Imidacloprid (IMI) and acetamiprid (ACE) belong to the neonicotinoids, a new class pesticide, which are widely used in the world to protect crops from pest insects and domestic animals from flea. They act as agonists on nicotinic acetylcholine receptors (nAChRs) and their selective toxicities against insect are well established, while their precise effects on mammalian nAChRs remain to be elucidated. The objective of this study was to determine to what extent the neonicotinoids affect the nAChRs of rat cerebellar neurons, and compare their effects with nicotine by using in vitro excitatory Ca-influx assay. The results indicate the neonicotinoids as well as nicotine directly act on mammalian nAChRs and, therefore, may have various adverse effects on the human health, especially on the developmental brain.
The significant excitatory Ca-influx was evoked by IMI and ACE even at ≥1 μM as seen by nicotine in small neurons, which expressed nAChR subunits α3, α4 and α7. Firing patterns of nicotine and ACE (≥10 μM) were sharp, while those of IMI and ACE (1 μM) were rather broad. Nicotine excited rather higher proportions of neurons and showed higher peak of Ca-influx as compared with ACE and IMI. Then ACE and IMI were more effective on mammalian neurons than previously estimated from the binding assays. Further the effects of neonicotinoids were significantly inhibited with nAChR antagonists, mecamylamine, α-bungarotoxin, and dihydro-β-erythroidine. These results indicate the neonicotinoids as well as nicotine directly act on mammalian nAChRs and, therefore, may have various adverse effects on the human health, especially on the developmental brain.
Source: Kimura-Kuroda J, Komuta Y, Kuroda Y, Hayashi M, Kawano H (2012) Nicotine-Like Effects of the Neonicotinoid Insecticides Acetamiprid and Imidacloprid on Cerebellar Neurons from Neonatal Rats. PLoS ONE 7(2): e32432. doi:10.1371/journal.pone.0032432 (attached)
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