title: GABAA receptors facilitate spontaneous glutamate release in rat periaqueductal gray neurons.
abstract: The functional role of presynaptic γ-aminobutyric acid (GABA)(A) receptors in excitatory glutamatergic transmission was examined in rat periaqueductal gray neurons recorded using a conventional whole-cell patch clamp technique. Muscimol, a GABA(A) receptor agonist, significantly increased the frequency of spontaneous excitatory postsynaptic currents without affecting their amplitude, and this effect was completely blocked by the selective GABA(A) receptor antagonist. The muscimol-induced facilitation of spontaneous excitatory postsynaptic current frequency disappeared either in the presence of tetrodotoxin or Cd. The results suggest that the activation of presynaptic GABA(A) receptors directly depolarizes glutamatergic terminals resulting in the facilitation of spontaneous glutamate release, and that presynaptic GABA(A) receptors play an important role in the regulation of various physiological functions mediated by the periaqueductal gray.
authors.affiliation: Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea. jis7619@mail.knu.ac.kr
authors.forename: Il-Sung
authors.initials: IS
authors.lastname: Jang
mesh_terms: D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism*; D009118:Muscimol / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D010487:Periaqueductal Gray / Q000166:cytology / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D011963:Receptors, GABA-A; D009118:Muscimol; D018698:Glutamic Acid