Modulation of trigeminal nociceptive transmission by serotonin in mice = Modulation of trigeminal nociceptive transmission by serotonin in mice

다국어 초록 (Multilingual Abstract)

The substantia gelatinosa (SG) of trigeminal subnucleus caudalis (Vc) receives many thin myelinated Aδ fiber and unmyelinated C primary afferent fibers and implicated in the processing of nociceptive information. The actions of serotonin (5-hydroxy-
tryptamine, 5-HT) in the substantia gelatinosa are important for their antinociceptive effects. In order to clarify the possible mechanisms underlying 5-HT actions on the SG neurons of Vc, the direct membrane effects were examined by gramicidin-perforated patch clamp recording using brain slice preparation from juvenile ICR mice brainstem. The major effects of 5-HT on SG neurons tested were hyperpolarization (22/41,53.7%), and these hyperpolarizing effects were maintained in the presence of TTX (Na^(+) channel blocker, 0.5 μM), CNQX (non-NMDA glutamate receptor antagonist, 10μM), AP-5 (NMDA receptor antagonist, 20 μM), picrotoxin (GABAA receptor antagonist, 50μM) and strychnine (glycine receptor antagonist, 2 μM). Buspirone, a 5-HT_(1A) receptor agonist and 5-CT, 5-HT 1, 5A and 7 receptor agonist induced membrane hyperpolarization. 5-HT-induced membrane hyperpolarization was partially blocked by Ba^(2+), a non specific potassium channel blocker.
In this study, we demonstrate that 5-HT hyperpolarizes in the majority of SG neuron of Vc in juvenile ICR mice by acting on the postsynaptic SG neuronal membrane or dendrites through 5-HT_(1A), 5-HT_(5A) or 5-HT_(7) receptor subtypes at least partly. We suggest that these receptor subtypes can be potential target for modulation of orofacial pain processing.

목차 (Table of Contents)

• I.Abstract 1
• II.Introduction 3
• III.Materials and Methods 6
• Animals 6
• Brain slice preparation a the electrophysiology 6
• Chemicals 8
• Statistical analysis 8
• IV.Results 10
• 5-HT- mediated response on SG neurons 10
• Action site of 5-HT for membrane hyperpolarization
• is postsynaptic SG neurons 11
• Potassium ion channels are involved in 5-HT-mediated hyper- polarization 12
• 5-HT receptor type 1, 5A and 7 are involved in the 5-HT- mediated membrane hyperpolarization 13
• V.Discussion 15
• The majority of SG neurons of Vc were hyperpolarized by 5-HT 15
• Characteristics of postsynaptic 5-HT actions 17
• 5-HT receptor type 1A, 5A and 7 are involved in the 5-HT- mediated membrane hyperpolarization 18
• Potassium ion channels are involved in 5-HT-mediated hyperpolarization 20
• VI.References 22
• VII.Figures 32