动物造模 z-bio 2022-06-05 745

　　Objective To observe the occurrence of spontaneous tumors in SD rats, and to provide background data for the carcinogenicity test of new drugs.

　　Methods A total of 120 4-week-old SPF SD rats in the normal control group of a carcinogenic test, half male and half male, were observed for 1 week before the experiment, and euthanized after being fed with conventional feed for 104 weeks. The heart, lung, liver, spleen, kidney, adrenal gland, thymus, brain, testis and epididymis (or uterus) and other organs were weighed after the anatomy of the dead rats and the sacrificed rats during the experiment. The types and incidence of spontaneous tumors in various organs were observed.

　　Results A total of 113 SD rats were observed (7 rats were lost during the experiment), among which 66.4% (75/113) had tumors, among which benign tumors accounted for 48.7% (55/113) and malignant tumors accounted for 17.7% ( 20/113). Male rats developed tumors in 49.1% (28/57), of which benign tumors accounted for 50.9% (26/57) and malignant tumors accounted for 3.5% (2/57); benign tumors were mainly pituitary adenomas (36.8%) and adrenal medulla stromal adenoma (7.0%), malignancies were mainly thyroid adenocarcinoma (18%) and fibrosarcoma (1.8%). Tumors occurred in 83.9% (47/56) of female rats, among which benign tumors accounted for 51.8% (2956) and malignant tumors accounted for 32.1% (18/56); benign tumors were mainly pituitary adenomas (50.0%), breast fibroadenomas ( 12.5%) and breast adenoma (12.5%), the malignancies were mainly breast adenocarcinoma (25.0%) and fibrosarcoma (3.6%).

　　Conclusion The incidence of spontaneous tumors in SD rats over 2 years old in normal feeding is higher, and the incidence of benign tumors is higher than that of malignant tumors, which may be related to aging, tumors and individual differences.