Figure 2.
Bumblebee brain neurons undergo mitochondrial depolarization when nAChR are hyperstimulated. A) Bumblebee neurons in culture undergo mitochondrial depolarization in the presence of high levels (1 mM; open circles) but not low levels (100 μM; filled circles) of acetylcholine. The neonicotinoid, clothianidin (B), induces mitochondrial depolarization at 10 nM (open circles) but not at 1 nM (filled circles), and imidacloprid (C) induces mitochondrial depolarization at 1 µM (open circles) but not at 10 nM (filled circles). (D) Neurons pre-exposed to the nAChR antagonist d-tubucurarine (500 μM) do not undergo mitochondrial depolarization in the presence of clothianidin (100 nM), demonstrating an nAChR-dependent process. In all cases, mitochondrial depolarization was monitored using ratiometric (red/green) JC-1 imaging, and the experiment was terminated by full mitochondrial depolarization using 2,4-dinitophenol (1 mM). In all cases, 15–20 regions of interest were monitored (n = 3).
