Rat tooth pulp projections to spinal trigeminal subnucleus caudalis are glutamate-like immunoreactive

1991 ◽  
Vol 309 (2) ◽  
pp. 281-288 ◽  
Author(s):  
J. R. Clements ◽  
K. R. Magnusson ◽  
J. Hautman ◽  
A. J. Beitz
Keyword(s):  
Tooth Pulp ◽  
Trigeminal Subnucleus Caudalis

Endogenous ATP Involvement in Mustard-Oil-Induced Central Sensitization in Trigeminal Subnucleus Caudalis (Medullary Dorsal Horn)

2005 ◽  
Vol 94 (3) ◽  
pp. 1751-1760 ◽  
Author(s):  
C. Y. Chiang ◽  
S. Zhang ◽  
Y. F. Xie ◽  
J. W. Hu ◽  
J. O. Dostrovsky ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Dorsal Horn ◽  
Central Sensitization ◽  
P2x Receptor ◽  
Field Size ◽  
Mustard Oil ◽  
Tooth Pulp ◽  
Nociceptive Neurons ◽  
Medullary Dorsal Horn ◽  
Trigeminal Subnucleus Caudalis

Central sensitization represents a sustained hypersensitive state of dorsal horn nociceptive neurons that can be evoked by peripheral inflammation or injury to nerves and tissues. It reflects neuroplastic changes such as increases in neuronal spontaneous activity, receptive field size, and responses to suprathreshold stimuli and a decrease in activation threshold. We recently demonstrated that purinergic receptor mechanisms in trigeminal subnucleus caudalis (Vc; medullary dorsal horn) are also involved in the initiation and maintenance of central sensitization in brain stem nociceptive neurons of trigeminal subnucleus oralis. The aim of the present study was to investigate whether endogenous ATP is involved in the development of central sensitization in Vc itself. The experiments were carried out on urethan/α-chloralose anesthetized and immobilized rats. Single neurons were recorded and identified as nociceptive-specific (NS) in the deep laminae of Vc. During continuous saline superfusion (0.6 ml/h it) over the caudal medulla, Vc neuronal central sensitization was readily induced by mustard oil application to the tooth pulp. However, this mustard-oil-induced central sensitization could be completely blocked by continuous intrathecal superfusion of the wide-spectrum P2X receptor antagonist pyridoxal-phosphate-6-azophenyl-2, 4-disulphonic acid tetra-sodium (33–100 μM) and by apyrase (an ectonucleotidase enzyme, 30 units/ml). Superfusion of the selective P2X1, P2X3 and P2X2/3 receptor antagonist 2′,3′- O-(2,4,6-trinitrophenyl) adenosine 5′-triphosphate (6–638 μM) partially blocked the Vc central sensitization. The two P2X receptor antagonists did not significantly affect the baseline nociceptive properties of the Vc neurons. These findings implicate endogenous ATP as an important mediator contributing to the development of central sensitization in nociceptive neurons of the deep laminae of the dorsal horn.

scholarly journals P2X Receptors in Trigeminal Subnucleus Caudalis Modulate Central Sensitization in Trigeminal Subnucleus Oralis

2002 ◽  
Vol 88 (4) ◽  
pp. 1614-1624 ◽  
Author(s):  
Bo Hu ◽  
Chen Yu Chiang ◽  
James W. Hu ◽  
Jonathan O. Dostrovsky ◽  
Barry J. Sessle
Keyword(s):  
Central Sensitization ◽  
Receptor Agonist ◽  
P2x Receptors ◽  
Field Size ◽  
Mustard Oil ◽  
Tooth Pulp ◽  
Receptor Subtypes ◽  
Mechanical Stimuli ◽  
Nociceptive Neurons ◽  
Trigeminal Subnucleus Caudalis

This study investigated the role of trigeminal subnucleus caudalis (Vc) P2X receptors in the mediation of central sensitization induced in nociceptive neurons in subnucleus oralis (Vo) by mustard oil (MO) application to the tooth pulp in anesthetized rats. MO application produced a long-lasting central sensitization reflected in neuroplastic changes (i.e., increases in neuronal mechanoreceptive field size and responses to innocuous and noxious mechanical stimuli) in Vo nociceptive neurons. Twenty minutes after MO application, the intrathecal (i.t.) administration to the rostral Vc of the selective P2X1, P2X3, and P2X2/3 receptor antagonist, 2′-(or 3′-) O-trinitrophenyl-ATP (TNP-ATP), significantly and reversibly attenuated the MO-induced central sensitization for more than 15 min; saline administration had no effect. Administration to the rostral Vc of the selective P2X1, P2X3, and P2X2/3 receptor agonist, α,β-methylene ATP (α,β-meATP, i.t.) produced abrupt and significant neuroplastic changes in Vo nociceptive neurons, followed by neuronal desensitization as evidenced by the ineffectiveness of a second i.t. application of α,β-meATP and subsequent MO application to the pulp. Administration to the rostral Vc of the selective P2X1 receptor agonist β,γ-methylene ATP (β,γ-meATP, i.t.) produced no significant neuroplastic changes per se and did not affect the subsequent MO-induced neuroplastic changes in Vo nociceptive neurons. These results suggest that P2X3 and possibly also the P2X2/3 receptor subtypes in Vc may play a role in the initiation and maintenance of central sensitization in Vo nociceptive neurons induced by MO application to the pulp.

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