Suganuma T, Suzuki T, Oshimi M, Hanano M
Department of Pharmaceutical Science, College of Pharmacy, Nihon University, Chiba, Japan.
Biol Pharm Bull. 1998 Jul;21(7):756-60. doi: 10.1248/bpb.21.756.
This study aimed to investigate the behavior of an endogenous beta-endorphin (beta-EP) in the brain after subcutaneous (s.c.) injection of carrageenin or intravenous (i.v.) injection of indomethacin (IDM). The carrageenin was injected into rat hind paw subcutaneously in order to evoke only a local nociceptive stimulus. The beta-EP concentration in the brain region was determined by radioimmunoassay at designated sampling times after the injection. It was observed that the beta-EP concentration in the midbrain declined from 2.8+/-0.3 at 1 h to 1.3+/-0.02 ng/mg protein at 9 h. After the s.c. injection of carrageenin, the beta-EP concentrations in the midbrain were found to be closely related to the nociceptive sensitivity which was determined by the Randall-Selitto test. On the other hand, a significant elevation of the beta-EP concentration was observed in the hypothalamus from 3 h until 5 h compared with that of control. IDM was injected into rats at doses of 2.9, 5.8 and 8.6 mg/kg via the femoral vein. After i.v. administration of IDM, the beta-EP increased in the hypothalamus, medulla oblongata, and midbrain, depending on the doses used. The value of hypothalamic beta-EP concentration was two times higher than that of carrageenin. We found that nociceptive stimuli and IDM brought a change in the beta-EP concentration in the brain of rats.
本研究旨在探讨皮下注射角叉菜胶或静脉注射吲哚美辛（IDM）后，内源性β-内啡肽（β-EP）在大鼠脑内的行为变化。将角叉菜胶皮下注射到大鼠后爪，以仅诱发局部伤害性刺激。在注射后的指定采样时间，通过放射免疫测定法测定脑区中β-EP的浓度。观察到中脑内β-EP浓度从1小时时的2.8±0.3降至9小时时的1.3±0.02 ng/mg蛋白。皮下注射角叉菜胶后，发现中脑内β-EP浓度与通过Randall-Selitto试验测定的伤害性敏感性密切相关。另一方面，与对照组相比，下丘脑内β-EP浓度在3小时至5小时期间显著升高。以2.9、5.8和8.6 mg/kg的剂量通过股静脉向大鼠注射IDM。静脉注射IDM后，下丘脑、延髓和中脑内的β-EP根据所用剂量而增加。下丘脑内β-EP浓度的值比角叉菜胶组高两倍。我们发现伤害性刺激和IDM使大鼠脑内β-EP浓度发生了变化。
