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首页> 外文期刊>Life sciences >Characterization of [~3H]Met-enkephalin-Arg~6-Phe~7 binding to multiple sites in rat and guinea pig cerebellum
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Characterization of [~3H]Met-enkephalin-Arg~6-Phe~7 binding to multiple sites in rat and guinea pig cerebellum

机译：[〜3H] Met-脑啡肽-Arg〜6-Phe〜7与大鼠和豚鼠小脑多个部位结合的特征

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[~3H]Met-enkephalin-Arg~6-Phe~7 (MERF) has been shown to label opioid (#kappa#_2 and #delta#) and sigma_2 sites in rat and frog brain membrane preparations, and no specific binding to #kappa#_1 opioid receptors could be established (refs. 6 and 8). In this study the binding was examined in rat cerebellar membranes which are relatively rich in #kappa#_2-sites, and in guinea pig cerebellar preparations where #kappa#_1 opioid receptors are almost exclusively present. In accordance with our previous results, [~3H]MERF binding could not be displaced in guinea pig cerebellar membranes neither with U-69,593 nor with naloxone or levorphanol suggesting no interaction with opioid sites, nevertheless a K_d of 2.8 nM was calculated in cold saturation experiments. In rat cerebellar membrane fractions about the half of the specific [~3H]MERF binding sites was inhibited by opiate alkaloids such as naloxone, ethylketocyclazocine, or bremazocine. This portion of the heptapeptide binding sites was stereoselective as demonstrated by the difference in the affinities of the enantiomeric compounds levorphanol and dextrorphan, therefore it would represent an opioid site. In both tissues (-)N-allyl-normetazocine (SKF-10,047), which is also considered as sigma_2 ligand, displayed the highest affinities. Among opioid peptides #beta#-endorphin and dynorphin_(1-13) showed the highest potencies, displacing [~3H]MERF also from its non-opioid sites. It was concluded therefore that [~3H]MERF does not bind to #kappa#_1 sites, and besides #kappa#_2-opioid sites substantial binding to peptide preferring non-opioid sites, and/or sigma_2 receptors also occurs.
机译：[〜3H] Met-脑啡肽-Arg〜6-Phe〜7（MERF）已显示出可在大鼠和青蛙的脑膜制剂中标记阿片样物质（＃kappa＃_2和＃delta＃）和sigma_2位点，并且与之无特异性结合可以建立＃kappa＃_1阿片受体（参考文献6和8）。在这项研究中，检查了在＃kappa_2位置相对丰富的大鼠小脑膜和几乎只存在＃kappa＃_1阿片受体的豚鼠小脑制剂中的结合。根据我们之前的研究结果，[〜3H] MERF结合不能在豚鼠小脑膜中被U-69,593或与纳洛酮或左氧吗啡醇置换，这表明与阿片样物质位点无相互作用，尽管如此，在冷饱和下K_d为2.8 nM实验。在大鼠小脑膜部分中，鸦片生物碱（如纳洛酮，乙基酮基环偶氮星或溴代咪唑胺）抑制了特定的[〜3H] MERF结合位点的一半。七肽结合位点的这一部分是立体选择性的，这由对映体化合物左啡烷和右啡烷的亲和力差异证明，因此它将代表阿片样物质位点。在这两个组织中，也被认为是sigma_2配体的（-）N-烯丙基-去甲偶氮辛（SKF-10,047）显示出最高的亲和力。在阿片肽中＃beta＃-内啡肽和强啡肽_（1-13）显示出最高的效价，[〜3H] MERF也从其非阿片样位点取代。因此可以得出结论，[〜3H] MERF不与＃kappa＃_1位点结合，并且除了＃kappa＃_2-阿片样物质位点以外，还与多肽形成了实质性结合，从而更倾向于非阿片类药物位点和/或sigma_2受体。

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