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Barbiturates allosterically inhibit GABA antagonist and benzodiazepine inverse agonist binding

Barbiturates and the related depressant drugs, etazolate and etomidate, inhibited both the binding of [3H]bicuculline methochloride (BMC) to γ-aminobutyric acid (GABA) receptor sites and the binding of [3H]β-carboline-3-carboxylic acid methyl ester (βCCM) to benzodiazepine receptor sites in mammalian brain. These concentration-dependent effects were chemically specific and stereospecific in a mann

γ-Aminobutyric acid activation of 36Cl-flux in rat hippocampal slices and its potentiation by barbiturates

γ-Aminobutyric acid (GABA) increases the rate of 36Cl- efflux from preloaded rat hippocampal slices in a dose-dependent manner (EC50: 400 μM). This action has the pharmacological specificity expected of activation of GABA receptor in that it is mimicked by the agonists muscimol and 3-aminopropanesulfonic acid, and blocked by the antagonists bicuculline and picrotoxinin. GABA uptake inhibitors, nip

Covalent labeling of the cerebral cortex α1-adrenergic receptor with a new high affinity radioiodinated photoaffinity probe

A novel high affinity radioiodinated photoaffinity probe, 4-amino-6,7-dimethoxy-2[4-[5(3-[125I]iodo-4-azidophenyl)pentanoyl]-1-piperazinyl]- quinazoline, structurally related to the potent α1-adrenergic antagonist prazosin, was developed and used to covalently label the rat cerebral cortex α1-adrenergic receptor. In the absence of light, this ligand binds to cortex plasma membranes with a dissocia

Heterogeneity of benzodiazepine receptor interactions with γ-aminobutyric acid and barbiturate receptor sites

Benzodiazepine receptor binding heterogeneity evident from differential affinities of some ligands was compared with that suggested by differential interactions with γ-aminobutyric acid (GABA)/bicuculline and pyrazolopyridine/barbiturate receptor sites. The GABA receptor antagonist bicuculline only partially reverses pentobarbital enhancement of [3H] diazepam binding in rat brain membranes, while

Interaction of barbiturates of various pharmacological categories with benzodiazepine receptors

Numerous barbiturates, such as (±)-pentobarbital, reversibly enhance the affinity for equilibrium binding of [3H]diazepam to well-washed rat cortical membranes in a chloride-dependent and picrotoxinin-sensitive manner [Leeb-Lundberg et al., Proc. Natl. Acad. Sci. U.S.A. 77:7468-7472 (1980)]. The chemical specificity and stereospecificity of this barbiturate effect in vitro has been examined in det

Perturbation of benzodiazepine receptor binding by pyrazolopyridines involves picrotoxinin/barbiturate receptor sites

The two pyrazolopyridines, etazolate (SQ20009) and cartazolate (SQ65396), enhance the binding of [3H]diazepam to benzodiazepine receptor sites in rat brain. This enhancement is due to a change in affinity without a change in maximal binding. Pentobarbital also enhances [3H]diazepam binding by lowering the K(D). Pentobarbital gives a maximal enhancement of benzodiazepine binding slightly greater th

Dihydropicrotoxinin binding sites in mammalian brain : Interaction with convulsant and depressant benzodiazepines

The specific binding of [3H]α-dihydropicrotoxinin to rat brain membranes was inhibited competitively and potently (IC50 ≅ 100 nM) by a convulsant benzodiazepine drug, RO5-3663. This compound did not inhibit high affinity flunitrazepam binding to the same tissue under similar conditions, and its reported pharmacological activity as an antagonist of GABAergic synaptic transmission, which resembles t

Interaction of anticonvulsants with the barbiturate-benzodiazpine-gaba receptor complex

Unlike the anesthetic barbiturate pentobarbital and the anxiolytic pyrazolopyridine etazolate, which enhance [3H]diazepam binding to rat brain membranes, the anticonvulsant barbiturates phenobarbital and metharbital, and also chlormethiazole, at therapeutic concentrations (10-1000 μM), do not stimulate [3H]diazepam binding, but instead block the enhancement by both pentobarbital and etazolate. The

Barbiturate receptor sites are coupled to benzodiazepine receptors

Barbiturates enhance the binding of [3H]diazepam to benzodiazepine receptor sites in rat brain. This effect occurs at pharmacologically relevant concentrations of barbiturates, and the relative activity of a series of compounds correlates highly with anesthetic activity of the barbiturates and with their ability to enhance postsynaptic inhibitory responses to the neurotransmitter γ-aminobutyric ac

Picrotoxin and convulsant binding sites in mammalian brain

(3H)α-Dihydropicrotoxinin (DHP) binds to membrane sites in mammalian brain which appear to be related to the convulsant action of picrotoxin at the level of membrane Cl-channels which are at least partially regulated by the inhibitory neurotransmitter GABA. DHP binding to rat cerebral cortex (assayed by centrifugation) showed a single class of sites (Kd = 2μM) and Bmax of 4 pmol/mg protein, and wa

Remote sensing for mapping natural habitats and their conservation status - New opportunities and challenges

Safeguarding the diversity of natural and semi-natural habitats in Europe is one of the aims set out by the Habitats Directive (Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora) and one of the targets of the European 2020 Biodiversity Strategy, and is to be accomplished by maintaining a favourable conservation status. To reach this aim a high-level un

GMES4Mining - Description of a flooding process in mining areas using spectral indices on multioral landsat imagery

The R&D project GMES4Mining aims to support particular tasks within the different phases of a mining life cycle. Within this project one task concentrates on vegetation monitoring in order to detect damages caused by mining. In Germany several mining districts have been exploited for a long time. Mining areas are associated with certain environmental hazards, such as surface subsidence and flo

Circulating concentrations of placenta protein 14 during the natural menstrual cycle in women significantly reflect endometrial receptivity to implantation and pregnancy during successive assisted reproduction cycles

Placenta protein 14 (PP14), which is the most abundant product of the secretory endometrium, has been proposed as the best biochemical marker of endometrial function in women. In this study, 19 normogonadotrophic women of infertile couples were monitored with serial measurements of concentrations of PP14, gonadotrophins and sex steroids and ultrasound scanning of endometrial thickness throughout t

Using information layers for mapping grassland habitat distribution at local to regional scales

The Natura 2000 network of protected sites is one of the means to enable biodiversity conservation in Europe. EU member states have to undertake surveillance of habitats and species of community interest protected under the Habitat Directive. Remote sensing techniques have been applied successfully to monitor biodiversity aspects according to Natura 2000, but many challenges remain in assessing dy