Abstract:

Objective To establish a historical background database of SD rats' 90-day feeding study data to ensure the reliability of research data. Methods Summarized the blank control group data from six independent SD rat 90-day feeding study conducted at the National Institutes for Food and Drug Control from 2020 to 2023. A total of 120 SPF-grade SD rats (half male and half female) were used in the study, and they were only fed with a complete pelleted feed for mice and rats. After the quarantine period, the animals were observed for 90 days, and then anesthetized with ShuTai injection via the peritoneal cavity. Blood was collected and the animals were then fully exsanguinated and dissected. By analyzing the data of blank control group, the relevant background database of SD rats was established.Results The average body weight of both male and female rats increased steadily, with greater increases in males than females. By the 90th day, The average body weight of male and female rats increased to more than 500 g and 300 g, respectively. After 3 weeks, the average daily food intake of male rats was basically around 25-28 g/animal/day, while the average daily food intake of female animals was basically around 16-19 g/animal/day. The food utilization rate of all animals began to decline from the first week. The results of white blood cell classification showed that there were statistically significant differences in the values of WBC, Neut, Lymph, and Mono between female and male rats (P<0.001), but no statistically significant differences in %Neut, %Lymph, and %Mono between the two sexes (P>0.05). The average values of RBC, HGB, HCT, PLT, PT, and APTT in male rats were higher than those in female rats (P<0.05). The average values of ALT, AST, ALP, CK, LDH, GLU, and TG in male rats were higher than those in female rats (P<0.05). The urine pH values of male rats were within 5.0-8.5 and the urine pH values of female rats were within 6.5-9.0. The urine specific gravity of most male rats was lower than 1.020, while the urine specific gravity of most female rats was lower than 1.015. The absolute weights of all organs (except adrenal and reproductive organs) of male animals were higher than those of female animals (P<0.001), and all visceral-body ratios (except kidney and reproductive organs) of female animals were higher than those of male animals (P<0.001).Conclusion Summarized the reference range of weight, food intake, hematology, serum biochemistry, and other parameters in untreated SD rats of the SPF grade at 90-day test period, providing important reference data for related studies.

Key words: SD rats, 90-day feeding study test, Historical background data