A Conserved Dopamine-Cholecystokinin Signaling Pathway Shapes Context–Dependent Caenorhabditis elegans Behavior
(A) Schematic representation of the neural circuit underlying NLP-12 modulation of local searching. Synaptic connections (triangles, brackets) are as described by . DVA receives synaptic input from the dopaminergic neuron PDE and makes connections with both motor neurons and interneurons involved in locomotory control. DVA makes synaptic contacts onto all of the motor and interneurons indicated by brackets. In addition, DVA is connected to AVB and PVC by gap junctions. Assignments of interneurons into layers are as described by . Other neuron classes are as described in the text and references therein. DOP-1 modulation of DVA activity regulates NLP-12 release from DVA, altering the motor pattern during local food searching. (B) Average body bend amplitude for the genotypes as indicated measured during an initial five minute time interval (0–5) immediately following removal from food and a second five minute time interval 30 minutes after removal from food (30–35). Bars represent mean values (±SEM) calculated from 9–14 animals. (C) Representative tracks of wild type and nlp-12(ok335) mutants during an initial five minute period (0–5) following removal from food. Note the decreased number of reorientations and increased frequency of long forward runs for nlp-12(ok335) mutant as compared to the wild type. (D) Total directional reorientations measured during the 0–5 and 30–35 minute intervals following removal from food for wild type, transgenic wild type animals expressing Tetanus toxin in DVA [DVA::Tetx], nlp-12(ok335) and ckr-2(tm3082) mutants. Bars represent mean (±SEM) for at least 12 animals. (E) Quantification of reversal coupled omega turns and reorientations in the absence of omega turns during the first 5 minutes following removal from food for the genotypes indicated. (WT and nlp-12(ok335): n = 17). Rescue refers to the nlp-12(ok335) mutant expressing an extrachromosomal array carrying Pnlp-12::nlp-12::SL2::mCherry (n = 9). Bars represent mean (±SEM). ***, p<0.0001; **, p<0.001 by ANOVA with Sidak's post-hoc test.