Modulation of P2X receptors via adrenergic pathways in rat dorsal root ganglion neurons after sciatic nerve injury

• Published in: Pain (Amsterdam) Vol. 120; no. 1; pp. 106 - 112
• Main Authors: Maruo, Keishi, Yamamoto, Hideyuki, Yamamoto, Satoshi, Nagata, Tetsu, Fujikawa, Hirokazu, Kanno, Takeshi, Yaguchi, Takahiro, Maruo, Soji, Yoshiya, Shinichi, Nishizaki, Tomoyuki
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 2006; Elsevier
• Subjects: Adaptation, Physiological; Afferent Pathways - metabolism; Animals; Biological and medical sciences; Cells, Cultured; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Dorsal root ganglion; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - metabolism; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Noradrenaline; Norepinephrine - metabolism; P2X receptor; Posterior Horn Cells - metabolism; Protein kinase C; Rats; Rats, Wistar; Receptors, Adrenergic; Receptors, Purinergic P2 - metabolism; Receptors, Purinergic P2X; Sciatic Nerve - injuries; Sciatic Nerve - metabolism; Sciatic nerve injury; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; Sciatic nerve injury; Protein kinase C; Dorsal root ganglion; P2X receptor; Noradrenaline; Spinal cord; P2X3 purinergic receptor; Rat; Enzyme; Transferases; Rodentia; Central nervous system; Reverse transcription; P2X2 purinergic receptor; Vertebrata; Mammalia; Neuron; Protein kinase; Modulation; P2X purinergic receptor; Spinal ganglion; Adrenergic receptor; Time analysis; Sciatic nerve
• ISSN: 0304-3959; 1872-6623
• DOI: 10.1016/j.pain.2005.10.016

The present study examined noradrenaline-induced modulation of ATP-evoked currents in dorsal root ganglion (DRG) neurons after sciatic nerve injury (transection). ATP (10 μM) generated fast/mixed type of whole-cell membrane currents, possibly as mediated via P2X 3/P2X 3-like receptors, and slow type of the currents, possibly as mediated via P2X 2/3 receptors, in acutely dissociated L4/5 DRG neurons, without significant difference between sham and injury group. For sham group, noradrenaline (10 μM) enhanced fast/mixed type of ATP-evoked currents in ipsilateral DRG neurons, that is not inhibited by H-7, a broad inhibitor of protein kinases, but otherwise it had no effect on slow type of the currents. For injury group, noradrenaline (10 μM) significantly potentiated slow type of ATP-evoked currents in ipsilateral DRG neurons, that is abolished by H-7 or GF109203X, a selective inhibitor of protein kinase C (PKC), while it depressed fast/mixed type of the currents. In the analysis of real-time reverse transcription-polymerase chain reaction, an increase in the mRNAs for α 1b, α 2a, α 2d, and β 2 adrenergic receptors was found with the ipsilateral DRGs after sciatic nerve injury. Collectively, the results of the present study suggest that noradrenaline potentiates P2X 2/3 receptor currents by activating PKC via α 1 adrenergic receptors linked to G q protein, perhaps dominantly α 1b adrenergic receptors, in DRG neurons after sciatic nerve injury. This may account for a nociceptive pathway in response to noradrenergic sprouting after peripheral nerve injury.