Endogenous ATP involvement in mustard-oil-induced central sensitization in trigeminal subnucleus caudalis (medullary dorsal horn).
نویسندگان
چکیده
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/alpha-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 microM) and by apyrase (an ectonucleotidase enzyme, 30 units/ml). Superfusion of the selective P2X1, P2X3 and P2X(2/3) receptor antagonist 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (6-638 microM) 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.
منابع مشابه
Endogenous Atp Involvement in Mustard Oil-induced Central Sensitization in Trigeminal Subnucleus Caudalis (medullary Dorsal
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 ...
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Central sensitization is a crucial mechanism underlying the increased excitability of nociceptive pathways following peripheral tissue injury and inflammation. We have previously demonstrated that the small-fiber excitant and inflammatory irritant mustard oil (MO) applied to the tooth pulp produces glutamatergic- and purinergic-dependent central sensitization in brainstem nociceptive neurons of...
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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...
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Our recent studies have shown that application to the tooth pulp of the inflammatory irritant mustard oil (MO) produces a prolonged (>40 min) "central sensitization" reflected in neuroplastic changes in the mechanoreceptive field (RF) and response properties of nociceptive brain stem neurons in subnuclei oralis (Vo) and caudalis (Vc) of the trigeminal spinal tract nucleus. In view of the previo...
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ورودعنوان ژورنال:
- Journal of neurophysiology
دوره 94 3 شماره
صفحات -
تاریخ انتشار 2005