bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flavonols inhibit proinflammatory mediator release, intracellular calcium ion levels and protein kinase C theta phosphorylation in human mast cells
Authors: Kempuraj Duraisamy , Madhappan Bhuvaneshwari , Christodoulou Spyridon , Boucher William , Cao Jing , Papadopoulou Nikoletta , Cetrulo Curtis L , Theoharides Theoharis C 
Published: May 2005

Mast cells participate in allergies, and also in immunity and inflammation by secreting proinflammatory cytokines.
Flavonoids are naturally occurring polyphenolic plant compounds, one group of which – the flavonols, inhibits histamine and some cytokine release from rodent basophils and mast cells. However, the effect of flavonols on proinflammatory mediator release and their possible mechanism of action in human mast cells is not well defined.
Human umbilical cord blood‐derived cultured mast cells (hCBMCs) grown in the presence of stem cell factor (SCF) and interleukin (IL)‐6 were preincubated for 15 min with the flavonols quercetin, kaempferol, myricetin and morin (0.01, 0.1, 1, 10 or 100 μM), followed by activation with anti‐IgE. Secretion was quantitated for IL‐6, IL‐8, tumor necrosis factor‐alpha (TNF‐α), histamine and tryptase levels.
Release of IL‐6, IL‐8 and TNF‐α was inhibited by 82–93% at 100 μM quercetin and kaempferol, and 31–70% by myricetin and morin. Tryptase release was inhibited by 79–96% at 100 μM quercetin, kampferol and myricetin, but only 39% by morin; histamine release was inhibited 52–77% by the first three flavonols, but only 28% by morin. These flavonols suppressed intracellular calcium ion elevations in a dose–response manner, with morin being the weakest; they also inhibited phosphorylation of the calcium‐insensitive protein kinase C theta (PKC θ).
Flavonol inhibition of IgE‐mediated proinflammatory mediator release from hCBMCs may be due to inhibition of intracellular calcium influx and PKC θ signaling. Flavonols may therefore be suitable for the treatment of allergic and inflammatory diseases.

British Journal of Pharmacology (2005) 145, 934–944. doi:10.1038/sj.bjp.0706246
Opioid antagonists differ according to negative intrinsic efficacy in a mouse model of acute dependence
Authors: Walker Ellen A , Sterious Steven N 
Published: May 2005

The purpose of the present study is to compare the capacity of opioid antagonists to elicit withdrawal jumping in mice following two acute pretreatment doses of the opioid agonist morphine. Antagonists that precipitate vigorous withdrawal jumping across both morphine treatment doses are hypothesized to be strong inverse agonists at the μ‐opioid receptor, whereas antagonists that elicit withdrawal jumping in mice treated with the high but not the low dose of morphine are hypothesized to be weak inverse agonists.
Male, Swiss‐Webster mice (15–30 g) were acutely treated with 56 or 180 mg kg−1 morphine 4 h prior to injection with naloxone, naltrexone, diprenorphine, nalorphine, or naloxonazine. Vertical jumping, paw tremors, and weight loss were recorded. Naloxone, naltrexone, and diprenorphine produced withdrawal jumping after 56 and 180 mg kg−1morphine pretreatment. Nalorphine and naloxonazine produced moderate withdrawal jumping after 180 mg kg−1 morphine pretreatment, but failed to elicit significant withdrawal jumping after 56 mg kg−1 morphine pretreatment. Nalorphine and naloxonazine blocked the withdrawal jumping produced by naloxone. All antagonists produced paw tremors and weight loss although these effects were generally not dose‐dependent.
Taken together, these findings reveal a rank order of negative intrinsic efficacy for these opioid antagonists as follows: naloxone=naltrexonediprenorphine>nalorphine=naloxonazine. Furthermore, the observation that nalorphine and naloxonazine blocked the naloxone‐induced withdrawal jumping provides additional evidence that nalorphine and naloxonazine are weaker inverse agonists than naloxone.

British Journal of Pharmacology (2005) 145, 975–983. doi:10.1038/sj.bjp.0706247
Anticonvulsant enaminones depress excitatory synaptic transmission in the rat brain by enhancing extracellular GABA levels
Authors: Kombian Samuel B , Edafiogho Ivan O , Ananthalakshmi Kethireddy V V 
Published: May 2005

Enaminones are a novel group of compounds that have been shown to possess anticonvulsant activity in in vivo animal models of seizures. The cellular mechanism by which these compounds produce their anticonvulsant effects is not yet known. This study examined the effects of enaminones on excitatory synaptic transmission.
We studied the effects of 3‐(4′‐chlorophenyl)aminocyclohex‐2‐enone (E118), methyl 4‐(4′‐bromophenyl)aminocyclohex‐3‐en‐6‐methyl‐2‐oxo‐1‐oate (E139) and ethyl 4‐(4′‐hydroxyphenyl)aminocyclohex‐3‐en‐6‐methyl‐2‐oxo‐1‐oate (E169) on isolated evoked, glutamate‐mediated excitatory synaptic responses by recording whole‐cell currents and potentials in cells of the nucleus accumbens (NAc) contained in forebrain slices.
The anticonvulsant enaminones (E118 and E139), but not E169, depressed NMDA and non‐NMDA receptor‐mediated synaptic responses. The inhibition of the non‐NMDA response was concentration‐dependent (1.0–100 μM) with a maximal depression of ∼−30%. E118 and E139 had similar potencies (EC50=3.0 and 3.5 μM, respectively) in depressing this response but E139 was more efficacious (Emax=−31.3±3.8%) than E118 (Emax=−22.6±1.6%).
The excitatory postsynaptic current (EPSC) depression caused by 10 μM E139 (−27.7±3.8%) was blocked by 1 μM CGP55845 (6.3±8.1%), a potent GABAB receptor antagonist.
Pretreatment of slices with γ‐vinylGABA and 1‐(2‐(((diphenylmethylene)imino)oxy)ethyl)‐1,2,5,6‐tetrahydro‐3‐pyridine‐carboxylic acid (NO‐711), an irreversible GABA transaminase (GABA‐T) inhibitor and a GABA reuptake blocker, respectively, like the anticonvulsant enaminones, also caused a depression of the evoked EPSC (−38.1±14.1 and −24.1±8.9%, respectively). In the presence of these compounds, E139 did not cause a further depression of the EPSC. Our data suggest that anticonvulsant enaminones cause EPSC depression by enhancing extracellular GABA levels possibly through the inhibition of either GABA reuptake or GABA‐T enzyme, or both.

British Journal of Pharmacology (2005) 145, 945–953. doi:10.1038/sj.bjp.0706250
Benzodiazepine modulation of partial agonist efficacy and spontaneously active GABAA receptors supports an allosteric model of modulation
Authors: Downing Scott S , Lee Yan T , Farb David H , Gibbs Terrell T 
Published: May 2005

Benzodiazepines (BZDs) have been used extensively for more than 40 years because of their high therapeutic index and low toxicity. Although BZDs are understood to act primarily as allosteric modulators of GABAA receptors, the mechanism of modulation is not well understood.
The applicability of an allosteric model with two binding sites for γ‐aminobutyric acid (GABA) and one for a BZD‐like modulator was investigated.
This model predicts that BZDs should enhance the efficacy of partial agonists.
Consistent with this prediction, diazepam increased the efficacy of the GABAA receptor partial agonist kojic amine in chick spinal cord neurons.
To further test the validity of the model, the effects of diazepam, flurazepam, and zolpidem were examined using wild‐type and spontaneously active mutant α1(L263S)β3γ2 GABAA receptors expressed in HEK‐293 cells.
In agreement with the predictions of the allosteric model, all three modulators acted as direct agonists for the spontaneously active receptors.
The results indicate that BZD‐like modulators enhance the amplitude of the GABA response by stabilizing the open channel active state relative to the inactive state by less than 1 kcal, which is similar to the energy of stabilization conferred by a single hydrogen bond.

British Journal of Pharmacology (2005) 145, 894–906. doi:10.1038/sj.bjp.0706251
Structural features of phenol derivatives determining potency for activation of chloride currents via α1 homomeric and α1β heteromeric glycine receptors
Authors: Haeseler Gertrud , Ahrens Jörg , Krampfl Klaus , Bufler Johannes , Dengler Reinhard , Hecker Hartmut , Aronson Jeffrey K , Leuwer Martin 
Published: May 2005

Phenol derivatives constitute a family of neuroactive compounds. The aim of our study was to identify structural features that determine their modulatory effects at glycine receptors.
We investigated the effects of four methylated phenol derivatives and two halogenated analogues on chloride inward currents via rat α1 and α1β glycine receptors, heterologously expressed in HEK 293.
All compounds potentiated the effect of a submaximal glycine concentration in both α1 homomeric and α1β glycine receptors. While the degree of maximum potentiation of the glycine 10 μM effect in α1β receptors was not different between the compounds, the halogenated compounds achieved half‐maximum potentiating effects in the low μM range – at more than 20‐fold lower concentrations compared with their nonhalogenated analogues (P<0.0001). The coactivating effect was over‐ridden by inhibitory effects at concentrations >300 μM in the halogenated compounds. Neither the number nor the position of the methyl groups significantly affected the EC50 for coactivation.
Only the bimethylated compounds 2,6 and 3,5 dimethylphenol (at concentrations >1000 μM) directly activated both α1 and α1β receptors up to 30% of the maximum response evoked by 1000 μM glycine.
These results show that halogenation in the para position is a crucial structural feature for the potency of a phenolic compound to positively modulate glycine receptor function, while direct activation is only seen with high concentrations of compounds that carry at least two methyl groups. The presence of the β subunit is not required for both effects.

British Journal of Pharmacology (2005) 145, 916–925. doi:10.1038/sj.bjp.0706254
Sympathoadrenal‐dependent sexually dimorphic effect of nonhabituating stress on in vivo neutrophil recruitment in the rat
Authors: Barker Laura A , Dazin Paul F , Levine Jon D , Green Paul G 
Published: May 2005

Since stress both activates the sympathoadrenal axis and profoundly affects inflammation and inflammatory diseases, many of which are sexually dimorphic, we tested whether the effect of stress on neutrophil recruitment, a primary component of the acute inflammatory response, is sexually dimorphic.
The effect of intermittent sound (over 4 days), a nonhabituating stress, on lipopolysaccharide (LPS)‐induced recruitment of neutrophils was evaluated in vivo in the rat air pouch model. At 24 h following the last stress exposure, LPS‐induced neutrophil recruitment was enhanced in male rats, but not in females.
When gonadectomized prepubertally and tested as adults, stress significantly inhibited the magnitude of LPS‐induced neutrophil recruitment in males, while it still had no effect in gonadectomized females. In males, following adrenal denervation, the increase in LPS‐induced neutrophil recruitment produced by stress was prevented. Since these data suggest that the effect of stress is dependent on the sympathoadrenal axis, we tested the hypothesis that catecholamines mediate the stress effects.
In male rats, the effect of stress on LPS‐induced neutrophil recruitment was significantly attenuated by continuous administration of the β‐adrenergic receptor antagonist, propranolol (4 mg kg−1 day−1), during sound stress exposure, and administration of isoproterenol (10 nmoles, i.v.) significantly increased neutrophil recruitment in males, an effect that was qualitatively and quantitatively similar to the effect of stress. Propranolol significantly increased neutrophil recruitment in nonstressed female rats, but did not significantly affect neutrophil recruitment in stressed females.
These findings indicate a marked male sex hormone‐dependent sexual dimorphism in the sympathoadrenal‐dependent effect of stress on neutrophil migration, a primary component of the inflammatory response, and suggest that the sympathoadrenal axis contributes to this effect via release of epinephrine.

British Journal of Pharmacology (2005) 145, 872–879. doi:10.1038/sj.bjp.0706257
Atorvastatin reverses age‐related reduction in rat hepatic PPARα and HNF‐4
Authors: Sanguino Elena , Roglans Nuria , Alegret Marta , Sánchez Rosa M , Vázquez‐Carrera Manuel , Laguna Juan C 
Published: May 2005

Old rats are resistant to fibrate‐induced hypolipidemia owing to a reduction in hepatic peroxisome proliferator‐activated receptor α (PPARα). We tested whether the age‐related decrease in PPARα is prevented by atorvastatin (ATV), a hypolipidemic statin.
We determined the activity and expression of Liver X receptor α (LXRα) and PPARα in the liver of 18‐month‐old rats treated with 10 mg kg−1 of ATV for 21 days. We measured fatty acid oxidation (FAO), the expression of PPARα‐target genes, liver triglyceride (TG) and cholesteryl ester (CE) contents and plasma concentrations of TG, cholesterol, glucose, nonesterified fatty acids (NEFA), insulin and leptin. While old female rats were practically unresponsive, ATV‐treated old males showed lower liver TG (−41%) and CE (−48%), and plasma TG (−35%), glucose (−18%) and NEFA (−39%). Age‐related alterations in LXRα expression and binding activity were reverted in ATV‐treated old males. These changes were related to an increase in hepatic FAO (1.2‐fold), and PPARα mRNA (2.2‐fold), PPARα protein (1.6‐fold), and PPARα‐binding activity.
Hepatic nuclear factor‐4 (HNF‐4) and chicken ovalbumin upstream‐transcription factor‐II participate in the transcriptional regulation of the PPARα gene, while peroxisome proliferator‐activated receptor gamma coactivator 1 (PGC‐1) behaves as a PPAR coactivator. Ageing reduced the hepatic content of HNF‐4 (74%) and PGC‐1 (77%) exclusively in male rats. ATV administration to old males enhanced the hepatic expression and binding activity (two‐fold) of HNF‐4.
ATV‐induced changes in hepatic HNF‐4 and PPARα may be responsible for the improvement of the lipid metabolic phenotype produced by ATV administration to senescent male rats.

British Journal of Pharmacology (2005) 145, 853–861. doi:10.1038/sj.bjp.0706260
Modulation of mitochondrial Ca2+ uptake by estrogen receptor agonists and antagonists
Authors: Lobatón Carmen D , Vay Laura , Hernández‐SanMiguel Esther , SantoDomingo Jaime , Moreno Alfredo , Montero Mayte , Alvarez Javier 
Published: May 2005

Ca2+ uptake by mitochondria is a key element in the control of cellular Ca2+ homeostasis and Ca2+‐dependent phenomena. It has been known for many years that this Ca2+ uptake is mediated by the mitochondrial Ca2+ uniporter, a specific Ca2+ channel of the inner mitochondrial membrane. We have shown previously that this channel is strongly activated by a series of natural phytoestrogenic flavonoids. We show here that several agonists and antagonists of estrogen receptors (ERs) also modulate the activity of the uniporter.
The specific α‐ER agonist 4,4′,4″‐(4‐propyl‐[1H]‐pyrazole‐1,3,5‐triyl)trisphenol (PPT) was the strongest activator, increasing the rate of mitochondrial Ca2+ uptake in permeabilized HeLa cells by 10‐fold at 2 μM. Consistently, PPT largely increased the histamine‐induced mitochondrial [Ca2+] peak and reduced the cytosolic one.
Diethylstilbestrol and 17‐β‐estradiol (but not 17‐α‐estradiol) were active at pharmacological concentrations while the β‐estrogen‐receptor agonist 2,3‐bis(4‐hydroxyphenyl)‐propionitrile (DPN) was little effective.
The ER modulators tamoxifen and 4‐hydroxy‐tamoxifen inhibited mitochondrial Ca2+ uptake (IC50 2.5±1.5 and 2.5±1.4 μM, mean±s.d., respectively) both in the presence and in the absence of PPT, but raloxifene and the pure estrogen antagonist ICI 182,780 produced no effect.
Activation by PPT was immediate and inhibition by tamoxifen or 4‐hydroxy‐tamoxifen required only 5 min to reach maximum.
Tamoxifen did not modify mitochondrial membrane potential and PPT induced a slow mitochondrial depolarization at higher concentrations than those required to activate mitochondrial Ca2+ uptake.
These results suggest that some kind of ER or related protein located in mitochondria controls the activity of the Ca2+ uniporter by a nongenomic mechanism. This novel mechanism of action of estrogen agonists and antagonists can provide a new interpretation for several previously reported effects of these compounds.

British Journal of Pharmacology (2005) 145, 862–871. doi:10.1038/sj.bjp.0706265
The KCa channel as a trigger for the cardioprotection induced by kappa‐opioid receptor stimulation – its relationship with protein kinase C
Authors: Cao Chun‐Mei , Chen Mai , Wong Tak‐Ming 
Published: May 2005

We first determined whether the cardioprotection resulting from kappa opioid receptor (κ‐OR) stimulation was blocked by the KCa channel inhibitor, paxilline (Pax), administered before or during ischaemic insults in vitro.
In isolated rat hearts, 30 min of ischaemia and 120 min of reperfusion induced infarction and increased lactate dehydrogenase (LDH) release. In isolated ventricular myocytes subjected to 5 min of metabolic inhibition and anoxia followed by 10 min of reperfusion, the percentage of live cells and the amplitude of the electrically induced intracellular Ca2+ ([Ca2+]i) transient decreased, while diastolic [Ca2+]i increased. Pretreatment with 10 μM U50,488H, a κ‐OR agonist, attenuated the undesirable effects of ischaemic insults in both preparations. The beneficial effects of κ‐OR stimulation, that were abolished by 5 μM nor‐BNI, a κ‐OR antagonist, were also abolished by 1 μM Pax administered before ischaemic insults or 20 μM atractyloside, an opener of the mitochondrial permeability transition pore.
Activation of protein kinase C (PKC) with 0.1 μM phorbol 12‐myristate 13‐acetate decreased the infarct size and LDH release in isolated rat hearts subjected to ischaemia/reperfusion, and these effects were abolished by blockade of PKC with its inhibitors, 10 μM GF109203X or 5 μM chelerythrine, and more importantly by 1 μM Pax. On the other hand, the cardioprotective effects of opening the KCa channel with 10 μM NS1619 were not altered by either PKC inhibitor.
In conclusion, the high‐conductance KCa channel triggers cardioprotection induced by κ‐OR stimulation that involves inhibition of MPTP opening. The KCa channel is located downstream of PKC.

British Journal of Pharmacology (2005) 145, 984–991. doi:10.1038/sj.bjp.0706268
Glibenclamide depletes ATP in renal proximal tubular cells by interfering with mitochondrial metabolism
Authors: Engbersen Richard , Masereeuw Rosalinde , van Gestel Miriam A , van der Logt Elise M J , Smits Paul , Russel Frans G M 
Published: May 2005

Sulfonylurea drugs, like glibenclamide, stimulate insulin secretion by blocking ATP‐sensitive potassium channels on pancreatic beta cells. Renal tubular epithelial cells possess a different class of KATP channels with much lower affinities for sulfonylurea drugs, necessitating the use of micromolar glibenclamide concentrations to study these channels.
Here, we describe the toxic effects of these concentrations on mitochondrial energy metabolism in freshly isolated renal proximal tubular cells. Glibenclamide, at concentrations of 50 and 100 μM, reduced intracellular ATP levels by 28±4 and 53±5%, respectively (P<0.01).
This decline in ATP could be attributed to a dose‐dependent inhibition of mitochondrial respiration. Glibenclamide (10–500 μM) inhibited ADP‐stimulated mitochondrial oxygen consumption.
In addition to this toxic effect, specific association of radiolabeled and fluorescent glibenclamide to renal mitochondria was found. Association of [3H]glibenclamide with renal mitochondria revealed a low‐affinity site with a KD of 16±6 μM and a Bmax of 167±29 pmol mg−1.
We conclude that micromolar concentrations of glibenclamide interfere with mitochondrial bioenergetics and, therefore, should be used with care for inhibition of epithelial KATP channels.

British Journal of Pharmacology (2005) 145, 1069–1075. doi:10.1038/sj.bjp.0706275
Inhibition of the cdk5/MEF2 pathway is involved in the antiapoptotic properties of calpain inhibitors in cerebellar neurons
Authors: Verdaguer Ester , Alvira Daniel , Jiménez Andrés , Rimbau Victor , Camins Antoni , Pallàs Mercè 
Published: May 2005

Experimental data implicate calpain activation in the pathways involved in neuronal apoptosis. Indeed, calpain inhibitors confer neuroprotection in response to various neurotoxic stimuli. However, the pathways involved in calpain activation‐induced apoptosis are not well known.
We demonstrate that apoptosis (40%) induced by serum/potassium (S/K) withdrawal on cerebellar granule cells (CGNs) is inhibited by selective calpain inhibitors PD150606 (up to 15%) and PD151746 (up to 29%), but not PD145305 in CGNs. zVAD‐fmk, a broad spectrum inhibitor of caspases, attenuates apoptosis (up to 20%) mediated by S/K deprivation and protects against cell death, as measured by MTT ([3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium]) assay.
PD150606 and PD151746 prevented apoptosis mediated by S/K withdrawal through inhibition of calpain. Furthermore, PD151746 was able to inhibit caspase‐3 activity.
After S/K withdrawal, we observed an increase in cdk5/p25 formation and MEF2 phosphorylation that was prevented by 40 μM PD150606 and PD151746. This indicates that calpain inhibition may be an upstream molecular target that prevents neuronal apoptosis in vitro.
Taken together, these data suggest an apoptotic route in S/K withdrawal in CGNs mediated by calpain activation, cdk5/p25 formation and MEF2 inhibition. Calpain inhibitors may attenuate S/K withdrawal‐induced apoptosis and may provide a potential therapeutic target for drug treatment in a neurodegenerative process.

British Journal of Pharmacology (2005) 145, 1103–1111. doi:10.1038/sj.bjp.0706280
Differing mechanisms of leukocyte recruitment and sensitivity to conditioning by shear stress for endothelial cells treated with tumour necrosis factor‐α or interleukin‐1β
Authors: Sheikh Sajila , Rahman Mahbub , Gale Zoe , Luu N Thin , Stone Philip C W , Matharu Nick M , Rainger G Edward Luu , Nash Gerard B 
Published: May 2005

The cytokines tumour necrosis factor‐α (TNFα) and interleukin‐1β (IL‐1B) induce endothelial cells to recruit leukocytes. However, the exact adhesion and activation mechanisms induced by each cytokine, and their relative sensitivities to modulation by endothelial exposure to shear stress remain unclear.
We cultured human umbilical vein endothelial cells (HUVEC) in glass capillaries at various shear stresses, with TNFα or IL‐1B added for the last 4 h. Subsequently, human neutrophils were perfused over the HUVEC, and adhesion and migration were recorded.
Both cytokines induced dose‐dependent capture of neutrophils. However, while conditioning of HUVEC by increasing shear stress for 24 h diminished their response to TNFα, the response of HUVEC to IL‐1B was similar at all shear stresses. The differing sensitivities were evident at levels of adhesive function and mRNA for adhesion molecules and chemokines.
Analysis of nuclear factor κB (NF‐κB)/Rel family of transcription factors showed that their expression and activation were modified by exposure to shear stress, but did not obviously explain differential responses to TNFα and IL‐1B.
Antibodies against selectins were effective against capture of neutrophils on TNFα‐treated but not IL‐1B‐treated HUVEC. Stable adhesion was supported by β2‐integrins in each case. Activation of neutrophils occurred dominantly through CXC‐chemokine receptor 2 (CXCR2) for TNFα‐treated HUVEC, while blockade of CXCR1, CXCR2 and of platelet‐activating factor receptors caused additive inhibition of migration on IL‐1B‐treated HUVEC.
The mechanisms which underlie neutrophil recruitment, and their modulation by the haemodynamic environment, differ between cytokines. Interventions aimed against leukocyte recruitment may not operate equally in different inflammatory milieu.

British Journal of Pharmacology (2005) 145, 1052–1061. doi:10.1038/sj.bjp.0706281