Developmental expression of GABA and subunits of the GABAA receptor complex in an inhibitory synaptic circuit in the rat cerebellum

Meinecke, Douglas L.; Rakić, Paško

doi:10.1016/0165-3806(90)90107-a

Cited by 65 publications

(41 citation statements)

References 35 publications

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“…The developmental pattern of GABAρ subunit localization partially agrees with earlier reports suggesting expression of GABAρ1 and GABAρ2 at low levels in rat Purkinje and Golgi neurons during early postnatal development (30,31). Previous studies have unequivocally demonstrated the presence of other GABA-A subunits (α x β x γ x ) in immature neurons of the cerebellum, and the expression of this receptor is a fundamental element in proper formation of the synaptic circuitry (32)(33)(34). Glial cells are also part of the tripartite synapse, and GABA-A subunits have been identified in Bergmann glia (α 2 γ 1 δ) and EGCs (α 1 ρ 1 ) (9, 10, 35), where they might play a key role as extrasynaptic sensors of GABAergic tone, similar to what occurs in astrocyte-like GFAP + progenitors (36).…”

Section: Discussionsupporting

confidence: 77%

GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum

Pétriz

Reyes‐Haro

González-González

et al. 2014

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

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GABA-A receptors mediating synaptic or extrasynaptic transmission are molecularly and functionally distinct, and glial cells are known to express a plethora of GABA-A subunits. Here we demonstrate that GFAP + cells of the granular layer of cerebellum express GABAρ subunits during early postnatal development, thereby conferring peculiar pharmacologic characteristics to GABA responses. Electron microscopy revealed the presence of GABAρ in the plasma membrane of GFAP + cells. In contrast, expression in the adult was restricted to Purkinje neurons and a subset of ependymal cells. Electrophysiological studies in vitro revealed that astrocytes express functional receptors with an EC 50 of 52.2 ± 11.8 μM for GABA. The evoked currents were inhibited by bicuculline (100 μM) and TPMPA (IC 50 , 5.9 ± 0.6 μM), indicating the presence of a GABAρ component. Coimmunoprecipitation demonstrated protein-protein interactions between GABAρ1 and GABAα1, and double immunofluorescence showed that these subunits colocalize in the plasma membrane. Three populations of GABA-A receptors in astrocytes were identified: classic GABA-A, bicuculline-insensitive GABAρ, and GABA-A-GABAρ hybrids. Clusters of GABA-A receptors were distributed in the perinuclear space and along the processes of GFAP + cells. Time-lapse microscopy showed GABAρ2-GFP accumulation in clusters located in the soma and along the processes. The clusters were relatively immobile, with mean displacement of 9.4 ± 0.9 μm and a net distance traveled of 1-2 μm, owing mainly to directional movement or simple diffusion. Modulation of GABAρ dynamics may be a novel mechanism of extrasynaptic transmission regulating GABAergic control of GFAP + cells during early postnatal development.astrocytes | cerebellum | GABA-A receptor | GABAρ receptor | protein trafficking

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Section: Discussionsupporting

confidence: 77%

GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum

Pétriz

Reyes‐Haro

González-González

et al. 2014

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

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“…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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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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“…GABAR α1 subunit expression in DGNs increases markedly during the first postnatal month Brooks-Kayal et al, 2001). Several lines of evidence suggest that neuronal activity (Meinecke and Rakic, 1990;Huntsman et al, 1994;Holopainen and Lauren, 2003), specifically synaptic signaling through the NMDA selective glutamate receptor (Memo et al, 1991;Harris et al, 1995;Zhu et al, 1995) may be critical for stimulating GABAR α1 receptor subunit expression. Thus the increased α1 subunit expression after P10 SE could be an "over-maturation" of DGN GABARs due to the excessive neuronal activity associated with SE.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Effects of status epilepticus on hippocampal GABAA receptors are age-dependent

et al. 2004

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Long-term GABA A receptor alterations occur in hippocampal dentate granule neurons of rats that develop epilepsy after status epilepticus in adulthood. Hippocampal GABA A receptor expression undergoes marked reorganization during the postnatal period, however, and the effects of neonatal status epilepticus on subsequent GABA A receptor development are unknown. In the current study, we utilize single cell electrophysiology and antisense mRNA amplification to determine the effect of status-epilepticus induced by lithium-pilocarpine in postnatal day 10 rat pups on GABA A receptor subunit expression and function in hippocampal dentate granule neurons. We find that rats subjected to lithium-pilocarpine-induced status epilepticus at postnatal day 10 show long-term GABA A receptor changes including a two-fold increase in α1 subunit expression (compared with lithiuminjected controls) and enhanced type I benzodiazepine augmentation that are opposite of those seen after status epilepticus in adulthood and may serve to enhance dentate gyrus inhibition. Further, unlike adult rats, postnatal day 10 rats subjected to status epilepticus do not become epileptic. These findings suggest age-dependent differences in the effects of status epilepticus on hippocampal GABA A receptors that could contribute to the selective resistance of the immature brain to epileptogenesis. Keywordsepilepsy; seizure; developing brain; dentate gyrus; benzodiazepine; mRNA amplification GABA A receptors (GABARs) are heteromeric protein complexes that mediate most fast synaptic inhibition in fore-brain. Many distinct subunit subtypes exist, and their distribution varies in a regional and cell type-specific manner Sperk et al., 1997;Barnard et al., 1998). GABARs can be assembled in different subunit combinations to produce a variety of different receptor compositions, pharmacological profiles, and intrinsic receptor characteristics (Pritchett et al., 1989;Sieghart, 1995;Barnard et al., 1998 refractory temporal lobe epilepsy demonstrate marked alterations in GABAR properties in hippocampal dentate granule neurons (DGNs; Buhl et al., 1996;Gibbs et al., 1997; BrooksKayal et al., 1998 BrooksKayal et al., , 1999. GABAR subunit expression in DGNs vary during early postnatal development Fritschy et al., 1994;Brooks-Kayal et al., 2001), however, and the effects of neonatal SE on GABARs is not known. Here we examine the effect of SE in postnatal day 10 (P10) rat pups on subsequent GABAR development in DGN and find increased α1 subunit expression and type I benzodiazepine augmentation when the rats reach adulthood. These findings are opposite of those seen after SE in adulthood and could contribute to the selective resistance of the immature brain to epileptogenesis. EXPERIMENTAL PROCEDURES Lithium-pilocarpine injectionsAll studies were carried out in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and with the approval of The Children's Hospital of Philadelphia Animal Care and Use Committee. Maximum care ...

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Developmental expression of GABA and subunits of the GABAA receptor complex in an inhibitory synaptic circuit in the rat cerebellum

Cited by 65 publications

References 35 publications

GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum

GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum

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

Effects of status epilepticus on hippocampal GABAA receptors are age-dependent

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Developmental expression of GABA and subunits of the GABAA receptor complex in an inhibitory synaptic circuit in the rat cerebellum

Cited by 65 publications

References 35 publications

GABAρ subunits confer a bicuculline-insensitive component to GFAP + cells of cerebellum

GABAρ subunits confer a bicuculline-insensitive component to GFAP + cells of cerebellum

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

Effects of status epilepticus on hippocampal GABAA receptors are age-dependent

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GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum

GABAρ subunits confer a bicuculline-insensitive component to GFAP ⁺ cells of cerebellum