A New Pain relief substance in spinal cord ; Parmacological Function and Metabolism of Spinorphin

本研究从牛脊髓中分离出一种有效的脑啡肽降解酶抑制剂，并测定了其氨基酸序列、药理功能和代谢。这种新物质由七肽（Leu-Val-Val-Tyr-Pro-Trp-Thr）组成，我们将其命名为“Sinorphin”。该新物质对脑啡肽降解酶的抑制活性（IC_<50>）分别为3.3ug/ml、1.4ug/ml、2.4ug/ml和10ug/ml。该物质对脑啡肽纯化后的肾脏和血液无抑制作用。Spinorphin对MVD（小鼠输精管）和GPI（豚鼠回肠）的电诱发浓度产生剂量相关的抑制作用。腹腔注射Spinorphin也能产生镇痛作用，剂量为100 ~ 200 nmol/只，且呈剂量依赖性。镇痛效果在5 min内达到最大，15 ~ 60min后消失。这些作用可被纳洛酮完全拮抗。大多数Spinorphin在人脊髓中孵育24小时后降解。然而，在HPLC上，当与probestin（一种氨基肽酶m的抑制剂）孵育时，大约86%的Spinorphin是完整的。与各种水解产物相比，Spinorphin对脑啡肽降解酶具有很高的抑制活性。综上所述，影响阿片活性的最重要结构是Spinorphin。提示脊髓啡肽作为脑啡肽代谢的神经调节剂在脊髓中起作用。

In this study, We isolated a potent inhibitor for enkephalin-degrading enzymes from the bovine spinal cord, and determined its amino-acid sequence, pharmacological function and metabolism. This new substance is composed of heptapeptide (Leu-Val-Val-Tyr-Pro-Trp-Thr), and has been named by us "Sinorphin". The inhibitory activity (IC_<50>) of this new substance toward enkephalin-degrading enzymes, purified frome monkey brain, was found to be 3.3ug/ml against aminopeptidase, 1.4ug/ml against dipeptidyl aminopeptidase, 2.4ug/ml against angiotensin-converting enzyme, and 10ug/ml against enkephalinase. This substance did not show inhibitory activity toward enkephalins purified kidney and blood. Spinorphin produces a dose-related inhibition of electrically evoked concentrations of both MVD(mouse vas deferens) and GPI(guinea-pig ileum). The intracisternally injected Spinorphin also produced a nalgesic effects in a dose-dependent manner, in dose of 100-200 nmol/mouse.The analgesic effect reached the maximum within 5 minand disapeard after 15-60min. These effects could be completely antagonised by naloxone. Most Spinorphin was degraded when incubated in the human spinal cord for 24hr. However, approximately 86% of the Spinorphin was intact on HPLC when incubated with probestin, which is an inhibitor of Aminopeptidase M.Spinorphin has a high inhibitory activity against enkephalin-degrading enzymes when compared to the various hydrolysis products. In conclusion, the most important structure for opioid activity is Spinorphin. It is suggested that Spinorphin acts as a neuromodulator of enkephalin metabolism in the spinal cord.