OBJECTIVES: To investigate the role of ferroptosis in diquat-induced acute kidney injury (AKI) and its molecular mechanisms. METHODS: Transgenic zebrafish models with Tg (Eco.Tshb:EGFP) labeling of the renal tubules and Tg (lyz:dsRed2) labeling of the neutrophils were both divided into control group, gentamicin (positive control) group, diquat poisoning group, ferroptosis inhibitor group. The indicators of kidney injury, inflammatory response, and ferroptosis were examined in the zebrafish, and the changes in expressions of voltage-dependent anion-selective channel protein 1 (VDAC1) and mitochondrial ferritin (FTMT) were detected using Western blotting. RESULTS: AKI induced by diquat exhibited a significant dose-effect relationship, and the severity of injury was proportional to the exposure concentration. Diquat also caused marked oxidative stress and inflammatory responses in the zebrafish models. Rhodamine metabolism assay and HE staining revealed significantly declined glomerular filtration function of the zebrafish as diquat exposure concentration increased. Immunofluorescence staining highlighted significant changes in the expressions of ferroptosis markers GPX4 and FTH1 in zebrafish renal tissues following diquat exposure. In diquat-exposed zebrafish, treatment with ferrostatin-1, a ferroptosis inhibitor, obviously upregulated GPX4 and downregulated FTH1 expressions and improved the metabolic rate of glucan labeled with rhodamine B. Diquat exposure significantly upregulated the expression of VDAC1 and FTMT in zebrafish, and the application of ferrostatin-1 and VBIT-12 (a VDAC1 inhibitor) both caused pronounced downregulation of FTMT expression. CONCLUSIONS Ferroptosis is a critical mechanism underlying diquat-induced AKI, in which VDAC1 and FTMT play important regulatory roles, suggesting their potential as therapeutic target for AKI caused by diquat.
Animals ; Zebrafish ; Ferroptosis/drug effects* ; Acute Kidney Injury/chemically induced* ; Diquat/toxicity* ; Animals, Genetically Modified ; Voltage-Dependent Anion Channel 1/metabolism* ; Ferritins/metabolism* ; Oxidative Stress

OBJECTIVE: To observe the toxicokinetic parameters, absorption characteristics and pathomorphological damage in different parts of the gastrointestinal tract of rats poisoned with different doses of diquat (DQ). METHODS: Ninety-six healthy male Wistar rats were randomly divided into a control group (six rats) and low (115.5 mg/kg), medium (231.0 mg/kg) and high (346.5 mg/kg) dose DQ poisoning groups (thirty rats in each dose group), and then the poisoning groups were randomly divided into 5 subgroups according to the time after exposure (15 minutes and 1, 3, 12, 36 hours; six rats in each subgroup). All rats in the exposure groups were given a single dose of DQ by gavage. Rats in the control group was given the same amount of saline by gavage. The general condition of the rats was recorded. Blood was collected from the inner canthus of the eye at 3 time points in each subgroup, and rats were sacrificed after the third blood collection to obtain gastrointestinal specimens. DQ concentrations in plasma and tissues were determined by ultra-high performance liquid chromatography and mass spectrometry (UPHLC-MS), and the toxic concentration-time curves were plotted to calculate the toxicokinetic parameters; the morphological structure of the intestine was observed under light microscopy, and the villi height and crypt depth were determined and the ratio (V/C) was calculated. RESULTS: DQ was detected in the plasma of the rats in the low, medium and high dose groups 5 minutes after exposure. The time to maximum plasma concentration (Tmax) was (0.85±0.22), (0.75±0.25) and (0.25±0.00) hours, respectively. The trend of plasma DQ concentration over time was similar in the three dose groups, but the plasma DQ concentration increased again at 36 hours in the high dose group. In terms of DQ concentration in gastrointestinal tissues, the highest concentrations of DQ were found in the stomach and small intestine from 15 minutes to 1 hour and in the colon at 3 hours. By 36 hours after poisoning, the concentrations of DQ in all parts of the stomach and intestine in the low and medium dose groups had decreased to lower levels. Gastrointestinal tissue (except jejunum) DQ concentrations in the high dose group tended to increase from 12 hours. Higher doses of DQ were still detectable [gastric, duodenal, ileal and colonic DQ concentrations of 6 400.0 (1 232.5), 4 889.0 (6 070.5), 10 300.0 (3 565.0) and 1 835.0 (202.5) mg/kg respectively]. Light microscopic observation of morphological and histopathological changes in the intestine shows that acute damage to the stomach, duodenum and jejunum of rats was observed 15 minutes after each dose of DQ, pathological lesions were observed in the ileum and colon 1 hour after exposure, the most severe gastrointestinal injury occurred at 12 hours, significant reduction in villi height, significant increase in crypt depth and lowest V/C ratio in all segments of the small intestine, damage begins to diminish by 36-hour post-intoxication. At the same time, morphological and histopathological damage to the intestine of rats at all time points increased significantly with increasing doses of the toxin. CONCLUSIONS The absorption of DQ in the digestive tract is rapid, and all segments of the gastrointestinal tract may absorb DQ. The toxicokinetics of DQ-tainted rats at different times and doses have different characteristics. In terms of timing, gastrointestinal damage was seen at 15 minutes after DQ, and began to diminish at 36 hours. In terms of dose, Tmax was advanced with the increase of dose and the peak time was shorter. The damage to the digestive system of DQ is closely related to the dose and retention time of the poison exposure.
Animals ; Male ; Rats ; Diquat/toxicity* ; Gastrointestinal Diseases ; Intestines ; Poisons ; Rats, Wistar ; Toxicokinetics