Subpopulations of rat dorsal root ganglion neurons express active vesicular acetylcholine transporter.
The vesicular acetylcholine transporter (VAChT) is a transmembrane protein required, in cholinergic neurons, for selective storage of acetylcholine into synaptic vesicles. Although dorsal root ganglion (DRG) neurons utilize neuropeptides and amino acids for neurotransmission, we have previously demonstrated the presence of a cholinergic system. To investigate whether, in sensory neurons, the vesicular accumulation of acetylcholine relies on the same mechanisms active in classical cholinergic neurons, we investigated VAChT presence, subcellular distribution, and activity. RT-PCR and Western blot analysis demonstrated the presence of VAChT mRNA and protein product in DRG neurons and in the striatum and cortex, used as positive controls. Moreover, in situ hybridization and immunocytochemistry showed VAChT staining located mainly in the medium/large-sized subpopulation of the sensory neurons. A few small neurons were also faintly labeled by immunocytochemistry. In the electron microscope, immunolabeling was associated with vesicle-like elements distributed in the neuronal cytoplasm and in both myelinated and unmyelinated intraganglionic nerve fibers. Finally, [(3)H]acetylcholine active transport, evaluated either in the presence or in the absence of ATP, also demonstrated that, as previously reported, the uptake of acetylcholine by VAChT is ATP dependent. This study suggests that DRG neurons not only are able to synthesize and degrade ACh and to convey cholinergic stimuli but also are capable of accumulating and, possibly, releasing acetylcholine by the same mechanism used by the better known cholinergic neurons.
Tata
Ada Maria
AM
Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy.
De Stefano
M Egle
ME
Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy.
Srubek Tomassy
Giulio
G
Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy.
Vilaró
M Teresa
MT
Department of Neurochemistry, CSIC-IDIBAPS, Barcelona, Spain.
Levey
Allan I
AI
Department of Neurology, Emory University School of Medicine, Atlanta, Georgia.
Biagioni
Stefano
S
Dipartimento Biologia Cellulare e dello Sviluppo, Università "La Sapienza," Rome, Italy.
D000109:Acetylcholine / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D048429:Cell Size; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000648:ultrastructure; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000378:metabolism* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D022161:Transport Vesicles / Q000378:metabolism / Q000648:ultrastructure; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C493461:Slc18a3 protein, rat; D050494:Vesicular Acetylcholine Transport Proteins; D033921:Vesicular Transport Proteins; D000255:Adenosine Triphosphate; D000109:Acetylcholine