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Occurrence and Analysis of Spontaneous Tumors in Sprague-Dawley
Rat Background Data Acquisition Test
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2020, 37(02):
37.
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Objective Sprague-Dawley rat is one of the important species in rats. To supply the reference data of spontaneous tumors of Sprague-Dawley rat for the drug preclinical safety evaluation, the types of spontaneous tumors of Sprague-Dawley rat were observed and their incidence of statistics was analyzed. Above all, the data would be so important to the long-term toxicity test, the carcinogenic test and the reproductive toxicity test. Method In the background data of acquisition test, 260 SD rats were randomly divide into eight groups ( A group, B group, C group, D group, E group, F group, G group and H group) according to weight. The animals of the above groups were dissected respectively in the planning anatomy at 2 weeks, 4 weeks, 8 weeks, 13 weeks, 26 weeks, 52 weeks, 78 weeks and 104 weeks. Result During the test, no tumor was found in the first five groups, but the tumor of the other three groups appeared notonly in the planning anatomy butalso in the urgent anatomy.The tumor was firstly discovered at 24th week of the test ( the age of the animal was 30 weeks ) among the animal necropsy and was found in total of 94 rats among which had 59 female rats and 35 male rats. A total of 185 tumors were detected, of which 81. 1% were benign tumors and 18.9% were malignant tumors. In the benign tumors, the breast fibroadenoma and the anterior pituitary adenoma were the most common. The major malignant tumors were as follows: breast cancer, pituitary cell adenocarcinoma, leukemia, deputy lachrymal cancer. Meanwhile, the malignant tumor such as pituitary cell adenocarcinoma, histiocytic sarcoma, leukemia, bronchial adenocarcinoma, breast cancer transferred to the surrounding or the whole visceralorgan. In addition to the obvious spontaneous tumors, the atypical hyperplasia and altered hepatocyte foci were visible. Conclusion According to the result derived from the background data acquisition test of SD rats of our center , the occurrence probability of spontaneous tumors had increased after 30 weeks old and the sites of predilection for the tumor were pituitarium , breast , skin and subcutaneous tissue.Such asthepituitaryadenoma , breast fibroadenoma are the most common spontaneous tumors.The occurrence rate of the tumors in females was higher than males.At the same time , compared with the result from the different research institutions athome and abroad , the data had some differences.The different occurrence rates of the spontaneous tumors were considered to have a tight correlation of the individual difference and the feeding conditions.
