In vivo Mammalian Bone Marrow Micronucleus Test is included in the standard battery genotoxicity testing,with great application prospects in medicine,public health,food and drug safety evaluation fields.Establishing standardized experimental methods and conditions in GLP condition and accumulating a certain range of background data could effectively ensure the reliability of the test system,and also provide strong basis to support the experimental data.We herein summarized the background data of mouse and rat bone marrow micronucleus tests performed from 2007 to 2015,to expound the standardized data collection method for rodent animal bone marrow micronucleus test.

OBJECTIVE： To evaluate the DNA damage response of procarbazine hydrochloride （PCZ） and ethyl carbamate （EC） to different tissues in rats by performing alkaline comet assay， to validate the feasibility of alkaline comet assay of various tissues. METHODS： Totally 30 SD rats were randomly divided into 6 groups according to body weight， with 5 rats in each group， such as negative control group （hyperpure water）， PCZ 75 mg/kg group， PCZ 150 mg/kg group， EC 400 mg/kg group， EC 800 mg/kg group， positive control group （N-ethyl-N-nitrosourea 40 mg/kg）. Those rats were given relevant medicine intragasttrically for 4 d； clinical symptoms of rats were observed and body weight was recorded during experiment. Within 3 h after last medication， the rats were sacrificed； liver， renal and lung weight were weighed； liver， kidney， lung and peripheral blood lymphocytes were collected. The single cell suspension was prepared to perform alkaline comet assay. After lysis， unwind， electrophoresis and dying， tail DNA％ and tail distance of samples were analyzed by Komet 6.0 software. RESULTS： Compared with negative control group， body weight， liver and renal weight of rats were decreased significantly in PCZ 75 mg/kg group， PCZ 150 mg/kg group and positive control group 4 d after medication （P＜0.05 or P＜0.01）. Body weight of rats were decreased significantly in EC 800    mg/kg 4 d after medication （P＜0.05 or P＜0.01）； there was no statistical significance （P＞0.05）. Compared with negative control group， tail DNA％ and tail distance in liver， kidney and peripheral blood lymphocytes were increased significantly in PCZ 75    mg/kg group， PCZ 150 mg/kg group and positive control group （P＜0.05 or P＜0.01）； PCZ showed more significant effects on liver and lung. Tail DNA％ and tail distance of liver， kidney and peripheral blood lymphocytes were increased significantly in EC 800 mg/kg group （P＜0.05 or P＜0.01）， and tail DNA％ and tail distance of renal tissue was increased significantly in EC 400   mg/kg group （P＜0.05）. CONCLUSIONS： PCZ induced stronger DNA damage； liver and lung are the major genotoxicity target of PCZ. EC-induced DNA damage is relatively weak， and kidney is the most sensitive organ for EC-induced genotoxicity.

ABSTRACT OBJECTIVE：To evaluate the in vitro and in vivo genotoxicity of emodin-8-O-β-D-glucoside（EG），and to compare the difference of in vitro cell test and in vivo test of rats. METHODS：2D and 3D hepatocyte models were established by in vitro two-dimensional（2D）and three-dimensional（3D）cell culture. After modeling，2D and 3D hepatocyte were divided into blank control group（0.5％ DMSO），mitomycin C group（positive control，0.1 μg/mL），EG low-dose，medium-dose and high-dose groups（10，50，200 μg/mL），respectively. The micronucleus ratio and tail DNA％ of HepaRG cells were detected. SD rats were divided into blank control group（0.5％ sodium carboxymethyl cellulose），ethyl methanesulfonate group（positive control，200 mg/kg），EG low-dose，medium-dose and high-dose groups（100，300，1 000 mg/kg），with 6 rats in each group. They were given medicine intragastrically for consecutive 15 d，once a day. 15 days later，the micronucleus formation rate of bone marrow polychromatic erythrocytes and hepatocytes，the tail DNA％ and tail distance of peripheral blood lymphocytes and hepatocytes were measured. RESULTS：In the in vitro 2D HepaRG hepatocyte model，compared with blank control group，the micronucleus formation rate and tail DNA％ of HepaRG cell were increased significantly in mitomycin C group （P＜0.01）. There was no statistical significance in micronucleus formation rate and tail DNA％ of HepaRG cell among EG groups（P＞0.05）. In 3D HepaRG cell model， compared with blank control group， micronucleus formation rate and tail DNA％ of HepaRG cell were increased significantly in mitomycin C group （P＜0.01 or P＜0.001）， while tail DNA％ of HepaRG cell wasincreased significantly in EG high-dose group（P＜0.01）. In the in vivo test，compared with blank control group，the micronucleus formation rate of bone marrow polychromatic erythrocytes and hepatocytes，the tail DNA％ and tail distance of peripheral blood lymphocytes and hepatocytes were all increased significantly in ethyl methanesulfonate group（P＜0.01）. Tail DNA％ of peripheral blood lymphocytes was increased significantly in EG high-dose group （P＜0.01）. There was no statistical significance in the micronucleus formation rate of bone marrow polychromatic erythrocytes and hepatocytes，the tail DNA％ and tail distance of hepatocytes among EG groups（P＞0.05）；with the increase of dose，there was an increasing trend. CONCLUSIONS：The results of this study suggest that in 2D cell model，EG not lead to chromosome breakage and DNA damage，but the long-term administration and repeated administration in vivo of 3D cell model show that EG has a certain risk of DNA damage，so the evaluation results of 3D HepaRG cell model are more similar to those of rats in vivo. KEYWORDS Emodin-8-O-β-D-glucoside；Genotoxicity；Two-dimensional culture；Three-dimensional culture；Rat；Micronucleus test

ObjectiveTo establish background data for a 90-day feeding trial of SD rats to ensure the reliability of research data. MethodsBackground data from six independent 90-day feeding trials of SD rats conducted by the National Center for Safety Evaluation of Drugs from 2020 to 2023 were summarized. These studies involved a blank control group of 120 SPF-grade 4-week-old SD rats, with an equal number of males and females, which were only given standard full-nutrient pelleted rat feed. After the quarantine period, the animals were observed for an additional 90 days, followed by intraperitoneal injection of Zoletil (50 mg/mL) for anesthesia, blood sampling, euthanasia, and necropsy. By analyzing the data from the blank control group, a relevant background database for SD rats was established. ResultsBoth male and female rats exhibited steady weight gain, with a more pronounced increase in male rats. Within 90 days, the average body weight of male and female rats increased to over 500 g and 300 g, respectively. Three weeks later, the average daily food intake of male rats stabilized at approximately 25~28 g per rat, while that of female rats remained stable at approximately 16~19 g per rat. The food utilization rate of all animals gradually decreased from the first week of the experiment. In the white blood cell (WBC) differential count results, significant differences were observed in the counts of WBCs, neutrophils (Neut), lymphocytes (Lymph), and monocytes (Mono) between males and females (P<0.001). However, there were no significant differences in the percentages of neutrophil (%Neut), lymphocyte (%Lymph), and monocyte (%Mono) between the sexes (P>0.05). The average red blood cell count (RBC), hemoglobin concentration (HGB), hematocrit (HCT), platelet count (PLT), prothrombin time (PT), and activated partial thromboplastin time (APTT) were higher in male animals than in female animals (P<0.05). The average values of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatine phosphokinase (CK), lactate dehydrogenase (LDH), glucose (GLU), and triglyceride (TG) in male rats were higher than those in female rats (P<0.05). The urinary pH range for male animals was 5.0 to 8.5, while for female animals it was 6.5 to 9.0. The majority of male animals had a urinary specific gravity lower than 1.020, and the majority of female animals had a urinary specific gravity lower than 1.015. The weights of various organs (excluding the adrenal glands and reproductive organs) in male animals were heavier than those in female animals (P<0.001), while the organ/body weight ratios (excluding the kidneys and reproductive organs) of female animals were higher than those of male animals (P<0.001). ConclusionThis study summarizes the background reference ranges for body weight, food intake, hematology, and serum biochemistry indicators in SPF-grade SD rats in the untreated control group from six 90-day feeding trials conducted by the National Center for Safety Evaluation of Drugs. It provides important reference data for related research. By summarizing the background and spontaneous histopathological changes in rats, this study aids in the standardization and normalization of subsequent research, as well as in the evaluation and analysis of abnormal results.