title: Kainate acts at presynaptic receptors to increase GABA release from hypothalamic neurons.
abstract: Recent reports suggest that kainate acting at presynaptic receptors reduces the release of the inhibitory transmitter GABA from hippocampal neurons. In contrast, in the hypothalamus in the presence of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor antagonists [1-(4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466) and D,L-2-amino-5-phosphonopentanoic acid (AP5)], kainate increased GABA release. In the presence of tetrodotoxin, the frequency, but not the amplitude, of GABA-mediated miniature inhibitory postsynaptic currents (IPSCs) was enhanced by kainate, consistent with a presynaptic site of action. Postsynaptic activation of kainate receptors on cell bodies/dendrites was also found. In contrast to the hippocampus where kainate increases excitability by reducing GABA release, in the hypothalamus where a much higher number of GABAergic cells exist, kainate-mediated activation of transmitter release from inhibitory neurons may reduce the level of neuronal activity in the postsynaptic cell.
authors.affiliation: Department of Neurosurgery, Yale University Medical School, New Haven, Connecticut 06520, USA.
authors.forename: Q S
authors.initials: QS
authors.lastname: Liu
authors.forename: P R
authors.initials: PR
authors.lastname: Patrylo
authors.forename: X B
authors.initials: XB
authors.lastname: Gao
authors.forename: A N
authors.initials: AN
authors.lastname: van den Pol
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D001569:Benzodiazepines; D002478:Cells, Cultured; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D017661:Receptors, Presynaptic / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D014151:Anti-Anxiety Agents; D018691:Excitatory Amino Acid Antagonists; D017661:Receptors, Presynaptic; C061950:GYKI 52466; D001569:Benzodiazepines; D005680:gamma-Aminobutyric Acid; D007608:Kainic Acid