bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular cloning, expression and characterization of cDNA encoding a mouse α1a‐adrenoceptor
Authors: Xiao Lei , Scofield Margaret A , Jeffries William B 
Published: January 2005

In this study, we have cloned, expressed, and characterized an α1a‐adrenoceptor gene from the mouse. We designed oligonucleotide PCR primers complementary to regions of the rat α1a‐adrenoceptor sequence and amplified cDNA fragments from total RNA of mouse cerebral cortex, liver and kidney by reverse transcription‐polymerase chain reaction (RT–PCR).
Both the nucleotide and deduced peptide sequences of the cDNA showed high sequence identity with those of cloned α1a‐adrenoceptors from other species. The cDNA clone had an open reading frame of 1398 nucleotides encoding a 466 amino acid peptide which had 97%, 92% and 90% identity with the deduced amino acid sequences of the rat, human and bovine α1a‐adrenoceptor, respectively.
The amplified mouse cDNA was inserted into a mammalian expression vector pcDNA3.1(+) and expressed in COS‐1 cells. The pharmacological properties of the mouse cDNA clone were examined in radioligand binding studies and functional assays. The expressed mouse protein had a high affinity for [3H]‐prazosin (Kd=0.48 nM) and pattern of affinity for antagonists in competition studies that is similar to that of the rat α1a‐adrenoceptor. Chloroethylclonidine (CEC) could slowly alkylate the expressed protein, with a rate similar to that of the rat α1a‐adrenoceptor.
The expressed receptors were able to mediate noradrenaline (NA) stimulation of the production of inositol phosphates in COS‐1 cells, consistent with coupling to phospholipase C. This response to NA could be reversed by pretreatment of the transfected cells with prazosin.
Based on the above evidence, we concluded that the cloned cDNA is that of the mouse α1a‐adrenoceptor.
Enhancement of opioid inhibition of GABAergic synaptic transmission by cyclo‐oxygenase inhibitors in rat periaqueductal grey neurones
Authors: Vaughan C. W. 
Published: January 2005

Cyclo‐oxygenase (COX) inhibitors potentiate opioid inhibition of GABAergic synaptic transmission in rat periaqueductal grey (PAG) (Vaughan et al., 1997). In the present study, the relative contribution of cyclo‐oxygenase‐1 (COX‐1) and COX‐2 inhibition to this phenomenon was examined by use of whole‐cell patch clamp recordings in brain slices. The μ‐receptor partial agonist morphine (10 μM) had little effect on GABAergic synaptic transmission. Morphine reduced the frequency of spontaneous miniature inhibitory postsynaptic currents (m.i.p.s.cs) by 13%. The nonselective COX inhibitor, indomethacin, produced a dose‐dependent potentiation of the morpine inhibition of m.i.p.s.c. frequency (maximum inhibition 42%, IC50=6 nM). More selective COX‐2 inhibitors produced a similar potentiation of the morphine inhibition of m.i.p.s.c. frequency; however, at greater concentrations (IC50=57 nM piroxicam, 1.7 μM DFU). Maintaining slices in the protein synthesis inhibitor cycloheximide (1 μM), to prevent COX‐2 induction, had no effect on the potentiation action of DFU (10 μM). These results demonstrate that the potentiation of opioid inhibition of GABAergic synaptic transmission in PAG is largely a result of inhibition of COX‐1 activity. These findings suggest that COX‐1, rather than COX‐2 inhibition, mediates the synergistic analgesic actions of opioids and non‐steroidal anti‐inflammatory drugs (NSAIDs) in the midbrain PAG.British Journal of Pharmacology (1998) 123, 1479–1481; doi:10.1038/sj.bjp.0701818
Respiratory and cardiovascular effects of the μ‐opioid receptor agonist [Lys7]dermorphin in awake rats
Authors: Negri Lucia , Lattanzi Roberta , Tabacco Fabio , Melchiorri Pietro 
Published: January 2005

Changes in respiratory variables, arterial blood pressure and heart rate were studied in awake rats after injection of the opioid peptide [Lys7]dermorphin and its main metabolites, [1‐5]dermorphin and [1‐4]dermorphin.
Fifteen minutes after injection, doses of [Lys7]dermorphin producing antinociception (i.c.v., 36–120 nmol; s.c., 0.12–4.7 μmol kg−1) significantly increased respiratory frequency and minute volume of rats breathing air or hypoxic inspirates. This respiratory stimulation was reversed to depression by the 5‐HT receptor antagonist ritanserin (2 mg kg−1, s.c.), was blocked by naloxone (0.1 mg kg−1, s.c.), significantly reduced by the μ1 opioid receptor antagonist naloxonazine (10 mg kg−1, s.c., 24 h before) but unaffected by peripherally acting opioid antagonist naloxone methyl bromide (3 mg kg−1, s.c.). Forty five minutes after injection, doses of the peptide producing catalepsy (s.c., 8.3–14.2 μmol kg−1, i.c.v., 360 nmol) significantly reduced respiratory frequency and volume of rats breathing air and blocked the hypercapnic ventilator response of rats breathing from 4% to 10% CO2. I.c.v. administration of [1‐5]dermorphin and [1‐4]dermorphin (from 36 to 360 nmol) never stimulated respiration but significantly reduced basal and CO2‐stimulated ventilation. Opioid respiratory depression was only antagonized by naloxone.
In awake rats, [Lys7]dermorphin (0.1–1 mg kg−1, s.c.) decreased blood pressure. This hypotensive response was abolished by naloxone, reduced by naloxone methyl bromide and unaffected by naloxonazine.
In conclusion, the present study indicates that analgesic doses of [Lys7]dermorphin stimulate respiration by activating central μ1 opioid receptors and this respiratory stimulation involves a forebrain 5‐hydroxytryptaminergic excitatory pathway.
Outward current produced by somatostatin (SRIF) in rat anterior cingulate pyramidal cells in vitro
Authors: Hicks G A , Feniuk W , Humphrey P P A 
Published: January 2005

A high density of receptors for somatostatin (SRIF) exists in the anterior cingulate cortex but their function is unknown. Whole‐cell patch clamp recordings were made from visualized deep layer pyramidal cells of the rat anterior cingulate cortex contained in isolated brain slices to investigate the putative effects of SRIF and to identify the receptor subtype(s) involved.
SRIF (1–1000 nM) produced a concentration‐dependent outward current which was associated with an increased membrane conductance, was sensitive to Ba2+ (300 μM–1 mM), and was absent in the presence of a maximal concentration of the GABAB receptor agonist, baclofen (100 μM). These observations suggest the outward current was carried by K+ ions.
SRIF analogues also elicited outward currents with a rank potency order of (EC50, nM): octreotide (1.8)>BIM‐23027 (3.7)>SRIF (20)=L‐362,855 (20). BIM‐23056 was without agonist or antagonist activity. Responses to L‐362,855 were unlike those to the other agonists since they were sustained for the duration of the application.
The sst2 receptor antagonist, L‐Tyr8Cyanamid 154806 (1 μM), had no effect alone but partially reversed responses to submaximal concentrations of SRIF (100 nM, 44±6% reversal) and L‐362,855 (100 nM, 70±6% reversal) and fully reversed the response to BIM‐23027 (10 nM). In contrast, L‐Tyr8Cyanamid 154806 did not antagonize the response to baclofen (10 μM).
We conclude that SRIF activates a K+ conductance in anterior cingulate pyramidal neurones via an action predominantly at sst2 receptors.
Modulation of striatal quinolinate neurotoxicity by elevation of endogenous brain kynurenic acid
Authors: Harris C A , Miranda A F , Tanguay J J , Boegman R J , Beninger R J , Jhamandas K 
Published: January 2005

Nicotinylalanine, an inhibitor of kynurenine metabolism, has been shown to elevate brain levels of endogenous kynurenic acid, an excitatory amino acid receptor antagonist. This study examined the potential of nicotinylalanine to influence excitotoxic damage to striatal NADPH diaphorase (NADPH‐d) and γ‐aminobutyric acid (GABA)ergic neurones that are selectively lost in Huntington's disease.
A unilateral injection of the N‐methyl‐D‐aspartate (NMDA) receptor agonist, quinolinic acid, into the rat striatum produced an 88% depletion of NADPH‐d neurones. Intrastriatal infusion of quinolinic acid also produced a dose‐dependent reduction in striatal GABA content.
Nicotinylalanine (2.3, 3.2, 4.6, 6.4 nmol 5 μl−1, i.c.v.) administered with L‐kynurenine (450 mg kg−1), a precursor of kynurenic acid, and probenecid (200 mg kg−1), an inhibitor of organic acid transport, 3 h before the injection of quinolinic acid (15 nmol) produced a dose‐related attenuation of the quinolinic acid‐induced loss of NADPH‐d neurones. Nicotinylalanine (5.6 nmol 5 μl−1) in combination with L‐kynurenine and probenecid also attenuated quinolinic acid‐induced reductions in striatal GABA content.
Nicotinylalanine (4.6 nmol, i.c.v.), L‐kynurenine alone or L‐kynurenine administered with probenecid did not attenuate quinolinic acid‐induced depletion of striatal NADPH‐d neurones. However, combined administration of kynurenine and probenecid did prevent quinolinic acid‐induced reductions in ipsilateral striatal GABA content.
Injection of nicotinylalanine, at doses (4.6 nmol and 5.6 nmol i.c.v.) which attenuated quinolinic acid‐induced striatal neurotoxicity, when combined with L‐kynurenine and probenecid produced increases in both whole brain and striatal kynurenic acid levels. Administration of L‐kynurenine and probenecid without nicotinylalanine also elevated kynurenic acid, but to a lesser extent.
The results of this study demonstrate that nicotinylalanine has the potential to attenuate quinolinic acid‐induced striatal neurotoxicity. It is suggested that nicotinylalanine exerts its effect by increasing levels of endogenous kynurenic acid in the brain. The results of this study suggest that agents which influence levels of endogenous excitatory amino acid antagonists such as kynurenic acid may be useful in preventing excitotoxic damage to neurones in the CNS.
Modulation of angiotensin‐converting enzyme by nitric oxide
Authors: Ackermann A , Fernández‐Alfonso M S , Sánchez de Rojas R , Ortega T , Paul M , González C 
Published: January 2005

The aim of the present study was to determine the effect of nitric oxide (NO) on angiotensin‐converting enzyme (ACE) activity.
A biochemical study was performed in order to analyse the effect of the NO‐donors, SIN‐1 and diethylamine/NO (DEA/NO), and of an aqueous solution of nitric oxide on the ACE activity in plasma from 3‐month old male Sprague‐Dawley rats and on ACE purified from rabbit lung. SIN‐1 significantly inhibited the activity of both enzymes in a concentration‐dependent way between 1 and 100 μM. DEA/NO inhibited the activity of purified ACE from 0.1 μM to 10 μM and plasma ACE, with a lower potency, between 1 and 100 μM. An aqueous solution of NO (100 and 150 μM) also inhibited significantly the activity of both enzymes. Lineweaver‐Burk plots indicated an apparent competitive inhibition of Hip‐His‐Leu hydrolysis by NO‐donors.
Modulation of ACE activity by NO was also assessed in the rat carotid artery by comparing contractions elicited by angiotensin I (AI) and AII. Concentration‐response curves to both peptides were performed in arteries with endothelium in the presence of the guanylyl cyclase inhibitor, ODQ (10 μM), and the inhibitor of NO formation, L‐NAME (0.1 mM). NO, which is still released from endothelium in the presence of 10 μM ODQ, elicited a significant inhibition of AI contractions at low concentrations (1 and 5 nM). In the absence of endothelium, 1 μM SIN‐1 plus 10 μM ODQ, as well as 10 μM DEA/NO plus 10 μM ODQ induced a significant inhibition on AI‐induced contractions at 1 and 5 nM and at 1–100 nM, respectively.
In conclusion, we demonstrated that (i) NO and NO‐releasing compounds inhibit ACE activity in a concentration‐dependent and competitive way and that (ii) NO release from endothelium physiologically reduces conversion of AI to AII.
The contribution of nitric oxide to cardiovascular status and responses to vasodilators in conscious, hypertensive, transgenic ((mRen‐2)27) rats
Authors: Gardiner S M , March J E , Kemp P A , Bennett T 
Published: January 2005

The aim of the study was to measure the regional haemodynamic responses to vasodilators, and the effects of nitric oxide (NO) synthase inhibition, in conscious, hypertensive, transgenic ((mRen‐2)27) rats (TG rats) and normotensive, Hannover Sprague‐Dawley (SD) rats.
The hypotensive response to acetylcholine was greater in TG than in SD rats, but the renal vasodilator responses were not different.
The responses to bradykinin were similar in the two strains, except that hindquarters vasodilatation occurred only in SD rats.
Salbutamol caused smaller renal and hindquarters vasodilatation in TG rats than in SD rats, and there was mesenteric vasodilatation only in the latter strain.
The hypotensive response to sodium nitroprusside was smaller, but the accompanying mesenteric vasodilatation was greater, in SD than in TG rats.
The contribution of NO to the vasodilator responses was taken as the difference between the responses in the presence of the NO synthase inhibitor, NG‐nitro‐L‐arginine methylester (L‐NAME), compared to those in the presence of a co‐infusion of angiotensin II and vasopressin (to match the haemodynamic effects of L‐NAME).
In TG rats, L‐NAME caused a greater absolute pressor effect, but a smaller mesenteric vasoconstriction, than in SD rats.
L‐NAME affected the vasodilator responses to all the challenges similarly in the two strains.
Collectively, the results provide no direct evidence for impaired NO‐mediated vasodilator mechanisms in TG rats. It is feasible that the reduced hindquarters response to bradykinin and the reduced renal and hindquarters responses to salbutamol, in TG rats are due to abnormal β2‐adrenoceptor‐mediated processes.
The profile of sabcomeline (SB‐202026), a functionally selective M1 receptor partial agonist, in the marmoset
Authors: Harries M H , Samson N A , Cilia J , Hunter A J 
Published: January 2005

Sabcomeline (SB‐202026, 0.03 mg kg−1, p.o.), a potent and functionally selective M1 receptor partial agonist, caused a statistically significant improvement in the performance of a visual object discrimination task by marmosets. No such improvement was seen after RS86 (0.1 mg kg−1, p.o.).
Initial learning, which only required an association of object with reward and an appropriate response to be made, was not significantly affected. Reversal learning, which required both the extinction of the previously learned response and the acquisition of a new response strategy, was significantly improved after administration of sabcomeline (0.03 mg kg−1, p.o.).
Sabcomeline (0.03 and 0.1 mg kg−1, p.o.) had no significant effect on mean blood pressure measured for 2 h after administration in the conscious marmoset.
Sabcomeline (0.03 mg kg−1, p.o.) caused none of the overt effects such as emesis or behaviours often seen after the administration of muscarinic agonists, e.g. face rubbing and licking.
This is the first study to demonstrate cognitive enhancement by a functionally selective M1 receptor partial agonist in a normal (i.e. non‐cognitively impaired) non‐human primate and this effect was seen at a dose which did not cause side effects.
Perseverative behaviour and deficient acquisition of new information are seen in patients with Alzheimer's disease (AD). Therefore the data suggest that sabcomeline might be of therapeutic benefit in the treatment of AD.
Superoxide and endothelium‐dependent constriction to flow in porcine small pulmonary arteries
Authors: Liu Qiang , Wiener Charles M , Flavahan Nicholas A 
Published: January 2005

The aim of this study was to determine the response of porcine small pulmonary arteries to intralumenal flow and to identify the cellular mechanisms and potential mediators involved in the response.
Porcine small pulmonary arteries were isolated from a branch of the main intrapulmonary artery of the lower lung lobe and studied in a perfusion myograph system that allowed independent control of transmural pressure and intralumenal flow. At a transmural pressure of 20 mmHg, the baseline internal diameter (BID) of the arteries was 251.2±16.1 μm (n=16).
Under quiescent conditions or during constriction with U46619 to ∼60% of BID, intralumenal flow caused reversible constriction in arteries with endothelium (in the presence of U46619, flow decreased diameter from 60.0±2.5% to 49.5±3.0% BID at 10 μl min−1, n=16, P<0.05) but no change in diameter of arteries without endothelium.
In the presence of superoxide dismutase (SOD, 150 u ml−1), the response to flow was converted from constriction to vasodilatation (in presence of U46619 and SOD, flow increased diameter from 54.2±3.4% to 76.7±4.5% BID at 10 μl min−1, n=10, P<0.05). Inhibition of NO synthase with L‐NAME (3×10−5 M) abolished the flow‐induced vasodilatation occurring in the presence of SOD and the flow‐induced constriction occurring in the absence of SOD. In arteries with endothelium, L‐NAME (3×10−5 M) caused significant vasoconstriction, whereas SOD did not alter vasomotor tone.
Acetylcholine (10−8 to 10−6 M) caused endothelium‐dependent relaxation of small pulmonary arteries that was not significantly affected by SOD (150 u ml−1) but was inhibited by L‐NAME (3×10−5 M).
These results suggest that in small, porcine, isolated pulmonary arteries, intralumenal flow increases the production of NO but this is obscured by the generation of superoxide which causes vasoconstriction.
Effect of rolipram and dibutyryl cyclic AMP on resequestration of cytosolic calcium in FMLP‐activated human neutrophils
Authors: Anderson R , Mahomed A Goolam , Theron A J , Ramafi G , Feldman C 
Published: January 2005

We have investigated the effects of the selective phosphodiesterase (PDE) type 4 inhibitor, rolipram (0.01–1 μM) on cytosolic Ca2+ fluxes in FMLP‐activated human neutrophils, as well as on superoxide production by, and release of elastase from, these cells.
Cytosolic Ca2+ fluxes were measured by use of fura‐2 spectrofluorimetry in combination with a radiometric procedure that enables distinction between net efflux and influx of the cation. Superoxide production and elastase release were measured by lucigenin‐enhanced chemiluminescence and a colorimetric procedure, respectively.
Pretreatment of neutrophils with rolipram did not affect the FMLP‐activated release of Ca2+ from intracellular stores, but was associated with dose‐related acceleration of the rate of decline in fura‐2 fluorescence and with decreased efflux, as well as store‐operated influx of 45Ca2+, indicative of enhancement of resequestration of the cation by the endo‐membrane Ca2+‐ATPase.
Inhibition of superoxide production and elastase release was observed at concentrations of rolipram which accelerated the clearance of Ca2+ from the cytosol of FMLP‐activated neutrophils.
These effects of rolipram on FMLP‐activated Ca2+ fluxes, superoxide generation and elastase release were mimicked by pretreatment of neutrophils with dibutyryl cyclic AMP (0.5–4 mM), while theophylline (10–150 μM), a non‐specific PDE inhibitor, as well as the β2‐agonist, salbutamol, were less effective.
We conclude that rolipram deactivates FMLP‐stimulated human neutrophils by enhancement of cyclic AMP‐dependent resequestration of cytosolic Ca2+.
The effect of nitric oxide on cytokine‐induced release of PGE2 by human cultured astroglial cells
Authors: Mollace Vincenzo , Colasanti Marco , Muscoli Carolina , Lauro Giuliana M , Iannone Michelangelo , Rotiroti Domenicantonio , Nistico' Giuseppe 
Published: January 2005

The role of the L‐arginine‐nitric oxide (NO) pathway on the formation of prostaglandin E2 (PGE2) by human cultured astroglial cells incubated with interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) was investigated.
Incubation of T 67 astroglial cell line with IL‐β (10 ng ml−1) and TNF‐α (500 u ml−1) produced a significant (P<0.05) increase of both nitrite (the breakdown product of NO), cyclic GMP and PGE2 levels in cell supernatants. Nω‐nitro‐L‐arginine methyl ester (L‐NAME; 20–300 μM), an inhibitor of NO synthase (NOS), inhibited the increase of cyclic GMP and nitrite levels found in supernatants of cytokine‐treated astroglial cells and reduced the release of PGE2. The latter effect showed that the enhanced arachidonic acid (AA) metabolism subsequent to stimulation of astroglial cells with IL‐1β and TNF‐α was, at least in part, induced by NO. This occurred also when sodium nitroprusside (SNP; 120 μM), an NO donor, was incubated with astroglial cells, an effect antagonized by oxyhaemoglobin (OxyHb; 10 μM).
The inhibition elicited by L‐NAME on PGE2‐release by cytokine‐treated astroglial cells was reversed by adding AA (40 μM), showing that the effect of NO on cytokine‐dependent PGE2 release occurred at the cyclo‐oxygenase (COX) level. Furthermore, the release of PGE2 in cytokine‐treated astroglial cells was inhibited by indomethacin (10 μM), a COX inhibitor as well as by preincubating cells with dexamethasone (20 μM), an inhibitor of inducible enzymes, showing that the inducible isoform of COX (COX‐2) was involved.
On the other hand, pretreating astroglial cells with methylene blue (MB; 10 μM), an inhibitor of NO biological activity acting at the guanylate cyclase level, failed to affect PGE2 release in cytokine‐treated astroglial cells, leading to the conclusion that cyclic GMP changes related to NO formation are not involved in the generation of AA metabolites.
The present experiments demonstrated that the release of PGE2 by astroglial cells pretreated with IL‐1β and TNF‐α is due to enhanced COX‐2 activity via activation of the L‐arginine‐NO pathway, and this may be relevant to the understanding of the pathophysiological mechanisms underlying neuroimmune disorders.
Inhibition of the ATP‐sensitive potassium channel from mouse pancreatic β‐cells by surfactants
Authors: Smith Paul A , Proks Peter 
Published: January 2005

We have used patch‐clamp methods to study the effects of the detergents, Cremophor, Tween 80 and Triton X100 on the KATP channel in the pancreatic β‐cell from mouse.
All three detergents blocked KATP channel activity with the following order of potency: Tween 80 (Ki<∼83 nM)>Triton X100 (Ki=350 nM)>Cremophor. In all cases the block was poorly reversible.
Single‐channel studies suggested that at low doses, the detergents act as slow blockers of the KATP channel.
Unlike the block produced by tolbutamide, that produced by detergent was not affected by intracellular Mg2+‐nucleotide, diazoxide or trypsin treatment, nor did it involve an acceleration of rundown or increase in ATP sensitivity of the chanel.
The detergents could block the pore‐forming subunit, Kir6.2ΔC26, which can be expressed independently of SUR1 (the regulatory subunit of the KATP channel). These data suggest that the detergents act on Kir6.2 and not SUR1.
The detergents had no effect on another member of the inward rectifier family: Kir1.1a (ROMK1).
Voltage‐dependent K‐currents in the β‐cell were reversibly blocked by the detergents with a far lower potency than that found for the KATP channel.
Like other insulin secretagogues that act by blocking the KATP channel, Cremophor elevated intracellular Ca2+ in single β‐cells to levels that would be expected to elicit insulin secretion.
Given the role of the KATP channel in many physiological processes, we conclude that plasma borne detergent may have pharmacological actions mediated through blockage of the KATP channel