title: A₁ receptors inhibit glutamate release in rat medullary dorsal horn neurons.
abstract: We have investigated the adenosine-mediated presynaptic inhibition of primary afferent-evoked glutamate release in rat substantia gelatinosa neurons of the trigeminal subnucleus caudalis using a conventional whole-cell patch clamp technique. Adenosine reversibly and concentration dependently decreased the amplitude of glutamatergic excitatory postsynaptic currents and increased the paired-pulse ratio, indicating that adenosine acts presynaptically to reduce glutamate release from primary afferents. The adenosine-induced inhibition of excitatory postsynaptic currents was occluded by a selective A₁ receptor antagonist, DPCPX, and was mimicked by a selective A₁ receptor agonist CPA. The results suggest that presynaptic A₁ receptors decrease action potential-dependent glutamate release from trigeminal primary afferents onto medullary dorsal horn neurons, and thus adenosine A₁ receptors could be a potential target for the treatment of pain of orofacial tissues.
authors: Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.
authors: In-Sun
authors: IS
authors: Choi
authors: Jin-Hwa
authors: JH
authors: Cho
authors: Il-Sung
authors: IS
authors: Jang
mesh_terms: D058907:Adenosine A1 Receptor Agonists / Q000494:pharmacology; D058916:Adenosine A1 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism*; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism*; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000502:physiology*; D014970:Xanthines / Q000494:pharmacology
chemical_list: D058907:Adenosine A1 Receptor Agonists; D058916:Adenosine A1 Receptor Antagonists; D018691:Excitatory Amino Acid Antagonists; D043682:Receptor, Adenosine A1; D014970:Xanthines; D018698:Glutamic Acid; C051360:1,3-dipropyl-8-cyclopentylxanthine