title: Effects of prostaglandin E2 on synaptic transmission in the rat spinal trigeminal subnucleus caudalis.
abstract: The spinal trigeminal subnucleus caudalis (Vc) receives preferentially nociceptive afferent signals from the orofacial area. Nociceptive stimuli to the orofacial area induce cyclooxygenase both peripherally and centrally, which can synthesize a major prostanoid prostaglandin E2 (PGE2) that implicates in diverse physiological functions. To clarify the roles of centrally-synthesized PGE2 in nociception, effects of exogenous PGE2 on synaptic transmission in the Vc neurons were investigated in the rat brainstem slice. Spontaneously occurring excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) were recorded, respectively, under pharmacological blockade of inhibitory and excitatory transmission by whole-cell patch-clamp mode. Perfusion of PGE2 (1-5 μM) increased the frequency of sIPSCs in a concentration-dependent manner but had no significant effect on the amplitude. Similarly to the effects on sIPSCs, PGE2 increased the sEPSC frequency without any effect on the amplitude. These facilitatory effects of PGE2 on spontaneous synaptic transmissions were blocked by an EP1 antagonist SC19220 but not by an EP4 antagonist AH23848. Electrical stimulation of the trigeminal tract evoked short latency EPSCs (eEPSCs) in the Vc neurons. PGE2 (5 μM) was ineffective on the eEPSCs. The present study demonstrated that PGE2 facilitated spontaneous synaptic transmissions in the Vc neurons through activating the presynaptic EP1 receptors but had no effect on the trigeminal tract-mediated excitatory transmission. These results suggest that centrally-synthesized PGE2 modifies the synaptic transmission in the Vc region, thereby contributing to the processing of nociceptive signals originated from the orofacial area.
authors: Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan; Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: ag123d26@dpc.agu.ac.jp.
authors: Yuka
authors: Y
authors: Mizutani
authors: Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: yohi@dpc.agu.ac.jp.
authors: Yoshiaki
authors: Y
authors: Ohi
authors: Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: s-kimura@dpc.agu.ac.jp.
authors: Satoko
authors: S
authors: Kimura
authors: Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: miyaken@dpc.agu.ac.jp.
authors: Ken
authors: K
authors: Miyazawa
authors: Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: shig@dpc.agu.ac.jp.
authors: Shigemi
authors: S
authors: Goto
authors: Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan. Electronic address: haji@dpc.agu.ac.jp.
authors: Akira
authors: A
authors: Haji
mesh_terms: D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D012531:Dibenz(b,f)(1,4)oxazepine-10(11H)-carboxylic acid, 8-chloro-, 2-acetylhydrazide / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D010852:Picrotoxin / Q000494:pharmacology; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*; D014279:Trigeminal Nucleus, Spinal / Q000166:cytology*
chemical_list: D001713:Biphenyl Compounds; D012531:Dibenz(b,f)(1,4)oxazepine-10(11H)-carboxylic acid, 8-chloro-, 2-acetylhydrazide; D015232:Dinoprostone; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D010852:Picrotoxin; D011448:Prostaglandin Antagonists; D011810:Quinoxalines; C056723:FG 9041; C046926:AH 23848
keywords: Prostaglandin E(2); Spinal trigeminal nucleus; Synaptic transmission; Whole-cell voltage-clamp recordings