title: Dual excitatory and inhibitory serotonergic inputs modulate egg laying in Caenorhabditis elegans.
abstract: Serotonin (5-HT) regulates key processes in both vertebrates and invertebrates. Previously, four 5-HT receptors that contributed to the 5-HT modulation of egg laying were identified in Caenorhabditis elegans. Therefore, to assess potential receptor interactions, we generated animals containing combinations of null alleles for each receptor, especially animals expressing only individual 5-HT receptors. 5-HT-stimulated egg laying and egg retention correlated well with different combinations of predicted excitatory and inhibitory serotonergic inputs. For example, 5-HT did not stimulate egg laying in ser-1, ser-7, or ser-7 ser-1 null animals, and ser-7 ser-1 animals retained more eggs than wild-type animals. In contrast, 5-HT-stimulated egg laying in ser-4;mod-1 animals was greater than in wild-type animals, and ser-4;mod-1 animals retained fewer eggs than wild-type animals. Surprisingly, ser-4;mod-1;ser-7 ser-1 animals retained the same number of eggs as wild-type animals and exhibited significant 5-HT-stimulated egg laying that was dependent on a previously uncharacterized receptor, SER-5. 5-HT-stimulated egg laying was absent in ser-5;ser-4;mod-1;ser-7 ser-1 animals, and these animals retained more eggs than either wild-type or ser-4;mod-1;ser-7 ser-1 animals. The 5-HT sensitivity of egg laying could be restored by ser-5 muscle expression. Together, these results highlight the dual excitatory/inhibitory serotonergic inputs that combine to modulate egg laying.
authors.affiliation: Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606-3390, USA.
authors.forename: Vera M
authors.initials: VM
authors.lastname: Hapiak
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hobson
authors.forename: Lindsay
authors.initials: L
authors.lastname: Hughes
authors.forename: Katherine
authors.initials: K
authors.lastname: Smith
authors.forename: Gareth
authors.initials: G
authors.lastname: Harris
authors.forename: Christina
authors.initials: C
authors.lastname: Condon
authors.forename: Patricia
authors.initials: P
authors.lastname: Komuniecki
authors.forename: Richard W
authors.initials: RW
authors.lastname: Komuniecki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism; D005260:Female; D008124:Locomotion / Q000187:drug effects; D008954:Models, Biological; D008969:Molecular Sequence Data; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010058:Oviposition / Q000187:drug effects / Q000502:physiology*; D010802:Phylogeny; D011985:Receptors, Serotonin / Q000737:chemistry; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029742:Caenorhabditis elegans Proteins; D011985:Receptors, Serotonin; D012701:Serotonin