Neonicotinoid insecticides inhibit cholinergic neurotransmission in a molluscan (Lymnaea stagnalis) nervous system.
Neonicotinoids are highly potent and selective systemic insecticides, but their widespread use also has a growing impact on non-target animals and contaminates the environment, including surface waters. We tested the neonicotinoid insecticides commercially available in Hungary (acetamiprid, Mospilan; imidacloprid, Kohinor; thiamethoxam, Actara; clothianidin, Apacs; thiacloprid, Calypso) on cholinergic synapses that exist between the VD4 and RPeD1 neurons in the central nervous system of the pond snail Lymnaea stagnalis. In the concentration range used (0.01-1 mg/ml), neither chemical acted as an acetylcholine (ACh) agonist; instead, both displayed antagonist activity, inhibiting the cholinergic excitatory components of the VD4-RPeD1 connection. Thiacloprid (0.01 mg/ml) blocked almost 90% of excitatory postsynaptic potentials (EPSPs), while the less effective thiamethoxam (0.1 mg/ml) reduced the synaptic responses by about 15%. The ACh-evoked membrane responses of the RPeD1 neuron were similarly inhibited by the neonicotinoids, confirming that the same ACh receptor (AChR) target was involved. We conclude that neonicotinoids act on nicotinergic acetylcholine receptors (nAChRs) in the snail CNS. This has been established previously in the insect CNS; however, our data indicate differences in the background mechanism or the nAChR binding site in the snail. Here, we provide the first results concerning neonicotinoid-related toxic effects on the neuronal connections in the molluscan nervous system. Aquatic animals, including molluscs, are at direct risk while facing contaminated surface waters, and snails may provide a suitable model for further studies of the behavioral/neuronal consequences of intoxication by neonicotinoids.
Department of Experimental Zoology, MTA Centre for Ecological Research, Balaton Limnological Institute, H-8237 Tihany, POB 35, Hungary. Electronic address: vehovszky.agnes@okologia.mta.hu.
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Vehovszky
Department of Experimental Zoology, MTA Centre for Ecological Research, Balaton Limnological Institute, H-8237 Tihany, POB 35, Hungary.
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Farkas
Department of Experimental Zoology, MTA Centre for Ecological Research, Balaton Limnological Institute, H-8237 Tihany, POB 35, Hungary.
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Ács
Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, M. Kryvonosa Str., 2, Ternopil 46027, Ukraine.
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Stoliar
Department of Environmental Analysis, Agro-Environmental Research Institute, National Agricultural Research and Innovation Centre, H-1022 Budapest, Herman O. u. 15, Hungary.
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Székács
Department of Environmental Analysis, Agro-Environmental Research Institute, National Agricultural Research and Innovation Centre, H-1022 Budapest, Herman O. u. 15, Hungary.
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Mörtl
Department of Experimental Zoology, MTA Centre for Ecological Research, Balaton Limnological Institute, H-8237 Tihany, POB 35, Hungary.
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Győri
D000818:Animals; D002490:Central Nervous System / Q000187:drug effects; D007093:Imidazoles / Q000633:toxicity; D007306:Insecticides / Q000633:toxicity*; D008195:Lymnaea / Q000187:drug effects*; D000073943:Neonicotinoids; D009474:Neurons / Q000187:drug effects; D009574:Nitro Compounds / Q000633:toxicity; D010078:Oxazines / Q000633:toxicity; D011978:Receptors, Nicotinic / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects*; D000077922:Thiamethoxam; D013844:Thiazoles / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity
D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D011978:Receptors, Nicotinic; D013844:Thiazoles; D014874:Water Pollutants, Chemical; C082359:imidacloprid; D000077922:Thiamethoxam
Acetamiprid; Clothianidin; Imidacloprid; Neuron; Thiacloprid; Thiamethoxam