Diazepam-insensitive GABAA receptors on postnatal spiral ganglion neurones in culture.
Using dissociated spiral ganglion cell cultures obtained from 3-day-old rat cochlea, we investigated the response of auditory neurones to gamma-aminobutyric acid (GABA) using patch-clamp techniques. In our recording conditions, GABA elicited inward currents in > 95% of the neurones which reversed around 0 mV. Similar inward currents were measured using isoguvacin, a specific agonist of GABAA receptors. GABA-gated currents were reversibly inhibited by the channel blocker picrotoxin and the GABA competitive antagonist bicuculline. These functional GABAA receptors are characterized by an insensitivity to benzodiazepines and a relatively high sensitivity to beta-carbolines and barbiturates. These results show that the GABAA receptor pharmacological properties of spiral ganglion neurones are close to those of cerebellar granule cells.
Malgrange
B
B
Department of Human Physiology and Pathophysiology, University of Liège, Belgium.
Rigo
J M
JM
Lefebvre
P P
PP
Coucke
P
P
Goffin
F
F
Xhauflaire
G
G
Belachew
S
S
Van de Water
T R
TR
Moonen
G
G
D000818:Animals; D000831:Animals, Newborn; D001418:Baclofen / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D002243:Carbolines / Q000494:pharmacology; D002478:Cells, Cultured; D003292:Convulsants / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology*; D005445:Flunitrazepam / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010424:Pentobarbital / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects / Q000502:physiology*; D013136:Spiral Ganglion / Q000502:physiology*; D015032:Zinc / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D001418:Baclofen; D001640:Bicuculline; D002243:Carbolines; D003292:Convulsants; D003975:Diazepam; D005445:Flunitrazepam; D010424:Pentobarbital; D010852:Picrotoxin; D011963:Receptors, GABA-A; D015032:Zinc; D005680:gamma-Aminobutyric Acid; C034818:methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate