Cerebellar granule-cell-specific GABAA receptors attenuate benzodiazepine-induced ataxia: evidence from alpha 6-subunit-deficient mice.
Eur J Neurosci
; 11(1): 233-40, 1999 Jan.
Article
in En
| MEDLINE
| ID: mdl-9987027
ABSTRACT
Benzodiazepine- and alcohol-induced ataxias in rodents have been proposed to be affected by the gamma-aminobutyric acid type A (GABAA) receptor alpha 6 subunit, which contributes to receptors specifically expressed in cerebellar granule cells. We have studied an alpha 6 -/- mouse line for motor performance and drug sensitivity. These mice, as a result of a specific genetic lesion, carry a precise impairment at their Golgi-granule cell synapses. On motor performance tests (rotarod, horizontal wire, pole descending, staircase and swimming tests) there were no robust baseline differences in motor function or motor learning between alpha 6 -/- and alpha 6 +/+ mice. On the rotarod test, however, the mutant mice were significantly more impaired by diazepam (5-20 mg/kg, i.p.), when compared with alpha 6 +/+ control and background C57BL/6J and 129/SvJ mouse lines. Ethanol (2.0-2.5 g/kg, i.p.) produced similar impairment in the alpha 6 -/- and alpha +/+ mice. Diazepam-induced ataxia in alpha 6 -/- mice could be reversed by the benzodiazepine site antagonist flumazenil, indicating the involvement of the remaining alpha 1 beta 2/3 gamma 2 GABAA receptors of the granule cells. The level of activity in this synapse is crucial in regulating the execution of motor tasks. We conclude that GABAA receptor alpha 6 subunit-dependent actions in the cerebellar cortex can be compensated by other receptor subtypes; but if not for the alpha 6 subunit, patients on benzodiazepine medication would suffer considerably from ataxic side-effects.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Purkinje Cells
/
Ataxia
/
Benzodiazepines
/
Receptors, GABA-A
Limits:
Animals
Language:
En
Journal:
Eur J Neurosci
Journal subject:
NEUROLOGIA
Year:
1999
Document type:
Article
Affiliation country:
Finland