Sensory presynaptic and widespread somatodendritic immunolocalization of central ionotropic P2X ATP receptors

• Published in: Neuroscience 1998-03, Vol.83 (1), p.177-190
• Main Authors: Leˆ, K.-T., Villeneuve, P., Ramjaun, A.R., McPherson, P.S., Beaudet, A., Séguéla, P.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Sequence; Animals; ATP-gated channel; Biological and medical sciences; Blotting, Western; Cell Line; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Dendrites - metabolism; Dendrites - physiology; Epitopes - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Immunohistochemistry; Ion Channel Gating - physiology; Male; Molecular Sequence Data; Molecular Weight; Neurons, Afferent - metabolism; Neurons, Afferent - physiology; nucleotide; olfactory bulb; Presynaptic Terminals - metabolism; purinergic; Rats; Rats, Sprague-Dawley; Receptors, Purinergic P2 - metabolism; spinal cord; Spinal Cord - metabolism; Spinal Cord - physiology; substantia gelatinosa; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(97)00365-5

Recent evidence suggests that extracellular ATP plays a neurotransmitter role in the central nervous system. Its fast ionotropic effects are exerted through a family of P2X ATP-gated channels expressed in brain and spinal cord. To determine the physiological significance of central ATP receptors, we have investigated the localization of a major neuronal P2X receptor at the cellular and subcellular levels using affinity-purified antibodies directed against the C-terminal domain of P2X 4 subunit. Subunit-specific anti-P2X 4 antibodies detected a single band of 57, 000±3000 mol. wt in transfected HEK-293 cells and in homogenates from adult rat brain. The strongest expression of central P2X receptors was observed in the olfactory bulb, lateral septum, cerebellum and spinal cord. P2X 4 immunoreactivity was also evident in widespread areas including the cerebral cortex, hippocampus, thalamus and brainstem. In all regions examined, P2X receptors were associated with perikarya and dendrites where they were concentrated at the level of afferent synaptic junctions, confirming a direct involvement of postsynaptic ATP-gated channels in fast excitatory purinergic transmission. Moreover, P2X 4 containing purinoceptors were localized in axon terminals in the olfactory bulb and in the substantia gelatinosa of nucleus caudalis of the medulla and dorsal horn of the spinal cord, demonstrating an important selective presynaptic role of ATP in the modulation of neurotransmitter release in central sensory systems.