治疗帕金森病新药:腺苷A_(2A)受体拮抗剂

腺苷A2A受体在基底神经节选择性表达并与运动行为有关。流行病学研究和实验室研究均表明阻断腺苷A2A受体能减轻多巴胺能神经元的退行性病变。腺苷A2A受体拮抗剂在改善PD症状的同时还能减缓疾病的进程。因此,腺苷A2A受体拮抗剂很可能成为治疗PD的新药物。     

葛根黄豆甙元-PVP分散物的研究

本文采用聚乙烯吡咯烷酮(PVP)为载体,制备了葛根黄豆甙元固体分散物。经差热分析、X-射线衍射、偏光显微镜观察实验证明黄豆甙元-PVP 1∶9固体分散物为固体溶液或共沉淀物,其胶囊在人工胃液中最高累积释放百分量和人工肠液中平衡溶解度均是普通胶囊的8倍左右。     

环孢素A与CYP3A

环孢霉素A是一种广泛用于器官移植的免疫抑制剂,其生物利用度低且个体差异大,本文从环孢霉素A代谢的影响因素、环孢霉素A与药物和食物的相互作用等方面探讨了环孢霉素A与CYP3A的关系。则时介绍了CYP3A活性的体内测定方法。     

SCH 58261: A selective A2A adenosine receptor antagonists

The recent discovery of selective antagonists for the A_2A adenosine receptors has been of great help to further research in this field. One compound, SCH 58261, 5- amino-7-(β-phenylethyl)-2-(8-furyl)pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine, is playing a key part in a variety of studies. This review describes its pharmacological characteristics as they are emerging in various laboratories. The compound has an affinity in the low nM range (Ki value of 1–2 nM) for A_2A receptors located on membranes from a variety of tissues and cell types, including rat and bovine brain striatum, human platelets, lymphocytes and neutrophils, porcine coronary arteries, and CHO cells transfected with the cloned human A_2A receptors. SCH 58261 has little or no affinity up to the μM range for adenosine A_2B, A₃, or other G protein-coupled receptors. Selectivity for A_2A vs. A₁ receptors varies from 53- to 750-fold, depending on membranes or type of assay. SCH 58261 blocks A_2A-receptor mediated increase of cyclic AMP formation with high potency (e.g., IC₅₀ values between 15 and 20 nM in human white blood cells). The tritiated form of SCH 58261 specifically labels A_2A receptors in discrete regions of the rat brain such as caudate-putamen, nucleus accumbens, and tuberculum olfactorium. In classic in vitro bioassays, such as A_2A-receptor-mediated vasodilation in coronary arteries, SCH 58261 displays competitive antagonistic properties (e.g., pA₂ value of 9.5 in porcine coronary arteries). In assays involving responses mediated by A₁ or A_2B receptors, SCH 58261 shows little or no activity up to concentrations about 100-fold higher than those affecting A_2A receptors (higher concentrations not being testable due to its poor water solubility). In the rat, SCH 58261 enhances locomotor activity (at 3.7 mg/kg ip), increases wakefulness (10 mg/kg ip) and slightly increases both blood pressure and heart rate (10 mg/kg ip). These activities appear to be specifically mediated by A_2A receptors since the drug counteracts the effect of A_2A receptor agonists in some experimental paradigms. In models mimicking CNS disorders, SCH 58261 potentiates the activity of L-DOPA or dopamine receptor agonists in the 6-hydroxydopamine-lesioned rat model. Moreover, the compound reduces brain infarct size in a rat model of cerebral ischemia. Altogether, SCH 58261 and its radiolabeled form have emerged as interesting tools for better understanding the function of A_2A receptors in physiological or altered conditions. Moreover, the neuroprotective properties of SCH 58261 indicate that drugs of this class have a potential for treatment of brain damage produced by Parkinson's disease or stroke. Drug Dev. Res. 42:63–70, 1997. © 1997 Wiley-Liss, Inc.     

Neurokinin A. A pharmacological study

Discovered in 1983, the decapeptide neurokinin A has been shown to occur in several peripheral organs and to exert a variety of biological effects. In this article, we review the most sensitive and selective in vivo and in vitro tests which have been used in various laboratories to evaluate naturally occurring or synthetic neurokinin A. A comparison of the effects of neurokinin A and those of its mammalian homologues, substance P and neurokinin B as well as those of tachykinins and related peptides is presented in the frame of a study directed toward characterization of neurokinin receptors. Indeed, neurokinin A has been shown to be particularly active on a neurokinin receptor subtype, the NK-2. Structure-activity studies performed with neurokinin A and its fragments as well as with several analogues of both the decapeptide and the heptapeptide NKA(4-10) have brought to the identification of the minimum structure required for activation of NK-2 receptors. Selective agonists for this receptor have been identified, in particular [Nle10]-NKA(4-10) and [beta-Ala8]-NKA(4-10).     

β-淀粉样蛋白和载脂蛋白E4升高神经元胞内游离钙

目的　研究 β 淀粉样蛋白 (Aβ)和载脂蛋白E4(ApoE4)对神经元胞内游离Ca2 +浓度的影响 ,探索它们对神经元的毒性效应。方法　制备 0～ 3d新生SD大鼠的海马和皮层神经元悬液 ,负载上fura 2 /AM ,实验组分别加入Aβ2 5～ 3 5、ApoE4以及Aβ2 5～ 35+ApoE4孵育液温孵 3min后 ,用荧光双波长分光光度计测定神经元 [Ca2 +]i;采用显微准弹性激光散射技术 (MQLS) ,分析Aβ2 5～ 35及ApoE4对单个神经元散射光强度自相关函数 (ACF)的影响 ,通过公式由ACF拟合出反映细胞膜流动性的频移线宽Г。结果　Aβ2 5～ 35和ApoE4均能升高海马和皮层神经元静息 [Ca2 +]i(P <0 0 5 ) ,其中 5 μmol·L-1Aβ2 5～ 35的作用大于 1μmol·L-1Aβ2 5～ 3 5的作用 (P <0 0 5 ) ;Aβ2 5～ 35和ApoE4也能增强KCl去极化诱导的海马和皮层神经元 [Ca2 +]i 升高 (P <0 0 5 )。Aβ2 5～ 3 5(1μmol·L-1) +ApoE4(0 1μmol·L-1)共同作用也使神经元静息 [Ca2 +]i及KCl去极化诱导的神经元 [Ca2 +]i升高 (P <0 0 5 ) ,但两者共同作用未见其升 [Ca2 +]i 效应进一步增大。Aβ2 5～ 3 5和ApoE4均降低海马和皮层神经元的频移线宽Г。结论　Aβ2 5～ 35和ApoE4均能升高神经元静息[Ca2 +]i 及降低神经元膜流动性 ,但两者共同作用未能显示升 [C