大鼠胃粘膜上皮微核试验

AN IN VIVO MICRONUCLEUS ASSAY IN THE RAT GASTRIC MUCOSAL CELLS

为筛选遗传毒胃致癌物,我们以N-甲基-N′-硝基-N-亚硝基胍(MNNG)为模型诱变剂,发展大鼠胃粘膜微核试验。Wistar大鼠经口给以MNNG灌胃2次,间隔24h,末次染毒后24h处死。取腺胃,以1％链霉蛋白酶E于37℃消化30～45min,离心消化液收集胃粘膜细胞,制片,Giemsa染色。胃粘膜细胞收率为每鼠4.0 ×10~6细胞。在涂片上,胃粘膜细胞可分为3组:表面上皮细胞、泌酸细胞、腺颈细胞和酶原细胞。研究结果表明:MNNG可引起大鼠胃粘膜细胞微核率增加,并有剂量一效应关系。

Gastric carcinoma is one of the common cancer in human. We developed the micronucleus assay of gastric mucosal cells (GMC) in rat in order to screen the genotoxic stomach-carcinogens N-Methyl -N'-nitro-N-nitrosoguanidine (MNNG) was given twice to wistar rats by oral gavage with 24 h interval. The rats were killed at 24 h after the last treatment. The glandular stomach was filled up with the enzyme solution(1.0% pronase E)and digested for 30-45 min in 37℃. The GMC were collected by centrifuge, smeared and stained with Giemsa.The yields of GMC was approximately 4 × 106 cells per rat. The GMC in smears were divided into three groups : the surface epithelial cells (34%), parietal cells(22%), mucous neck cells and chief cells(43%) .The frequencies of micronucleated GMC were 0.40, 1.60, 2.20 and 6.60‰ respectively at the dose of MNNG 0, 25, 50 and 100 mg/ kg. At the double dose of MNNG 50 mg/kg and 24, 48 and 72 h sample time, the micronucleus frequencies of GMC were 2.60, 2.80 and 0.60 ‰ respectively. the results indicated that MNNG induce a dose-dependant increase of micronucleus frequencies of GMC.