Neuronal P2X7 receptors are targeted to presynaptic terminals in the central and peripheral nervous systems.
The ionotropic ATP receptor subunits P2X(1-6) receptors play important roles in synaptic transmission, yet the P2X(7) receptor has been reported as absent from neurons in the normal adult brain. Here we use RT-PCR to demonstrate that transcripts for the P2X(7) receptor are present in extracts from the medulla oblongata, spinal cord, and nodose ganglion. Using in situ hybridization mRNA encoding, the P2X(7) receptor was detected in numerous neurons throughout the medulla oblongata and spinal cord. Localizing the P2X(7) receptor protein with immunohistochemistry and electron microscopy revealed that it is targeted to presynaptic terminals in the CNS. Anterograde labeling of vagal afferent terminals before immunohistochemistry confirmed the presence of the receptor in excitatory terminals. Pharmacological activation of the receptor in spinal cord slices by addition of 2'- and 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP; 30 microm) resulted in glutamate mediated excitation of recorded neurons, blocked by P2X(7) receptor antagonists oxidized ATP (100 microm) and Brilliant Blue G (2 microm). At the neuromuscular junction (NMJ) immunohistochemistry revealed that the P2X(7) receptor was present in motor nerve terminals. Furthermore, motor nerve terminals loaded with the vital dye FM1-43 in isolated NMJ preparations destained after application of BzATP (30 microm). This BzATP evoked destaining is blocked by oxidized ATP (100 microm) and Brilliant Blue G (1 microm). This indicates that activation of the P2X(7) receptor promotes release of vesicular contents from presynaptic terminals. Such a widespread distribution and functional role suggests that the receptor may be involved in the fundamental regulation of synaptic transmission at the presynaptic site.
Deuchars
S A
SA
School of Biomedical Sciences, University of Leeds, LS2 9NQ, Leeds, United Kingdom. J.Deuchars@leeds.ac.uk
Atkinson
L
L
Brooke
R E
RE
Musa
H
H
Milligan
C J
CJ
Batten
T F
TF
Buckley
N J
NJ
Parson
S H
SH
Deuchars
J
J
D000818:Animals; D002490:Central Nervous System / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000294:innervation; D009469:Neuromuscular Junction / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism; D009620:Nodose Ganglion / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D018408:Patch-Clamp Techniques; D017933:Peripheral Nervous System / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013116:Spinal Cord / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology
D018377:Neurotransmitter Agents; C546469:P2rx7 protein, mouse; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D018698:Glutamic Acid