| Background The drug toxicity is the main research content in nonclinical safety evaluation, which is up to 26% is cardiovascular toxicity. At present, themechanism of action of exogenous drugs cause cardiac toxicity mainly include oxidativestress, lipid peroxidation and immune inflammation. CYP2E1 is a kind of importantenzyme in the oxidative metabolism of catalytic effection, at the same time produce reactive oxygen free radicals (ROS), causes oxidant stress, inflammatory responseand apoptosis and so on, then produce toxicity to the body. Humanized CYP2E1 genetically modified mice,provides a complete biological genetic system to human CYP2E1 gene expression regulation and function, a lot of researches have been applied to the CYP2E1 metabolism and CYP2E1 gene related diseases such asthe pathogenesis of fatty liver disease in the study. To choose a higher sensitivityanimalmodel to evaluate the cardiotoxicity of drugs, we used the heart-specific CYP2E1 genetically modified mice(a-MHC CYP2E1 transgenic mice,Tg(+)and a-MHC CYP2E1 silencing transgenicmice,sTg(+)) to evaluate the drug acetaminophen and sibutramine-induced toxicity.Methods (1) The breeding and identification of the two heart-specific CYP2E1 genetically modified mouse (Tg(+) and sTg(+)):The genotype of Tg(+) and sTg(+) were detected by PCR, and offsprings were used in present study.(2) Evaluation of acetaminophen-induced acute toxicity:The 8-week old male Tg(+), sTg(+), and C51BL/6 mice (wild type, WT),50 mice in each group, were randomly divided into 2 groups, the solvent control group (intragastric gavage of pure drinking water), and the acetaminophen (300 mg/kg) treatment groups, respectively. The general condition of the mice was observed. At 3 days after the acetaminophen administration, measure each group of blood biochemical indicators (cardiac toxicity index (lactate dehydrogenase(LDH), creatine kinase(CK), creatine kinase isoenzyme(CK-MB)), liver toxicity index (alanine aminotransferase(ALT), aspartate aminotrans ferase(AST) and alkaline phosphatase(ALP) and renal toxicity index (urea nitrogen(UN), creatinine (CREA)), and then the mice were sacrificed and heart, liver, kidney tissue samples were taken for pathological examination.(3) Evaluation of sibutramine-induced toxicity:The 8-week old male Tg(+), sTg(+), and C57BL/6 mice (wild type, WT),50 mice in each group, were randomly divided into 5 groups, the solvent control group (intragastric gavage of pure drinking water), and the four sibutramine (50 mg/kg,100 mg/kg,150 mg/kg and 300 mg/kg) treatment groups, respectively. The general condition of the mice was observed and the survival rate was determined during the drug treatment period. At 15 days after the sibutramine administration, measure each group of blood biochemical indicators (cardiac toxicity index (lactate dehydrogenase(LDH), creatine kinase(CK), creatine kinase isoenzyme (CK-MB)), liver toxicity index (alanine Aminotransferase(ALT), aspartate aminotrans ferase(AST) and alkaline phosphatase(ALP) and renal toxicity index (urea nitrogen (UN), creatinine(CREA)), and then the mice were sacrificed and heart, liver, kidney tissue samples were taken for pathological examination and immunohistochemical observation of the expression of connexin 43 (CX43).2)Results (1)Evaluation of acetaminophen-induced acute toxicity:1) The blood biochemical indicators that the liver toxicity index (ALT, AST, ALP) and the cardiac toxicity index (LDH, CK, CK-MB) in the treaed teams of Tg(+) and sTg(+) mice were significantly higher than those in the WT mice (P<0.05 or P<0.01), and the increasing degree of the liver toxicity index (ALT, AST, ALP)in WT mice is the most(P<0.01), but the cardiac toxicity index (LDH, CK, CK-MB) in the treaed teams of sTg(+) mice were decrease(P<0.05). The pathological examination revealed hepatotoxicity changes in the Tg(+), sTg(+) and WT mice.(2)Evaluation of sibutramine-induced toxicity:1) The blood biochemical indicators in the sibutramine 50 mg/kg and 100 mg/kg Tg(+) mice were significantly higher than those in the WT mice (P<0.05 or P<0.01), and significantly higher in the 50 mg/kg,100 mg/kg and 150 mg/kg sibutramine treated Tg(+) mice than in the sTg(+) mice (P<0.05 or P<0.01). However, when the sibutramine was given at a dose of 300 mg/kg, the values of those indicators in the Tg(+) mice were significantly lower than that in the WT and sTg(+) mice (P<0.05 or P<0.01), with the lowest level in the sTg(+) mice.2) The pathological examination revealed cardiotoxic changes in the Tg(+) and WT mice.3) The immunohistochemical analysis showed that alongside with the increasing drug dose, the expression of CX43 was decreased in the intercalated disks of cardiomyocytes in the Tg(+), sTg(+) and WT mice, and the color staining intensity was mostly decreased in an order of Tg(+)> WT> sTg(+) mice.Conclusions Tg(+) mice may have a higher sensitivity in the evaluation of potential cardiotoxicity than WT mice, but sTg(+) mouse maybe is a protection model.Background Cassiae Semen is the dry and mature seeds of Cassia obtusifolia L. and Cassia tora L., which is a traditional Chinese herbal plant that has the classical efficacy such as heat-clearing and eyesight-improving, water-eliminating and bowel-relaxing since ancient times. Currently, it also has been used to anti-hypertension, anti-hyperlipidemia, and liver-protection, and to treat hyperlipidemia, hypertension, constipation in clinical, and is included in the list of" homology of medicine and food " issued by the Ministry of Health in China. Anthraquinones are the main biological active ingredients in Cassiae Semen, such as emodin, rhubarb phenol, rhubarb acid, which not only have a wide range of pharmacological effects, but also a variety of toxic side effects. Therefore, in our study, we uesd freeze-dried powdered Cassiae Semen as the test substance, to evaluate the chronic toxicity and potential toxic target organ in male and female Sprague-Dawley (SD) rats after 6-month intragastric administration.Methods 240 SD rats with half males and half females(♂or♀:80-100g), were ra ndomly divided into four groups:high dose group(10g/kgBW), middle dose group (2.2g/kgBW), low dose group(0.5g/kgBW) and solvent control group (pure water). The time of gavage administration lasted 6 months. The growth of the mice was also observed after administration. Then we should measure body weight and food consumption at regular intervals. Meanwhile, hematology, coagulation, serum chem istry, organ weight, organ coefficient and histopathologic examination were perfor med on 3-month and 6-month, and following by 4-weeks recovery period,20/grou p with half males and half females, respectively.Results 1、 In our laboratory conditions, there were no abnormalities, dead rats and toxicology change both in treatment group and control group.2、 The weight of each treatment group and the control group are both increase, the growth rate of which in this order respectively:CN>T1>T2>T3, and present a certain dose-re sponse relationship.3、 Compared with the control group, the reticulocyte percentag e(RET%) and total bilirubin (TBIL) in each treatment group of ♂rats are on the 1 ow side, and the recovery after 4 weeks, RET%returned to normal, but the TBI L in T3 of ♂rats is still on the low side.4、 The kidney coefficients inT2 and T3 of ♂arats are higher than that of control group in different degree significantly (P< 0.05 or P<0.01).5、 After 6 months treatment, the rats in T1 and T2 dosen’t appe ar any toxicology changes in connection with semen cassiae, but the T3 group ca n cause the pigment deposition in epithelial cells of renal proximal convoluted tub ules, and may cause renal tubular atrophy and regeneration, and the above pheno menon still exist in recovery after 4 weeks.Conclusions In our laboratory conditions, when we treated with Cassiae Semen for 6 month, the no observed adverse effect level (NOAEL) for freeze-dried powdered Cassiae Semen is 2.2 g/kg in rats, and the toxic target organ in T3 group is kidney. However, the T1 and T2 group does not appear obvious toxic effects. |
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