Stark H, Lössner B, Matthies H
Biomed Biochim Acta. 1986;45(4):557-63.
The degradation of beta-casomorphin 1-5 (Tyr-Pro-Phe-Pro-Gly (beta CM]--an opiate-like acting pentapeptide--was investigated in brain stem and corpus striatum of male Wistar rats during the first 20 min after an intracerebroventricular (i.c.v.) application of 166 nmol [3H]Phe3-beta CM. Dependent on the time after [3H]Phe3-beta CM injection, the radioactivity carried by beta CM and its metabolites was estimated in the HCl-soluble tissue fraction of these brain structures. The separation of the intact pentapeptide from its metabolites was performed using HPLC-technique. In both brain regions a rapid decrease in the concentration of beta CM was observed during the first 10 min after [3H]Phe3-beta CM application (1st phase). 10 to 20 min after injection, the decrease in beta CM concentration was found to be considerably smaller (2nd phase). Moreover, beta CM is rapidly degraded forming phenylalanine and tyrosine as the main metabolites. Furthermore, at any time, small amounts of Phe-Pro-Gly, Phe-Pro, Pro-Phe-Pro-Gly and Tyr-Pro-Phe-Pro were estimated. From these results, the analgesic effect by i.c.v. application of 166 nmol beta CM is assumed to be caused rather by the intact pentapeptide molecule than by one of its metabolites.
在雄性Wistar大鼠脑室内注射166 nmol [³H]苯丙氨酸³-β-酪蛋白吗啡1-5（酪氨酸-脯氨酸-苯丙氨酸-脯氨酸-甘氨酸（β-CM），一种具有类阿片样作用的五肽）后的最初20分钟内，研究了其在脑干和纹状体中的降解情况。根据[³H]苯丙氨酸³-β-CM注射后的时间，在这些脑结构的盐酸可溶性组织部分中估计β-CM及其代谢产物携带的放射性。使用高效液相色谱技术将完整的五肽与其代谢产物分离。在[³H]苯丙氨酸³-β-CM给药后的最初10分钟内（第一阶段），在两个脑区均观察到β-CM浓度迅速下降。注射后10至20分钟，发现β-CM浓度下降幅度明显较小（第二阶段）。此外，β-CM迅速降解，形成苯丙氨酸和酪氨酸作为主要代谢产物。此外，在任何时候，均检测到少量的苯丙氨酸-脯氨酸-甘氨酸、苯丙氨酸-脯氨酸、脯氨酸-苯丙氨酸-脯氨酸-甘氨酸和酪氨酸-脯氨酸-苯丙氨酸-脯氨酸。根据这些结果，推测脑室内注射166 nmol β-CM的镇痛作用是由完整的五肽分子而非其代谢产物之一引起的。
