Broderson J R, Lindsey J R, Crawford J E
Am J Pathol. 1976 Oct;85(1):115-30.
Young adult, pathogen-free rats of Sherman and Fischer (F344) substrains were inoculated intranasally with 10(8) colony-forming units (GFU) of M. pulmonis and housed for 4 to 6 weeks in environments with ammonia maintained at specific concentrations from 25 to 250 ppm. All levels of NH3--whether produced naturally from soiled bedding or derived from a purified source--significantly increased the severity of the rhinitis, otitis media, tracheitis, and pneumonia (including bronchiectasis) characteristic of murine respiratory mycoplasmosis (MRM). The prevalence of pneumonia, but not that of other respiratory lesions of MRM, showed a strong tendency to increase directly with environmental NH3 concentration. In contrast, NH3 exposure of rats not infected with M. pulmonis caused anatomic lesions that were unlike those of MRM and were limited to the nasal passages. It was concluded that environmental NH3, at concentrations commonly encountered in present day cage environments for rats, plays an important role in pathogenesis of MRM.
选用了无特定病原体的青年成年谢尔曼和费舍尔（F344）亚系大鼠，经鼻内接种10⁸ 个肺炎支原体菌落形成单位（CFU），并在氨浓度维持在25至250 ppm特定水平的环境中饲养4至6周。所有氨水平——无论是由脏垫料自然产生的，还是来自纯化源的——均显著加重了小鼠呼吸道支原体病（MRM）特有的鼻炎、中耳炎、气管炎和肺炎（包括支气管扩张）的严重程度。肺炎的患病率，而非MRM其他呼吸道病变的患病率，呈现出随环境氨浓度直接升高的强烈趋势。相比之下，未感染肺炎支原体的大鼠接触氨会导致与MRM不同的解剖学病变，且仅限于鼻道。得出的结论是，在当今大鼠笼养环境中常见的浓度下，环境氨在MRM的发病机制中起重要作用。
