Peripheral-type Benzodiazepine Research Articles

Differential Expressions of p53, p53R2, hRRM2 and PBR in Chronic Lymphocytic Leukemia: A Correlation with Intracellular Cholesterol.

Regulation of intracellular cholesterol homeostasis exists under balance between intracellular biosynthesis and uptake from extracellular origin by cell surface transport proteins. Expected role of cholesterol on either tumor suppressor gene and/or DNA synthesis has been aimed in the present study to explore intracellular cholesterol homeostasis in CLL subjects. Higher expressions of p53R2 (p53 dependent subunit of ribonucleotide reductase) and p53 were found in lymphocytes of chronic human lymphocytic leukemia as comparison to their normal counterparts. Inverse relation was found with p53 independent R2 subunit (in human hRRM2) of ribonucleotide reductase, which was found to be decreased from its control group. More expression of peripheral type benzodiazepine receptor, a cholesterol transporter, was noticed in isolated nuclear fraction with simultaneous increase of cholesterol concentration in cytoplasmic and nuclear compartments. A parallel increase of cholesterol in cell nucleus with increased p53R2 expression shows priority of the involvement of cholesterol in the process of cell replication.

Imaging Neuroinflammation in Ischemic Stroke and in the Atherosclerotic Vascular Disease

Neuroinflammation is a complex biological response to any injury occurring to the central nervous system. It is mainly characterized by the recruitment of immune system cells, namely the microglial cells, in the site of injury. Once activated, microglia expresses a cholesterol transporter protein (TSPO), previously also known as peripheral type benzodiazepine receptor. PK11195 is a ligand for TSPO and, labelled with a positron emitter, it is also the most used tracer for PET molecular imaging to in vivo map the microglia activation in various neurological disorders, including ischemic stroke. Recent [(11)C]PK11195 PET studies proved activated microglia both locally in the area of the infarct and at distance along the affected fibre tracts, suggesting the presence of two different microglia subtypes with peculiar functions in disease progression. The aim of this review is to discuss the most recent knowledge about imaging neuroinflammation in ischemic stroke and in the atherosclerotic and vascular inflammatory disorders, trying to elucidate the interplay between the clinical course and the activation of a microglial response.

Effects of icariin on reproductive functions in male rats.

The present study investigated the effects and potential mechanism(s) of action of icariin on the reproductive functions of male rats. Adult rats were treated orally with icariin at doses of 0 (control), 50, 100, or 200 mg/kg body weight for 35 consecutive days. The results show that icariin had virtually no effect on the body weight or organ coefficients of the testes or epididymides. However, 100 mg/kg icariin significantly increased epididymal sperm counts. In addition, 50 and 100 mg/kg icariin significantly increased testosterone levels. Real-time PCR suggests icariin may be involved in testosterone production via mRNA expression regulation of genes such as peripheral type benzodiazepine receptor (PBR) and steroidogenic acute regulatory protein (StAR). Furthermore, 100 mg/kg icariin treatment also affected follicle stimulating hormone receptor (FSHR) and claudin-11 mRNA expression in Sertoli cells. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were measured in the testes; 50 and 100 mg/kg icariin treatment improved antioxidative capacity, while 200 mg/kg icariin treatment upregulated oxidative stress. These results collectively suggest that icariin within a certain dose range is beneficial to male reproductive functions; meanwhile, higher doses of icariin may damage reproductive functions by increasing oxidative stress in the testes.

Sleep bruxism is affected by peripheral benzodiazepine receptor gene polymorphisms

Background There is increasing interest in genetic effects on sleep bruxism, as well as on psychological stress. Peripheral type benzodiazepine receptor (PBR) gene polymorphisms are associated with stress sensitivity but it is not yet clear whether polymorphisms in this gene have any influence on psychological stress before and after sleep bruxism. The present study was performed to examine the relationship between sleep bruxism and PBR gene polymorphisms.

The anticonvulsant of choice in pyrethroid induced convulsions.

Sir, Seizures following pyrethroid ingestion and its non-responsiveness to anticonvulsants were lamented by Panwar et al.[1] along with literature support. The authors have also stressed that the practitioners shall consider this entity in the differential diagnosis of poisoning with seizures. We would like to mention some more mechanisms for seizures in pyrethroid poisoning and the anticonvulsant to be used under such circumstances. In epileptic patients, often there will be a focus on aberrant electrical activity in the cortical area; whereas pyrethroid lowers seizure threshold and induces seizure activity from previously normal neurons.[2] Furthermore, it exerts proconvulsant activity through an interaction with peripheral type benzodiazepine bridging sites.[3] In an animal model, pre-treatment with phenytoin, an anticonvulsant which binds to activation gates of sodium channels to slow recovery from inactivation, failed to antagonize either the permethrin or deltamethrin proconvulsant action.[4] Furthermore, aside from being not effective as observed in this case also, phenytoin may worsen the overall toxicity. Hence, phenobarbitone controls pyrethroid-evoked seizure foci through its dual action such as chloride channel agonist and as a membrane stabilizer.[5] As pyrethroid insecticides have come into prominent use in recent years, the incidence of poisoning has increased. Hence, practitioners may be sensitized on the clinical manifestations, course, selection of anticonvulsants and outcome of pyrethroid poisoning, as well as be informed that these cases shall not be considered as simple or taken lightly.

The combined effects of midazolam and propofol sedation on muscle power

We performed a randomised, crossover study to investigate the effects of intravenous sedation on grip strength and bite force. Twenty male volunteers received a bolus intravenous injection of midazolam (0.02 mg.kg(-1)) together with a 30-min propofol infusion designed to achieve an effect-site concentration of 1.0 μg.ml(-1). Observed variables included bispectral index, observer's assessment of alertness/sedation, correct answer rate of Stroop colour-word test, grip strength and bite force. Grip strength decreased from a median (IQR [range]) of 483 (443-517 [380-586]) N to 358 (280-405 [108-580]) N (p < 0.001) during sedation and recovered following flumazenil administration, while bite force increased from 818 (593-1026 [405-1406]) N to 1377 (1243-1585 [836-2357]) N (p < 0.001) during sedation. Although bite force gradually returned to baseline following flumazenil administration, it remained increased throughout the experimental period. We conclude that bite force increased during intravenous sedation and that this may have clinical implications.

Erythrocyte peripheral type benzodiazepine receptor/voltage-dependent anion channels are upregulated by Plasmodium falciparum

AbstractPlasmodium falciparum relies on anion channels activated in the erythrocyte membrane to ensure the transport of nutrients and waste products necessary for its replication and survival after invasion. The molecular identity of these anion channels, termed “new permeability pathways” is unknown, but their currents correspond to up-regulation of endogenous channels displaying complex gating and kinetics similar to those of ligand-gated channels. This report demonstrates that a peripheral-type benzodiazepine receptor, including the voltage dependent anion channel, is present in the human erythrocyte membrane. This receptor mediates the maxi-anion currents previously described in the erythrocyte membrane. Ligands that block this peripheral-type benzodiazepine receptor reduce membrane transport and conductance in P falciparum-infected erythrocytes. These ligands also inhibit in vitro intraerythrocytic growth of P falciparum. These data support the hypothesis that dormant peripheral-type benzodiazepine receptors become the “new permeability pathways” in infected erythrocytes after up-regulation by P falciparum. These channels are obvious targets for selective inhibition in anti-malarial therapies, as well as potential routes for drug delivery in pharmacologic applications.

Aspectos moleculares de la encefalopatía hepática

Introduction Liver fibrosis and its end stage, cirrhosis, is an enormous worldwide health problem. Hepatic encephalopathy (HE) or portal-systemic encephalopathy continues to be a major clinical problem of long-term cirrhosis. In this review we emphasise the molecular basis of HE and the involvement of oxidative stress in the development of this disease. Background Several studies suggest that the pathogenesis of HE could be multifactorial and have implicated different factors, such as alterations in blood brain barrier, substances; such as ammonia and manganese, neurotransmission disorders such as dopamine, glutamate and GABA. Development HE is a severe complication of both acute and chronic liver failure. Neuropathologically, it is characterized by astrocyte changes known as Alzheimer type II astrocytosis. In addition, astrocytes manifest altered expression of astrocyte-specific proteins, such as, glial fibrillary acidic protein, glutamine synthetase, monoamine oxidase and peripheral type benzodiazepine receptors. Conclusions HE is a complex neuropsychiatric syndrome associated with liver failure. These alterations are products of increases in oxidative stress in brain due to neurotoxin activity. The main strategy for HE treatment is directed at ammonia reduction, which can be achieved either by decreasing its absorption/production or increasing its removal.

11C-PK11195 PET for the In Vivo Evaluation of Neuroinflammation in the Rat Brain After Cortical Spreading Depression

Neurogenic inflammation triggered by extravasation of plasma protein has been hypothesized as a key factor in the generation of the pain sensation associated with migraine. The principal immune cell that responds to this inflammation is the parenchymal microglia of the central nervous system. Using a PET technique with (11)C-(R)-[1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propyl)-3-isoquinolinecarboxamide] ((11)C-PK11195), a PET ligand for peripheral type-benzodiazepine receptor, we evaluated the microglial activation in the rat brain after generation of unilateral cortical spreading depression, a stimulation used to bring up an experimental animal model of migraine. We found a significant increase in the brain uptake of (11)C-PK11195, which was completely displaceable by the excess amounts of unlabeled ligands, in the ipsilateral hemisphere of the spreading depression-generated rats. Moreover, the binding potential of (11)C-PK11195 in the spreading depression-generated rats was significantly higher than that in the sham-operated control rats. These results suggest that as an inflammatory reaction, microglial cells are activated in response to the nociceptive stimuli induced by cortical spreading depression in the rat brain. Therefore, the (11)C-PK11195 PET technique could have a potential for diagnostic and therapeutic monitoring of neurologic disorders related to neuroinflammation such as migraine.

In vitro antiproliferative characteristics of flavonoids and diazepam on SNU-C4 colorectal adenocarcinoma cells

The need for beneficial use of sedatives in oncologic patients is increasing. Therefore, in this study, antiproliferative characteristics of herbal and synthetic sedatives were examined in vitro in SNU-C4 human colorectal adenocarcinoma cells. Apigenin (50% inhibition concentration, IC(50) = 1.8 +/- 0.5 microM) and diazepam (IC(50) = 7.0 +/- 0.5 microM) showed concentration-dependent inhibition of SNU-C4 cancer cell survival. Efficacy of cancer cell survival inhibition by apigenin and diazepam was much lower than that of 5-fluorouracil (5-FU), a known chemotherapeutic drug. However, 10(-6) M concentration of apigenin and diazepam potentiated 5-FU-induced cytotoxicity. In SNU-C4 cells, 10(-6) M concentrations of diazepam, flumazenil (Ro15-1788), Ro5-4864, or PK11195, all ligands for central- or peripheral-type benzodiazepine (BZD) receptors, inhibited cell survival like the flavonoid apigenin (4',5,7-trihydroxyflavone) and fisetin (3,7,3',4'-tetrahydroxyflavone). Also like the plant flavonoids, treatment with 10(-6) M concentration of diazepam for 3 days hardly affect the peripheral-type BZD receptor (PBR) messenger RNA (mRNA) expression and inhibited glucose utilization of SNU-C4 cells. Treatment with flavonoids or diazepam for 6 days upregulated PBR mRNA expression and cell cytotoxicity of SNU-C4 cells. Furthermore, treatment with 10(-6) M concentration of apigenin, a natural sedative material originating from traditional herbs, positively modulated BZD-induced antiproliferative cytotoxicity in SNU-C4 cells. Overall, the in vitro antiproliferative activity on SNU-C4 cancer cells of herbal sedatives, such as apigenin, plus additive enhancement of synthetic BZD- and 5-FU-induced antiproliferative activities, were shown. In conclusion, this study provides experimental basis for advanced trial in the future.

Abstract 5331: Gene Transfer Of The Peripheral Type Benzodiazepine Receptor Alters The Spatio-temporal Dynamics Of The Mitochondrial Membrane Potential (ΔΨ M ) Across The Intact Heart

The peripheral type benzodiazepine receptor (mBZR) is a key mediator of mitochondrial dysfunction during oxidative stress. In isolated cardiomyocytes agonists of the mBZR cause ΔΨ m depolarization, KATP channel activation, and subsequent loss of cellular excitability. However, the spatiotemporal dynamics of ΔΨ m in the intact heart and their relationship to arrhythmias are unknown. Here, we investigate the mechanistic link between mBZR and ΔΨ m directly using adenoviral mediated gene transfer of the mBZR encoding gene (PKBS) in rat myocardium. Methods : Optical imaging was performed at a subcellular resolution in ex vivo perfused hearts from AdPKBS (n=5), AdGFP (n=2), and normal (n=4) rats. Normalized ΔΨ m was measured using a novel quantitative technique of TMRM imaging during global ischemia (7.5 min) followed by reperfusion. Mean and SD of baseline corrected &amp; normalized ΔΨ m across 6400 sites were compared between groups. Results : In sharp contrast to normal and GFP groups, 4 of 5 PKBS hearts exhibited a paradoxical increase in ΔΨ m during ischemia (Fig A ) as ΔΨ m was significantly (p&lt;0.05) greater in PKBS (+0.18±0.07) compared to GFP (−0.62±0.21) and normal hearts (−0.17±0.16) following 7.5min of ischemia. A transient overshoot in ΔΨ m observed in all groups during early (&lt;30sec) reperfusion was greatest in PKBS hearts (Fig A ). Finally, ΔΨ m heterogeneity indexed by SD was markedly greater in PKBS compared to GFP and normal hearts during ischemia (p&lt;0.01) and reperfusion (p&lt;0.01) (Fig B ). Conclusion : PKBS alters spatiotemporal dynamics of ΔΨ m and increases ΔΨ m heterogeneity across the intact heart. Modulating PKBS expression may be a novel therapeutic strategy for arrhythmias. Figure 1. Influence of PKBS gene transfer on myocardial ΔΨm during ischemia and reperfusion. Mean myocardial ΔΨm ( A ) and spatial Δψm heteroogeneity ( B ) during ischemia and reperfusion.

PBRL, a putative peripheral benzodiazepine receptor, in primitive erythropoiesis

Benzodiazepines are a class of psychoactive drugs widely used for their anxiolytic, anticonvulsant, muscle relaxant and hypnotic properties. Although the benzodiazepine receptor in the central nervous system has been well studied, the role of peripheral type benzodiazepine receptor, PBR, remains elusive. Here, we show that there are two PBR homologous genes in amniotes, PBR and PBRL, based on phylogenetic analysis. In chickens, PBRL is exclusively expressed during early development in differentiating primitive erythrocytes and this expression is tightly correlated with that of hemoglobin genes. PBR is not expressed in hematopoietic system during this period and is weakly expressed in developing central nervous system. Because one of PBRs’ known functions is to regulate heme transport between the mitochondria and cytoplasm, we investigated expression profiles of heme biosynthesis genes. Seven of the eight enzymes involved in heme biosynthesis, with the exception of protoporphyrinogen oxidase, are present in chicken genome. Five of them, δ-aminolevulinate synthase, δ-aminolevulinic acid dehydrogenase, porphobilinogen deaminase, coproporphyrinogen decarboxylase and ferrochelatase, show stage-specific increase in gene expression correlated with primitive hematopoiesis, but not with primitive erythrocyte differentiation. PBRL protein is localized to the mitochondria in culture cells, and pharmacological inhibition of PBRL activity results in a decrease in globin protein levels during primitive erythropoiesis. Our data suggest a developmental role of PBRs in erythropoiesis in chickens, possibly via the regulation of heme availability for the assembly of functional hemoglobins.

GCP60 Preferentially Interacts with a Caspase-generated Golgin-160 Fragment

Golgin-160, a ubiquitous protein in vertebrates, localizes to the cytoplasmic face of the Golgi complex. Golgin-160 has a large coiled-coil C-terminal domain and a non-coiled-coil N-terminal ("head") domain. The head domain contains important motifs, including a nuclear localization signal, a Golgi targeting domain, and three aspartates that are recognized by caspases during apoptosis. Some of the caspase cleavage products accumulate in the nucleus when overexpressed. Expression of a non-cleavable form of golgin-160 impairs apoptosis induced by some pro-apoptotic stimuli; thus cleavage of golgin-160 appears to play a role in apoptotic signaling. We used a yeast two-hybrid assay to screen for interactors of the golgin-160 head and identified GCP60 (Golgi complex-associated protein of 60 kDa). Further analysis demonstrated that GCP60 interacts preferentially with one of the golgin-160 caspase cleavage fragments (residues 140-311). This strong interaction prevented the golgin-160 fragment from accumulating in the nucleus when this fragment and GCP60 were overexpressed. In addition, cells overexpressing GCP60 were more sensitive to apoptosis induced by staurosporine, suggesting that nuclear-localized golgin-160-(140-311) might promote cell survival. Our results suggest a potential mechanism for regulating the nuclear translocation and potential functions of golgin-160 fragments.

Interaction of Novel Condensed Triazine Derivatives with Central and Peripheral Type Benzodiazepine Receptors: Synthesis, in vitro Pharmacology and Modelling.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Diazepam Enhances Inotropic Responses to Dopamine in Rat Ventricular Myocardium

Diazepam inhibits phosphodiesterase type 4 and enhances the effect of some 3',5'-cyclic adenosine monophosphate (cAMP)-dependent positive inotropic drugs. We sought to determine whether diazepam and the selective phosphodiesterase type 4 inhibitor rolipram enhances the contractile response and cAMP levels induced by dopamine in rat myocardium. Dopamine (3-100 microM) produced concentration-dependent positive inotropic effects (-log EC50 = 5.21 +/- 0.2, n = 5), which were augmented in the presence of 10 microM diazepam (-log EC50 = 5.40 +/- 0.08, n = 6, P < 0.05) or 1 microM rolipram (-log EC50 = 5.41 +/- 0.1, n = 6, P < 0.05). The effect of diazepam was not mimicked by 100 microM gamma-aminobutyric acid nor it was antagonized by a 5 microM concentration of the blockers of central and peripheral type benzodiazepine receptors, flumazenil and PK 11195. cAMP levels (pmol/g) produced by dopamine (744.4 +/- 111.8, n = 5) in this tissue were enhanced by the presence of diazepam (1073 +/- 97.7, n = 6, P < 0.05) or rolipram (1034.0 +/- 245.2, n = 5, P < 0.05). Therefore, diazepam, like rolipram, augments the inotropic and biochemical effects of dopamine in rat myocardium. This effect is not mediated by benzodiazepine receptors but is probably the consequence of the phosphodiesterase type 4 inhibitory activity of diazepam.

Low grade cerebral edema and the pathogenesis of hepatic encephalopathy in cirrhosis

Low grade cerebral edema and the pathogenesis of hepatic encephalopathy in cirrhosis

Lack of evidence of direct mitochondrial involvement in the neuroprotective effect of minocycline

Minocycline has been reported to exert neuroprotection through inhibition of inflammatory processes and of mitochondrial cell death pathway. To further characterize the neuroprotective effect of minocycline, we determined its efficacy in different neuronal damage paradigms involving inflammation or mitochondrial dysfunction. In transient global ischaemia in gerbils, minocycline reduced hippocampal neuronal damage measured by peripheral type benzodiazepine binding sites density, a marker of microglial activation. The antiinflammatory properties of minocycline were confirmed on the model of carrageenan-induced paw oedema in rats. The use of two experimental animal models involving administration of mitochondrial toxins inhibiting a different complex of the mitochondrial respiratory chain permitted the exploration of the mitochondrial impact of minocycline. Although minocycline exhibited a marked efficacy in 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP; complex I inhibitor)-induced neurotoxicity in mice, it was ineffective in malonate (complex II inhibitor)-induced striatal lesion in rats. In vitro investigations on energized mitochondria isolated from rat liver showed that minocycline (1 μM) did not inhibit the swelling induced by MPP +(1-methyl-4-phenylpyridinium). Moreover, higher concentrations of minocycline induced swelling. From these experiments, the neuroprotective activity of minocycline appears more related to its antiinflammatory activity than to a direct beneficial action on mitochondria.

Peripheral type benzodiazepine receptor in human parathyroid glands: Up-regulation in adenoma

In this study we report the presence of peripheral benzodiazepine receptors (PBRs) in human parathyroid glands and describe the effect of their benzodiazepine type ligands on parathyroid cell function. PBR binding features in normal parathyroid tissue were characterized and compared to parathyroid adenoma, using a specific and selective ligand for PBR, [3H] 1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propyl)-3-isoquinoline-carboxamide ([3H]PK11195). Affinity and density of [3H]PK11195 binding sites in homogenate membrane preparations from adenomatous and normal tissues were determined. Parathyroid adenoma showed a statistically significant 2.2 fold increase of [3H]PK11195 binding sites, while the affinity remained unchanged. Our results represent the first evidence of PBRs in parathyroid glands and suggest for them a role in influencing PTH release. A clear trend of PBR up-regulation in parathyroid adenoma was also found.

Characterization of endozepines in the human testicular tissue: effect of triakontatetraneuropeptide on testosterone secretion.

Previous studies have shown that endozepines, i.e. endogenous ligands of benzodiazepine (BZD) receptors, stimulate steroidogenesis in adrenocortical and Leydig cells. In the present report, we have investigated the presence and action of endozepines in the human testis. Immunohistochemical labeling revealed the occurrence of endozepine-like immunoreactivity in Leydig, Sertoli, and germ cells. HPLC analysis combined with a specific RIA resolved two immunoreactive peaks that coeluted with synthetic octadecaneuropeptide (ODN) and triakontatetraneuropeptide (TTN). RT-PCR amplification showed that the mRNA encoding the endozepine precursor diazepam-binding inhibitor is expressed in the human testis. The action of endozepines on testosterone production was studied in vitro using perifused human testicular fragments. Administration of TTN provoked a dose-dependent increase in testosterone secretion, whereas ODN had no effect. The stimulatory action of TTN on testosterone production was totally blocked by flunitrazepam, a peripheral-type BZD receptor antagonist/central-type BZD receptor (CBR) agonist. Conversely, the CBR agonist clonazepam and the CBR antagonist flumazenil did not affect testosterone secretion. Collectively, these results suggest that, in the human testicular tissue, TTN may exert an intracrine and/or paracrine control of steroidogenesis through activation of a peripheral-type BZD receptor.

Increase in peripheral benzodiazepine receptors and loss of glutamate NMDA receptors in a mouse model of closed head injury: a quantitative autoradiographic study☆

Increases in peripheral type benzodiazepine receptors (PTBR) have been utilized for the detection of neuroinflammation and neurotoxicity in the brain. We have investigated the relationship between PTBR and NMDA receptor binding density in mice with closed head injury (CHI) using quantitative autoradiography. CHI was induced by a weight drop in nine mice, four of which received a single injection of the rat sarcoma (Ras) inhibitor famesyl thiosalicylate (FTS) 1 h after the insult. Sham controls received anesthesia but no contusion. The neurological status of the mice was evaluated at 1 h, and hence up to 7 days using a neurological severity score (NSS). Animals were killed 7 days after CHI and consecutive brain sections were incubated with [ 3H]PK11195, a PTBR antagonist, or [ 3H]MK801, an n-methyl- d-aspartate receptor (NMDAR) use-dependent antagonist. CHI produced large (two- to threefold), widespread increases in PK11195 binding in the traumatized hemisphere and a significant decrease (20%–40%) in NMDAR binding limited to regions at close proximity to the lesion. Histologically, these regions were characterized by glial proliferation and neuronal loss. Significant increases in PTBR binding, but no concomitant decrease in NMDAR, were identified in several regions remote from the lesion, including the contralateral ventrolateral striatum and the ipsilateral ventral thalamus. Drug treatment significantly improved the neurological deficits but had only a marginal effect on PTBR. These results support a complex role for glial activation and PTBR increases in the context of CHI.