关键词: 慢性毒性联合致癌性试验, SD 大鼠, 体质量, 死亡率, 血常规值, 血生化值, 背景数据

Abstract: Abstract: Objective To investigate the change of reference value for body weight、mortality、hematology and serum biochemistry of SD rats in test method of combined chronic toxicity / carcinogenicity study． Method 135 male and 138 female specific pathogen free SD rat of 4 weeks were selected． We measured the body weights once a week between 4 ～ 17 weeks of age and once four week between 18 ～ 108 weeks of age． The indexes of hematology and biochemistry of SD rats were measured at the age of 8 weeks old、30 weeks old、56 weeks old、82 weeks old、108 weeks old and record the mortality rate every day． Result The body weight of male rats was much higher than female rats from 6 weeks old． The 82 ～ 108 weeks of age was the rapid growth of mortality in rats． The coefficient of variation of indexes of hematology and biochemistry of male and female become larger with increasing age． Gender has a significant impact on hematology and serum biochemistry in rats． But the hematology and serum biochemistry which has significant difference between female and male become less with increasing age． Conclusion During the safety evaluation tests，expecially combined chronic toxicity / carcinogenicity study，both of gender and age have a greater impact on the body weight、hematology and serum biochemistry． Male and female should be separated from the statistics and the animals background data should be used at the same weeks．

Key words: combined chronic toxicity / carcinogenicity study, SD rats, body weight, mortality rate, hematology and
serum biochemistry, background data