The 5-HT/SER-4-dependent inhibition of either the AIB interneurons or cholinergic motor neurons causes locomotory paralysis.

<p><b>A.</b> Confocal images of 5-HT <i>quint</i> expressing SER-4::GFP in the AIB interneurons (P<i>npr-9</i>)(A1) or cholinergic motor neurons (P<i>unc-17β</i>)(A2). GFP fluorescence (A2) or GFP fluorescence overlaid on DIC image (A1). The red stain in A2 is coelomocyte-specific RFP screening marker. <b>B.</b> Paralysis of wild type, mutant and transgenic <i>C</i>. <i>elegans</i> on hypotonic, non-NGM agar plates. Wild type, quadruple 5-HT receptor null animals expressing only SER-4 (SER-4 <i>quad</i>) or 5-HT <i>quint</i> expressing the <i>C</i>. <i>elegans</i> 5-HT₁-like receptor, SER-4, in either the cholinergic motor neurons (P<i>unc-17β</i>) or the two AIB interneurons (P<i>npr-9</i>) were examined for 5-HT (1 mM)-dependent paralysis as outlined in Methods. Data are presented as mean ± SE (n = 3).</p

<i>C</i>. <i>elegans</i> mutants with increased cuticular permeability are hypersensitive to 5-HT-dependent paralysis.

<p><b>A-B.</b> Paralysis of wild type and mutant <i>C</i>. <i>elegans</i> on NGM agar plates. <b>A.</b> Wild type animals examined for 5-HT-dependent paralysis as outlined in Methods. Data are presented as mean ± SE (n = 3). <b>B.</b> Dose-response curves for 5-HT-dependent paralysis on NGM plates at 10 min exposure for wild type and 5-HT <i>quint</i> animals. <b>C-D.</b> Paralysis of wild type and mutant <i>C</i>. <i>elegans</i> on non-NGM agar (hypotonic) plates. <b>C.</b> Wild type animals were examined for 5-HT-dependent paralysis as outlined in Methods. Data are presented as mean ± SE (n = 3). <b>D.</b> Dose-response curves for 5-HT-dependent paralysis in hypotonic conditions at 15 min exposure for wild type and 5-HT <i>quint</i> animals. <b>E-F.</b> 5-HT-dependent paralysis of wild type and mutant <i>C</i>. <i>elegans</i> on NGM agar plates. <b>E.</b> 5-HT (0.25 mM)-dependent paralysis of wild-type, <i>bus-8</i> (<i>e2968</i>), <i>bus-16</i> (<i>e2802</i>) and <i>bus-17</i> (<i>e2800</i>) mutants. Data are presented as mean ± SE (n = 3). <b>F.</b> Dose-response curves for 5-HT-dependent paralysis at 10 min exposure for wild type and <i>bus</i> mutants.</p

PAPP paralyzes <i>C</i>. <i>elegans</i> via SER-4 and DOP-3.

<p><b>A-C.</b> Paralysis of wild type, mutant and transgenic <i>C</i>. <i>elegans</i> on hypotonic non-NGM agar plates. <b>A.</b> PAPP (0.5 mM)-dependent paralysis of wild-type, 5-HT <i>quint</i> and 5-HT <i>quint</i> animals expressing SER-4 in the cholinergic motor neurons (P<i>unc-17β</i>). Data are presented as mean ± SE (n = 3). <b>B.</b> Dose-response curves for PAPP-dependent paralysis at 15 min exposure for wild type, 5-HT <i>quint</i> and 5-HT <i>quint</i> animals expressing SER-4 in the cholinergic motor neurons (P<i>unc-17β</i>). <b>C.</b> PAPP (0.5 mM)-dependent paralysis of 5-HT <i>quint</i> and 5-HT <i>quint</i> animals expressing P<i>dop-3</i>::<i>dop-3</i> RNAi. Data are presented as mean ± SE (n = 3). ‘*’ p≤0.001, significantly different from 5-HT <i>quint</i> animals assayed under identical conditions.</p

5-HT and 5-HT receptor agonists selectively paralyze <i>C</i>. <i>elegans</i> 5-HT receptor mutant animals expressing nematode, insect or human 5-HT₁-like receptors in the cholinergic motor neurons.

<p><b>A-C.</b> Paralysis of wild type, mutant and transgenic <i>C</i>. <i>elegans</i> on hypotonic, non-NGM agar plates. <b>A.</b> 5-HT (1 mM)-dependent paralysis of 5-HT <i>quint</i> animals expressing either <i>C</i>. <i>elegans</i> 5-HT₁-like (SER-4), <i>Drosophila</i> 5-HT₁-like, or human 5-HT_1A receptor in cholinergic motor neurons (P<i>unc-17β</i>). Data are presented as mean ± SE (n = 3). <b>B.</b> 8-OH-DPAT (2 mM)-dependent paralysis of 5-HT <i>quint</i> animals expressing either <i>C</i>. <i>elegans</i> 5-HT₁-like (SER-4), <i>Drosophila</i> 5-HT₁-like, or human 5-HT_1A receptor in cholinergic motor neurons (P<i>unc-17β</i>). Data are presented as mean ± SE (n = 3). <b>C.</b> Sumatriptan (1 mM)-dependent paralysis of wild type, 5-HT <i>quint</i> animals expressing either <i>C</i>. <i>elegans</i> 5-HT₁-like (SER-4), <i>Drosophila</i> 5-HT₁-like, or human 5-HT_1A receptor in cholinergic motor neurons (P<i>unc-17β</i>). Data are presented as mean ± SE (n = 3).</p