| IntroductionScoparone ( Sco ,6,7- dimethoxycoumarin) is a coumarin derivative extracted from a cholagogic traditional Chinese herb " Yinchen" . It produces a variety of pharmacological effects including cholagogue, hepatic protection, analgesia, immusuppression, hypertension, anti -inflammation and scavenging oxygen free radicals. Bronchial asthma is a common disease of respiratory system and the chronic non - specific airway inflammation is thought to be an important pathologic factor, which has emerged as an important aspect of mechanism of asthma. Recently, there was increasing evidence that reactive oxygen species (ROS) are involved in inflammatory airway diseases, including asthma. Early studies in vitro in our department indicate that Sco has anti - asthmatic effect and the mechanism is due to dilating airway smooth muscle. Until now, there are no reports that Sco can inhibit airway inflammation. Therefore, we observed scoparone 's effect of anti - inflammation and scavenging ROS on ovalbumin ( OA) induced late asthmatic guinea pigs in order to confirm the mechanism and provide theoretic basis for developing anti - asthmatic traditional Chinese new drug.Materials and Methods1. Preparation of asthmatic models of guinea pigs and the measurement of specific asthmogenic latent periods.The healthy guinea pigs were randomly grouped into 4 teams: normal, asthma, Sco and Dex and each group has 6 ~ 8 animals. Guinea pigs in the asthmatic group were sensitized by exposure to aerosolized OA (1 % in saline) for 5 minutes on three occasions, separated by 3 days. These animals were used for challenge 14 days after the third sensitization. The solvent that dissolved Sco and Dex ( abbreviated solvent later) 10ml/kg was administrated intraperitoneally, 1 day before challenge and for 2 times. The animals were treated with the solvent 10ml/kg and diphenhydramine (10ml/kg,both intraperitoneally) 30 minutes before antigen challenge. Then guinea pigs were challenged with 2% OA for 5 minutes and meanwhile the time from exposure to OA to contraction of abdominal muscles was recorded, which was specific asthmogenic latent periods. In normal group, except for the sensitization and challenge by 0. 9% NaCl, the other processes were done the same as that of the asthmatic group. In the Sco and Dex groups, we used Sco 20mg/kg and Dex Img/kg respectively instead of solvent.2. Bronchoalveolar lavage and the specimen collection.All the guinea pigs were used for the experiment 24h after antigen or saline challenge. After anesthesia, the animals were fixed and exsanguinated by severing the carotid arteries and then 5ml blood was collected. Towards the end of exsanguinations, the trachea was exposed by a midline incision and annulated with a tube. The lung waslavaged with 5ml sterile saline at 37 T! instilled through the tracheal cannula by syringe for two times only at 3 minutes intervals. The lav-age fluid were combined and then cooled to 4 and filtered through surgical gauze. After BAL, 300mg lung tissue was removed and made into 10% homogenate. The blood and homogenate were centrifuged (2000rpm, at room temperature) for 6 minutes and the supernatants were collected for measurement of SOD , MDA. The lung with trachea was removed and fixed in 10% buffered formal for histopathologic observation.3. Total leukocyte counts and differentials in BALFThe BALF was centrifuged(200 x g for 10 min at 4 ) to remove the supernatant. The cell pellet was washed by centrifugation(200 X g for 10 min at 4 ) with Hank' s solution for 3 times. Finally the cells were suspended in 2ml Hank' s solution for total leukocyte counts and differentials.4. Histopathologic examination of the trachea and bronchiole.After fixation, specimens of trachea and lung lobes were embedded in paraffin wax, and 5 m sections were cut and stained with he-matoxylin - eosin and then used for examination under the light microscopy.5. Measurement of SOD and MDAWe used modified method of oxidation of hydroxylamine to measure SOD, spectropho...
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