ORIGINAL ARTICLES
HU Xiaozhen, MA Lina, ZHENG Changhui, GUO Yuanyuan, YE Zuguang, CAO Junling
OBJECTIVE To study the differences in toxicity between intravenous (iv) administration and aqueous solution exposure of Dichroa alkali salt (DAS) in zebrafish. METHODS ① Well-developed zebrafish larvae of 2 d post fertilization (2 dpf) were randomly divided into the normal control (no treatment), solvent control (saline, iv), and DAS groups (0.125, 0.25, 0.50, 1.00 and 2.00 mg·kg-1, iv) before being observed for 3 consecutive days after administration. A heart rate of 0 was determined as death of zebrafish, and the mortality rate, maximum non-lethal dose (MNLD), and 10 percent lethal dose (LD10) were calculated. The incidence of venous sinus congestion, pericardial edema, slowing heart rate and blood flow of zebrafish in the 0.50 and 2.00 mg·kg-1 groups were observed and calculated by somatoscopic microscopy at 4 h after drug administration. Zebrafish larvae were iv given DAS at doses of 0.041, 0.136, 0.412, and 0.452 mg·kg-1 while the malformation phenotypes of zebrafish larvae development were observed under a stereomicroscope for 3 consecutive days, including pericardial edema, abnormal heart rate, slow blood flow, loss of circulation, eye abnormalities, brain malformations, jaw abnormalities, loss/degeneration of the liver, delayed yolk sac absorption, intestinal abnormalities, abnormal body coloration, body edema, curvature of the trunk/tail/nodal cord and muscle degeneration before the incidence was calculated. ② Zebrafish larvae were randomly divided into a normal control group and DAS aqueous solution exposure groups at concentrations of 2.5, 5.0, 10.0, 25.0, 50.0, 75.0, and 100.0 mg·L-1, observed for 3 d until the mortality rate, LD10, and MNLD were calculated. Zebrafish were exposed to DAS aqueous solutions at concentrations of 0.32, 1.06, 3.20, and 11.00 mg·L-1, and the malformation phenotypes of zebrafish larvae development were observed under a stereomicroscope for 3 consecutive days to calculate the incidence. RESULTS ① The MNLD and LD10 of DAS iv administered to zebrafish larvae were 0.412 and 0.452 mg·kg-1, respectively. Compared with the solvent control group, 4 h after DAS iv administration, the incidence of sinus congestion, slow heart rate and pericardial edema in the 0.50 and 2.00 mg·kg-1 groups significantly increased (P<0.05, P<0.01), so was the incidence of slow blood flow in the 2.00 mg·kg-1 group (P<0.01). The rate of delayed yolk sac absorption was significantly increased in the 0.041, 0.136, 0.412, and 0.452 mg·kg-1 groups (P<0.05, P<0.01), so was the mortality rate in the 0.452 mg·kg-1 group (P<0.05), with pericardial edema observed in the dead zebrafish. ② The MNLD and LD10 of DAS aqueous solution exposure for zebrafish larvae were 3.20 and 11.00 mg·L-1, respectively. Compared with the normal control group, the incidence of decreased heart rate and slow blood flow was significantly increased in the 3.20 and 11.00 mg·L-1 groups (P<0.01), so was the incidence of significantly darkened intestines in the 1.06, 3.20, and 11.00 mg·L-1 groups (P<0.01). The incidence of delayed yolk sac absorption was significantly increased in the 0.32, 1.06, 3.20, and 11.00 mg·L-1 groups (P<0.05, P<0.01), so was the incidence of trunk curvature and lower jaw malformation in the 11.00 mg·L-1 group (P<0.01). CONCLUSION The toxic phenotypes of DAS are different between iv administration and aqueous solution exposure in zebrafish larvae. DAS aqueous solution exposure can not only lead to slow heart rate, slow blood rheology, delayed yolk sac absorption and intestinal blackening, but also induce neurodevelopmental toxicity. However, iv administration can effectively ward off significant gastrointestinal damage and neurodevelopmental toxicity.
