A NOVEL G-PROTEIN-COUPLED RECEPTOR MEDIATING BOTH VASOPRESSIN-LIKE AND OXYTOCIN-LIKE FUNCTIONS OF LYS-CONOPRESSIN IN LYMNAEA-STAGNALIS

We have cloned a receptor, named LSCPR, for vasopressin-related Lys-co nopressin in Lymnaea stagnalis. Lys-conopressin evokes Ca2+-dependent Cl- currents in Xenopus oocytes injected with LSCPR cRNA. Expression o f LSCPR mRNA was detected in central neurons and peripheral muscles as sociated with reproduction. Upon application of Lys-conopressin, both neurons and muscle cells depolarize owing to an enhancement of voltage -dependent Ca2+ currents and start firing action potentials. Some neur ons coexpress LSCPR and Lys-conopressin, suggesting an autotransmitter -like function for this peptide. Lysconopressin also induces a depolar izing response in LSCPR-expressing neuroendocrine cells that control c arbohydrate metabolism. Thus, in addition to oxytocin-like reproductiv e functions, LSCPR mediates vasopressin-like metabolic functions of Ly s-conopressin as well.