Expression of vesicular glutamate transporters, VGLUT1 and VGLUT2, in cholinergic spinal motoneurons.
Mammalian spinal motoneurons are cholinergic neurons that have long been suspected to use also glutamate as a neurotransmitter. We report that VGLUT1 and VGLUT2, two subtypes of vesicular glutamate transporters, are expressed in rat spinal motoneurons. Both proteins are present in somato-dendritic compartments as well as in axon terminals in primary cultures of immunopurified motoneurons and sections of spinal cord from adult rat. However, VGLUT1 and VGLUT2 are not found at neuromuscular junctions of skeletal muscles. After intracellular injection of biocytin in motoneurons, VGLUT2 is observed in anterogradely labelled terminals contacting Renshaw inhibitory interneurons. These VGLUT2- and VGLUT1-positive terminals do not express VAChT, the vesicular acetylcholine transporter. Overall, our study establishes for the first time that (i) mammalian spinal motoneurons express vesicular glutamate transporters, (ii) these motoneurons have the potential to release glutamate (in addition to acetylcholine) at terminals contacting Renshaw cells, and finally (iii) the VGLUTs are not present at neuromuscular synapses of skeletal muscles.
Herzog
E
E
INSERM U 513, Faculte de Medecine, 94010 Creteil 94010 cedex, France.
Landry
M
M
Buhler
E
E
Bouali-Benazzouz
R
R
Legay
C
C
Henderson
C E
CE
Nagy
F
F
Dreyfus
P
P
Giros
B
B
El Mestikawy
S
S
D000818:Animals; D001933:Brain Stem / Q000502:physiology; D017931:DNA Primers; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D026901:Membrane Transport Proteins; D009046:Motor Neurons / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013116:Spinal Cord / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2
D017931:DNA Primers; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C493475:Slc17a6 protein, rat; C493466:Slc17a7 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D012313:RNA