Extrasynaptic release of dopamine in a retinal neuron: activity dependence and transmitter modulation.
Extrasynaptic release of dopamine is well documented, but its relation to the physiological activity of the neuron is unclear. Here we show that in absence of presynaptic active zones, solitary cell bodies of retinal dopaminergic neurons release by exocytosis packets of approximately 40,000 molecules of dopamine at irregular intervals and low frequency. The release is triggered by the action potentials that the neurons generate in a rhythmic fashion upon removal of all synaptic influences and therefore depends upon the electrical events at the neuronal surface. Furthermore, it is stimulated by kainate and abolished by GABA and quinpirole, an agonist at the D(2) dopamine receptor. Since the somatic receptors for these ligands are extrasynaptic, we suggest that the composition of the extracellular fluid directly modulates extrasynaptic release.
Puopolo
M
M
Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
Hochstetler
S E
SE
Gustincich
S
S
Wightman
R M
RM
Raviola
E
E
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D048429:Cell Size / Q000502:physiology; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009479:Neuropeptides; D009489:Neurosecretion / Q000187:drug effects / Q000502:physiology; D010316:Particle Size; D010507:Periodicity; D012160:Retina / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D050492:Vesicular Biogenic Amine Transport Proteins
D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; D050492:Vesicular Biogenic Amine Transport Proteins; D004298:Dopamine