A Conserved Dopamine-Cholecystokinin Signaling Pathway Shapes Context–Dependent Caenorhabditis elegans Behavior
(A) Time course of paralysis in the presence of the L-AChR agonist levamisole (200 µM) for wild type, L-AChR(gf), nlp-12 mutants and nlp-12;L-AChR(gf) animals as indicated. Each data point represents the mean (± SEM) for at least 10 trials. (B) Current responses to pressure application (1 s) of levamisole (500 µM) recorded from body wall muscles of control (− transgene) (n = 5), L-AChR(gf) (n = 6) and nlp-12;L-AChR(gf) (n = 4) animals as indicated. Holding potential was −60 mV. (C) The ratio of the current amplitude 1 s after the start of levamisole application (steady state) to the peak current for control, L-AChR(gf), and nlp-12;L-AChR(gf) animals as indicated. (D) Current responses to photostimulation of motor neurons (10 ms, upper or 800 ms, lower) recorded from body wall muscles of control, L-AChR(gf), and nlp-12;L-AChR(gf) animals as indicated. Holding potential was −80 mV. Recordings were made in the presence of the N-AChR antagonist dHβE (10 µM) to isolate the L-AChR mediated current. (E, F) Average amplitude (E) decay time constant (F) for synaptic responses to 10 ms motor neuron photostimulation for the genotypes indicated. The decay phase of L-AChR mediated evoked current responses were fit with a single exponential. Bars represent mean (± SEM) of amplitude and decay time constant values calculated for responses from control (n = 19), L-AChR(gf) (n = 11), and nlp-12;L-AChR(gf) (n = 11) animals. ***, p<0.0001 by ANOVA with Sidak's post-hoc test. Each strain stably expressed the Pacr-2::ChR2-GFP transgene (ufIs23) for photostimulation of motor neurons.