Tissue distribution, metabolism and hepatic tissue injury in Chinese lizards (Eremias argus) after a single oral administration of lambda-cyhalothrin

Abstract

a b s t r a c tLambda-cyhalothrin (LCT) is a widely used pyrethroid with neurotoxicity. However, little is known about the toxicokinetics of LCT in reptiles. In this study, the absorption, distribution, metabolism and excretion of LCT in Chinese lizards (Eremias Argus) were determined following a single dose (10 mg kg À1 ) treatment. In the liver, brain, gonads and skin, LCT levels peaked within several hours and then decreased rapidly. However, the concentration of LCT gradually increased in the fat tissue. More than 90% of the LCT dose was excreted in the faeces. One LCT metabolite, 3-phenoxybenzoic acid (PBA), was detected in lizard plasma and tissues. PBA preferentially accumulates in the brain and plasma. The half-life of PBA in the brain was 3.2 days, which was 35.4-fold greater than that of LCT. In the plasma, the concentration of PBA was significantly higher than that of LCT. The bioaccumulation of LCT in tissues was enantioselective, and the enantiomeric fractions (EF) ranged from 0.72 to 0.26. The preferential accumulation of enantiomers changed according to exposure time, but the reasons behind this phenomenon were not clear. For pathological analysis, vacuolation of the cytoplasm and large areas of necrosis were observed in the liver sections after 168 h of dosing. The liver tissues exhibited both decreases in the hepatosomatic index and histopathological lesions during the exposure period. In this study, the effect concentration of LCT in lizards was 200-fold lower than its LD 50 value used in risk assessments for birds. These results may provide additional information for the risk assessment of LCT for reptiles and indicate that birds may not be an ideal surrogate for reptile toxicity evaluation.

The tissue distribution, metabolism and hepatotoxicity of benzoylurea pesticides in male Eremias argus after a single oral administration

“…As the liver is also one of the major organs to accumulate flufenoxuron, the decrease of hepatic index can be attributed to the low degree for detoxification of flufenoxuron in the liver. Similar with the result of flufenoxuron, lizards exposed to pyrethroid pesticides showed significant decrease in the hepatosomatic index (Chang et al, 2016;Chen et al, 2016). In that case, the liver can be considered as an indicator of detoxification ability of lizards.…”

“…In this study, the concentration of diflubenzuron in the fat was the highest while the skin could quickly eliminate or release the diflubenzuron. Our previous study also showed that the level of lambda-cyhalothrin increased with time in the lizard fat but not in the skin (Chang et al, 2016). Several studies have found that diflubenzuron treatment decreased the lipid level in the fat body of mealworms (Khebbeb et al, 1997) and birds (Whitmore et al, 1993).…”

“…In the exposure group, the lizards were killed at 1, 3, 6, 12, 24, 72, 120, 168 h after dosing. In the control group, the lizards were only sacrificed at 168 h because of its non distinctiveness among different time points (Chang et al, 2016). The body weights of lizards were measured.…”

Enantioselective Elimination and Gonadal Disruption of Lambda-Cyhalothrin on Lizards (Eremias argus)

“…The elimination of LCT follows the first-order kinetics and most of the dose is eliminated within the first 1−6 h after absorption in lizard tissues. 9 Pyrethroids are rapidly degraded to inactive metabolites, which are excreted primarily through urine. 34 However, the format of LCT metabolites in feces has not been well studied.…”

“…It is found to be ubiquitous in treated wastewater − and soil. , Uncontrolled use of these insecticides resulted in their entry into the food chain, thereby causing toxicity to different organism systems. Compared with dermal exposure, oral and inhalation result in faster systemic exposure. , Because of its lipophilic properties, pyrethroids tend to deposite in the fat of lizard, rat, and pig. − Pyrethroids are demonstrated to be accumulated in fish tissues. , However, the body burden of pyrethroids in terrestrial animals has been seldomly studied.…”