In Vivo Effects of Neonicotinoid-Sulfoximine Insecticide Sulfoxaflor on Acetylcholinesterase Activity in the Tissues of Zebrafish (Danio rerio).

Petek Piner Benli,Mehmet Çelik

doi:10.3390/toxics9040073

Abstract

Sulfoxaflor is the first member of the neonicotinoid-sulfoximine insecticides that acts as an agonist of nicotinic acetylcholine receptors (nAChRs). This study investigated the acute effects of sulfoxaflor on acetylcholinesterase (AChE; EC 3.1.1.7) enzyme activity in the brain and muscle tissues of zebrafish (Danio rerio) as a model organism. The zebrafish were exposed to 0.87 mg/L (2.5% of 96 h 50% lethal concentration (LC50), 1.75 mg/L (5% of 96 h LC50) and 3.51 mg/L (10% of 96 h LC50) of sulfoxaflor for 24 h–48 h and 96 h periods. AChE enzyme activities were analysed by a spectrophotometric method in the brain and muscle tissues. The results of this study showed that in vivo acute sulfoxaflor exposure significantly increased AChE enzyme activity in the brain and muscle tissues of zebrafish. The induction percentages of AChE were between 10 and 83%, and 19 and 79% for brain and muscle tissues, respectively. As a result, it was found that sulfoxaflor had an effect on AChE enzyme activity in the two main tissues containing this enzyme, and it can be considered as a potential neuroactive compound for zebrafish.

Highlights

Sufoxaflor[methyl(oxo){1-[6-(trifluoromethyl)-3-pyridyl]ethyl}-λ6-sulfanylidene]cyanamide (IUPAC) (Chemical Abstracts Service No 946578-00-3) is one of the newly developed neonicotinoid-sulfoximine insecticides [1] and it acts as a nicotinic acetylcholine receptor agonist in insects [2]
Based on previous research into the effects of neonicotinoids on other nontarget organisms, the present study investigated the effects of acute exposure to sulfoxaflor on zebrafish brain and muscle by evaluating the AChE activity
Significant induction was determined by sulfoxaflor exposure; AChE induction might not be suggested as a biomarker due to the lack of a dose–response relationship for sulfoxaflor exposure

Summary

Introduction

Sufoxaflor[methyl(oxo){1-[6-(trifluoromethyl)-3-pyridyl]ethyl}-λ6-sulfanylidene]cyanamide (IUPAC) (Chemical Abstracts Service No 946578-00-3) is one of the newly developed neonicotinoid-sulfoximine insecticides [1] and it acts as a nicotinic acetylcholine receptor (nAChR) agonist in insects [2]. Recent studies reported that sulfoxaflor is highly toxic to some aquatic organisms [3] and bees [4,5,6]. Studies have reported that neonicotinoids have certain adverse effects on wildlife, considering direct (toxic) or indirect (e.g., food chain) impacts on birds, amphibians, fish, reptiles and mammals [13]. While neonicotinoids are highly selective on insect nicotinic receptors, a number of studies have shown that the compounds can activate and/or modulate the nicotinic receptors of humans [14] and other vertebrates [15,16,17,18]. Recent studies have demonstrated that specific neonicotinoids or their metabolites may lead to neurotoxic effects in model

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