Further evidence on the contribution of GABAA receptors to the GABA-mediated inhibition of medial vestibular nucleus neurones in vitro.
The present study investigated the electrophysiological effects of the selective and potent GABAA receptor agonist, isoguvacine, on guinea-pig medial vestibular nucleus (MVN) neurones in brainstem slices. The results confirm that many MVN neurones have GABAA receptors and that, even at concentrations as low as 10(-8) M, GABA is capable of exerting a powerful inhibitory effect on these neurones via GABAA receptors. The finding that > 50% of neurones did not respond to isoguvacine, even at concentrations of 10(-6) M, suggested that only a specific subset of MVN neurones have GABAA receptors. Since many type I MVN neurones are believed to have postsynaptic GABAA receptors, it is possible that selective agonists such as isoguvacine may be useful in identifying type I neurones in vitro.
Department of Psychology, University of Otago, Dunedin, New Zealand.
M
M
Hutchinson
P F
PF
Smith
C L
CL
Darlington
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001933:Brain Stem / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D018755:GABA Agonists / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007539:Isonicotinic Acids / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D011963:Receptors, GABA-A / Q000187:drug effects*; D013997:Time Factors; D014726:Vestibular Nuclei / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D018755:GABA Agonists; D007539:Isonicotinic Acids; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C015300:isoguvacine