神经元减少87.2%),其次是骶段(减少69.6%),胸段损伤不明显(减少8.2%)。     

孕酮对吗啡精神依赖大鼠相关脑区中强啡肽A水平的影响

目的:观察孕酮对于吗啡所致奖赏效应及相关脑区中强啡肽A水平的影响。方法:建立吗啡条件性位置偏爱(CPP)模型,采用放射免疫法测定大鼠不同脑区中强啡肽A(dynorphinA,DynA)的含量。结果:与生理盐水对照组比较,5mg·kg-1吗啡可诱导大鼠产生稳定的CPP效应(P<0·01),15mg·kg-1孕酮本身不产生CPP效应,但能抑制吗啡CPP效应的获得。与生理盐水对照组比较,吗啡CPP形成时,下丘脑和额叶皮质中的DynA水平显著降低(P<0·05)。与吗啡组比较,合用15mg·kg-1孕酮可使下丘脑和额叶皮质中DynA水平显著升高(P<0·05),而在海马、伏隔核和中脑内未见显著性变化。结论:孕酮可以有效抑制吗啡CPP效应,其机制可能与其逆转吗啡诱导的相关脑区中的DynA水平的变化有关。     

胡黄连苷Ⅱ调节cAMP/PKA信号轴对脊髓损伤大鼠神经功能恢复的影响

目的 探讨胡黄连苷Ⅱ(PicrosideⅡ,PⅡ)对脊髓损伤(spinal cord injury, SCI)大鼠神经功能恢复的影响及对环磷酸腺苷(cAMP)-蛋白激酶A(PKA)信号通路的调节作用。方法 建立SCI大鼠模型,大鼠分为正常组(CT组)、SCI模型组(SCI组)、PⅡ低剂量组(PⅡL组,5 mg·kg^-1·d^-1)、PⅡ高剂量组(PⅡH组,20 mg·kg^-1·d^-1)和PⅡ高剂量+PKA抑制剂组(PⅡH+H-89组,20 mg·kg^-1·d^-1 PⅡ+5 mg·kg^-1·d^-1),每组18只。Basso-Beattie-Bresnahan(BBB)评分评价SCI大鼠运动功能,HE染色评价脊髓组织病理学特征,劳克坚牢蓝(LFB)染色观察脱髓鞘情况,免疫荧光检测胶质纤维酸性蛋白(GFAP)、离子钙结合适配器分子-1(IBA-1)表达,ELISA检测丙二醛(MDA)、超氧化物歧化酶(SOD)、环腺苷酸(...     

强啡肽A（1—17）对大鼠脊髓组织钙调蛋白含量和磷酸二酯酶活…

观察强啡肽Ａ（１－１７）经大鼠蛛网膜下腔注射后对胞内Ｃａ＾２＋受体钙调蛋白（ＣａＭ）含量及其依赖于Ｃａ＾２＋／ＣａＭ的磷酸二酯酶（ＰＤＥ）活性的影响。     

Identification of Stabilized Dynorphin Derivatives for Suppressing Tolerance in Morphine-Dependent Rats

PURPOSE: Modulatory actions on morphine-induced effects, such as tolerance and withdrawal, have been noted for dynorphin A(1-13) [Dyn A(1-13)] and similar peptides. These are currently of limited therapeutic potential due to extensive metabolism by human metabolic enzymes resulting in a half-life of less than 1 min in human plasma. The purpose of this study was to identify stabilized dynorphin A (Dyn A) derivatives, to determine their metabolic routes in human plasma, and to assess whether the pharmacodynamic activity is retained. METHODS: The stability of peptides in human plasma was tested using in vitro metabolism studies with and without enzyme inhibitors. Identification of the generated metabolites was performed by mass spectrometry after high performance liquid chromatography (HPLC) separation. The in vivo activity of a stabilized dynorphin was tested by tail-flick assay in morphine-tolerant rats. RESULTS: Though amidation of the Dyn A(1-13) was able to stop the majority of C-terminal degradation, metabolism of Dyn A(1-10) amide continued by captopril sensitive enzymes, suggesting that Dyn A(1-13) amide is a better candidate for additional stabilization. Two Dyn A(1-13) amide derivatives further stabilized at the N-terminal end, [D-Tyr1]-Dyn A(1-13) amide and [N-Met-Tyr1]-Dyn A(1-13) amide, showed half-lives in plasma of 70 and 130 min, respectively. The most stable derivative [N-Met-Tyr1]-Dyn A(1-13) amide was tested successfully for retention of the pharmacological activity in modulating antinociceptive activity. CONCLUSIONS: [N-Met-Tyr1]-Dyn A(1-13) amide showed significant stability and antinociceptive activity in the tail-flick test, thus pointing to the clinical potential of this derivative in the management of pain as well as its potential activity in suppressing opiate tolerance and withdrawal.     

Dopaminergic Involvement in Improving Effects of Dynorphin A-(1-13) on Galanin-Induced Impairment of Passive Avoidance Learning in Mice

The present study was designed to clarify whether dopaminergic systems are involved in the effects of dynorphin A-(1-13), an endogenous κ-opioid receptor agonist, on the galanin-induced impairment of passive avoidance learning in mice. Galanin (0·3 μg, i.c.v.) shortened step-down latency of passive avoidance learning, while the dopamine D₁ receptor agonist SKF 38393 (3 and 10 mg/kg, s.c.), the dopamine D₂ receptor agonist RU 24213 (0·3 and 1 mg/kg, s.c.), the dopamine D₁ receptor antagonist SCH 23390 (0·01 and 0·03 mg/kg, i.p.) or the dopamine D₂ receptor antagonist S(−)-sulpiride (10 and 30 mg/kg, i.p.) failed to influence it. Dynorphin A-(1-13) (3 μg, i.c.v.) and SKF 38393 (10 mg/kg, s.c.) markedly improved the galanin (0·3 μg, i.c.v.)-induced shortening of step-down latency. However, RU 24213 (0·3 and 1 mg/kg, s.c.), SCH 23390 (0·01 and 0·03 mg/kg, i.p.) or S(−)-sulpiride (10 and 30 mg/kg, i.p.) did not affect the galanin (0·3 μg, i.c.v.)-induced shortening of step-down latency. In contrast, SCH 23390 (0·3 mg/kg, i.p.) significantly reversed the improving effects of dynorphin A-(1-13) (3 μg, i.c.v.) on the galanin (0·3 μg, i.c.v.)-induced dysfunction of passive avoidance learning, although SKF 38393 (1 and 3 mg/kg, s.c.), RU 24213 (0·3 and 1 mg/kg, s.c.) or S(−)-sulpiride (10 and 30 mg/kg, i.p.) did not influence the effects of dynorphin A-(1-13) (3 μg, i.c.v.). These results suggest that dynorphin A-(1-13) improves the galanin-induced amnesia resulting from indirect stimulation of dopamine D₁ receptors. © 1997 John Wiley & Sons, Ltd.     

Role of tryptophan-14 in the interaction of dynorphin A(1-17) with micelles

Fluorescence spectroscopy has been used to examine the interaction between the opioid peptide dynorphin A(1-17) (dynorphin) and dodecylphosphocholine (DPC) micelles. Fluorescence emission spectra as a function of added lipid indicate insertion of the Trp¹⁴ side chain into the hydrophobic portion of the micelle, supporting NMR results from this laboratory. A model of interaction with micelles consistent with the fluorescence results and earlier NMR results is proposed. The critical micelle concentration in the presence of peptide was also determined, and is discussed in the context of relevance to both NMR spectroscopy and peptide-lipid interactions. © Munksgaard 1997.     

Metabolism of Dynorphin A 1-13 in Human Blood and Plasma

Purpose. A detailed investigation of the metabolic routes and rates of Dyn A1-13 in human blood and plasma was performed. Methods. Human plasma was incubated at 37°C with dynorphin A 1-13 (Dyn Al-13, 15-20 µM). The generated dynorphin fragments were separated by a new ion-pair chromatographic method and identified by matrix assisted laser desorption mass spectroscopy. The kinetic behavior of parent compound and metabolites was evaluated in the absence and presence of enzyme inhibitors. Results. The major plasma metabolites of Dyn Al-13 were Dyn A1-12, A2-12, A4-12 and A4-8. Further metabolites were Dyn A2-13, A3-13, A3-12, A5-12, A6-12, A7-12, Al-10, A2-10, A2-8 and A3-8. At 37°C, Dyn Al-13 had a half-life of less than one minute in plasma and blood. Plasma half-lives of major metabolites ranged between 0.5 and 4 min. Inter-and intra-individual differences in healthy volunteers were 30% (c.v.). Dyn Al-13 is mainly metabolized by carboxypeptidases to Dyn Al-12 (80%) and by aminopeptidases to Dyn A2-13 (15%). Dyn A1-12 and Dyn A2-13 are predominantly converted into Dyn A2-12 (67% of Dyn Al-13). Subsequent metabolic steps yield Dyn A3-12 (16%), Dyn A4-12 (37%) and Dyn A4-8 (33%). Aminopeptidases generate Dyn A2-12, A3-12, A4-12, A5-12. ACE metabolizes Dyn Al-12 (19%), A2-12 (33%), A3-12 (34%) and A4-12 (46%). Bestatin-sensitive endopeptidases (possibly endopeptidase 24.11) metabolize 30% of Dyn A2-12. Dyn A4-8 is formed via Dyn A4-12 (23% of Dyn A4-12) and Dyn A2-10 (37% of Dyn A2-10). Conclusions. The combination of enzyme inhibition experiments and noncompartmental kinetic analysis proved to be a powerful tool for the detailed evaluation of the metabolic fate of Dyn Al-13 in human blood and plasma.     

Synthesis of Z- and E-1-Methyl-2-(1-hydroximinoethyl)-6-methoxy-3,4-dihydronaphthalene and Evaluation as Inhibitors of 17α-Hydroxylase-C17,20-Lyase (P450 17)

The synthesis and biological evaluation of Z- and E-1-methyl-2-(1-hydroximinoethyl)-6-methoxy-3,4-dihydro-naphthalene ( Z-1 and E-1 ) as nonsteroidal inhibitors of 17α-hydroxylase-C17,20-lyase (P450 17, CYP17) is described. Z-1 and E-1 were separated by column chromatography and identified by ¹H NMR. The synthesis of the key compound 3 was accomplished by a new reaction acetylating the 1-methyl-6-methoxy-3,4-dihydronaphthalene compound 2 under Friedel-Crafts conditions. Compound 2 was obtained from the 1-tetralone via Wittig reaction. Using a microsomal fraction of human testicular enzyme, Z-1 and E-1 inhibited the target enzyme only marginally.     

Role of phosphodiesterase and adenylate cyclase isozymes in murine colonic glucagon-like peptide 1 secreting cells

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) is secreted from enteroendocrine L-cells after food intake. Increasing GLP-1 signalling either through inhibition of the GLP-1 degrading enzyme dipeptidyl-peptidase IV or injection of GLP-1-mimetics has recently been successfully introduced for the treatment of type 2 diabetes. Boosting secretion from the L-cell has so far not been exploited, due to our incomplete understanding of L-cell physiology. Elevation of cyclic adenosine monophosphate (cAMP) has been shown to be a strong stimulus for GLP-1 secretion and here we investigate the activities of adenylate cyclase (AC) and phosphodiesterase (PDE) isozymes likely to shape cAMP responses in L-cells.

EXPERIMENTAL APPROACH

Expression of AC and PDE isoforms was quantified by RT-PCR. Single cell responses to stimulation or inhibition of AC and PDE isoforms were monitored with real-time cAMP probes. GLP-1 secretion was assessed by elisa.

KEY RESULTS

Quantitative PCR identified expression of protein kinase C- and Ca²⁺-activated ACs, corresponding with phorbolester and cytosolic Ca²⁺-stimulated cAMP elevation. Inhibition of PDE2, 3 and 4 were found to stimulate GLP-1 secretion from murine L-cells in primary culture. This corresponded with cAMP elevations monitored with a plasma membrane targeted cAMP probe. Inhibition of PDE3 but not PDE2 was further shown to prevent GLP-1 secretion in response to guanylin, a peptide secreted into the gut lumen, which had not previously been implicated in L-cell secretion.

CONCLUSIONS AND IMPLICATIONS

Our results reveal several mechanisms shaping cAMP responses in GLP-1 secreting cells, with some of the molecular components specifically expressed in L-cells when compared with their epithelial neighbours, thus opening new strategies for targeting these cells therapeutically.     

Increased release of immunoreactive dynorphin A1-17 from the spinal cord after intrathecal treatment with endomorphin-2 in anesthetized rats

We previously demonstrated pretreatment with antiserum against dynorphin A1-17 attenuates endomorphin-2-induced analgesia and antianalgesia, suggesting that these endomorphin-2 effects are mediated by the release of dynorphin A1-17. Lumbar-cisternal spinal perfusion was used to measure the release of immunoreactive dynorphin A1-17 into spinal perfusates from urethane-anesthetized rats following endomorphin-2 or endomorphin-1 treatment within the perfusion solution. Treatment with endomorphin-2 (5-50 nmol) for 3 min caused a dose-dependent increase of immunoreactive dynorphin A1-17 in spinal perfusates, with a maximal increase detected between 24 and 48 min after endomorphin-2 treatment, while levels returned to baseline within 60 min. Endomorphin-2-induced release of immunoreactive dynorphin A1-17 was attenuated by pretreatment with mu-opioid receptor antagonist naloxone or 3-methoxynaltrexone. Endomorphin-1 induced a slight increase in immunoreactive dynorphin1-17 as well, but only at the highest dose used (50 nmol). Our results suggest that endomorphin-2 stimulated a specific subtype of mu-opioid receptor to induce the release of immunoreactive dynorphin A1-17 in spinal cords of rats.     

咪苯嗪酮对血小板聚集、血栓形成和血小板环磷酸腺苷含量的影响

本文观察了新型强心剂咪苯嗪酮(Cl-914)对血小板聚集、血栓形成和血小板cAMP含量的影响。用比浊法测定Cl-914体外抑制AA,ADP和胶原诱导兔血小板聚集的IC_(50),分别为2.6,8.9和15.8μM;大鼠iv Cl-914 1.25mg/kg能抑制实验性血栓形成,20 mg/kg能抑制上述三种诱导剂引起的血小板聚集。在体外,用竞争性蛋白结合法测定,CI-914可使洗涤兔血小板cAMP含量明显升高。CI-914能以剂量依赖方式协同PGE_1抑制血小板聚集和升高血小板cAMP的含量。提示CI-914升高血小板cAMP含量可能是其抑制血小板聚集和抗血栓形成的主要机理。