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At least 865 records · Page 48Linked to original sources
PubMed2026

Add-on treatment with vinpocetine reduces seizure frequency and improves comorbidities in patients with loss-of-function γ-aminobutyric acid type A receptor variants.

OBJECTIVE: The semisynthetic compound vinpocetine has gained attention as a potential precision medicine for developmental and epileptic encephalopathies caused by loss-of-function (LoF) variants in γ-aminobutyric acid type A (GABAA) receptor genes. As a positive allosteric modulator of GABAA receptors, case reports suggest that vinpocetine can reduce epileptiform activity and seizure frequency, while improving cognitive function in patients with GABAA receptor-related epilepsies. Here, we extend these observations with a retrospective observational study evaluating the response to vinpocetine in an additional seven patients. METHODS: Patients initiated treatment with vinpocetine between 2018 and 2025 at the Danish Epilepsy Centre or abroad. Clinical data were collected from medical records, seizure diaries, and neuropsychological assessments. The modulatory efficacy of vinpocetine was investigated using electrophysiological studies. RESULTS: Nine patients harboring eight GABAA receptor LoF variants were given add-on vinpocetine treatment. Electrophysiological analyses confirmed dose-dependent positive modulation by vinpocetine across tested variants. Six patients with a median age of 15.5 years (range = 6-29) continued treatment for a median of 24 months (range = 12-90), whereas three discontinued due to adverse effects (AEs) or lack of efficacy. The patients' level of function ranged from normal to moderate intellectual disability, psychiatric comorbidities, and behavioral disturbances. Four patients initiated vinpocetine due to uncontrolled seizures. One became seizure-free, and two experienced a 50%-55% reduction. Electroencephalograms demonstrated improved spike-wave indexes in four patients. Six showed improvement in nonseizure factors, and caregivers reported reduced aggressivity and better vocabulary in one. Vinpocetine was well tolerated, with only mild and reversible AEs reported. SIGNIFICANCE: Adjunctive vinpocetine shows promise as a targeted therapy for patients with GABAA receptor LoF variants, decreasing seizure frequency and positively impacting nonseizure factors, with only mild AEs reported. Vinpocetine may be a safe and effective therapy for patients with GABAA receptor-related epilepsies, which should be investigated further in future N-of-1 trials.

Humans↗
PubMed2001

Progesterone and the oligodendroglial lineage: stage-dependent biosynthesis and metabolism.

Evidence has been accumulated showing that neurosteroids, particularly progesterone (PROG) and its metabolites, may participate in myelination and remyelination in the peripheral nervous system, but very few studies have been undertaken in the central nervous system (CNS). The aim of this work was to investigate the capacities of synthesis and metabolism of PROG at three important stages of the oligodendroglial lineage: oligodendrocyte pre-progenitors (OPP), oligodendrocyte progenitors (OP), and fully differentiated oligodendrocytes (OL). Experiments have been conducted in vitro using highly purified primary cell cultures from rat brain. Cells were incubated with (3)H-pregnenolone ((3)H-PREG), the immediate precursor of PROG, or with (3)H-PROG, and steroids metabolites were then identified by thin layer chromatography and high-performance liquid chromatography (HPLC). mRNA expression of key steroidogenic enzymes was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that only OPP and OP, but not OL, expressed 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4 isomerase mRNA and were able to synthesize PROG from PREG. In the three cell types studied, PROG was metabolized by the type 1 isoform of 5 alpha-reductase into 5 alpha-dihydroprogesterone (5 alpha-DHPROG). This enzyme exhibited a 5-fold higher activity in OL than in OPP and OP. 5 alpha-DHPROG was further transformed either into 3 alpha,5 alpha-tetrahydroprogesterone (3 alpha,5 alpha-THPROG), known as a positive allosteric modulator of the GABA(A) receptor, or into the 3 beta-isomer. The 3 alpha,5 alpha-THPROG synthesis was 10 times higher in OPP than in the other cell studied, while the 3 beta,5 alpha-THPROG production did not change with cell differentiation. PROG synthesis and metabolism and the dramatic changes in neurosteroidogenesis observed during the oligodendroglial differentiation may contribute to oligodendrocyte development or the myelination process.

Aging↗
PubMed2001

Galantamine: a randomized, double-blind, dose comparison in patients with Alzheimer's disease.

OBJECTIVES: To investigate whether Galantamine significantly improves the core symptoms of Alzheimer's disease (AD). BACKGROUND: Galantamine is a reversible, competitive, selective inhibitor of acetylcholinesterase (AChE) that also allosterically modulates nicotinic acetylcholine receptors. This dual mechanism of action provided the rationale for a phase II trial of galantamine in AD. METHOD: A multicentre, randomized, parallel, double-blind, placebo-controlled trial was carried out to evaluate the efficacy and tolerability of galantamine 18, 24 and 36 mg/day administered for 3 months in 285 patients with mild-to-moderate probable AD. The primary outcome measure was the Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog); secondary outcome measures were the Clinical Global Impression of Change (CGIC) and the Progressive Deterioration Scale (PDS). RESULTS: Patients treated with galantamine 24 mg/day had a significantly better outcome than placebo on ADAS-cog; the treatment difference was 3 points on the intention-to-treat (ITT) analysis ( p = 0.01) and 4.2 points on per protocol analysis ( p = 0.001). Per protocol analysis showed that galantamine had a significantly better outcome than placebo on PDS ( 24-mg/day dose, p < 0.05) and CGIC (36-mg/day dose, p < 0.05). Galantamine was well tolerated at the lower doses of 18 and 24 mg/day where it produced mild, transient effects typical of cholinomimetic agents. CONCLUSION: This study shows that, relative to placebo, galantamine significantly improves the core symptoms of Alzheimer's disease.

Aged↗
PubMed1996

Neuroactive amino acids and glutamate (NMDA) receptors in frontal cortex of rats with experimental acute liver failure.

It has been proposed that alterations of excitatory and inhibitory amino acids play a role in the pathogenesis of hepatic encephalopathy in acute liver failure. To evaluate this possibility, in vivo cerebral microdialysis was used to sample extracellular concentrations of amino acids in the frontal cortex of unanesthetized rats at various times during the progression of encephalopathy resulting from acute liver failure. Liver failure was induced by portacaval anastomosis followed 24 hours later by hepatic artery ligation. Dialysate concentrations of amino acids were measured by high-performance liquid chromatography (HPLC) with fluorescence detection. Deterioration of neurological status was accompanied by two- to four-fold increases in extracellular glutamate, glutamine, and glycine; concentrations of gamma-aminobutyric acid (GABA) and taurine were unchanged. Densities of binding sites for the glutamate (N-methyl-D-aspartate [NMDA]) receptor ligand 3H-MK801, assessed using quantitative receptor autoradiography, however, were unchanged in the frontal cortex of rats at coma stages of ischemic liver failure. Increased extracellular glutamate concentrations were positively correlated with the severity of encephalopathy and with arterial ammonia concentrations. Such changes may result from an ammonia-induced reduction in the capacity for astrocytes to uptake glutamate. Increased extracellular glutamate in brain, together with increases in concentrations of glycine, a positive allosteric modulator of glutamate (NMDA) receptors, are consistent with increased NMDA-related glutamatergic neurotransmission in this model of acute liver failure. Increased extracellular glutamate, therefore, could contribute to the pathogenesis of hepatic encephalopathy and brain edema in acute liver failure.

Animals↗
PubMed2005

Osteoblast calcium-sensing receptor has characteristics of ANF/7TM receptors.

There is evidence for a functionally important extracellular calcium-sensing receptor in osteoblasts, but there is disagreement regarding its identity. Candidates are CASR and a putative novel calcium-sensing receptor, called Ob.CASR. To further characterize Ob.CASR and to distinguish it from CASR, we examined the extracellular cation-sensing response in MC3T3-E1 osteoblasts and in osteoblasts derived from CASR null mice. We found that extracellular cations activate ERK and serum response element (SRE)-luciferase reporter activity in osteoblasts lacking CASR. Amino acids, but not the calcimimetic NPS-R568, an allosteric modulator of CASR, also stimulate Ob.CASR-dependent SRE-luciferase activation in MC3T3-E1 osteoblasts. In addition, we found that the dominant negative Galphaq(305-359) construct inhibited cation-stimulated ERK activation, consistent with Ob.CASR coupling to Galphaq-dependent pathways. Ob.CASR is also a target for classical GPCR desensitization mechanisms, since beta-arrestins, which bind to and uncouple GRK phosphorylated GPCRs, attenuated cation-stimulated SRE-luciferase activity in CASR deficient osteoblasts. Finally, we found that Ob.CASR and CASR couple to SRE through distinct signaling pathways. Ob.CASR does not activate RhoA and C3 toxin fails to block Ob.CASR-induced SRE-luciferase activity. Mutational analysis of the serum response factor (SRF) and ternary complex factor (TCF) elements in SRE demonstrates that Ob.CASR predominantly activates TCF-dependent mechanisms, whereas CASR activates SRE-luciferase mainly through a RhoA and SRF-dependent mechanism. The ability of Ob.CASR to sense cations and amino acids and function like a G-protein coupled receptor suggests that it may belong to the family of receptors characterized by an evolutionarily conserved amino acid sensing motif (ANF) linked to an intramembranous 7 transmembrane loop region (7TM).

Amino Acids↗
PubMed2004

3alpha,5alpha-Tetrahydroprogesterone (allopregnanolone) and gamma-aminobutyric acid: autocrine/paracrine interactions in the control of neonatal PSA-NCAM+ progenitor proliferation.

The earliest identified neonatal neural progenitors are cells that express the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). One of these progenitors is the early PSA-NCAM+ progenitor (ePSA-NCAM+ progenitor; Gago et al. [2003] Mol Cell Neurosci 22:162-178), which corresponds to a multipotential cell with a default differentiation through glial lineages. The ePSA-NCAM+ progenitor can synthesize the neurosteroid progesterone (PROG) and its reduced metabolite 3alpha,5alpha-tetrahydroprogesterone (3alpha,5alpha-THP, or allopregnanolone; Gago et al. [ 2001] Glia 36:295-308). The latter is a potent positive allosteric modulator of gamma-aminobutyric acid type A (GABAA) receptors. In the present work, we demonstrate that PROG and 3alpha,5alpha-THP both stimulate ePSA-NCAM+ progenitor proliferation. PROG exerted its mitogenic effect indirectly, through its conversion to 3alpha,5alpha-THP, since it could be abolished by an inhibitor of the 5alpha-reductase (L685-273) and mimicked by 3alpha,5alpha-THP. A dose-response curve revealed a bell-shaped effect of 3alpha,5alpha-THP on ePSA-NCAM+ progenitor proliferation, with greatest stimulation at nanomolar concentrations. The mitogenic effect of 3 alpha,5 alpha-THP was mediated by GABAA receptors, insofar as it could be blocked by the selective antagonist bicuculline. ePSA-NCAM+ progenitors indeed expressed mRNAs for GABAA receptor subunits, and GABA enhanced cell proliferation, an effect that was also bicuculline sensitive. Moreover, these cells synthesized GABA, which was involved in a tonic stimulation of their proliferation. These results reveal complex autocrine/paracrine loops in the control of ePSA-NCAM+ progenitor proliferation, involving both neurosteroid and GABA signaling, and suggest a novel key role for 3alpha,5alpha-THP in the development of the nervous system.

Animals↗
PubMed2005

Acute effects of physostigmine and galantamine on the binding of [18F]fluoro-A-85380: a PET study in monkeys.

2-[18F]fluoro-3-[2S-2-azetidinylmethoxy]pyridine ([18F]fluoro-A-85380) is an alpha4beta2 subtype selective nicotinic cholinergic agonist with potential suitability for studying changes in endogenous acetylcholine synaptic concentration. Physostigmine, a potent AChE inhibitor, and galantamine, an allosteric modulator of nAChRs, are widely used for the treatment of Alzheimer's disease. Before studying patients with this neurodegenerative disease, positron emission tomography (PET) studies in monkeys were performed to assess the impact of these two compounds on the radiotracer distribution volumes. Physostigmine was administered i.v. at two dosages: 150 microg/kg/h and 37.5 microg/kg/h for 160 min. Galantamine was administered i.v. at two dosages: 2 or 4 mg over 20 min. For PET data analysis, a model with one tissue (radioactivity of the parent compound in plasma and radioactivity in brain tissue) compartment was chosen because reliable parameter estimates could not be obtained with a more complex model. The higher dose of physostigmine produced a 40%, 23%, and 30% reduction of distribution volumes in the putamen, the temporal, and frontal cortices, respectively. The lower dose of physostigmine produced a reduction of 33%, 31%, and 24% in the same structures, respectively. Galantamine (4 mg or 2 mg) produced no significant change of distribution volumes in the basal ganglia, the temporal and frontal cortex. The effects of physostigmine, a more potent AChE inhibitor than galantamine, could be interpreted as a desensitization of nAChRs, due to a prolonged exposure to high synaptic concentration of acetylcholine or as a competition with acetylcholine.

Analysis of Variance↗
PubMed1993

Calciseptine binding to a 1,4-dihydropyridine recognition site of the L-type calcium channel of rat synaptosomal membranes.

Calciseptine (CaS) is a natural peptidic L-type Ca2+ channel blocker consisting of 60 amino acids with four disulfide bonds. The effects of synthetic CaS on the binding of various ligands to Ca2+ channels of rat brain synaptosomal membranes were studied. The membranes possessed specific binding sites for L-type Ca2+ channel ligands [3H]nitrendipine, [3H]diltiazem and [3H]verapamil, derivatives of 1,4-dihydropyridine, benzothiazepine and papaverine, respectively, and also for N-type Ca2+ channel ligand omega-[125I]-conotoxin GVIA (omega-[125I]CTX). Lineweaver-Bulk plot analysis disclosed that CaS competitively inhibited the binding of [3H]nitrendipine, with maximal binding capacity of 0.19 pmol/mg protein and dissociation constant (Kd) of 290 nM, being about 10(3) times the Kd value of [3H]nitrendipine. Similar to nitrendipine, CaS noncompetitively enhanced the binding of [3H]diltiazem, but did not affect the binding of [3']verapamil. CaS at up to 10.0 microM did not affect the binding of omega-[125I]CTX. These observations indicate that CaS shares the properties of 1,4-dihydropyridine derivatives, and allosterically modulates the binding of other L-type Ca2+ channel ligands.

Animals↗
PubMed1994

Cloning of a complete protein-coding sequence of human platelet-type phosphofructokinase isozyme from pancreatic islet.

We have cloned a full length protein-coding sequence of human platelet-type phosphofructokinase (PFK) from pancreatic islet cDNA library. The platelet-type PFK was composed of 784 amino acids and had a deduced molecular weight of 85,590. Homologies in the primary structure with muscle- and liver-type PFK were 71 and 67%. Clear similarities of the amino and carboxyl halves with a prokaryotic PFK indicated an evolutionary event that duplicated genes of a prototype PFK fused into larger genes of eukaryotic PFKs. Amino acid residues constituting the binding sites for various allosteric modulators were well conserved, while a couple of different residues at the inhibitory ATP sites among three isozymes may partly explain their varied degree of sensitivities to ATP. Considerable amount of platelet-type PFK expression was demonstrated in brain, heart, kidney, colon and testis.

Amino Acid Sequence↗
PubMed1996

Antagonistic effect of inositol pentakisphosphate on inositol triphosphate receptors.

We present evidence that inositol 1,3,4,5,6-pentakisphosphate acts as an antagonist of inositol triphosphate receptors in vitro by dampening the activity of Ca(2+)-mobilizing inositol phosphates. This antagonism bears physiological significance as cells maintain substantial quantities of this phosphoinositol in the cytosol, especially during cell differentiation or proliferation. Over a concentration range from 30 to 150 microM, this pentakisphosphate causes a two- to five-fold increase in the EC50 values of inositol 1,4,5-trisphosphate and other active phosphoinositols in effecting Ca2+ efflux from brain microsomes. This specific inhibition results from competitive receptor binding, and is not noted with inositol hexaphosphate or related metabolites at comparable concentrations. Thus, inositol 1,3,4,5,6-pentakisphosphate in concert with other allosteric modulators may constitute an integral component for the receptor regulation.

Animals↗
PubMed1999

High-resolution solution structure of the 18 kDa substrate-binding domain of the mammalian chaperone protein Hsc70.

The three-dimensional structure for the substrate-binding domain of the mammalian chaperone protein Hsc70 of the 70 kDa heat shock class (HSP70) is presented. This domain includes residues 383-540 (18 kDa) and is necessary for the binding of the chaperone with substrate proteins and peptides. The high-resolution NMR solution structure is based on 4150 experimental distance constraints leading to an average root-mean-square precision of 0.38 A for the backbone atoms and 0.76 A for all atoms in the beta-sandwich sub-domain. The protein is observed to bind residue Leu539 in its hydrophobic substrate-binding groove by intramolecular interaction. The position of a helical latch differs dramatically from what is observed in the crystal and solution structures of the homologous prokaryotic chaperone DnaK. In the Hsc70 structure, the helix lies in a hydrophobic groove and is anchored by a buried salt-bridge. Residues involved in this salt-bridge appear to be important for the allosteric functioning of the protein. A mechanism for interdomain allosteric modulation of substrate-binding is proposed. It involves large-scale movements of the helical domain, redefining the location of the hinge area that enables such motions.

Amino Acid Sequence↗
PubMed1988

Interactions of DPI 201-106, a novel cardiotonic agent, with cardiac calcium channels.

The interaction of DPI 201-106, a novel cardiotonic agent, with the calcium entry blocker receptor complex was studied using porcine cardiac sarcolemmal membranes. DPI 201-106 and the chemically-related calcium antagonist, cinnarizine, produce concentration-dependent inhibition of nitrendipine, gallopamil and diltiazem binding to their respective sites in these vesicles. This effect of DPI 201-106 is not stereoselective since resolved stereoisomers of this compound display equal potency in inhibiting each of the binding reactions. Equilibrium ligand binding studies revealed that DPI 201-106 and cinnarizine cause mixed inhibitory patterns at the aralkylamine and benzothiazepine sites (i.e. both Kd and Bmax values were affected) while mainly increasing Kd at the dihydropyridine site. The kinetics of ligand dissociation from the three calcium entry blocker receptors, together with measurements of dihydropyridine association kinetics, further demonstrate that DPI 201-106 interacts at a unique site in the receptor complex and allosterically modulates binding of nitrendipine, gallopamil and diltiazem. The functional consequences of the above interactions with the calcium channel were studied in isolated cardiac preparations. In guinea-pig atria, DPI 201-106 increased force of contraction. This inotropic effect is seen only with the S(-) enantiomer and is unaltered by nitrendipine-, verapamil- or diltiazem-pretreatment, indicating DPI 201-106 does not act as a stimulant of this channel. Furthermore, DPI 201-106 did not alter the inotropic action of Bay K 8644, a calcium channel stimulant. Spontaneous rate of guinea-pig right atria is decreased by both DPI 201-106 and cinnarizine. In addition, potassium-induced contractures in cat papillary muscles are reduced by both agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Characterization of [3H]brevetoxin binding to voltage-dependent sodium channels in adrenal medullary cells.

We have previously reported that in bovine adrenal chromaffin cells Ptychodiscus brevis toxin-3 (PbTx-3) does not alter the veratridine-induced 22Na influx when given alone, but increases the influx of 22Na when co-applied with either alpha- or beta-scorpion venom (Wada et al. 1992). In the present study, we characterized [3H]PbTx-3 binding in bovine adrenal chromaffin cells. [3H]PbTx-3 binding was saturable, reversible and of high-affinity with an equilibrium dissociation constant (Kd) of 32.0 +/- 4.9 nmol/l and a maximum binding capacity (Bmax) of 6.2 +/- 1.2 pmol/4 x 10(6) cells (4.5 +/- 0.9 pmol/mg cell protein). A Hill plot revealed the lack of cooperative interaction among the binding sites. Unlabelled PbTx-3 inhibited [3H]PbTx-3 binding with an IC50 of 31 nmol/l. However, tetrodotoxin, veratridine, alpha- and beta-scorpion venom, or veratridine in combination with either alpha- or beta-scorpion venom did not alter [3H]PbTx-3 binding. All these results suggest that PbTx-3 binds to a site (site 5) distinct from the previously known four toxin binding sites, which does not gate voltage-dependent Na channels by itself, but is specifically involved in the allosteric modulation of Na channels in adrenal medullary cells.

Adrenal Medulla↗
PubMed1996

Cyclic nucleotide phosphodiesterase (PDE) isoenzymes in the human detrusor smooth muscle. I. Identification and characterization.

Phosphodiesterases (PDEs) are key enzymes involved in the regulation of intracellular cyclic nucleotide metabolism. The aim of the present study was to identify and to characterize the PDE isoenzymes present in the human detrusor smooth muscle. Human detrusor PDE isoenzymes were separated by Q-Sepharose anion exchange and calmodulin-agarose affinity chromatography and characterized upon their kinetic characteristics and their sensitivity to allosteric modulators and inhibitors. All five presently known PDE isoenzyme families were identified: one high-affinity, low-Km calcium/calmodulin-stimulated PDE I with a slight preference for cGMP over cAMP, one cGMP-stimulated PDE II, one cGMP-inhibited PDE III, one cAMP-specific PDE IV and one cGMP-specific PDE IV. All five known PDE isoenzyme families exist in human detrusor smooth musculature. The kinetic characteristics, together with functional in vitro studies, suggest that the PDE I may be of importance in the intracellular regulation of the human detrusor smooth muscle tone.

Anion Exchange Resins↗
PubMed1996

Physiology of pyruvate metabolism in Lactococcus lactis.

Lactococcus lactis, a homofermentative lactic acid bacterium, has been studied extensively over several decades to obtain sometimes conflicting concepts relating to the growth behaviour. In this review some of the data will be examined with respect to pyruvate metabolism. It will be demonstrated that the metabolic transformation of pyruvate can be predicted if the growth-limiting constraints are adequately established. In general lactate remains the major product under conditions in which sugar metabolism via a homolactic fermentation can satisfy the energy requirements necessary to assimilate anabolic substrates from the medium. In contrast, alternative pathways are involved when this energy supply becomes limiting or when the normal pathways can no longer maintain balanced carbon flux. Pyruvate occupies an important position within the metabolic network of L. lactis and the control of pyruvate distribution within the various pathways is subject to co-ordinated regulation by both gene expression mechanisms and allosteric modulation of enzyme activity.

Adenosine Triphosphate↗
PubMed1990

Photoaffinity labeling of the receptor site for alpha-scorpion toxins on purified and reconstituted sodium channels by a new toxin derivative.

1. A methyl-4-azidobenzimidyl (MAB) derivative of the alpha-scorpion toxin from Leiurus quinquestriatus (LqTx) specifically labels only the alpha subunit of the rat brain sodium channel in synaptosomes or in purified and reconstituted sodium-channel preparations. 2. Unlike previous photoreactive toxin derivaties, binding and photolabeling by MAB-LqTx are allosterically modulated by tetrodotoxin and batrachotoxin, as observed for native LqTx binding to sodium channels in synaptosomes. 3. Proteolytic cleavage of the alpha subunit photolabeled with MAB-LqTx shows that the label is located within a 60 to 70-kDa protease-resistant core structure in domain I of the sodium-channel alpha subunit. 4. MAB-LqTx will be valuable in further defining the structure-activity relationships at the alpha-scorpion toxin receptor site.

Animals↗
PubMed1996

The parathyroid calcium receptor: a novel therapeutic target for treating hyperparathyroidism.

Parathyroid cells, C-cells, and certain cells in the kidney express a cell surface calcium (Ca2+) receptor which enables these cells to detect and respond to changes in the concentration of extracellular Ca2+. This receptor protein is a member of the G protein-coupled receptor superfamily and shares limited sequence homology only with metabotropic glutamate receptors. The Ca2+ receptor is the primary physiological mechanism regulating the secretion of parathyroid hormone (PTH) and plays a pivotal role in maintaining systemic Ca2+ homeostasis. Compounds that act as Ca2+ receptor agonists are called calcimimetics because they mimic or potentiate the effects of extracellular Ca2+ on parathyroid cell function. NPS R-568 is a small organic calcimimetic compound that acts as a positive allosteric modulator to increase the sensitivity of the Ca2+ receptor to activation by extracellular Ca2+. In normal rats, orally administered NPS R-568 decreases plasma levels of PTH and Ca2+ and, at higher doses, increases plasma levels of calcitonin. The changes in the circulating levels of these two hormones explain the hypocalcemia caused by this compound. NPS R-568 also effectively lowers plasma PTH levels in normal humans and in rat models of secondary hyperparathyroidism. Calcimimetic compounds that target the Ca2+ receptor provide a novel therapeutic approach for treating primary and secondary hyperparathyroidism.

Animals↗
PubMed1992

gamma-Hydroxybutyric acid binding sites: interaction with the GABA-benzodiazepine-picrotoxin receptor complex.

The effect of three compounds known to allosterically modulate binding to the GABA/benzodiazepine/picrotoxin receptor complex on 4-hydroxy-2,3 [3H]butyric acid (GHB) binding was investigated. Pentobarbital, pentylenetetrazole, and picrotoxin enhanced [3H]GHB binding in a dose dependent fashion. Pentobarbital enhanced 4-hydroxy-2,3 [3H]butyric acid binding was associated with an increase in Bmax while pentylenetetrazole and picrotoxin altered the affinity of GHB for its binding site producing a decrease in Kd. These findings suggest that the GHB and GABA receptor complex may share certain moieties in common.

Animals↗