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. During the present study, the authors 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 (0.01-1mg/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 (0.01mg/ml) blocked almost 90% of excitatory postsynaptic potentials (EPSPs), while the less effective thiamethoxam (0.1mg/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. The authors concluded that neonicotinoids act on nicotinergic acetylcholine receptors (nAChRs) in the snail CNS. This has been established previously in the insect CNS; however, this data indicate differences in the background mechanism or the nAChR binding site in the snail. These results 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 behavioural/neuronal consequences of intoxication by neonicotinoids.

Authors: Vehovszky Á, Farkas A, Ács A, Stoliar O, Székács A, Mörtl M, Gy?ri J. ;Full Source: Aquatic Toxicology. 2015 Aug 24;167:172-179. doi: 10.1016/j.aquatox.2015.08.009. [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][Epub ahead of print] ;[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]