bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of depolarizing stimuli on calcium homeostasis in cultured rat motoneurones
Authors: Hubert Jean‐Pierre , Burgevin Marie‐Claude , Terro Faraj , Hugon Jacques , Doble Adam 
Published: January 2005

Intracellular calcium concentrations in individual rat motoneurones in enriched primary cultures were measured by Indo‐1 fluorimetry.
Motoneurones in the cultures were characterized morphometrically and by cholineacetyltransferase immunocytochemistry.
Depolarization of the cells with glutamic acid or veratridine increased intracellular calcium levels, which returned to baseline only slowly after removal of the depolarizing agent.
The use of selective agonists (N‐methyl‐d‐aspartic acid, AMPA, kainic acid, quisqualic acid and 1R‐3S‐ACPD) and antagonists (MK 801 and CNQX) showed that the excitatory amino acid‐evoked responses were mediated by AMPA/kainate receptors rather than by NMDA receptors.
Depolarization‐evoked calcium transients in motoneurones are blocked by the neuroprotective drug riluzole
Calcium transients reflected entry of calcium from without the cell, and their blockade by nitrendipine and lanthanum chloride suggested that this entry took place primarily through voltage‐dependent calcium channels.
These findings may be relevant for understanding the selective vulnerability of motoneurones to excitotoxicity in amyotrophic lateral sclerosis, and the therapeutic activity of riluzole in the treatment of this disease.

British Journal of Pharmacology (1998) 125, 1421–1428; doi:10.1038/sj.bjp.0702207
Mechanism of ETA‐receptor stimulation‐induced increases in intracellular Ca2+ in SK‐N‐MC cells
Authors: Heinroth‐Hoffmann Ingrid , Vogelsang Magdalene , Schiewe Pia , Morawietz Henning , Holtz Jürgen , Pönicke Klaus , Brodde Otto‐Erich 
Published: January 2005

The mechanism underlying endothelin‐1 (ET‐1)‐induced increases in intracellular Ca2+ concentrations in the human neuroblastoma cell‐line SK‐N‐MC was investigated.
ET‐receptor agonists increased inositol phosphate (IP)‐formation (assessed as accumulation of total [3H]‐IPs in [3H]‐myo‐inositol prelabelled cells) and intracellular Ca2+ (assessed by the FURA‐2 method) with an order of potency: ET‐1>sarafotoxin 6b (S6b)>ET‐3=S6c; the ETA‐receptor antagonist BQ‐123 inhibited both responses with apparent pKi‐values of 8.3 and 8.6, respectively, while the ETB‐receptor antagonist BQ‐788 did not.
Pretreatment of the cells with pertussis toxin (PTX, 500 ng ml−1 overnight) reduced ET‐1‐induced Ca2+ increases by 46±5%, but rather enhanced ET‐1‐induced IP‐formation.
Chelation of extracellular Ca2+ by 5 mm EGTA did not affect ET‐1‐induced IP‐formation. However, in the presence of 5 mm EGTA or SKF 96365, an inhibitor of receptor mediated Ca2+ influx (1.0–3.0×10−5 m) ET‐1‐induced Ca2+ increases were inhibited in normal, but not in PTX‐treated cells.
[125I]‐ET‐1 binding studies as well as mRNA expression studies (by RT–PCR) detected only ETA‐receptors whereas expression of ETB‐receptor mRNA was marginal.
ET‐1 (10−8 m) inhibited isoprenaline‐evoked cyclic AMP increases; this was antagonized by BQ‐123, not affected by BQ‐788 and abolished by PTX‐treatment.
We conclude that SK‐N‐MC cells contain a homogeneous population of ETA‐receptors that couple to IP‐formation and inhibition of cyclic AMP formation. Stimulation of these ETA‐receptors increases intracellular Ca2+ by at least two mechanisms: a PTX‐insensitive IP‐mediated Ca2+ mobilization from intracellular stores and a PTX‐sensitive influx of extracellular Ca2+.

British Journal of Pharmacology (1998) 125, 1202–1211; doi:10.1038/sj.bjp.0702208
Brain sites involved in the antinociceptive effect of bradykinin in rats
Authors: Couto L B , Corrêa F M A , Pelá I R 
Published: January 2005

The localization of brain sites where bradykinin (BK) induces its antinociceptive effect in rats, was studied using as index the threshold for the jaw‐opening reflex elicited by the dental pulp electrical stimulation test (DPEST).
The microinjection of BK into the lateral or fourth cerebral ventricles induced an antinociceptive effect, with Index of Antinociception (IA) of 0.51±0.03 and 0.68±0.05, respectively. However, microinjections of the peptide into the third ventricle induced a less marked antinociception (IA=0.28±0.08).
The brain sites where the microinjection of BK caused an antinociceptive effect were: locus coeruleus, principal nucleus, oral part of the spinal sensorial trigeminal nucleus, and the sensory root of the trigeminal nerve.
The antinociceptive effect was more intense when BK (4–16 nmol) was injected into the locus coeruleus. Microinjection of BK (4 nmol) into the fourth ventricle, but not into the locus coeruleus, induced an increase in blood pressure. The microinjection of the peptide into the nucleus tractus solitarius, a site that is also involved in the pressor effect of BK, did not induce an antinociceptive effect. These results indicate that the antinociceptive effect of BK is not related to blood pressure changes.
The microinjection of BK into some of the sites involved in the mechanisms of analgaesia, including the periaquenductal gray matter (dorsal, lateral and ventrolateral) and the dorsal raphe nucleus did not induce an antinociceptive effect.
The results suggest that the most likely brain sites involved in the antinociceptive effect of BK are the locus coeruleus and the principal sensory trigeminal nucleus. The present results did not exclude the involvement of other brain sites surrounding the lateral and the third ventricles.

British Journal of Pharmacology (1998) 125, 1578–1584; doi:10.1038/sj.bjp.0702209
Modulation of AT1 receptor‐mediated contraction of rat uterine artery by AT2 receptors
Authors: Zwart Adam S. , Davis Elizabeth A. , Widdop Robert E. 
Published: January 2005

The aim of this study was to characterize the angiotensin II receptors in isolated uterine arteries from non pregnant and pregnant rats, since it has been reported from binding studies that ovine uterine arteries contain AT2 receptors.
Uterine arterial segments were obtained from virgin, non‐pregnant and late pregnant (18–21 days) Sprague‐Dawley rats and mounted in small vessel myographs. Concentration‐response curves were constructed to angiotensin II (1 nm–10 μm) in the absence and presence of various angiotensin II receptor subtype selective compounds. These included losartan (AT1 antagonist; 1, 10 and 100 nm), PD 123319 (AT2 antagonist; 1 μm) and CGP 42112 (AT2 agonist; 1 μm). Responses to angiotensin II were measured as increases in force (mN) and expressed as a per cent of the response to a K+ depolarizing solution.
Losartan (1, 10 and 100 nm) caused significant concentration‐dependent rightward shifts of the angiotensin II concentration‐response curve in uterine arteries from non‐pregnant and pregnant rats. The pA2 values calculated from these data were 9.8 and 9.2, respectively, although the slope of the Schild plot in the non‐pregnant group was less than unity.
PD 123319 (1 μm) caused significant 6‐ and 3 fold leftward shifts of the angiotensin II concentration‐response curve in uterine arteries from non‐pregnant and pregnant rats, respectively. In vessels from pregnant rats, PD 123319 also significantly increased the maximum response to angiotensin II.
CGP 42112 (1 μm) attenuated the response to angiotensin II of uterine arteries from non‐pregnant rats. This was reflected by a 14 fold rightward shift of the angiotensin II concentration‐response curve and a decrease in the maximum response. In uterine arteries from pregnant rats, CGP 42112 (1 μm) caused a 3 fold rightward shift of the angiotensin II concentration‐response curve, but had no effect on the maximum response.
PD 123319 (1 μm) and CGP 42112 (1 μm) had no effect on the concentration‐response curves to phenylephrine (PE) of uterine arteries from non‐pregnant or pregnant rats. In addition, CGP 42112 (1 nm–1 mm) had no vasodilator effect on tissues precontracted with phenylephrine.
These results suggest that the contractile responses of the rat uterine artery are mediated by the AT1 receptor. Furthermore, in this vascular preparation, the AT2 receptor appears to inhibit the response mediated by the AT1 receptor, although, this is not uniform between the non‐pregnant and pregnant states.

British Journal of Pharmacology (1998) 125, 1429–1436; doi:10.1038/sj.bjp.0702210
Endothelium‐dependent contractile actions of proteinase‐activated receptor‐2‐activating peptides in human umbilical vein: release of a contracting factor via a novel receptor
Authors: Saifeddine Mahmoud , Roy Samir S. , Al‐Ani Bahjat , Triggle Chris R. , Hollenberg Morley D. 
Published: January 2005

The contractile actions of the proteinase‐activated receptor‐2‐activating peptides (PAR2APs), SLIGRL‐NH2 (SL‐NH2), SLIGKV‐NH2 (KV‐NH2), trans‐cinnamoyl‐LIGRLO‐NH2 (tc‐NH2), and the PAR1‐AP, TFLLR‐NH2 (TF‐NH2) as well as trypsin and thrombin were studied in endothelium‐denuded and intact human umbilical vein (HUV) ring preparations.
In HUV rings with, but not without an intact endothelium, PAR2APs caused a concentration‐dependent contractile response, whereas LSIGRL‐NH2 trypsin and PAR1APs were inactive. The contractile response was not affected by the endothelin ETA receptor antagonist, BQ123, the cyclooxygenase inhibitor, indomethacin, the leukotriene synthesis inhibitor, MK886, or the epoxygenase/P450 inhibitor, SKF‐525A. Other pharmacological antagonists (prazosin, Losartan®) were similarly inactive.
The order of potencies of the PAR2APs to cause a contraction in the endothelium‐intact preparation was: SL‐NH2>>KV‐NH2tc‐NH2.
Using an endothelium‐free rat aorta ring as a reporter tissue, surrounded with endothelium‐intact HUV as a donor tissue in a ‘sandwich assay,’ we also monitored the ability of SL‐NH2, TF‐NH2, trypsin and thrombin to release either contractile (EDCF) or relaxant (EDRF) factors.
In the ‘sandwich assay’ done in the presence of L‐NAME (0.1 mm), the endothelium‐intact HUV tissue (but not endothelium‐denuded HUV) released a contractile factor (EDCF) in response to SL‐NH2 (50 μm) but not to trypsin or LSIGRL‐NH2. The SL‐NH2‐mediated release/action of the EDCF was not affected by BQ123, indomethacin, MK886 or SKF‐525A.
In the ‘sandwich assay’, trypsin (4–10 nm), SL‐NH2, KV‐NH2 and tc‐NH2 caused the release of a relaxant activity (EDRF) from the endothelium‐intact (but not the denuded) HUV preparation. The release of EDRF was blocked by 0.1 mm ωnitro‐L‐arginine‐methylester (L‐NAME). Neither thrombin (10 u ml−1, 100 nm) nor TF‐NH2 (50 μm) were active in this EDRF‐release assay.
The relative potencies of the PAR2 agonists for causing the release of EDRF in the HUV sandwich assay were: trypsin>>SL‐NH2>>tc‐NH2>KV‐NH2. This order of potencies differed from the one observed for the same agonists in the HUV contraction assay (above) and in an intracellular calcium signalling assay, conducted with cloned human PAR2 that was expressed in cultured rat kidney KNRK cells: trypsin>>SL‐NH2=tc‐NH2>KV‐NH2.
We conclude that PAR2APs (but not PAR1APs) via a receptor distinct from PAR2, can cause a contractile response in endothelium‐intact HUV tissue via the release of a diffusable EDCF, that is different from previously recognized smooth muscle agonists (e.g. prostanoid metabolites, endothelin, noradrenaline, angiotensin‐II, acetylcholine).

British Journal of Pharmacology (1998) 125, 1445–1454; doi:10.1038/sj.bjp.0702213
Persistent nicotinic blockade by chlorisondamine of noradrenergic neurons in rat brain and cultured PC12 cells
Authors: Reuben M , Louis M , Clarke P B S 
Published: January 2005

Chlorisondamine (CHL) blocks behavioural responses to nicotine for several weeks or months in rats. Persistent blockade has also been demonstrated ex vivo, in assays of nicotine‐evoked striatal dopamine release. Central administration of [3H]‐CHL leads to long‐term retention of radiolabel in nigrostriatal dopaminergic neurons and in few other cell groups. We investigated whether an analogous blockade also occurs in noradrenergic neurons in the brain and in cultured pheochromocytoma (PC12) cells, which have a similar noradrenergic phenotype.
Administration of CHL (10 mg kg−1 s.c. or 10 μg i.c.v.), 21 days prior, resulted in a near‐total block of nicotine‐evoked release of hippocampal [3H]‐noradrenaline ([3H]‐NA) from superfused rat synaptosomes; NMDA‐evoked [3H]‐NA release was unaffected.
Three weeks after administration of [3H]‐CHL (10 μg i.c.v.), preferential accumulation of radiolabel was observed in the locus coeruleus, which provides the entire noradrenergic innervation to hippocampus, as well as in previously noted structures.
In rat pheochromocytoma (PC12) cells, nicotine evoked [3H]‐NA release (EC50 approximately 30 μm). This effect was blocked by co‐incubation with mecamylamine (10 μm) or CHL (1 μm) but was not affected by α‐bungarotoxin. As in the hippocampus, the nicotinic agonist cytisine was at least as efficacious as nicotine.
Acute exposure of PC12 cells to CHL 10 or 100 μm (but not 1 μm), followed by 90 min wash‐out, almost completely blocked release evoked by 30 μm nicotine. More prolonged (24 h) exposure to CHL 100 μm (but not 1 or 10 μm), followed by 3 days of wash‐out, partially inhibited release evoked by nicotine, leaving responses to high K+ unchanged. A significant (30%) reduction was also seen 5 days after exposure.
We conclude that persistent nicotinic blockade by CHL is neither restricted to mesostriatal dopamine neurons, nor to the CNS, nor to neurons possessing the same nicotinic receptor pharmacology. In addition, the persistent blockade does not appear to result from an acute blocking action, but may be dependent upon intracellular accumulation of the antagonist.

British Journal of Pharmacology (1998) 125, 1218–1227; doi:10.1038/sj.bjp.0702215
The role of nitric oxide and metalloproteinases in the pathogenesis of hyperoxia‐induced lung injury in newborn rats
Authors: Radomski Anna , Sawicki Grzegorz , Olson David M. , Radomski Marek W. 
Published: January 2005

The effects of nitric oxide (NO) and metalloproteinases (MMP‐2 and MMP‐9) in the pathogenesis of hyperoxia‐induced lung damage in newborn rats were examined.
Three‐day‐old rat pups were subjected to hyperoxia (95% O2) or room air for 7 and 14 days.
Some animals were treated with NG‐L‐nitro‐L‐arginine methyl ester (L‐NAME, 10 mg kg−1, s.c., daily).
Histology, morphometry, oedema, Ca2+‐dependent and ‐independent NO synthase (NOS) activities, expression of NOS isoforms and the activities of MMP‐2 and MMP‐9 were measured in lungs of hyperoxic and control animals.
Exposure of rats to hyperoxia for 7 days resulted in alveolar sac injury characterized by the presence of cellular debris, red cell extravasation and inflammatory infiltration with mononuclear cells. Lung water content, epithelial, smooth muscle layers and total airway thickness was similar to controls.
In contrast, exposure of rats to hyperoxia for 14 days resulted in lung oedema, inflammation and epithelial proliferation.
Hyperoxia caused a decrease in Ca2+‐dependent NOS activity, an effect that was associated with increased expression of eNOS protein.
In control rats, Ca2+‐dependent NOS activity and expression of eNOS were reduced at 14 days.
Hyperoxia caused 10 fold increase in the activity of Ca2+‐independent NOS that remained significantly elevated after 14 days of exposure to hyperoxia. The activity of this enzyme was unchanged in control rats.
In lungs of hyperoxic rats, the immunoblot showed time‐dependent, biphasic expression (peak at 7 days) of iNOS. The profile of expression of iNOS in control rats was similar.
The activities of MMPs were increased in lungs of hyperoxic animals.
The L‐NAME treatment of hyperoxic animals reduced lung oedema and epithelial proliferation, but enhanced the activities of MMPs. L‐NAME exerted no significant effects in control rats.
It is concluded that increased generation of NO contributes to the pathogenesis of hyperoxia‐induced lung damage in newborn rats.

British Journal of Pharmacology (1998) 125, 1455–1462; doi:10.1038/sj.bjp.0702216
Priming and induction of eosinophil trafficking in guinea‐pig cutaneous inflammation by tumour necrosis factor α
Authors: Macari David M T , Teixeira Mauro M , Ansari Tareq , Jeffery Peter K , Hellewell Paul G 
Published: January 2005

Tissue eosinophilia is a hallmark of allergic and parasitic diseases. Priming mechanisms may play an important role in mediating the process of eosinophil accumulation in these conditions. We have previously shown that blockade of tumour necrosis factor α (TNFα) inhibited the capacity of lipopolysaccharide to prime skin sites for chemoattractant‐induced eosinophil recruitment. The present study was carried out to investigate the capacity of TNFα to prime an inflammatory site for enhanced eosinophil accumulation.
Initial experiments investigated the capacity of TNFα itself to induce eosinophil accumulation. Intradermal injection of murine TNFα (10–300 ng per site) in the guinea‐pig induced significant accumulation of 111In‐eosinophils. Kinetic studies showed the response to be delayed in onset and inhibited by cycloheximide, consistent with a dependency on protein synthesis. Trafficking of 111In‐eosinophils to sites treated for 2 h with TNFα (10–100 ng per site) was inhibited by monoclonal antibodies (mAbs) against β2 or α4 integrins.
Intradermal injection of a low dose (3 ng) of TNFα (which by itself had no significant effect on eosinophil trafficking) prior to chemoattractants or antigen in sensitized skin sites, induced significant priming of eosinophil accumulation. Recruitment of both 111In‐eosinophils and endogenous eosinophils was enhanced. Trafficking to TNFα‐primed responses was dependent on protein synthesis and β2 integrins. In contrast, the α4 integrin mAb failed to inhibit the TNFα primed response.
Thus, TNFα can induce and also prime eosinophil recruitment in guinea‐pig skin. Our results provide further evidence that this cytokine may be an important mediator of allergic‐ or parasite‐induced eosinophilic inflammation.

British Journal of Pharmacology (1998) 125, 1228–1235; doi:10.1038/sj.bjp.0702224
Nociceptin receptor binding in mouse forebrain membranes: thermodynamic characteristics and structure activity relationships
Authors: Varani K. , Calo' G. , Rizzi A. , Merighi S. , Toth G. , Guerrini R. , Salvadori S. , Borea P. A. , Regoli D. 
Published: January 2005

The present study describes the labelling of the nociceptin (NC) receptor, ORL1, in mouse forebrain membranes with a new ligand partially protected from metabolic degradation at the C‐terminal; the ligand, [3H]‐NC‐NH2, has a specific activity of 24.5 Ci mmol−1
Saturation experiments revealed a single class of binding sites with a KD value of 0.55 nm and Bmax of 94 fmol mg−1 of protein. Non specific binding was 30% of total binding. Kinetic binding studies yielded the following rate constants: Kobs=0.104 min−1; K1=0.034 min−1; T1/2=20 min; K+1=0.07 min nm−1.
Thermodynamic analyses indicated that [3H]‐NC‐NH2 binding to the mouse ORL1 is totally entropy driven, similar to what has been observed for the labelled agonists to the opioid receptors OP1(δ), OP2(κ) and OP3(μ).
Receptor affinities of several NC fragments and analogues, including the newly discovered ORL‐1 receptor antagonist [Phe1ψ(CH2‐NH)Gly2]NC(1–13)‐NH2 ([F/G]NC(1–13)‐NH2), were also evaluated in displacement experiments. The competition curves for these compounds were found to be parallel to that of NC and the following order of potency was determined for NC fragments: NC‐OH=NC‐NH2=NC(1–13)‐NH2 >> NC(1–12)‐NH2 > NC(1–13)‐OH >> NC(1–11)‐NH2, and for NC and NC(1–13)‐NH2 analogues: [Tyr1]NC‐NH2 [Leu1]NC(1–13)‐NH2 [Tyr1]NC(1–13)‐NH2 [F/G]NC(1–13)‐NH2 >> [Phe3]NC(1–13)‐NH2 > [DF/G]NC(1–13)‐NH2.
Standard opioid receptor ligands (either agonists or antagonists) were unable to displace [3H]‐NC‐NH2 binding when applied at concentrations up to 10 μm indicating that this new radioligand interacts with a non opioid site, probably the ORL1 receptor.

British Journal of Pharmacology (1998) 125, 1485–1490; doi:10.1038/sj.bjp.0702226
Behavioural and biochemical evidence for signs of abstinence in mice chronically treated with Δ‐9‐tetrahydrocannabinol
Authors: Hutcheson Daniel M , Tzavara Eleni Th. , Smadja Claire , Valjent Emmanuel , Roques Bernard P , Hanoune Jacques , Maldonado Rafael 
Published: January 2005

Tolerance and dependence induced by chronic Δ‐9‐tetrahydrocannabinol (THC) administration were investigated in mice. The effects on body weight, analgesia and hypothermia were measured during 6 days of treatment (10 or 20 mg kg−1 THC twice daily). A rapid tolerance to the acute effects was observed from the second THC administration.
The selective CB‐1 receptor antagonist SR 141716A (10 mg kg−1) was administered at the end of the treatment, and somatic and vegetative manifestations of abstinence were evaluated. SR 141716A administration precipitated several somatic signs that included wet dog shakes, frontpaw tremor, ataxia, hunched posture, tremor, ptosis, piloerection, decreased locomotor activity and mastication, which can be interpreted as being part of a withdrawal syndrome.
Brains were removed immediately after the behavioural measures and assayed for adenylyl cyclase activity. An increase in basal, forskolin and calcium/calmodulin stimulated adenylyl cyclase activities was specifically observed in the cerebellum of these mice.
The motivational effects of THC administration and withdrawal were evaluated by using the place conditioning paradigm. No conditioned change in preference to withdrawal associated environment was observed. In contrast, a conditioned place aversion was produced by the repeated pairing of THC (20 mg kg−1), without observing place preference at any of the doses used.
This study constitutes a clear behavioural and biochemical model of physical THC withdrawal with no motivational aversive consequences. This model permits an easy quantification of THC abstinence in mice and can be useful for the elucidation of the molecular mechanisms involved in cannabinoid dependence.

British Journal of Pharmacology (1998) 125, 1567–1577; doi:10.1038/sj.bjp.0702228
Pharmacological modulation of GABAA receptor‐mediated postsynaptic potentials in the CA1 region of the rat hippocampus
Authors: Manuel Nicholas A , Davies Ceri H 
Published: January 2005

It is unclear whether GABAA receptor‐mediated hyperpolarizing and depolarizing synaptic potentials (IPSPAs and DPSPAs, respectively) are evoked by (a) the same populations of GABAergic interneurones and (b) exhibit similar regulation by allosteric modulators of GABAA receptor function. We have attempted to address these questions by investigating the effects of (a) known agonists for presynaptic receptors on GABAergic terminals, and (b) a range of GABAA receptor ligands, on each response.
The GABA uptake inhibitor NNC 05‐711 (10 μm) enhanced whereas bicuculline (10 μm) inhibited both IPSPAs and DPSPAs.
(−)‐Baclofen (5 μm), [D‐Ala2,N‐Me‐Phe4,Gly5‐ol]‐enkephalin (DAGO; 0.5 μm), and carbachol (10 μm) caused substantial depressions (up to 99%) of DPSPAs that were reversed by CGP 55845A (1 μm), naloxone (10 μm) and atropine (5 μm), respectively. In contrast, 2‐chloroadenosine (CADO; 10 μm) only slightly depressed DPSPAs. Quantitatively, the effect of each agonist was similar to that reported for IPSPAs.
The neurosteroid ORG 21465 (1–10 μm), the anaesthetic propofol (50–500 μm), the barbiturate pentobarbitone (100–300 μm) and zinc (50 μm) all enhanced DPSPAs and IPSPAs.
The benzodiazepine (BZ) agonist flunitrazepam (10–50 μm) and inverse agonist DMCM (1 μm) caused a respective enhancement and inhibition of both IPSPAs and DPSPAs. The BZω1 site agonist zolpidem (10–30 μm) produced similar effects to flunitrazepam.
The anticonvulsant loreclezole (1–100 μm) did not affect either response.
These data demonstrate that similar populations of inhibitory interneurones can generate both IPSPAs and DPSPAs by activating GABAA receptors that are subject to similar allosteric modulation.

British Journal of Pharmacology (1998) 125, 1529–1542; doi:10.1038/sj.bjp.0702237