Enss M L, Wagner S, Liebler E, Coenen M, Hedrich H J
Institut for Laboratory Animal Science and Animal Facility, Medical School Hannover, Germany.
J Exp Anim Sci. 1996;38(2):58-65.
Suggestive to induce an immunoreactive response in the colon mucosa of germfree rats 3 diets, autoclaved or gamma-irradiated, respectively, were administered to groups of 30 days old GF Ztm:SPRD rats. Diets and rats were studied in parallel after a feeding period of 20 days. The microbiological controls confirmed the sterility of diets and animals. The aqueous suspensions of one diet displayed obviously dead yeast and Gram positive and negative bacteria, which consistently were evident in colonic cast preparations of animals fed with this diet. These findings apparently were not related to the pathohistological alterations, observed in hematoxilin-eosin stained colon sections. However, dietary endotoxin concentrations between 0.6 and 10 micrograms LPS/g corresponded with the endotoxin concentrations in feces (0.3 to 3.1 micrograms LPS/g wet weight) and in colonic tissue (0.01 to 0.6 microgram LPS/g wet weight). These endotoxins obviously mediated a dose-dependent immunoreactive response of the colonic mucosa: in parallel to the dietary endotoxin content, the cellular infiltrations ranged from single mononuclear cells to severe, cell mediated, mucosal alteration. GF rats, used as an experimental animal model for inflammatory disorders of the intestine obviously necessitate diets with low endotoxin concentrations.
为了诱导无菌大鼠结肠黏膜产生免疫反应，分别给30日龄的GF Ztm:SPRD大鼠喂食经高压灭菌或γ射线辐照的3种日粮。在20天的喂养期后，对日粮和大鼠进行平行研究。微生物学对照证实了日粮和动物的无菌状态。一种日粮的水悬浮液中明显可见死亡的酵母以及革兰氏阳性和阴性细菌，在用这种日粮喂养的动物的结肠铸型制剂中始终可见这些细菌。这些发现显然与苏木精-伊红染色的结肠切片中观察到的病理组织学改变无关。然而，日粮中内毒素浓度在0.6至10微克脂多糖/克之间，与粪便（0.3至3.1微克脂多糖/克湿重）和结肠组织（0.01至0.6微克脂多糖/克湿重）中的内毒素浓度相对应。这些内毒素明显介导了结肠黏膜的剂量依赖性免疫反应：与日粮内毒素含量平行，细胞浸润范围从单个单核细胞到严重的细胞介导的黏膜改变。GF大鼠作为肠道炎症性疾病的实验动物模型，显然需要低内毒素浓度的日粮。
