bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of spinal neuropeptides and prostaglandins in opioid physical dependence
Authors: Trang Tuan , Sutak Maaja , Quirion Remi , Jhamandas Khem
Published: January 2005

This study examined the role of spinal calcitonin gene‐related peptide (CGRP), substance P, and prostaglandins in the development and expression of opioid physical dependence.

Administration of escalating doses (5 – 100 mg kg−1, i.p.) of morphine for 7 days markedly elevated CGRP and substance P− immunoreactivity in the dorsal horn of the rat spinal cord. Naloxone (2 mg kg−1, i.p.) challenge decreased both CGRP and substance P immunoreactivity and precipitated a robust withdrawal syndrome.

Acute intrathecal pre‐treatment with a CGRP receptor antagonist, CGRP8 – 37 (4, 8 μg), a substance P receptor antagonist, SR 140333 (1.4, 2.8 μg), a cyclo‐oxygenase (COX) inhibitor, ketorolac (30, 45 μg), and COX‐2 selective inhibitors, DuP 697 (10, 30 μg) and nimesulide (30 μg), 30 min before naloxone challenge, partially attenuated the symptoms of morphine withdrawal. CGRP8 – 37 (8 μg), but no other agents, inhibited the decrease in CGRP immunoreactivity.

Chronic intrathecal treatment with CGRP8 – 37 (4, 8 μg), SR 140333 (1.4 μg), ketorolac (15, 30 μg), DuP 697 (10, 30 μg), and nimesulide (30 μg), delivered with daily morphine injection significantly attenuated both the symptoms of withdrawal and the decrease in CGRP but not substance P immunoreactivity.

The results of this study suggest that activation of CGRP and substance P receptors, at the spinal level, contributes to the induction and expression of opioid physical dependence and that this activity may be partially expressed through the intermediary actions of prostaglandins.

British Journal of Pharmacology (2002) 136, 37–48; doi:10.1038/sj.bjp.0704681
Effects of morphine and morphine withdrawal on brainstem neurons innervating hypothalamic nuclei that control thepituitary‐adrenocortical axis in rats
Authors: Laorden Maria Luisa , Castells Maria Teresa , Milanés Maria Victoria
Published: January 2005

Different data support a role for brainstem noradrenergic inputs to the hypothalamic paraventricular nucleus (PVN) in the control of hypothalamus – pituitary – adrenocortical (HPA) axis. However, little is known regarding the functional adaptive changes of noradrenergic afferent innervating the PVN and supraoptic nucleus (SON) during chronic opioid exposure and upon morphine withdrawal.

Here we have studied the expression of Fos after administration of morphine and during morphine withdrawal in the rat hypothalamic PVN and SON. Fos production was also studied in brainstem regions that innervate hypothalamic nuclei: the nucleus of solitary tract (NTS – A2) and the ventrolateral medulla (VLM – A1) and combined with immunostaining for tyrosine hydroxylase (TH) for immunohistochemical identification of active neurons during morphine withdrawal. Male rats were implanted with s.c. placebo or morphine (tolerant/dependent) pellets for 7 days. On day 8 rats received an injection of saline i.p., morphine i.p., saline s.c. or naloxone s.c.

Acute morphine administration produced an increase in Fos expression at hypothalamic nuclei and in the brainstem regions, and tolerance developed towards this effect. Precipitated morphine withdrawal induced marked Fos immunoreactivity within the PVN and SON. Concomitantly, numerous neurons in the brainstem were stimulated by morphine withdrawal. Moreover, catecholaminergic‐positive neurons in the brainstem showed a significant increase in Fos expression in response to morphine withdrawal.

These findings demonstrate that chronic activation of opioid receptors results in altered patterns of immediate‐early genes (IEG) expression in the PVN and SON, which occurs concurrently with an increased activity of their inputs from the brainstem.

British Journal of Pharmacology (2002) 136, 67–75; doi:10.1038/sj.bjp.0704684
Mechanism of suppression of insulin signalling with lignocaine
Authors: Hirose Munetaka , Martyn J A Jeevendra , Kuroda Yoshihiro , Marunaka Yoshinori , Tanaka Yoshifumi
Published: January 2005

Lignocaine suppresses insulin‐stimulated glucose transport into the cells and insulin‐stimulated glycogenesis at doses equivalent to that used in the treatment of muscle pain disorder. We evaluated the direct effect of lignocaine on insulin receptor (IR) kinase activity.

After lignocaine (40 mM, approximately equivalent to 1%) or an equal volume (100 μl) saline had been injected into the tibialis anterior muscle of rat, insulin (50 mM g−1 body weight) was administered into the portal vein in vivo. Immunoprecipitation and immunoblotting were used to detect insulin‐mediated tyrosine phosphorylation of both IR‐β and insulin receptor substrate (IRS)‐1, and insulin‐stimulated binding of IRS‐1 to p85 regulatory subunit of phosphatidylinositol 3‐kinase (PI3‐K) in the extracted muscle.

In the in vitro study, purified IR from rat liver and/or recombinant IRS‐1 protein with adenosine triphosphate were incubated with lignocaine (4 or 40 mM).

Lignocaine reduced insulin‐stimulated tyrosine phosphorylation of IR‐β to 12.6±5.7% (P<0.001), and IRS‐1 to 32.1±18.8% (P<0.01), and also reduced insulin‐stimulated binding of IRS‐1 to p85 to 27.4±12.7% (P<0.001) relative to control (100%) in muscle in vivo.

The in vitro study revealed that lignocaine directly inhibited both basal and insulin‐stimulated tyrosine phosphorylation of IR.

These results indicate that clinically used doses of lignocaine inhibit insulin signalling in skeletal muscle. The inhibitory effect of lignocaine on tyrosine kinase activity of the IR underlies the suppression of insulin signalling with lignocaine.

British Journal of Pharmacology (2002) 136, 76–80; doi:10.1038/sj.bjp.0704691
Blockade of body weight gain and plasma corticosterone levels in Zucker fatty rats using an orally active neuropeptide Y Y1 antagonist
Authors: Ishihara Akane , Kanatani Akio , Okada Megumu , Hidaka Masayasu , Tanaka Takeshi , Mashiko Satoshi , Gomori Akira , Kanno Tetsuya , Hata Mikiko , Kanesaka Maki , Tominaga Yushin , Sato Naga‐aki , Kobayashi Masahiko , Murai Takashi , Watanabe Keiko , Ishii Yasuyuki , Fukuroda Takahiro , Fukami Takehiro , Ihara Masaki
Published: January 2005

An experiment was conducted to examine whether a potent, orally active and highly selective neuropeptide Y Y1 receptor antagonist attenuates hyperphagia and obesity in genetically obese Zucker fatty rats.

Oral administration of the Y1 antagonist (30 and 100 mg kg−1, once daily for 2 weeks) significantly suppressed the daily food intake and body weight gain in Zucker fatty rats accompanied with a reduction of fat cell size and plasma corticosterone levels.

Despite the fact that food intake was gradually returned to near the control level, the body weight of the treated animals remained significantly less when compared to that of the controls for the duration of the treatment.

These results suggest that the Y1 receptor, at least in part, participate in pathophysiological feeding and/or fat accumulation observed in Zucker fatty rats. Y1 antagonists might be useful for the treatment of obesity.

British Journal of Pharmacology (2002) 136, 341–346; doi:10.1038/sj.bjp.0704696
Protective effects of neurokinin‐1 receptor during colitis in mice: role of the epidermal growth factor receptor
Authors: Castagliuolo I , Morteau O , Keates A C , Valenick L , Wang C ‐C , Zacks J , Lu B , Gerard N P , Pothoulakis C
Published: January 2005

The role of substance P and its high affinity neurokinin‐1 receptor in colitis has not been fully elucidated. We assessed the participation of neurokinin‐1 receptor in colitis using the 2,4,6,‐trinitrobenzensulphonic acid and dextran sulphate‐induced animal models of colitis and genetically‐engineered, neurokinin‐1 receptor‐deficient mice.

Clinical signs, macroscopic and histologic damage associated with 2,4,6,‐trinitrobenzensulphonic acid (12 days) and dextran sulphate (5 days) colitis were more severe in neurokinin‐1 deficient than in wild‐type mice, while immunoreactivities for epidermal growth factor and its receptor were similar in the colon of both mice strains before and after colitis.

Substance P, dose‐dependently induced intestinal fibroblast proliferation and enhanced epidermal growth factor‐induced proliferation in intestinal fibroblasts isolated from wild‐type, but not from neurokinin‐1 receptor deficient mice.

Substance P‐induced intestinal fibroblast proliferation required the presence of epidermal growth factor receptor with kinase activity. Furthermore, substance P induced epidermal growth factor tyrosine phosphorylation and activation in normal intestinal fibroblasts.

Our results indicate that in mice lacking the neurokinin ‐ 1 receptor, substance P plays a protective role in prolonged experimental colitis.

British Journal of Pharmacology (2002) 136, 271–279; doi:10.1038/sj.bjp.0704697
Physiological antagonism between ventricular β1‐adrenoceptors and α1‐adrenoceptors but no evidence for β2‐ and β3‐adrenoceptor function in murine heart
Authors: Heubach Jürgen F , Rau Thomas , Eschenhagen Thomas , Ravens Ursula , Kaumann Alberto J
Published: January 2005

Murine left atrium lacks inotropic β2‐adrenoceptor function. We investigated whether β2‐adrenoceptors are involved in the cardiostimulant effects of (−)‐adrenaline on spontaneously beating right atria and paced right ventricular myocardium of C57BL6 mice. We also studied a negative inotropic effect of (−)‐adrenaline.

Sinoatrial tachycardia, evoked by (−)‐adrenaline was resistant to blockade by β2‐selective ICI 118,551 (50 nM) but antagonized by β1‐selective CGP 20712A (300 nM). This pattern was unaffected by pretreatment with pertussis toxin (PTX, 600 μg kg−1 i.p. 24 h) which reversed carbachol‐evoked bradycardia to tachycardia.

Increases of ventricular force by (−)‐adrenaline and (−)‐noradrenaline were not blocked by ICI 118,551 but antagonized by CGP 20712A.

Under blockade of β‐adrenoceptors, (−)‐adrenaline and (−)‐noradrenaline depressed ventricular force (−logIC50M=7.7 and 6.9). The cardiodepressant effects of (−)‐adrenaline were antagonized by phentolamine (1 μM) and prazosin (1 μM) but not by (−)‐bupranolol (1 μM). Prazosin potentiated the positive inotropic effects of (−)‐adrenaline (in the absence of β‐blockers) from −logEC50M=6.2–6.8.

PTX‐treatment reduced carbachol‐evoked depression of ventricular force in the presence of high catecholamine concentrations. Inhibition of ventricular function of Gi protein was verified by 82% reduction of in vitro ADP‐ribosylation. PTX‐treatment tended to increase the positive inotropic potency of (−)‐adrenaline under all conditions investigated, including the presence of ICI 118,551.

(−)‐Adrenaline causes murine cardiostimulation through β1‐adrenoceptors but not through β2‐adrenoceptors. The negative inotropic effects of (−)‐adrenaline are mediated through ventricular α1‐adrenoceptors but not through β3‐adrenoceptors. Both Gi protein and α1‐adrenoceptors restrain (−)‐adrenaline‐evoked increases in right ventricular force mediated through β1‐adrenoceptors.

British Journal of Pharmacology (2002) 136, 217–229; doi:10.1038/sj.bjp.0704700
Intracisternal urocortin inhibits vagally stimulated gastric motility in rats: role of CRF2
Authors: Chen C ‐Y , Million M , Adelson D W , Martínez V , Rivier J , Taché Y
Published: January 2005

Corticotropin‐releasing factor (CRF) acts in the brain to inhibit thyrotropin‐releasing hormone (TRH) analogue, RX‐77368‐induced vagal stimulation of gastric motility. We investigated CRF receptor‐mediated actions of rat urocortin (rUcn) injected intracisternally (ic) on gastric motor function.

Urethane‐anaesthetized rats with strain gauges on the gastric corpus were injected i.c. with rUcn and 20 min later, with i.c. RX‐77368. CRF antagonists were injected i.c. 10 min before rUcn.

RX‐77368 (1.5, 3, 10, 30 and 100 ng, i.c.) dose‐dependently increased corpus contractions, expressed as total area under the curve (AUC, mV min−1) to 2.6±2.5, 6.1±5.9, 9.8±2.6, 69.7±21.7 and 74.9±28.7 respectively vs 0.2±0.1 after i.c. saline. Ucn (1, 3 or 10 μg) inhibited RX‐77368 (30 ng)‐induced increase in total AUC by 28, 62 and 93% respectively vs i.c. saline+RX‐77368.

The CRF1/CRF2 antagonist, astressin‐B (60 μg, i.c.) completely blocked i.c. rUcn (3 μg, i.c.)‐induced inhibition of gastric motility stimulated by RX‐77368 (30 ng).

The selective CRF2 antagonist, astressin2‐B (30, 60 or 100 μg, i.c.) dose‐dependently prevented i.c. rUCn action while the CRF1 antagonist, NBI‐27914 did not.

In conscious rats, rUcn (0.6 or 1 μg, i.c.) inhibited gastric emptying of an ingested chow meal by 61 and 92% respectively. rUcn action was antagonized by astressin2‐B.

These data show that i.c. rUcn acts through CRF2 receptors to inhibit central vagal gastric contractile response and postoprandial emptying.

British Journal of Pharmacology (2002) 136, 237–247; doi:10.1038/sj.bjp.0704713
Inhibitory effect of aprindine on Na+/Ca2+ exchange current in guinea‐pig cardiac ventricular myocytes
Authors: Watanabe Yasuhide , Iwamoto Takahiro , Shigekawa Munekazu , Kimura Junko
Published: January 2005

Using the whole‐cell voltage clamp technique, the effect of aprindine on Na+/Ca2+ exchange current (INCX) was examined in guinea‐pig single cardiac ventricular myocytes and CCL39 fibroblasts expressing a dog cardiac Na+/Ca2+ exchanger (NCX1).

INCX was recorded by ramp pulses from the holding potential of −60 mV with the external solution containing 140 mM Na+ and 1 mM Ca2+, and the pipette solution containing 20 mM Na+, 20 mM BAPTA and 13 mM Ca2+ (433 nM free Ca2+).

External application of aprindine suppressed INCX in a concentration‐dependent manner. The IC50 values of outward (measured at 50 mV) and inward (measured at −100 mV) INCX components were 48.8 and 51.8 μM with Hill coefficients of 1.3 and 1, respectively.

Intracellular application of trypsin via the pipette solution did not change the blocking effect of aprindine, suggesting that aprindine does not affect the exchanger from the cytoplasmic side.

Aprindine inhibited INCX of a mutant NCX1 with a deletion of amino acids 247 – 671 in the large intracellular domain between the transmembrane segments 5 and 6 in a similar manner to that of the wild‐type, suggesting that the site of aprindine inhibition is not in the large intracellular domain of NCX1.

A kinetic study indicated that aprindine was cooperatively competitive with KB‐R7943, another inhibitor of NCX and that aprindine was a competitive inhibitor with respect to external Ca2+.

We conclude that aprindine may modestly inhibit INCX in a therapeutic range of concentrations (around 2.5∼6.9 μM) possibly at an external or intra‐membranous site of the exchanger.

British Journal of Pharmacology (2002) 136, 361–366; doi:10.1038/sj.bjp.0704721
Hyper‐reactivity of diacylglycerol kinase is involved in the dysfunction of aortic smooth muscle contractility in streptozotocin‐induced diabetic rats
Authors: Nobe Koji , Sakai Yasushi , Maruyama Yoshiaki , Momose Kazutaka
Published: January 2005

Dysfunction of vascular contraction in diabetes has been reported; however, the mechanisms are poorly understood. In this study, calcium sensitization involving increases in contraction in streptozotocin‐induced diabetic rat aorta was detected. We hypothesize that an alteration in the intracellular signalling system plays a role in the dysfunction of vascular contractility in diabetes. Therefore, diacylglycerol (DG) kinase as a key enzyme of phosphatidylinositol (PI) turnover was investigated.

Treatment with norepinephrine (NE) caused time‐ and dose‐dependent activation of DG kinase in control rats. This activation required simultaneous increases in intracellular calcium concentration ([Ca2+]i) and protein kinase C (PKC) activation.

In diabetic rats, hyper‐reactivity of DG kinase involving inactivation in the resting state and over‐activation in NE stimulation was observed. During hyper‐reactivity, [Ca2+]i dependency of DG kinase was enhanced. Treatment with 50 mM KCl induced significant escalation in activity; moreover, basal activation of PKC was detected only in diabetes. These results suggested that PKC had been activated in the resting state. In contrast, these conditions were insufficient for DG kinase activation due to the absence of [Ca2+]i elevation.

During NE‐stimulation, PKC activation was maintained and [Ca2+]i increased. Therefore, DG kinase was activated and an elevation in calcium dependency enhanced this activation.

The present study suggested that DG kinase hyper‐reactivity in diabetes involved both an increase in [Ca2+]i and basal activation of PKC. This phenomenon may be associated with increased vascular contraction in diabetes mediated by acceleration of PI‐turnover.

British Journal of Pharmacology (2002) 136, 441–451; doi:10.1038/sj.bjp.0704722
Involvement of NO in the failure of neutrophil migration in sepsis induced by Staphylococcus aureus
Authors: Crosara‐Alberto D P , Darini A L C , Inoue R Y , Silva J S , Ferreira S H , Cunha F Q
Published: January 2005

Sepsis induced by S. aureus was used to investigate whether neutrophil migration failure to infectious focus correlates with lethality in Gram‐positive bacteria‐induced sepsis in mice.

By contrast with the sub‐lethal (SL‐group), the lethal (L‐group) intraperitoneal inoculum of S. aureus caused failure of neutrophil migration (92% reduction), high CFU in the exudate, bacteremia and impairment of in vitro neutrophil chemotactic activity.

Pre‐treatments of L‐group with adequate doses of aminoguanidine prevented the neutrophil migration failure and improved the survival of the animals (pre‐treated: 43%; untreated: 0% survival). Thus, the impairment of neutrophil migration in the L‐group appears to be mediated by nitric oxide (NO).

The injection of S. aureus SL‐inoculum in iNOS deficient (−/−) or aminoguanidine‐treated wild‐type mice (pre‐ and post‐treatment), which did not present neutrophil migration failure, paradoxically caused severe peritonitis and high mortality. This fact is explainable by the lack of NO dependent microbicidal activity in migrated neutrophils.

In conclusion, although the NO microbicidal mechanism is active in neutrophils, the failure of their migration to the infectious focus may be responsible for the severity and outcome of sepsis.

British Journal of Pharmacology (2002) 136, 645–658; doi:10.1038/sj.bjp.0704734
Cardiac electrophysiologic and antiarrhythmic actions of a pavine alkaloid derivative, O‐methyl‐neocaryachine, in rat heart
Authors: Chang Gwo‐Jyh , Su Ming‐Jai , Hung Li‐Man , Lee Shoei‐Sheng
Published: January 2005

O‐methyl‐neocaryachine (OMNC) suppressed the ischaemia/reperfusion‐induced ventricular arrhythmias in Langendorff‐perfused rat hearts (EC50=4.3 μM). Its electrophysiological effects on cardiac myocytes and the conduction system in isolated hearts as well as the electromechanical effects on the papillary muscles were examined.

In rat papillary muscles, OMNC prolonged the action potential duration (APD) and decreased the maximal rate of depolarization (Vmax). As compared to quinidine, OMNC exerted less effects on both the Vmax and APD but a positive inotropic effect.

In the voltage clamp study, OMNC decreased Na+ current (INa) (IC50=0.9 μM) with a negative‐shift of the voltage‐dependent inactivation and a slowed rate of recovery from inactivation. The voltage dependence of INa activation was, however, unaffected. With repetitive depolarizations, OMNC blocked INa frequency‐dependently. OMNC blocked ICa with an IC50 of 6.6 μM and a maximum inhibition of 40.7%.

OMNC inhibited the transient outward K+ current (Ito) (IC50=9.5 μM) with an acceleration of its rate of inactivation and a slowed rate of recovery from inactivation. However, it produced little change in the steady‐state inactivation curve. The steady‐state outward K+ current (ISS) was inhibited with an IC50 of 8.7 μM. The inward rectifier K+ current (IK1) was also reduced by OMNC.

In the perfused heart model, OMNC (3 to 30 μM) prolonged the ventricular repolarization time, the spontaneous cycle length and the atrial and ventricular refractory period. The conduction through the AV node and His‐Purkinje system, as well as the AV nodal refractory period and Wenckebach cycle length were also prolonged (30 μM).

In conclusion, OMNC blocks Na+, Ito and ISS channels and in similar concentrations partly blocks Ca2+ channels. These effects lead to a modification of the electromechanical function and may likely contribute to the termination of ventricular arrhythmias. These results provide an opportunity to develop an effective antiarrhythmic agent with modest positive inotropy as well as low proarrhythmic potential.

British Journal of Pharmacology (2002) 136, 459–471; doi:10.1038/sj.bjp.0704736
Multiple effects of trichloroethanol on calcium handling in rat submandibular acinar cells
Authors: Pochet S , Keskiner N , Fernandez M , Marino A , Chaïb N , Dehaye J P , Métioui M
Published: January 2005

The effect of trichloroethanol (TCEt), the active metabolite of chloral hydrate, on the intracellular concentration of calcium ([Ca2+]i) was investigated in rat submandibular glands (RSMG) acini loaded with fura‐2.

TCEt (1–10 mM) increased the [Ca2+]i independently of the presence of calcium in the extracellular medium. Dichloroethanol (DCEt) and monochloroethanol (MCEt) reproduced the stimulatory effect of TCEt but at much higher concentrations (about 6 fold higher for DCEt and 20 fold higher for MCEt).

TCEt mobilized an intracellular pool of calcium, which was depleted by a pretreatment with thapsigargin, an inhibitor of the sarcoplasmic and endoplasmic reticulum calcium‐dependent ATPases, but not with FCCP, an uncoupler of mitochondria.

TCEt 10 mM inhibited by 50% the thapsigargin‐sensitive microsomal Ca2+‐ATPase. DCEt 10 mM and MCEt 10 mM inhibited the ATPase by 20 and 10%, respectively.

TCEt inhibited the increase of the [Ca2+]i and the production of inositol phosphates in response to carbachol, epinephrine and substance P.

TCEt inhibited the uptake of calcium mediated by the store‐operated calcium channel (SOCC).

ATP and Bz‐ATP increased the [Ca2+]i in RSMG acini and this effect was blocked by extracellular magnesium, by Coomassie blue and by oxydized ATP (oATP).

TCEt potentiated the increase of the [Ca2+]i and of the uptake of extracellular calcium in response to ATP and Bz‐ATP.

TCEt had no effect on the uptake of barium and of ethidium bromide in response to purinergic agonists.

These results suggest that TCEt, at sedative concentrations, exerts various effects on the calcium regulation: (1) it mobilizes a thapsigargin‐sensitive intracellular pool of calcium in RSMG acini; (2) it inhibits the uptake of calcium via the SOCC; (3) it inhibits the activation by G protein‐coupled receptors of a polyphosphoinositide‐specific phospholipase C. It does not interfere with the activation of the ionotropic P2X receptors.

The use of chloral hydrate should be avoided in studies exploring the in vivo responses to sialagogues.

British Journal of Pharmacology (2002) 136, 568–580; doi:10.1038/sj.bjp.0704745
Differences in potency and efficacy of a series of phenylisopropylamine/phenylethylamine pairs at 5‐HT2A and 5‐HT2C receptors
Authors: Acuña‐Castillo Claudio , Villalobos Claudio , Moya Pablo R , Sáez Patricio , Cassels Bruce K , Huidobro‐Toro J Pablo
Published: January 2005

The pharmacological profile of a series of (±)‐2,5‐dimethoxy‐4‐(X)‐phenylisopropylamines (X=I, Br, NO2, CH3, or H) and corresponding phenylethylamines, was determined in Xenopus laevis oocytes injected with cRNA coding for rat 5‐HT2A or 5‐HT2C receptors. The efficacy and relative potency of these drugs were determined and compared to classical 5‐HT2 receptor agonists and antagonists.

The rank order of agonist potency at the 5‐HT2A receptor was: α‐methyl‐5‐HT=5‐HT>m‐CPP>MK‐212; at the 5‐HT2C receptor the order was: 5‐HT>α‐methyl‐5‐HT>MK‐212>m‐CPP. All these compounds were full agonists at the 5‐HT2C receptor, but α‐methyl‐5‐HT and m‐CPP showed lower efficacy at the 5‐HT2A receptor.

4‐(4‐Fluorobenzoyl)‐1‐(4‐phenylbutyl)piperidine (4F 4PP) was 200 times more potent as a 5‐HT2A antagonist than at 5‐HT2C receptors. Conversely, RS 102221 was 100 times more potent as a 5‐HT2C antagonist, confirming their relative receptor selectivities.

The phenylisopropylamines were partial agonists at the 5‐HT2A receptor, with Imax relative to 5‐HT in the 22±7 to 58±15% range; the corresponding phenylethylamines had lower or undetectable efficacies. All these drugs had higher efficacies at 5‐HT2C receptors; DOI was a full 5‐HT2C agonist. 2C‐I and the other phenylethylamines examined showed relative efficacies at the 5‐HT2C receptor ranging from 44±10% to 76±16%.

2C‐N was a 5‐HT2 receptor antagonist; the mechanism was competitive at the 5‐HT2A, but non‐competitive at the 5‐HT2C receptor. The antagonism was time‐dependent at the 5‐HT2C receptor but independent of pre‐incubation time at the 5‐HT2A receptor subtype.

The α‐methyl group determines the efficacy of these phenylalkylamines at the 5‐HT2A and 5‐HT2C receptors.

British Journal of Pharmacology (2002) 136, 510–519; doi:10.1038/sj.bjp.0704747
Extracellular ATP and UTP activate the protein kinase B/Akt cascade via the P2Y2 purinoceptor in renal mesangial cells
Authors: Huwiler Andrea , Rölz Waltraud , Dorsch Simone , Ren Shuyu , Pfeilschifter Josef
Published: January 2005

Extracellular nucleotides can activate a common purinoceptor mediating various cell responses. In this study we report that stimulation of rat mesangial cells with ATP and UTP leads to a rapid activation of the protein kinase B/Akt (PKB) pathway. Time‐course studies reveal a rapid and transient phosphorylation of both Ser473 and Thr308 of PKB with a maximal effect after 5 min of stimulation. The response is concentration‐dependent with a maximal effect at 30 μM of ATP and UTP. Western blot analysis of mesangial cells reveals the expression of the isoenzymes PKB‐α and PKB‐γ, but not the PKB‐β.

ATP and UTP also activate the upstream located PI 3‐kinase‐dependent kinase. Furthermore, the ATP‐ and UTP‐induced PKB phosphorylation is abolished by two inhibitors of the PI 3‐kinase. In addition, suramin, a putative P2Y2 receptor antagonist, and pertussis toxin, an inhibitor of Gi/Go activation, markedly block ATP‐ and UTP‐induced PKB phosphorylation.

A series of ATP and UTP analogues were tested for their ability to stimulate PKB phosphorylation. UTP, ATP and γ‐thio‐ATP are the only compounds capable of activating PKB.

Stress‐induced apoptosis of mesangial cells is reduced by the stable ATP analogue, γ‐thio‐ATP, and this inhibitory effect is reversed in the presence of LY 294002.

In summary, these results demonstrate that extracellular nucleotides are able to activate the PI 3‐kinase/PDK/PKB cascade via the P2Y2‐receptor and a pertussis toxin‐sensitive Gi protein. Moreover, in mesangial cells this cascade may have an important role in the antiapoptotic response but not in the mitogenic or inflammatory response produced by extracellular nucleotides.

British Journal of Pharmacology (2002) 136, 520–529; doi:10.1038/sj.bjp.0704748
Dual effect of nitric oxide in articular inflammatory pain in zymosan‐induced arthritis in rats
Authors: Rocha José C da S , Peixoto Magno E B , Jancar Sônia , Cunha Fernando de Q , Ribeiro Ronaldo de A , Rocha Francisco A C da
Published: January 2005

The contribution of nitric oxide (NO) to articular pain in arthritis induced by zymosan (1 mg, intra articular) in rats was assessed by measuring articular incapacitation (AI).

Systemic treatment with the non‐selective NO synthase (NOS) inhibitor L‐NAME (10–100 mg kg−1 i.p.) or with the selective iNOS inhibitors aminoguanidine (AG; 10–100 mg kg−1 i.p.) or 1400W (0.5–1 mg kg−1 s.c.) inhibited the AI induced by injection of zymosan 30 min later.

Local (intra articular) treatment with the NOS inhibitors (L‐NAME or AG, 0.1–1 μmol; 1400W, 0.01 (μmol) 30 min before zymosan also inhibited the AI.

Systemic or local treatment with the NOS inhibibitors (L‐NAME; AG, 100 mg kg−1 i.p. or 0.1 μmol joint−1; 1400W, 1 mg kg−1 s.c. or 0.01 μmol joint−1), 2 h after zymosan did not affect the subsequent AI.

Local treatment with the NO donors SNP or SIN‐1, 2 h after zymosan did inhibit AI.

L‐NAME and AG, given i.p. inhibited nitrite but not prostaglandin E2 (PGE2) levels in the joints. L‐NAME (100 mg kg−1) but not AG (100 mg kg−1) increased mean arterial blood pressure. Neither L‐NAME, AG nor the NO donor SIN‐1 altered articular oedema induced by zymosan.

In conclusion, inhibitors of iNOS decrease pain in zymosan arthritis only when given before the zymosan. This was not due to inhibition of articular PGE2 release or oedema. NO donors also promoted antinociception in zymosan arthritis without affecting oedema.

British Journal of Pharmacology (2002) 136, 588–596; doi:10.1038/sj.bjp.0704755
Effect of dopamine receptor agonists on sensory nerve activity: possible therapeutic targets for the treatment of asthma and COPD
Authors: Birrell Mark A , Crispino Natascia , Hele David J , Patel Hema J , Yacoub Magdi H , Barnes Peter J , Belvisi Maria G
Published: January 2005

Sensory nerves regulate central and local reflexes such as airway plasma leakage, and cough and their function may be enhanced during inflammation. Evidence suggests that dopamine receptor agonists may inhibit sensory nerve‐mediated responses.

In this study dopamine inhibited vagal sensory nerve induced microvascular leakage in the rat. In order to characterize the receptor involved rat vagus preparations were utilized. Quinagolide (D2/3 agonist), ropinirole (D2/3/4 agonist), SKF 38393 (D1/5 agonist), AR‐C68397AA (Viozan™) (dual D2/B2 agonist) and dopamine inhibited hypertonic saline induced depolarization by approximately 50%. Data suggests that AR‐C68397AA and quinagolide also inhibited depolarization of the human vagus.

The quinagolide response was blocked by sulpiride (D2/3 antagonist) but not SCH 23390 (D1/5 antagonist); ropinirole was partially blocked by sulpiride, totally blocked by spiperone (at a concentration that blocks all dopamine receptors) but not by SCH 23390. The response to SKF 38393 was not blocked by sulpiride but was by SCH 23390. The inhibition evoked by AR‐C68397AA was only partially blocked by SCH 23390 but not by sulpiride or spiperone whereas dopamine was blocked by spiperone. The effect of dopamine was not stimulus‐specific as it inhibited capsaicin‐induced depolarization of the rat vagus in a spiperone sensitive manner.

In conclusion, dopamine receptor ligands inhibit depolarization of the rat and human vagus. These data suggest that dopamine receptor agonists may be of therapeutic benefit in the treatment of symptoms such as cough and mucus secretion which are evident in respiratory diseases such as asthma and chronic obstructive pulmonary disease.

British Journal of Pharmacology (2002) 136, 620–628; doi:10.1038/sj.bjp.0704758
Role of adrenergic receptors in vascular remodelling of the rat choroid
Authors: Steinle Jena J , Smith Peter G
Published: January 2005

Choroidal blood vessels, located between the sclera and retina, constitute the principle source of blood flow to ocular structures. The choroid is innervated by vasoconstrictor sympathetic and vasodilator parasympathetic nerves.

We have shown previously that sympathetic denervation for 6 weeks leads to significant increases in choroidal thickness, percentage of choroid occupied by vascular lumina, and numbers of choroidal venules, large arterioles and outer retinal capillaries. Sympathetic deafferentation produces similar increases, indicating that loss of sympathetic nerve activity is responsible for increased vascularity after sympathectomy. Thus, sympathetic neurotransmission normally may be important in suppressing vascular proliferation in the adult rodent eye.

The aim of the present study was to determine whether sympathetic nerves act by way of adrenergic receptors to maintain normal choroidal vascular integrity.

The α‐adrenoceptor antagonist, phentolamine (1 mg kg−1 day−1), the β‐receptor antagonist, propranolol (1 mg kg−1 day−1), or saline vehicle was infused for 3 weeks using subcutaneously implanted osmotic minipumps.

In phentolamine treated rats, no significant changes were noted relative to saline infused controls. However, propranolol treatment resulted in increases in choroidal thickness, vascular luminal area, and numbers of large choroidal venules and both small and large arterioles, approximating the remodelling seen after chronic sympathectomy.

We conclude that sympathetic nerves play a role in maintaining normal choroidal vascular architecture through actions mediated primarily by β‐adrenoceptors.

British Journal of Pharmacology (2002) 136, 730–734; doi:10.1038/sj.bjp.0704771
Inhibition of glycine receptor function of native neurons by aliphatic n‐alcohols
Authors: Tao Liang , Ye Jiang Hong
Published: January 2005

The inhibitory effects of n‐alcohols (methanol to dodecanol) on glycine‐activated currents were studied in neurons freshly dissociated from the ventral tegmental area of neonatal rats using whole‐cell patch‐clamp recording technique.

Ethanol enhanced and depressed glycine‐activated currents in 35% and 45%, respectively, of neurons of ventral tegmental area of neonatal rats. In this report, we extended our focus of ethanol‐induced inhibition of glycine currents to other straight‐chain alcohols.

Aliphatic n‐alcohols, which have carbon numbers less than nine, suppressed glycine currents in 45% (71/158) of the neurons. All results from this study are obtained from the 45% of cells displaying inhibition; the other 55% of the neurons were not studied.

Alcohol potency increased as the number of carbon atoms increased from one to five, and was at a maximal plateau from five to nine; alcohols with 10 or more carbons did not inhibit glycine‐activated currents. Thus, a ‘cutoff’ point in their potency for inhibition of glycine receptor function occurred at about decanol.

A coapplication of dodecanol with ethanol eliminated the inhibition resulting from ethanol. Thus, dodecanol may bind to the receptor silently and compete with ethanol.

These observations indicate that straight‐chain n‐alcohols exhibit a ‘cutoff’ point in their potency for inhibition of the glycine receptor function between nine and 10 carbon atoms. The inability of longer alcohols to change the activation properties of the receptors may contribute to the cutoff effect.

British Journal of Pharmacology (2002) 136, 629–635; doi:10.1038/sj.bjp.0704775
Tonic inhibitory control exerted by opioid peptides in the paraventricular nuclei of the hypothalamus on regional hemodynamic activity in rats
Authors: Lessard Andrée , Bachelard Hélène
Published: January 2005

Systemic and regional cardiovascular changes were measured following bilateral microinjection of specific and selective opioid‐receptor antagonists into the paraventricular nuclei of the hypothalamus (PVN) of awake, freely moving rats.

PVN microinjection of increasing doses of the specific opioid antagonist naloxone – methiodide (1 – 5.0 nmol), or a selective μ‐opioid receptor antagonist, β‐funaltrexamine (0.05 – 0.5 nmol), evoked important cardiovascular changes characterized by small and transient increases in heart rate (HR) and mean arterial pressure (MAP), vasoconstriction in renal and superior mesenteric vascular beds and vasodilation in the hindquarter vascular bed.

No significant cardiovascular changes were observed following PVN administration of the highly selective δ‐opioid‐receptor antagonist, ICI 174864 (0.1 – 1 nmol), or the selective κ‐opioid‐receptor antagonist, nor‐binaltorphine (0.1 – 1 nmol).

Most of the cardiovascular responses to naloxone (3 nmol) and β‐funaltrexamine (0.5 nmol) were attenuated or abolished by an i.v. treatment with a specific vasopressin V1 receptor antagonist.

These results suggest that endogenous opioid peptides and μ‐type PVN opioid receptors modulate a tonically‐active central depressor pathway acting on systemic and regional haemodynamic systems. Part of this influence could involve a tonic inhibition of vasopressin release.

British Journal of Pharmacology (2002) 136, 753–763; doi:10.1038/sj.bjp.0704780
M3 muscarinic receptors mediate contraction of human urinary bladder
Authors: Fetscher Charlotte , Fleichman Marina , Schmidt Martina , Krege Susanne , Michel Martin C
Published: January 2005

Since muscarinic receptors appear to be the physiologically most important control system for urinary bladder contraction, we have characterized the receptor subtype mediating contraction in response to the muscarinic agonist carbachol in the human bladder. Experiments were based on four antagonists, the non‐selective atropine, the M1‐selective pirenzepine, the M2‐selective methoctramine and the M3‐selective darifenacin. All antagonists yielded Schild‐plots with a slope close to unity. The order of potency (atropinedarifenacin>pirenzepine>methoctramine) as well as the estimated antagonist affinities suggested that contraction of the human bladder occurs predominantly if not exclusively via the M3 receptor.

British Journal of Pharmacology (2002) 136, 641–644; doi:10.1038/sj.bjp.0704781
Inhibition of the current of heterologously expressed HERG potassium channels by flecainide and comparison with quinidine, propafenone and lignocaine
Authors: Paul Ashok A , Witchel Harry J , Hancox Jules C
Published: January 2005

The inhibition of the cardiac ‘rapid’ delayed rectifier current (IKr) and its cloned equivalent HERG mediate QT interval prolonging effects of a wide range of clinically used drugs. In this study, we investigated the effects of the Class Ic antiarrhythmic agent flecainide (FLEC) on ionic current (IHERG) mediated by cloned HERG channels at 37°C . We also compared the inhibitory potency of FLEC with other Class I agents: quinidine (QUIN, Class Ia); lignocaine (LIG, Class Ib) and propafenone (PROPAF, Class Ic).

Whole cell voltage clamp recordings of IHERG were made from an HEK293 cell line stably expressing HERG. FLEC inhibited IHERG ‘tails’ following test pulses to +30 mV with an IC50 of 3.91±0.68 μM (mean±s.e.mean) and a Hill co‐efficient close to 1 (0.76±0.09).

In experiments in which IHERG tails were monitored following voltage commands to a range of test potentials, IHERG inhibition by FLEC was observed to be voltage‐dependent and to be associated with a ∼−5 mV shift of the activation curve for the current. Voltage‐dependence of inhibition was greatest over the range of potentials corresponding to the steep portion of the IHERG activation curve. The time‐course of IHERG tail deactivation was not significantly altered by FLEC.

In experiments in which 10 s depolarizing pulses were applied from −80 to 0 mV, the level of current inhibition by FLEC did not increase between 1 and 10 s. Some time‐dependence of inhibition was observed during the first 200 – 300 ms of depolarization. This observation and the voltage‐dependence of inhibition are collectively consistent with FLEC exerting a rapid open channel state inhibition of IHERG.

Under similar recording conditions QUIN inhibited IHERG with an IC50 of 0.41±0.04 μM and PROPAF inhibited IHERG with an IC50 of 0.44±0.07 μM. Similar to FLEC, both QUIN and PROPAF showed voltage‐dependence of inhibition and blockade developed rapidly during a sustained depolarization.

LIG showed little effect on IHERG at low micromolar concentrations, but could inhibit the current at higher concentrations; the observed IC50 was 262.90±22.40 μM.

Our data are consistent with FLEC, PROPAF and QUIN exerting IHERG blockade at clinically relevant concentrations. The rank potency as HERG blockers of the Class I drugs tested in this study was QUIN=PROPAF>FLEC>>LIG.

British Journal of Pharmacology (2002) 136, 717–729; doi:10.1038/sj.bjp.0704784
Wetting morphologies at microstructured surfaces
Authors: Seemann Ralf , Brinkmann Martin , Kramer Edward J. , Lange Frederick F. , Lipowsky Reinhard
Published: January 2005

The wetting of microstructured surfaces is studied both experimentally and theoretically. Even relatively simple surface topographies such as grooves with rectangular cross section exhibit a large variety of different wetting morphologies as observed by atomic force microscopy. This polymorphism arises from liquid wedge formation along the groove corners and from contact line pinning along the groove edges. A global morphology diagram is derived that depends only on two system parameters: (
i
) the aspect ratio of the groove geometry and (
ii
) The contact angle of the underlying substrate material. For microfluidics, the most interesting shape regimes involve extended liquid filaments, which can grow and shrink in length while their cross section stays essentially constant. Thus, any method by which one can vary the contact angle can be used to switch the length of the filament, as is demonstrated in the context of electrowetting.
A non-ATP-competitive inhibitor of BCR-ABL overrides imatinib resistance
Authors: Gumireddy Kiranmai , Baker Stacey J. , Cosenza Stephen C. , John Premila , Kang Anthony D. , Robell Kimberly A. , Reddy M. V. Ramana , Reddy E. Premkumar
Published: January 2005

Imatinib, which is an inhibitor of the BCR-ABL tyrosine kinase, has been a remarkable success for the treatment of Philadelphia chromosome-positive (Ph
+
) chronic myelogenous leukemias (CMLs). However, a significant proportion of patients chronically treated with imatinib develop resistance because of the acquisition of mutations in the kinase domain of BCR-ABL. Mutations occur at residues directly implicated in imatinib binding or, more commonly, at residues important for the ability of the kinase to adopt the specific closed (inactive) conformation to which imatinib binds. In our quest to develop new BCR-ABL inhibitors, we chose to target regions outside the ATP-binding site of this enzyme because these compounds offer the potential to be unaffected by mutations that make CML cells resistant to imatinib. Here we describe the activity of one compound, ON012380, that can specifically inhibit BCR-ABL and induce cell death of Ph
+
CML cells at a concentration of <10 nM. Kinetic studies demonstrate that this compound is not ATP-competitive but is substrate-competitive and works synergistically with imatinib in wild-type BCR-ABL inhibition. More importantly, ON012380 was found to induce apoptosis of all of the known imatinib-resistant mutants at concentrations of <10 nM concentration
in vitro
and cause regression of leukemias induced by i.v. injection of 32Dcl3 cells expressing the imatinib-resistant BCR-ABL isoform T315I. Daily i.v. dosing for up to 3 weeks with a >100 mg/kg concentration of this agent is well tolerated in rodents, without any hematotoxicity.
Estrogen receptor α and imprinting of the neonatal mouse ventral prostate by estrogen
Authors: Omoto Yoko , Imamov Otabek , Warner Margaret , Gustafsson Jan-Åke
Published: January 2005

Exposure to estrogen in the neonatal period affects prostatic growth and leads to an increased incidence of prostatic intraepithelial neoplasia in later life. The effects of neonatal estrogen are clearly dependent on estrogen receptor (ER) α because they do not occur in ERα-knockout mice. Because ERα is expressed in the stroma, but not in the epithelium, of the adult ventral prostate, the concept of indirect estrogen effects through stromal signaling has been proposed. Here, we show that during the first 4 weeks of life, there are profound and rapid changes in the ER profile in the mouse ventral prostate. ERα is abundant in the stroma during week 1, but by week 2 it is exclusively epithelial, and then by week 4, ERα is lost and ERβ is dominant in the prostatic epithelium. The presence of ERα is associated with a high proliferation index, and ERβ is associated with quiescence. Branching morphogenesis was altered in ERα
-/-
, but not in ERβ
-/-
, mice. We conclude that imprinting and branching morphogenesis of the ventral prostate are mediated by estrogen acting directly on epithelial and stromal ERα during the first 2 weeks of life.
Changes in brain testosterone and allopregnanolone biosynthesis elicit aggressive behavior
Authors: Pinna Graziano , Costa Erminio , Guidotti Alessandro
Published: January 2005

In addition to an action on metabolism, anabolic/androgenic steroids also increase sex drive and mental acuity. If abused, such steroids can cause irritability, impulsive aggression, and signs of major depression [Pearson, H. (2004)Nature431, 500-501], but the mechanisms that produce these symptoms are unknown. The present study investigates behavioral and neurochemical alterations occurring in association with protracted (3-week) administration of testosterone propionate (TP) to socially isolated (SI) and group-housed male and female mice. Male but not female SI mice exhibit aggression that correlates with the down-regulation of brain neurosteroid biosynthesis. However, in female mice, long-term TP administration induces aggression associated with a decrease of brain allopregnanolone (Allo) content and a decrease (≈40%) of 5α-reductase type I mRNA expression. In spayed mice treated with TP, restitution experiments with progesterone and estrogen normalize brain Allo content and prevent aggression. Submicromolar doses ofS-norfluoxetine (S-NFLX) that are insufficient to inhibit serotonin reuptake selectively increase brain Allo content and abolish TP-induced aggression. Our results support the view that TP-induced aggressive behavior is the result of a TP-mediated neurosteroid biosynthesis down-regulation that can be reversed by the S-NFLX-induced increase of brain Allo content.
A combinatorial curvature flow for compact 3-manifolds with boundary
Authors: Luo Feng
Published: January 2005

We introduce a combinatorial curvature flow for piecewise constant curvature metrics on compact triangulated 3-manifolds with boundary consisting of surfaces of negative Euler characteristic. The flow tends to find the complete hyperbolic metric with totally geodesic boundary on a manifold. Some of the basic properties of the combinatorial flow are established. The most important one is that the evolution of the combinatorial curvature satisfies a combinatorial heat equation. It implies that the total curvature decreases along the flow. The local convergence of the flow to the hyperbolic metric is also established if the triangulation is isotopic to a totally geodesic triangulation.