Modulation of kainate-induced responses by pentobarbitone and GYKI-53784 in rat abducens motoneurons in vivo.

Ruiz, A. and Durand, J. (1999) Modulation of kainate-induced responses by pentobarbitone and GYKI-53784 in rat abducens motoneurons in vivo. Brain Research, 818 (2). pp. 421-430. 10.1016/S0006-8993(98)01335-3.

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DOI: 10.1016/S0006-8993(98)01335-3

Abstract

The modulation of kainate-induced responses by pentobarbitone and the 2,3-benzodiazepine GYKI-53784 (LY303070), a potent non-competitive AMPA antagonist, was studied in vivo using both extracellular recordings of antidromic field potentials and intracellular recordings from abducens motoneurons in ketamine/diazepam-anesthetized rats. In previous studies on pentobarbitone-anesthetized rats [M. Ouardouz, J. Durand, GYKI-52466 antagonizes glutamate responses but not NMDA and kainate responses in rat abducens motoneurons, Neurosci. Lett. 125 (1991) 5-8; M. Ouardouz, J. Durand, Involvement of AMPA receptors in trigeminal postsynaptic potentials recorded in rat abducens motoneurons in vivo, Eur. J. Neurosci. 6 (1994) 1662-1668; A. Ruiz, J. Durand, Blocking the trigeminal EPSPs in rat abducens motoneurons in vivo with the AMPA antagonists, NBQX and GYKI-53655, J. Neurophysiol. (1998) submitted], we showed that 2,3-benzodiazepines do not affect kainate-induced depolarizations in abducens motoneurons. Here, we tested whether pentobarbitone is involved in the pharmacological discrimination by 2,3-benzodiazepines between AMPA- and kainate-induced responses. Kainate-induced depolarizations were reversibly depressed after application of either GYKI-53784 and pentobarbitone. However, kainate-induced depolarizations were not inhibited by GYKI-53784 with pentobarbitone; they were even potentiated sometimes. Using extracellular recordings, we confirmed that in the presence of pentobarbitone, GYKI-53784 counteracts the effects of AMPA but not of kainate on antidromic field potentials in the abducens nucleus. Blockade of kainate-induced responses by GYKI-53784 was reversed with pentobarbitone, which appears relevant to the discrimination between AMPA- and kainate receptor-mediated responses in vivo. In the presence of pentobarbitone, kainate would depolarize motoneurons mainly via kainate receptors since kainate-induced responses were not depressed by 2,3-benzodiazepines. This finding strongly favors the existence of kainate receptors in adult motoneurons but their role is still unknown.

Item Type:Article
Uncontrolled Keywords:AMPA; Barbiturate anesthesia; 2,3-Benzodiazepine; Excitatory amino acid; Kainate; Ketamine
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:2457
Journal or Publication Title:Brain Research
Deposited By:Library Staff
Deposited On:11 Nov 2011 11:33
Last Modified:11 Nov 2011 11:33

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