听泡内注射法建立大鼠化脓性中耳炎模型

Injecting pneumococci into rats'tympanic bullae for establishing a model of suppurative otitis media

目的摸索大鼠听泡寻找及注射方法,了解建立化脓性中耳炎及粘连性中耳炎动物模型的方法。方法健康,鼓膜及听力正常的雄性Sprague-Dawley(SD)大鼠11只,体重220-320g。麻醉后2只经鼓膜、9只经头颈腹侧正中入路,右侧听泡内注入5×106CFU/ml肺炎球菌悬液0郾05ml,左侧注入无菌悬液0郾05ml作对照。于术后7天、14天观察鼓膜情况,各处死4只,随机分2组,取头、后固定,取听泡,一组PAS/alcainblue染色,立体显微镜下观察。特殊部位进行连续切片,HE染色,光学显微镜下观察粘连情况。另一组制成扫描电镜标本进行观察。结果因麻醉过深死亡3只。实验耳(8只右耳)鼓膜明显增厚,呈黄色化脓样改变;听泡内充满成团黄色物,粘膜层明显增厚,未见粘连形成。对照耳(8只左耳)鼓膜稍增厚,呈苍白或浑浊、内陷;听泡内无异物,粘膜光滑。结论SD大鼠麻醉量与致死量之间差距小。经鼓膜或头颈腹侧正中入路听泡内注射无差异,后一种方法寻找大鼠听泡简单易行、安全可靠。大鼠听泡内注射肺炎球菌是建立化脓性中耳炎动物模型的好方法,成功率100%,但粘连性中耳炎模型未成功,须进一步探索。

Object To master the measures of looking for Sprague-Dawley (SD)rats' tympanic bullae and learn about the technique for a rat model of suppurative and adhesive otitis media. Method Eleven SD rats were used. The right tympanic bullae were injected respectively with 0.05ml 5×106CFU/ml suspension of pneumococci and the left (control) with the suspension medium only. Two rats of which were injected through tympanic membranes and 9 through ventral midline incisions in the neck and head. At days 7 and 14 after operation, tympanic membranes were examined, then the rats were sacrificed, decapitated, postfixated for 1 week and randomly divided into 2 groups of 4 rats each. One group were stained with periodic acid-Schiff(PAS)/alcian blue, examined by stereomicroscope. In case of need, serial sections were made and stained with hematoxylin-eosin (HE), and further inspected mucosa adhesion by light microscope. The other group were prepared for scanning electron microscopy. Results Three rats died from overdose of anesthetic.The data from experimental ears (8R) showed that tympanic membranes thickened obviously presenting a suppurative change. There were full of suppurative matters and the mucosa layer thickened apparently in the tympanic bullae, no mucosa adhension was inspected. In control ears (8L), tympanic membranes were pale, turbid, retracted and thickened slightly,and there was nothing in the tympanic bullae and mucosae were smooth and thickened slightly. Conclusion The gap between anesthetic and lethal dose of sodium barbiturate on rats is little. There wasn′t difference between two injecting means by ways of tympanic membrane and ventral midline incision in the neck and head, and by the latter one can find tympanic bullae simply, quickly and safely. It′s an excellent measure to inject pneumococci into tympanic bullae for a rat model of supperative otitis media. However it didn't succeed in modeling adhesive otitis media.