A potential reservoir of immature dopaminergic replacement neurons in the adult mammalian olfactory bulb.
A significant fraction of the interneurons added in adulthood to the glomerular layer (GL) of the olfactory bulb (OB) are dopaminergic (DA). In the OB, DA neurons are restricted to the GL, but using transgenic mice expressing eGFP under the tyrosine hydroxylase (TH) promoter, we also detected the presence of TH-GFP+ cells in the mitral and external plexiform layers. We hypothesized that these could be adult-generated neurons committed to become DA but not yet entirely differentiated. Accordingly, TH-GFP+ cells outside the GL exhibit functional properties (appearance of pacemaker currents, synaptic connection with the olfactory nerve, intracellular chloride concentration, and other) marking a gradient of maturity toward the dopaminergic phenotype along the mitral-glomerular axis. Finally, we propose that the establishment of a synaptic contact with the olfactory nerve is the key event allowing these cells to complete their differentiation toward the DA phenotype and to reach their final destination.
Pignatelli
Angela
A
Sez. Fisiologia e Biofisica, Dipartimento di Biologia ed Evoluzione, Università degli Studi di Ferrara, Via Borsari 46, 44100, Ferrara, Italy.
Ackman
James B
JB
Vigetti
Davide
D
Beltrami
Antonio P
AP
Zucchini
Silvia
S
Belluzzi
Ottorino
O
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009830:Olfactory Bulb / Q000166:cytology* / Q000378:metabolism; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D018408:Patch-Clamp Techniques; D017470:Receptors, Glutamate / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism
D002712:Chlorides; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D017470:Receptors, Glutamate; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine