title: β-Phenylethylamine requires the dopamine transporter to increase extracellular dopamine in Caenorhabditis elegans dopaminergic neurons.
abstract: β-Phenylethylamine (βPEA) is an endogenous amine that has been shown to increase the synaptic levels of dopamine (DA). A number of in vitro and behavioral studies suggest the dopamine transporter (DAT) plays a role in the effects generated by βPEA, however the mechanism through which βPEA affects DAT has not yet been elucidated. Here, we used Caenorhabditis (C.) elegans DAT (DAT-1) expressing LLC-pk1 cells and neuronal cultures to investigate whether the βPEA-induced increase of extracellular DA required DAT-1. Our data show that βPEA increases extracellular dopamine both in DAT-1 transfected cells and cultures of differentiated neurons. RTI-55, a cocaine homologue and DAT inhibitor, completely blocked the βPEA-induced effect in transfected cells. However in neuronal cultures, RTI-55 only partly inhibited the increase of extracellular DA generated by βPEA. These results suggest that βPEA requires DAT-1 and other, not yet identified proteins, to increase extracellular DA when tested in a native system. Furthermore, our results suggest that βPEA-induced increase of extracellular DA does not require functional monoamine vesicles as genetic ablation of the C. elegans homologue vesicular monoamine transporter, cat-1, did not compromise the ability of βPEA to increase extracellular DA. Finally, our electrophysiology data show that βPEA caused fast-rising and self-inactivating amperometric currents in a subset of wild-type DA neurons but not in neurons isolated from dat-1 knockout animals. Taken together, these data demonstrate that in both DA neurons and heterogeneous cultures of differentiated C. elegans neurons, βPEA releases cytoplasmic DA through DAT-1 to ultimately increase the extracellular concentration of DA.
authors.affiliation: Department of Basic Science, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202-9037, United States.
authors.forename: Murad
authors.initials: M
authors.lastname: Hossain
authors.affiliation: Department of Basic Science, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202-9037, United States.
authors.forename: Rochelle N
authors.initials: RN
authors.lastname: Wickramasekara
authors.affiliation: Department of Basic Science, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202-9037, United States. Electronic address: lucia.carvelli@med.und.edu.
authors.forename: Lucia
authors.initials: L
authors.lastname: Carvelli
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D055786:Gene Knockout Techniques; D010627:Phenethylamines / Q000494:pharmacology*; D011619:Psychotropic Drugs / Q000494:pharmacology*; D050492:Vesicular Biogenic Amine Transport Proteins / Q000378:metabolism
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D010627:Phenethylamines; D011619:Psychotropic Drugs; D050492:Vesicular Biogenic Amine Transport Proteins; C029261:phenethylamine; D004298:Dopamine
keywords: Caenorhabditiselegans; Dopamine release; Dopamine transporter; Electrophysiology; β-Phenylethylamine