Region-specific expression of messenger RNAs encoding GABAa receptor subunits in the developing rat brain

Gambarana, Carla; Beattie, Ce; Rodriguez, Zr; Siegel, Re

doi:10.1016/0306-4522(91)90238-j

Cited by 102 publications

(84 citation statements)

References 35 publications

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“…The mRNAs encoding the (32 and (33 GABAA receptor subunits increase significantly during the second week of maturation in vivo (29,31). Also, in granule-cell cultures prepared at postnatal day 10, the 32 mRNA increases 4-fold from 3 to 10 DIV (33).…”

Section: Resultsmentioning

confidence: 99%

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Changes in gamma-aminobutyrate type A receptor subunit mRNAs, translation product expression, and receptor function during neuronal maturation in vitro.

Zheng

Zhu

Puia

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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The amounts of mRNAs encoding al, a'6, 132, 133, y2, and 8 subunits of y-aminobutyrate type A (GABAA) receptors and the gold immunolabeling density of their translation products were monitored during the growth of neonatal rat granule cells in primary culture. We investigated possible correlations (i) between temporal changes in mRNA content and expression density of their respective translation products and (ii) between the quantitative changes of receptor subunit expression, the GABA EC5. for Cl-channel activation, and diazepam efficacy in modulating GABA action on the Clchannels. At 3 days in vitro, the amount of GABAA receptor subunit mRNAs and the expression of their respective translation products were very low. During the next 2 weeks both parameters for every subunit studied increased asynchronously; moreover, at 14 days in vitro the sum of V2 and 8 subunit expression was smaller than the expression of the al or a6 or 182/133 subunits. This suggests that during in vitro maturation each subunit may be regulated independently and invites speculation as to possible changes in specific GABAA receptor subtype abundance during development in vitro. The maximal current intensity elicited by GABA failed to increase from 5 to 14 days in vitro, though the amount of mRNA encoding various subunits and the expression density of their respective translation products increased. Thus, qualitative changes in the GABAA receptor subtypes expressed and/or abnormalities in the subunit assembly very likely account for the uniformity of the maximal current intensity elicited by GABA during in vitro development. Also, during maturation of neuronal cultures from 5 to 20 days in vitro the extent of the positive modulation of GABA action by diazepam decreased dramatically. This finding might be related to an increase in the abundance of GABAA receptors including the a6 subunit and/or to the expression, during granule cell maturation in vitro, of GABAA receptors devoid of y2 subunits. To study whether changes in GABAA receptor subunit mRNA and protein expression occur synchronously during neuronal maturation in vitro (13) and whether eventual maturational variations in subunit expression could be associated with changes in GABAA receptor function, we used a competitive reverse transcription-polymerase chain reaction (RT-PCR) technique (14-16) to quantify specific GABAA subunit mRNAs, the label-fracture immunogold technique to monitor the expression of GABAA receptor subunits in the plasma membrane of cerebellar granule neurons (4, 5), and whole-cell recordings to assess GABA action and its modulation by diazepam (8). MATERIALS AND METHODSCell Culture. Primary cultures of cerebellar granule cells were prepared from 8-day-old Sprague-Dawley rat pups (13).Cells were dispersed with trypsin and plated at 2 x 10W cells per cm2 on 100-or 35-mm Nunc dishes coated with poly(Dlysine). Cultures were maintained in a humidified 6% CO2 atmosphere at 370C in basal Eagle's medium containing 10%6heat-inactivated fetal bovine serum, 2 mM ...

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Section: Resultsmentioning

confidence: 99%

“…The GABA-activated Cl-cur- (Fig. 2) approximates the increase in the respective mRNAs occurring either in vivo (15,16,(26)(27)(28)(29)(30)(31)(32) or in vitro ( Fig. 1 and refs.…”

Section: Resultsmentioning

confidence: 99%

Changes in gamma-aminobutyrate type A receptor subunit mRNAs, translation product expression, and receptor function during neuronal maturation in vitro.

Zheng

Zhu

Puia

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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“…␥2 subunits, along with ␣1 and ␤2 subunits, are the principal contributors to most native GABA A receptors (19)(20)(21)(22)(23), including in the primate cerebral cortex (24). ␣-Subunits are necessary for selectivity of the receptor for benzodiazepines (25), whereas the ␥2 subunit is essential for high-affinity benzodiazepine binding (18,(25)(26)(27)(28)(29)(30)(31).…”

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confidence: 99%

Altered ratios of alternatively spliced long and short γ2 subunit mRNAs of the γ-amino butyrate type A receptor in prefrontal cortex of schizophrenics

Huntsman

Tran²,

Potkin³

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

126

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The relative abundance of alternatively spliced long (␥2L) and short (␥2S) mRNAs of the ␥2 subunit of the ␥-amino butyrate type A (GABA A ) receptor was examined in dorsolateral prefrontal cortex of schizophrenics and matched controls by using in situ hybridization histochemistry and semiquantitative reverse transcription-PCR (RT-PCR) amplification. A cRNA probe identifying both mRNAs showed that the transcripts are normally expressed at moderately high levels in the prefrontal cortex. Consistent with previous studies, overall levels of ␥2 transcripts in prefrontal cortex of brains from schizophrenics were reduced by 28.0%, although this reduction did not reach statistical significance. RT-PCR, performed under nonsaturating conditions on total RNA from the same blocks of tissue used for in situ hybridization histochemistry, revealed a marked reduction in the relative proportion of ␥2S transcripts in schizophrenic brains compared with controls. In schizophrenics, ␥2S transcripts had fallen to 51.7% (؎7.9% SE; P < 0.0001) relative to control levels. Levels of ␥2L transcripts showed only a small and nonsignificant reduction of 16.9% (؎12.0% SE, P > 0.05). These findings indicate differential transcriptional regulation of two functionally distinct isoforms of one of the major GABA A receptor subunits in the prefrontal cortex of schizophrenics. The specific reduction in relative abundance of ␥2S mRNAs and the associated relative increase in ␥2L mRNAs should result in functionally less active GABA A receptors and have severe consequences for cortical integrative function.

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“…For example, it is suggested that the positive modulatory effect of DMCM, one modulator of GABA A receptor, depends on the presence of g1 subunit in the native GABA A receptors [18]; moreover, studies on recombinant GABA A receptors showed that the presence of γ1 subunit induced higher neurosteroid modulatory efficacy on GABA A receptors compared with the presence of γ 2 subunit [19]. In contrast to γ 2 subunit being abundantly expressed in mature mammalian CNS [20],γ 1 subunit is exclusively expressed in rat testis. Thus, we speculated that γ 1 subunit in rat testis might contribute to the specific function of GABA A receptors on the spermatozoa.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, other studies also suggested a possible relationship between γ 1 subunit and excitatory function of GABAA receptors in a few cases. It is accepted that during early development stage GABA exerts mainly an excitatory action via GABA A receptors through membrane depolarization and a rise in intracellular Ca 2+ , and these effects disappeared during development [21], [22], while studies on distribution of subunits of GABA A receptor revealed that g1 subunit was strongly expressed during early development stage and with development its expression dropped markedly and restricted to relatively few structures [23], whereas γ 2 subunit becomes the mainly expression type of gamma subunit in mature CNS [20]. Additionally, the excitatory effects of GABA A receptors were also proved in bromodeoxyundine (BrdU)+ neural precursor cells and γ 1 is also the expression pattern of gamma subunit in these cells [24].…”

Section: Discussionmentioning

confidence: 99%

Identification of γ1 subunit of GABAA receptor in rat testis

Yuan

2002

Cell Res

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The isoform type of g subunits of GABA A receptor is a molecular determinant of its pharmacological characteristics. At present, the existence of GABA A receptor in mammalian sperm is still a controversy. By using degenerate primers designed according to highly conserved region in all three γ (γ1, γ2 and γ3) subunits cloned in rat brain, we performed reverse transcription polymerase chain reaction (RT-PCR) to examine the expression pattern of g subunits of GABA A receptor in rat testis. Only one 370 bp fragment was obtained from RT-PCR in rat testis and sequencing results showed that it represented g1 subunit, but not γ2 or γ3 subunit. Using the cloned \fragment as probe, a 3.8 kb transcript which in size as same as γ1 subunit in rat brain was detected in rat testis mRNA by performing Northern blot assay. Furthermore, results of in situ hybridization assay confirmed that γ1 subunit was expressed in round spermatids and spermatozoa, maybe also in secondary spermatocyte. These evidences proved that γ1 subunit of GABA A receptor is exclusively expressed in rat testis and this feature may be the structural basis of the specific function of GABA A receptors in sperm acrosome reaction.

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Region-specific expression of messenger RNAs encoding GABAa receptor subunits in the developing rat brain

Cited by 102 publications

References 35 publications

Changes in gamma-aminobutyrate type A receptor subunit mRNAs, translation product expression, and receptor function during neuronal maturation in vitro.

Changes in gamma-aminobutyrate type A receptor subunit mRNAs, translation product expression, and receptor function during neuronal maturation in vitro.

Altered ratios of alternatively spliced long and short γ2 subunit mRNAs of the γ-amino butyrate type A receptor in prefrontal cortex of schizophrenics

Identification of γ1 subunit of GABAA receptor in rat testis

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