Toxicology Research PAPER Cite this: DOI: 10.1039/c4tx00006d Received 13th January 2014, Accepted 4th April 2014 DOI: 10.1039/c4tx00006d www.rsc.org/toxicology Biochemical alterations in kidneys of infant and adult male rats due to exposure to the neonicotinoid insecticides imidacloprid and clothianidin Ayse Dilek Ozsahin,* a Ramazan Bal b and Okkes Yılmaz c Imidacloprid (IMI) and clothianidin (CTD) are the most important of the neonicotinoid insecticides known to target the nicotinic acetylcholine receptor (nAChR) in insects and, potentially, in mammals. In the present study, we aimed to investigate if dailyoral administration of IMI and CTD at low subchronic doses for 90 days has any deleterious effects on the biochemical parameters of infant and adult male rats. Animals were randomly divided into five groups of seven rats each: controls, IMI-infant and IMI-adult treatments at 4 mg per kg BW per day, and CTD-infant and CTD-adult treatments at 12 mg per kg BW per day by oral gavage. Kidneys of rats exposed to IMI and CTD showed biochemical changes. Based on the biochemical studies it is evident that IMI and CTD produce significant effects in male rats at 4 and 12 mg per kg per day of exposure. In conclusion, the present animal experiments revealed that the treatment with IMI and CTD at NOAEL (no observed adverse effect level) dose-levels causes changes in kidney bio- chemical parameters which seem to be dependent on the pesticide and age of the animal (infant or adult). Introduction The neonicotinoids are a new major class of highly potent insecticides that are used for crop protection against piercing– sucking insects of cereals, vegetables, tea and cotton, and for flea control in cats and dogs. 1 Since their introduction in the market in 1991, they have been increasingly used worldwide and have sometimes replaced organophosphate and carba- mate insecticides due to their moderate toxicity to mammals. 2 The first commercialized neonicotinoid was imidacloprid (IMI), followed by clothianidin (CTD). The insecticidal activity of neonicotinoids is primarily attributed to their action on nic- otinic acetylcholine receptors (nAChRs). 3,4 The neonicotinoid acute toxicity mechanism is due to their nicotinic agonist effects, acting on insect and mammal nAChRs. 5 On the other hand, several lines of evidence in the literature show that neo- nicotinoid insecticides present a higher selectivity for insect nAChRs than for mammalian ones. 5,6 However, these neonico- tinoids are more selective towards mammal nAChRs when they are metabolized after their administration. 7,8 Imidacloprid, 1[(6-chloro-3-pyridinyl) methyl]-N-nitro-2-imi- dazolidinimine, a chloronicotyl has been an extensively used insecticide for crop protection worldwide during the last decade due to its low soil persistence and high insecticidal activity at low application rates. 9,10 Its sales are one of the fastest growing in the insecticide market globally due to its low selectivity for insects and relatively low risk to humans. 4,11 Toxicological studies of imidacloprid are limited and the acceptable daily intake (ADI) has been previously reported as 0.006 mg per kg per day based mostly on unpublished reports. 12–14 A case of acute poisoning in humans was recently reported following the ingestion of a formulation containing 10% imidacloprid 15 and few mortality reports due to ingestion have been published. 16 Animal studies have confirmed the relatively low toxicity in vertebrate animals when compared to insects. 17–21 It is moderately toxic and its acute oral LD 50 is 450 mg kg -1 for rats and 150 mg kg -1 for mice. 22 In male rats, the NOAEL dose of IMI is 14 mg per kg BW per day. However, acute ingestion of a 20% formulation of imidacloprid even fol- lowing a large ingestion in patients of self poisoning is rela- tively safe. 23 Clothianidin [(E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl- 2-nitroguanidine] (CTD) is a novel, broad-spectrum insecticide and one of the latest members of the synthetic organic insecti- cides the neonicotinoids. 4,17 CTD has low acute oral toxicity, with an oral LD 50 in rats of >5000 mg per kg body weight. In male rats, the NOAEL dose of CTD has been reported to be a Department of Biology, Faculty of Science and Arts, Bitlis Eren University, TR 13000 Bitlis, Turkey. E-mail: molekuler@gmail.com b Department of Physiology, Faculty of Medicine, Gaziantep University, TR 27310 Gaziantep, Turkey c Department of Biology, Faculty of Science and Arts, Firat University, TR 23119 Elazığ, Turkey This journal is © The Royal Society of Chemistry 2014 Toxicol. Res. Published on 07 April 2014. Downloaded by RSC Internal on 29/05/2014 11:43:07. View Article Online View Journal