In vivo binding of (3H) Ro 15-1788 in mice: Comparison with the in vivo binding of (3H) flunitrazepam

Potier, Marie‐Claude; Carvalho, Lia Prado de; Dodd, Robert H.; Brown, ChloëL.; Rossier, Jean

doi:10.1016/0024-3205(88)90583-8

Cited by 20 publications

(15 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The peak of both total and membrane-bound radioactivity was found to be 3 minutes after IV administration, in agreement with previous studies showing that [ 3 H]benzodiazepines rapidly enter the brain (Goeders and Kuhar 1985;Ciliax et al 1986;Potier et al 1988b). The fact that more than 75% of the radioactivity in the brain is membrane bound suggests that the majority of [ 3 H]Ro 15-1788 that gets into the brain is available for binding to the receptor and is not sequestered in pools unavailable for receptor binding.…”

Section: Discussionsupporting

confidence: 90%

“…A similar lack of regional selectivity for diazepam and flunitrazepam has been reported previously in various regions of the mouse (Potier et al 1988b) and rat (Benavides et al 1992 However, the ID 50 for diazepam observed in the present study (2 mg/kg) is appreciably lower than previous estimates (10 mg/kg, Benavides et al 1988).…”

Section: Discussionsupporting

confidence: 86%

“…This is consistent with the low levels of nonspecific binding (Ͻ5%) as defined by doses of flunitrazepam that saturate the binding site and is in agreement with previous work (Potier et al 1988a;Facklam et al 1992). Taken together, these data demonstrate the utility of [ 3 H]Ro 15-1788 as a radioligand with which to study benzodiazepine binding sites in vivo (Goeders and Kuhar 1985;Potier et al 1988b).…”

Section: Discussionmentioning

confidence: 56%

“…The methods used were essentially those of Goeders and Kuhar (1985) as modified to include the separation of membrane-bound from unbound radioactivity (Potier et al 1988a(Potier et al , 1988b, although this separation of bound from free radioligand is not absolutely necessary (Facklam et al 1992). Mice were then killed at varying times (0.5 to 30 min) later, and the whole brain was removed, weighed, and rapidly homogenized in 10 volumes of ice-cold buffer (10 mM potassium phosphate buffer containing 100 mM KCl, pH 7.4).…”

Section: In Vivo Binding Of [ 3 H]ro 15-1788mentioning

confidence: 99%

“…The benzodiazepine binding site of ␣ 1 , ␣ 2 , ␣ 3 , and ␣ 5 subunit-containing GABA A receptors can be labeled in vivo using radiolabeled Ro 15-1788 (Goeders and Kuhar 1985;Potier et al 1988aPotier et al , 1988bPersson et al 1985). However, within the cerebellum, binding is predominantly to ␣ 1 subunit-containing GABA A receptors because although the cerebellum is the major site of ␣ 6 subunit expression in the brain, Ro 15-1788 has a low affinity for this subpopulation of receptors.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Regional Differences in the Inhibition of Mouse In Vivo [3H]Ro 15-1788 Binding Reflect Selectivity for α1 versus α2 and α3 Subunit-Containing GABAA Receptors

Atack

Smith

Emms

et al. 1999

Neuropsychopharmacology

View full text Add to dashboard Cite

show abstract

Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 56%

Section: In Vivo Binding Of [ 3 H]ro 15-1788mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Regional Differences in the Inhibition of Mouse In Vivo [3H]Ro 15-1788 Binding Reflect Selectivity for α1 versus α2 and α3 Subunit-Containing GABAA Receptors

Atack

Smith

Emms

et al. 1999

Neuropsychopharmacology

View full text Add to dashboard Cite

show abstract

In vivo saturation binding of GABA‐A receptor ligands to estimate receptor occupancy using liquid chromatography/tandem mass spectrometry

Hopkins

Nofsinger

Allen

et al. 2009

Biopharm & Drug Disp

View full text Add to dashboard Cite

Typically, the dose-occupancy curves for GABA-A receptor ligands are determined using in vivo binding of [3H]flumazenil. This study describes in vivo binding experiments without the use of tracer ligands. Bound and free fractions were measured directly using a highly sensitive LC/MS/MS detection method after in vivo administration of the GABA-A ligands zolpidem, (RS)-zopiclone, L-838417 and flumazenil, to demonstrate affinity and saturation of the filter-retained, membrane-bound fraction. The in vivo binding of flumazenil and L-838417 both saturated around 200 nM, at a similar level to the specific binding of (S)-zopiclone after doses of the racemic zopiclone, using (R)-zopiclone to estimate non-specific binding. This saturable component represented an estimate of benzodiazepine binding sites available on GABA-A receptors in vivo (200 nM). Dose-occupancy curves were constructed to estimate the dose required to achieve 50% occupancy and matched estimates obtained with tracer methods. In contrast to tracer methods, this method is uniquely suitable to the demonstration of stereoselective binding of the (S)-isomer in vivo after doses of racemic zopiclone. These results demonstrate that the LC/MS/MS measurements of total drug concentrations typically used in early drug development can be adapted to provide information about receptor occupancy in vivo.

show abstract

Psychopharmacology of benzodiazepines—an update

Malizia

Nutt

1995

Hum. Psychopharmacol. Clin. Exp.

View full text Add to dashboard Cite

Benzodiazepines are one of the classes of compounds which bind at the benzodiazepine site in the central nervous system. The benzodiazepine site is phylogenetically new and modulates allostericaIly the GABA-chloride ionophore. This complex is a pentamer surrounding the chloride channel and is made up of various combinations of alpha, beta and gamma subunits. The anatomical distribution of these subunits is diverse and underlies the differential binding of a number of benzodiazepine modulators in the brain. Other compounds which act at this complex include bicuculline, musicmol, ethanol and neurosteroids. Modulation at the benzodiazepine site is bidirectional. The net result of positive modulation is facilitation of conductance and thus hyperpolarisation i.e. an inhibitory effect, while negative modulation has the inverse effects. There is considerable receptor reserve at this complex, in addition since modulators depend on the presence of GABA for their effects, supraphysiological stimulation does not occur. These factors account for the extreme safety of benzodiazepines and explain the lack of selectivity of action of full agonists, since small increases in fractional occupancy are enough to produce the full gamut of effects. The same however does not apply to partial agonists which manifest the different actions at well separated receptor occupation. Endogenous ligands have not yet been found for these sites, although benzodiazepines have been found in brains collected prior to their pharmaceutic marketing-these probably originate from vegetable foodstuffs and gut bacteria. Changes in this site can be induced by stress, convulsions and repeated administration of modulators and animals bred for different sensitivity at the benzodiazepine site manifest consistent behavioural differences. These observations have instigated a search for potential endogenous inverse agonists in human anxiety disorders and epilepsy and for endogenous agonists in metabolic encephalopathies. While thus far this has not been successful the putative isolation of endozapines in the rare condition of idiopathic recurrent stupor indicate that this may be a useful line of research. In addition the emergence of partial agonists at these sites which have fewer side effects is likely to rekindle interest in the clinical use of such compounds in a variety of neurological and psychiatric syndromes.

show abstract

In vivo binding of (3H) Ro 15-1788 in mice: Comparison with the in vivo binding of (3H) flunitrazepam

Cited by 20 publications

References 21 publications

Regional Differences in the Inhibition of Mouse In Vivo [3H]Ro 15-1788 Binding Reflect Selectivity for α1 versus α2 and α3 Subunit-Containing GABAA Receptors

Regional Differences in the Inhibition of Mouse In Vivo [3H]Ro 15-1788 Binding Reflect Selectivity for α1 versus α2 and α3 Subunit-Containing GABAA Receptors

In vivo saturation binding of GABA‐A receptor ligands to estimate receptor occupancy using liquid chromatography/tandem mass spectrometry

Psychopharmacology of benzodiazepines—an update

Contact Info

Product

Resources

About