Journal of Neuroscience, Vol 15, 8121-8130, Copyright © 1995 by Society for Neuroscience
Uncoupling of GABAA/benzodiazepine receptor alpha 1, beta 2, and gamma 2 subunit mRNA expression in cerebellar Purkinje cells of staggerer mutant mice
V Luntz-Leybman, A Rotter, D Zdilar and A Frostholm
Department of Pharmacology, Ohio State University, Columbus 43210, USA.
The mammalian GABAA/benzodiazepine (GABAA/BZ) receptor is comprised of
several subunit isoforms: alpha 1-6, beta 1-13, gamma 1-3 and delta. In the
present studies, the expression of alpha 1, beta 2, and gamma 2 subunit
mRNAs was examined in cerebellar Purkinje cells and deep cerebellar neurons
of staggerer mutant mice during postnatal development. In control animals,
the three subunit mRNAs were present at high density in Purkinje cells
which, in adult animals, form a monolayer at the interface of the granule
cell and molecular layers. The number of Purkinje cells in the staggerer
cerebellar cortex is reduced; the majority of those that remain are
retained within the granule cell layer and are unable to receive normal
afferent synapses from granule cells. The three subunit mRNAs were ex
pressed at similar levels in both staggerer and control Purkinje cells
until postnatal day 9. After this time, although the alpha 1 subunit mRNA
was maintained at control levels in staggerer Purkinje cells, the
expression of beta 2 and gamma 2 subunit mRNAs decreased, and was largely
absent by postnatal day 20. The loss of beta 2 and gamma 2 mRNA expression
in staggerer was specific to Purkinje cells, since all three mRNAs were
present throughout postnatal development in other brain regions, including
the deep cerebellar nuclei. The present studies indicate that in cerebellar
Purkinje cells, the GABAA/BZ receptor alpha 1, and beta 2, and gamma 2,
subunit mRNAs are regulated by distinct mechanisms which are differentially
affected by the staggerer mutation.