Study On The Genotoxicity And The Embryonic Developmental Toxicity Of Herba Taxilli

Objective: The purpose of this research was to detect the genotoxicity and embryonic developmental toxicity of Herba Taxilli decoction and study the probable toxicity mechanisms above, in order to provid a theoretical basis for safely using the decoction in clinical treatment. Methods: 1. Genetic toxicity test: (1) Acute toxicity test was used to detect maximal drug dose of Herba Taxilli decoction in KunMing mice. (2) 30 KunMing pregnant mice were randomly divided into five groups (6 mice in each group), negative control group (normal sodium, NS, 0.4ml/20g), Herba Taxilli high, middle and low dosage group respectively (40g/kg, 20g/kg, 10g/kg). From embryonic day 12 (E12) to E16, the mice of four groups above were treated with the corresponding dosage of Herba Taxilli by intragastric administration for 5 days. From E15 to E16, the mice of positive control group were injected intraperitoneally with cyclophosphamide (CP, 40mg/kg·d) for 2 days. On E16, the mice of each group were killed. Micronucleus test was used to detect the micronucleus rate of polychromatic erythrocytes of adult mice bone marrow and fetal mice hepar. (3) 30 male KunMing mice were selected, divided and administrated with the same method as above. Sperm malformation test was used to detect the sperm abnormality rate. 2. Embryonic developmental toxicity test: (1) Acute toxicity test was used to detect maximal drug dose of Herba Taxilli decoction in SD rats. (2) 36 SD pregnant rats were randomly divided into six groups (6 rats in each group). negative control group (NS, 2ml/200g), Herba Taxilli high, middle and low dosage group (40g/kg, 20g/kg, 10g/kg). From E6 to E18, the rats of above four groups were treated with the corresponding dosage by intragastric administration. Two positive control groups (a. CP group, rats were injected intraperitoneally with CP, 12.5mg/kg, on E13 once; b. RA group, rats were administered intragastrically with RA, 100mg/kg, on E10 once.). The pregnant mice were sacrificed to examine the fetuses on E18, including the numbers of absorbed fetus, live and dead fetuses, the appearance, body weight, body length and tail length of their embryos. (3) Immunohistochemistry (IHC) method was used to detect the expression of protein Pax3 and Cx43 of the fetal rat brain and spinal cord tissue. TUNEL method was used to detect the apoptosis of fetal rat brain and spinal cord tissue. Results: 1.Genetic toxicity test: (1) The maximum dosage of intragastric administration in a mouse was 80g/kg. (2) There were no statistically significant difference between 10g/kg dosage group of Herba Taxilli decoction and negative group in the micronucleus rate and the sperm abnormality rate. When Herba Taxilli's dosage was 20g/kg, the micronucleus rate of fetal mice' hepar increased significantly (P <0.05) . However, the rate of bone marrow micronucleus and sperm abnormality had no significant difference compared with that of negative group. When Herba Taxilli's dosage was 40g/kg, the rate of fetal hepar micronucleus, bone marrow micronucleus and sperm abnormality all increased significantly compared with those of negative group (P<0.05). 2. Embryonic developmental toxicity test: (1) The maximum dosage of intragastric administration in a rat was 80g/kg. (2) There were no significant differences between 10g/kg, 20g/kg dosage group of Herba Taxilli decoction and negative group in the number of embryo-implantation, absorbed fetus, dead fetus and and the body weight, body length and tail length of fetal rats. When Herba Taxilli's dosage was 40g/kg, the number of embryo-implantation, fetal rats body weight, body length and tail length decreased significantly compared with negative group (P <0.05). (3) There were no significant differences between three dosage groups of Herba Taxilli decoction and negative group in the expression of Pax3 and Cx43 of fetal rats' brain tissue and spinal cord tissue. As well as the 10g/kg, 20g/kg dosage group of Herba Taxilli decoction and negative group in the apoptotic index of fetal rats' brain tissue and spinal cord tissue. When Herba Taxilli's dosage was 40g/kg, the apoptotic index increased significantly compared with those of negative group (P <0.05). Conclusions: 1. The maximal tolerance dose of Herba Taxilli decoction to KunMing mice and SD rats is 80g/kg. 2. Herba Taxilli decoction doesn't have genotoxicity influence on adult mice and fetal mice when administered with low dosage. It has potential genotoxicity to fetal mice when administered with middle dosage only and has potential genotoxicity to adult mice and fetal mice when administered with high dosage. 3. Three dosage groups of Herba Taxilli decoction have no teratogenic effects on rats embryo. Middle dosage and low dosage of Herba Taxilli decoction have no embryonic developmental toxicity to rat embryo, but high dosage of it has influence on embryo-implantation and embryonic development. 4. Three dosage groups of Herba Taxilli decoction have no influences on the expressions of Pax3,Cx43 of fetal rats' brain and spinal cord tissue. But high dosage of it can increase the apoptosis of fetal rats' brain and spinal cord tissue, which may be a cause of hypoevolutism of fetal rats. 5. This study suggests that pregnant women should avoid taking high dose of Herba Taxilli.