Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam

F. Impagnatiello, C. Pesold, P. Longone, H. Caruncho, J. M. Fritschy, E. Costa, A. Guidotti

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

We evaluated whether tolerance to the antagonism of bicuculline-induced seizures by diazepam is associated with changes (i) in the content of mRNAs encoding for γ-aminobutyric acidA (GABAA) receptor subunits, (ii) in the expression density of these subunits, and (iii) in the 1,4-benzodiazepine binding site characteristics in discrete neocortical structures. We found that in diazepam-tolerant rats, the content of the mRNA encoding for the α1 subunit of the GABAA receptor decreased in the frontoparietal motor (FrPaM) cortex and in the hippocampus (42% and 20%, respectively) but not in the frontoparietal somatosensory (FrPaSS) cortex, striatum, olfactory bulb, and cerebellum. In the FrPaM cortex, γ2S and γ2L subunit mRNA contents were also decreased (48% and 30%, respectively), whereas that of α5 was increased (30%). In the FrPaM and FrPaSS cortices as well as in cerebellum of diazepam-tolerant rats, the content of α2, α3, α6, β2, and δ subunit mRNA was unchanged, as was the content of α2, α5, γ1, and γ2S subunit mRNA in the hippocampus. Furthermore, the reduction in α1 subunit mRNA content in the FrPaM cortex and the anticonvulsant tolerance to diazepam returned to control values 72 hr after termination of the protracted diazepam treatment. Rats receiving a treatment with imidazenil in doses equipotent and with a schedule identical to that of diazepam failed to exhibit tolerance to the anticonvulsant action of this drug or cross-tolerance to diazepam. In these rats, the content of mRNA encoding for α1, α2, α3, α5, α6, γ1, γ2S, γ2L, and δ GABAA receptor subunits failed to change in the FrPaM and FrPaSS cortices, in the hippocampus, and in the other brain areas that were studied in diazepam-tolerant rats. Although the density and affinity of[3H]flumazenil and [3H]imidazenil binding failed to change in the FrPaM and FrPaSS cortices of diazepam-tolerant rats, the expression density of α1 subunit immunogold labeling decreased by 37%, whereas that of α5, γ2L/S, and β2/3 increased by 158%, 50%, and 47%, respectively, in the FrPaM cortex, and the density of the α5 subunit selectively increased (209%) in the FrPaSS cortex. In contrast, the immunogold labeling density of the α1, α5, γ2L/S, and β2/3 subunits failed to change in either the FrPaM or FrPaSS cortex of rats receiving protracted imidazenil treatment.

Original languageEnglish
Pages (from-to)822-831
Number of pages10
JournalMolecular Pharmacology
Volume49
Issue number5
Publication statusPublished - May 1996

Fingerprint

Neocortex
Diazepam
Somatosensory Cortex
Motor Cortex
Messenger RNA
GABA-A Receptors
Hippocampus
Anticonvulsants
Cerebellum
Flumazenil
Bicuculline
Olfactory Bulb
Appointments and Schedules
Seizures
Binding Sites
Brain

ASJC Scopus subject areas

  • Pharmacology

Cite this

Impagnatiello, F., Pesold, C., Longone, P., Caruncho, H., Fritschy, J. M., Costa, E., & Guidotti, A. (1996). Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam. Molecular Pharmacology, 49(5), 822-831.

Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam. / Impagnatiello, F.; Pesold, C.; Longone, P.; Caruncho, H.; Fritschy, J. M.; Costa, E.; Guidotti, A.

In: Molecular Pharmacology, Vol. 49, No. 5, 05.1996, p. 822-831.

Research output: Contribution to journalArticle

Impagnatiello, F, Pesold, C, Longone, P, Caruncho, H, Fritschy, JM, Costa, E & Guidotti, A 1996, 'Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam', Molecular Pharmacology, vol. 49, no. 5, pp. 822-831.
Impagnatiello, F. ; Pesold, C. ; Longone, P. ; Caruncho, H. ; Fritschy, J. M. ; Costa, E. ; Guidotti, A. / Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam. In: Molecular Pharmacology. 1996 ; Vol. 49, No. 5. pp. 822-831.
@article{d6d225e60ba1418aa222b4205d6ba02d,
title = "Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam",
abstract = "We evaluated whether tolerance to the antagonism of bicuculline-induced seizures by diazepam is associated with changes (i) in the content of mRNAs encoding for γ-aminobutyric acidA (GABAA) receptor subunits, (ii) in the expression density of these subunits, and (iii) in the 1,4-benzodiazepine binding site characteristics in discrete neocortical structures. We found that in diazepam-tolerant rats, the content of the mRNA encoding for the α1 subunit of the GABAA receptor decreased in the frontoparietal motor (FrPaM) cortex and in the hippocampus (42{\%} and 20{\%}, respectively) but not in the frontoparietal somatosensory (FrPaSS) cortex, striatum, olfactory bulb, and cerebellum. In the FrPaM cortex, γ2S and γ2L subunit mRNA contents were also decreased (48{\%} and 30{\%}, respectively), whereas that of α5 was increased (30{\%}). In the FrPaM and FrPaSS cortices as well as in cerebellum of diazepam-tolerant rats, the content of α2, α3, α6, β2, and δ subunit mRNA was unchanged, as was the content of α2, α5, γ1, and γ2S subunit mRNA in the hippocampus. Furthermore, the reduction in α1 subunit mRNA content in the FrPaM cortex and the anticonvulsant tolerance to diazepam returned to control values 72 hr after termination of the protracted diazepam treatment. Rats receiving a treatment with imidazenil in doses equipotent and with a schedule identical to that of diazepam failed to exhibit tolerance to the anticonvulsant action of this drug or cross-tolerance to diazepam. In these rats, the content of mRNA encoding for α1, α2, α3, α5, α6, γ1, γ2S, γ2L, and δ GABAA receptor subunits failed to change in the FrPaM and FrPaSS cortices, in the hippocampus, and in the other brain areas that were studied in diazepam-tolerant rats. Although the density and affinity of[3H]flumazenil and [3H]imidazenil binding failed to change in the FrPaM and FrPaSS cortices of diazepam-tolerant rats, the expression density of α1 subunit immunogold labeling decreased by 37{\%}, whereas that of α5, γ2L/S, and β2/3 increased by 158{\%}, 50{\%}, and 47{\%}, respectively, in the FrPaM cortex, and the density of the α5 subunit selectively increased (209{\%}) in the FrPaSS cortex. In contrast, the immunogold labeling density of the α1, α5, γ2L/S, and β2/3 subunits failed to change in either the FrPaM or FrPaSS cortex of rats receiving protracted imidazenil treatment.",
author = "F. Impagnatiello and C. Pesold and P. Longone and H. Caruncho and Fritschy, {J. M.} and E. Costa and A. Guidotti",
year = "1996",
month = "5",
language = "English",
volume = "49",
pages = "822--831",
journal = "Molecular Pharmacology",
issn = "0026-895X",
publisher = "American Society for Pharmacology and Experimental Therapeutics",
number = "5",

}

TY - JOUR

T1 - Modifications of γ-aminobutyric acidA receptor subunit expression in rat neocortex during tolerance to diazepam

AU - Impagnatiello, F.

AU - Pesold, C.

AU - Longone, P.

AU - Caruncho, H.

AU - Fritschy, J. M.

AU - Costa, E.

AU - Guidotti, A.

PY - 1996/5

Y1 - 1996/5

N2 - We evaluated whether tolerance to the antagonism of bicuculline-induced seizures by diazepam is associated with changes (i) in the content of mRNAs encoding for γ-aminobutyric acidA (GABAA) receptor subunits, (ii) in the expression density of these subunits, and (iii) in the 1,4-benzodiazepine binding site characteristics in discrete neocortical structures. We found that in diazepam-tolerant rats, the content of the mRNA encoding for the α1 subunit of the GABAA receptor decreased in the frontoparietal motor (FrPaM) cortex and in the hippocampus (42% and 20%, respectively) but not in the frontoparietal somatosensory (FrPaSS) cortex, striatum, olfactory bulb, and cerebellum. In the FrPaM cortex, γ2S and γ2L subunit mRNA contents were also decreased (48% and 30%, respectively), whereas that of α5 was increased (30%). In the FrPaM and FrPaSS cortices as well as in cerebellum of diazepam-tolerant rats, the content of α2, α3, α6, β2, and δ subunit mRNA was unchanged, as was the content of α2, α5, γ1, and γ2S subunit mRNA in the hippocampus. Furthermore, the reduction in α1 subunit mRNA content in the FrPaM cortex and the anticonvulsant tolerance to diazepam returned to control values 72 hr after termination of the protracted diazepam treatment. Rats receiving a treatment with imidazenil in doses equipotent and with a schedule identical to that of diazepam failed to exhibit tolerance to the anticonvulsant action of this drug or cross-tolerance to diazepam. In these rats, the content of mRNA encoding for α1, α2, α3, α5, α6, γ1, γ2S, γ2L, and δ GABAA receptor subunits failed to change in the FrPaM and FrPaSS cortices, in the hippocampus, and in the other brain areas that were studied in diazepam-tolerant rats. Although the density and affinity of[3H]flumazenil and [3H]imidazenil binding failed to change in the FrPaM and FrPaSS cortices of diazepam-tolerant rats, the expression density of α1 subunit immunogold labeling decreased by 37%, whereas that of α5, γ2L/S, and β2/3 increased by 158%, 50%, and 47%, respectively, in the FrPaM cortex, and the density of the α5 subunit selectively increased (209%) in the FrPaSS cortex. In contrast, the immunogold labeling density of the α1, α5, γ2L/S, and β2/3 subunits failed to change in either the FrPaM or FrPaSS cortex of rats receiving protracted imidazenil treatment.

AB - We evaluated whether tolerance to the antagonism of bicuculline-induced seizures by diazepam is associated with changes (i) in the content of mRNAs encoding for γ-aminobutyric acidA (GABAA) receptor subunits, (ii) in the expression density of these subunits, and (iii) in the 1,4-benzodiazepine binding site characteristics in discrete neocortical structures. We found that in diazepam-tolerant rats, the content of the mRNA encoding for the α1 subunit of the GABAA receptor decreased in the frontoparietal motor (FrPaM) cortex and in the hippocampus (42% and 20%, respectively) but not in the frontoparietal somatosensory (FrPaSS) cortex, striatum, olfactory bulb, and cerebellum. In the FrPaM cortex, γ2S and γ2L subunit mRNA contents were also decreased (48% and 30%, respectively), whereas that of α5 was increased (30%). In the FrPaM and FrPaSS cortices as well as in cerebellum of diazepam-tolerant rats, the content of α2, α3, α6, β2, and δ subunit mRNA was unchanged, as was the content of α2, α5, γ1, and γ2S subunit mRNA in the hippocampus. Furthermore, the reduction in α1 subunit mRNA content in the FrPaM cortex and the anticonvulsant tolerance to diazepam returned to control values 72 hr after termination of the protracted diazepam treatment. Rats receiving a treatment with imidazenil in doses equipotent and with a schedule identical to that of diazepam failed to exhibit tolerance to the anticonvulsant action of this drug or cross-tolerance to diazepam. In these rats, the content of mRNA encoding for α1, α2, α3, α5, α6, γ1, γ2S, γ2L, and δ GABAA receptor subunits failed to change in the FrPaM and FrPaSS cortices, in the hippocampus, and in the other brain areas that were studied in diazepam-tolerant rats. Although the density and affinity of[3H]flumazenil and [3H]imidazenil binding failed to change in the FrPaM and FrPaSS cortices of diazepam-tolerant rats, the expression density of α1 subunit immunogold labeling decreased by 37%, whereas that of α5, γ2L/S, and β2/3 increased by 158%, 50%, and 47%, respectively, in the FrPaM cortex, and the density of the α5 subunit selectively increased (209%) in the FrPaSS cortex. In contrast, the immunogold labeling density of the α1, α5, γ2L/S, and β2/3 subunits failed to change in either the FrPaM or FrPaSS cortex of rats receiving protracted imidazenil treatment.

UR - http://www.scopus.com/inward/record.url?scp=0029944539&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029944539&partnerID=8YFLogxK

M3 - Article

C2 - 8622632

AN - SCOPUS:0029944539

VL - 49

SP - 822

EP - 831

JO - Molecular Pharmacology

JF - Molecular Pharmacology

SN - 0026-895X

IS - 5

ER -