Biomedical subjects

D W Hay

Publications and source records attributed to D W Hay.

At least 19 recordsLinked to original sources

PubMed2001

Stepwise modulation of neurokinin-3 and neurokinin-2 receptor affinity and selectivity in quinoline tachykinin receptor antagonists.

A stepwise chemical modification from human neurokinin-3 receptor (hNK-3R)-selective antagonists to potent and combined hNK-3R and hNK-2R antagonists using the same 2-phenylquinoline template is described. Docking studies with 3-D models of the hNK-3 and hNK-2 receptors were used to drive the chemical design and speed up the identification of potent and combined antagonsits at both receptors. (S)-(+)-N-(1-Cyclohexylethyl)-3-[(4-morpholin-4-yl)piperidin-1-yl]methyl-2-phenylquinoline-4-carboxamide (compound 25, SB-400238: hNK-3R binding affinity, K(i) = 0.8 nM; hNK-2R binding affinity, K(i) = 0.8 nM) emerged as the best example in this approach. Further studies led to the identification of (S)-(+)-N-(1,2,2-trimethylpropyl)-3-[(4-piperidin-1-yl)piperidin-1-yl]methyl-2-phenylquinoline-4-carboxamide (compound 28, SB-414240: hNK-3R binding affinity, K(i) = 193 nM; hNK-2R binding affinity, K(i) = 1.0 nM) as the first hNK-2R-selective antagonist belonging to the 2-phenylquinoline chemical class. Since some members of this chemical series showed a significant binding affinity for the human mu-opioid receptor (hMOR), docking studies were also conducted on a 3-D model of the hMOR, resulting in the identification of a viable chemical strategy to avoid any significant micro-opioid component. Compounds 25 and 28 are therefore suitable pharmacological tools in the tachykinin area to elucidate further the pathophysiological role of NK-3 and NK-2 receptors and the therapeutic potential of selective NK-2 (28) or combined NK-3 and NK-2 (25) receptor antagonists.

Amino Acid Sequence↗

PubMed2001

Molecular and pharmacological characterization of the murine tachykinin NK(3) receptor.

Starting with a partial sequence from Genbank, polymerase chain reaction (PCR) was utilized to isolate the full-length cDNA for NK(3) receptor from mouse brain. The murine NK(3) receptor has a predicted sequence of 452 amino acids, sharing 96% and 86% identity to the rat and human NK(3) receptors, respectively. Binding affinities and functional potencies of tachykinin receptor agonists were similar in HEK (human embryonic kidney) 293 cells expressing murine NK(3) receptor and human NK(3) receptor, although substance P and neurokinin A were more potent stimulators of Ca(2+) mobilization in murine NK(3) receptor cells. NK(3) receptor-selective antagonists from two structural classes, had 10- to 100-fold lower binding affinities for murine NK(3) receptor compared to human NK(3) receptor, and about 5- to 10-fold reduced potency in the murine NK(3) receptor functional assay. The results demonstrate species differences in the potencies of tachykinin receptor antagonists in murine and human NK(3) receptors, and the lower potencies in the former should be taken into consideration when using murine disease models.

Amino Acid Sequence↗

PubMed2001

Variation in river water temperatures in an upland stream over a 30-year period.

Stream water temperature data from the Girnock burn, a 30-km2 catchment in Scotland were examined for systematic variation across 30 years of record (1968-1997). The data suggest that there has been no change in mean annual temperature with time, but at a seasonal level there is some indication of an increase in mean daily maximum temperatures during the winter (December to February) and spring (March to May) seasons. For the spring season, there is also evidence that mean temperature has increased. There are no apparent or obvious changes in stream flow to account for this. The strong relationship between air and stream temperatures (r2 = 0.96) implies that changes in the stream are the result of changes in the climate. It is possible that this may occur as a result of the effect of increasing air temperatures which may have also reduced the influence of snow and snowmelt on the catchment during the winter and spring seasons.

Journal Article↗

PubMed2001

Interleukin-8 receptor antagonists in pulmonary diseases.

Inflammatory cells are thought to be instrumental in the pathophysiology of pulmonary diseases, and control of their recruitment and activation in the lung would appear to be an attractive strategy for therapeutic intervention. Interleukin-8 and related CXC chemokines are involved in the function of neutrophils and T cells, and have been implicated in several lung diseases. Small-molecule antagonists of the interleukin-8 receptors have been identified, which may help elucidate the role of interleukin-8 and related chemokines in the pathophysiology of lung diseases.

Animals↗

PubMed2001

Differential modulation of endothelin ligand-induced contraction in isolated tracheae from endothelin B (ET(B)) receptor knockout mice.

The role of endothelin B (ET(B)) receptors in mediating ET ligand-induced contractions in mouse trachea was examined in ET(B) receptor knockout animals. Autoradiographic binding studies, using [(125)I]-ET-1, confirmed the presence of ET(A) receptors in tracheal and bronchial airway smooth muscle from wild-type (+/+) and homozygous recessive (-/-) ET(B) receptor knockout mice. In contrast, ET(B) receptors were not detected in airway tissues from (-/-) mice. In tracheae from (+/+) mice, the rank order of potencies of the ET ligands was sarafotoxin (Stx) S6c>ET-1>ET-3; Stx S6c had a lower efficacy than ET-1 or ET-3. In tissues from (-/-) mice there was no response to Stx S6c (up to 0.1 microM), whereas the maximum responses and potencies of ET-1 and ET-3 were similar to those in (+/+) tracheae. ET-3 concentration-response curve was biphasic in (+/+) tissues (via ET(A) and ET(B) receptor activation), and monophasic in (-/-) preparations (via stimulation of only ET(A) receptors). In (+/+) preparations SB 234551 (1 nM), an ET(A) receptor-selective antagonist, inhibited the secondary phase, but not the first phase, of the ET-3 concentration-response curve, whereas A192621 (100 nM), an ET(B) receptor-selective antagonist, had the opposite effect. In (-/-) tissues SB 234551 (1 nM), but not A192621 (100 nM), produced a rightward shift in ET-3 concentration-response curves. The results confirm the significant influence of both ET(A) and ET(B) receptors in mediating ET-1-induced contractions in mouse trachea. Furthermore, the data do not support the hypothesis of atypical ET(B) receptors. In this preparation ET-3 is not an ET(B) receptor-selective ligand, producing contractions via activation of both ET(A) and ET(B) receptors.

Animals↗

PubMed2001

Spawning success in Atlantic salmon (Salmo salar L.): a long-term DNA profiling-based study conducted in a natural stream.

Spawning success of Atlantic salmon (Salmo salar L.) was investigated, under near-natural conditions, in the Girnock Burn, an 8-km long tributary of the River Dee in Scotland. Employing minisatellite-based DNA profiling, mating outcomes were resolved over three spawning seasons by assigning parentage to progeny samples removed from spawning nests ('redds'). While individual spawning patterns differed markedly, consistent trends were present over the 3 years studied. Multiple spawning was found to be prevalent. More than 50% of anadromous spawners of both sexes contributed to more than one redd. Up to six redds for a single female and seven for a single male were detected. Both sexes ranged extensively. Distance between redds involving the same parent varied from a few metres to > 5 km. Distances > 1 km were common. Both males and females ranged to a similar extent. Range limit was not correlated to fish size. Pairs were not monogamous, both males and females mating with different partners at different sites. Size assortative mating was apparent among 1991 spawners but was not detected for 1992 or 1995. Redd superimposition was found to be common (17-22% of redds over the 3 years), although it was not correlated to the number of anadromous spawners present. High levels of nonanadromous mature parr mating success (40-50% of total progeny sampled) were recorded, and these likely contribute greatly to the effective population size. The relevance of these findings at the individual and population level is discussed, with particular reference to management implications.

Animals↗

PubMed2000

Chronic obstructive pulmonary disease: emerging therapies.

Despite the high prevalence of and mortality from chronic obstructive pulmonary disease, extensive research on the underlying pathophysiology and specific therapeutics for this disease is, relatively, in its infancy. Several novel molecular targets are being investigated as potential treatments for the disease. The most exciting new class of compounds is the phosphodiesterase 4 inhibitors; Ariflo (SB 207499)-a member of this class, and the most advanced in development (Phase III)-was reported recently to have significant clinical efficacy in patients with chronic obstructive pulmonary disease. Phosphodiesterase 4 inhibitors, such as Ariflo, possibly represent the most important advance in pulmonary medicine in recent years.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2000

Human urotensin-II is a potent spasmogen of primate airway smooth muscle.

The contractile profile of human urotensin-II (hU-II) was examined in primate airway and pulmonary vascular tissues. hU-II contracted tissues from different airway regions with similar potencies (pD(2)s from 8.6 to 9.2). However, there were regional differences in the efficacy of hU-II, with a progressive increase in the maximum contraction from trachea to smaller airway regions (from 9 to 41% of the contraction to 10 microM carbachol). hU-II potently contracted pulmonary artery tissues from different regions with similar potencies and efficacies: pD(2)s=8.7 to 9.3 and maximal contractions=79 to 86% of 60 mM KCl. hU-II potently contracted pulmonary vein preparations taken proximal to the atria, but had no effect in tissues from distal to the atria. This is the first report describing the contractile activity of hU-II in airways and suggests that the potential pathophysiological role of this peptide in lung diseases warrants investigation.

Animals↗

PubMed2000

Differences in time-related cardiopulmonary responses to hypoxia in three rat strains.

The cardiopulmonary profile of three rat strains (Sprague-Dawley, Wistar and High altitude-sensitive) was compared upon exposure to hypoxia (9% O2) for 0, 7 or 14 days. No differences were observed among the in vitro contractile (ET-1) and relaxant (carbachol) responses of pulmonary artery isolated from the three strains during normoxia. Chronic hypoxia decreased ET-1 contractile responses and diminished relaxant responses to carbachol similarly in all strains. In Sprague-Dawley, Wistar and High altitude-sensitive rats, pulmonary arterial pressure rose time-dependently and was elevated by 108%, 116% and 167%, respectively, after 14 days of hypoxia compared to normoxic controls. Right ventricular hypertrophy was increased by 51%, 93% and 55%, respectively, at 14 days. Hypoxia-induced hypertrophy and medial thickening in the pulmonary vasculature were more pronounced in High altitude-sensitive rats. Sprague-Dawley exhibited hypoxia-induced airway hyperresponsiveness to intravenous methacholine, but there were no hypoxia- or strain-related differences in in vitro tracheal contractility. Although each strain exhibited greater sensitivity for a particular hypoxia-induced parameter, pulmonary vascular functional and structural changes suggest that High altitude-sensitive rats represent a choice model of hypoxia-induced pulmonary hypertension.

Altitude↗

PubMed2000

Targeted disruption of the endothelin-B-receptor gene attenuates inflammatory nociception and cutaneous inflammation in mice.

Endothelin-1 (ET-1) has been suggested to have a potential function as an inflammatory mediator. The study reported here assessed the putative inflammatory/nociceptive actions of the ET isopeptides using endothelin-B (ET(B))-receptor knockout (KO) mice and ET(A)- (SB 234551) and ET(B)- (A192621) selective antagonists. Phenylbenzoquinone (PBQ)-induced algesia was evident in the wild-type (WT) ET(B) (+/+) mice, attenuated by 80% in the heterozygous ET(B) (+/-) mice, and absent in the ET(B) (-/-) homozygotes. This was reproduced pharmacologically in WT ET(B) (+/+) mice where the algesic effect of PBQ was inhibited 74% by A192621, but unaffected by SB 234551 (both at 25 mg/kg p.o.). Similar observations were made in a model of cutaneous inflammation: ET(B) (+/+) mice had a marked inflammatory response to topical arachidonic acid, ET(B) (+/-) and ET(B) (-/-) mice had significantly reduced edema responses (37% and 65% inhibition). Neutrophil infiltration was reduced in the ET(B) (+/-) and ET(B) (-/-) mice (51% and 65% reduction, respectively). Topical administration of A192621 (500 microg/ear) inhibited arachidonic acid-induced swelling (39%) in WT ET(B) (+/+) mice. Collectively, these results support a role for the ET(B)-receptor in the mediation of inflammatory pain and cutaneous inflammatory responses. As such, the development of ET(B)-receptor-selective antagonists may be of therapeutic utility in the treatment of inflammatory disorders.

Animals↗

PubMed2000

Evidence that the proposed novel human "neurokinin-4" receptor is pharmacologically similar to the human neurokinin-3 receptor but is not of human origin.

There have been proposals that the tachykinin receptor classification should be extended to include a novel receptor, the "neurokinin-4" receptor (NK-4R), which has a close homology with the human NK-3 receptor (hNK-3R). We compared the pharmacological and molecular biological characteristics of the hNK-3R and NK-4R. Binding experiments, with (125)I-[MePhe(7)]-NKB binding to HEK 293 cell membranes transiently expressing the hNK-3R (HEK 293-hNK-3R) or NK-4R (HEK 293-NK-4R), and functional studies (Ca(2+) mobilization in the same cells) revealed a similar profile of sensitivity to tachykinin agonists and antagonists for both receptors; i.e., in binding studies with the hNK-3R, MePhe(7)-NKB > NKB > senktide >> NKA = Substance P; with the NK-4R, MePhe(7)-NKB > NKB = senktide >> Substance P = NKA; and with antagonists, SB 223412 = SR 142801 > SB 222200 >> SR 48968 >> CP 99994 for both hNK-3R and NK-4R. Thus, the pharmacology of the two receptors was nearly identical. However, attempts to isolate or identify the NK-4R gene by using various molecular biological techniques were unsuccessful. Procedures, including nested polymerase chain reaction studies, that used products with restriction endonuclease sites specific for either hNK-3R or NK-4R, failed to demonstrate the presence of NK-4R in genomic DNA from human, monkey, mouse, rat, hamster, or guinea pig, and in cDNA libraries from human lung, brain, or heart, whereas the hNK-3R was detectable in the latter libraries. In view of the failure to demonstrate the presence of the putative NK-4R it is thought to be premature to extend the current tachykinin receptor classification.

Binding, Competitive↗

PubMed2000

SB 239063, a p38 MAPK inhibitor, reduces neutrophilia, inflammatory cytokines, MMP-9, and fibrosis in lung.

The effects of a second generation p38 mitogen-activated protein kinase (MAPK) inhibitor, SB 239063 [trans-1-(4-hydroxycyclohexyl)-4-(4-fluorophenyl)-5-(2-methoxypyridim idi n-4-yl)imidazole; IC(50) = 44 nM vs. p38 alpha], were assessed in models that represent different pathological aspects of chronic obstructive pulmonary disease (COPD) [airway neutrophilia, enhanced cytokine formation and increased matrix metalloproteinase (MMP)-9 activity] and in a model of lung fibrosis. Airway neutrophil infiltration and interleukin (IL)-6 levels, assessed by bronchoalveolar lavage 48 h after lipopolysaccharide (LPS) inhalation, were inhibited dose dependently by 3-30 mg/kg of SB 239063 given orally twice a day. In addition, SB 239063 (30 mg/kg orally) attenuated IL-6 bronchoalveolar lavage fluid concentrations (>90% inhibition) and MMP-9 activity (64% inhibition) assessed 6 h after LPS exposure. In guinea pig cultured alveolar macrophages, SB 239063 inhibited LPS-induced IL-6 production (IC(50) of 362 nM). In a bleomycin-induced pulmonary fibrosis model in rats, treatment with SB 239063 (2.4 or 4.8 mg/day via osmotic pump) significantly inhibited bleomycin-induced right ventricular hypertrophy (indicative of secondary pulmonary hypertension) and increases in lung hydroxyproline synthesis (indicative of collagen synthesis and fibrosis). Therefore, SB 239063 demonstrates activity against a range of sequelae commonly associated with COPD and fibrosis, supporting the therapeutic potential of p38 MAPK inhibitors such as SB 239063 in chronic airway disease.

Animals↗

PubMed2000

Tumor necrosis factor-alpha-induced secretion of RANTES and interleukin-6 from human airway smooth-muscle cells. Modulation by cyclic adenosine monophosphate.

Although 3':5' cyclic adenosine monophosphate (cAMP) is known to modulate cytokine production in a number of cell types, little information exists regarding cAMP-mediated effects on this synthetic function of human airway smooth-muscle (HASM) cells. We examined the effect of increasing intracellular cAMP concentration ([cAMP](i)) on tumor necrosis factor (TNF)-alpha-induced regulated on activation, normal T cells expressed and secreted (RANTES) and interleukin (IL)-6 secretion from cultured HASM cells. Pretreatment of HASM with prostaglandin (PG) E(2), forskolin, or dibutyryl cAMP inhibited TNF-alpha-induced RANTES secretion but increased TNF-alpha-induced IL-6 secretion. Moreover, stimulation with PGE(2), forskolin, or dibutyryl cAMP alone increased basal IL-6 secretion in a concentration-dependent manner. SB 207499, a specific phosphodiesterase type 4 inhibitor, augmented the inhibitory effects of PGE(2) and forskolin on TNF-alpha-induced RANTES. Collectively, these data demonstrate that increasing [cAMP](i) in HASM effectively increases IL-6 secretion but reduces RANTES secretion promoted by TNF-alpha. Reverse transcriptase/polymerase chain reaction and ribonuclease protection assays suggested that these opposite effects of increased [cAMP](i) on TNF-alpha- induced IL-6 and RANTES secretion may occur at the transcriptional level. Accordingly, we examined the effects of TNF- alpha and cAMP on the regulation of nuclear factor (NF)-kappaB, a transcription factor known to modulate cytokine synthesis in numerous cell types. Stimulation of HASM cells with TNF-alpha increased NF-kappaB DNA-binding activity. However, increased [cAMP](i) in HASM neither activated NF-kappaB nor altered TNF-alpha- induced NF-kappaB DNA-binding activity. These results were confirmed using a NF-kappaB-luciferase reporter assay. Together, our data suggest that TNF-alpha-induced IL-6 and RANTES secretion may be associated with NF-kappaB activation, and that inhibition of TNF-alpha-stimulated RANTES secretion and augmentation of IL-6 secretion by increased [cAMP](i) in HASM cells occurs via an NF-kappaB-independent mechanism.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2000

The antitussive activity of delta-opioid receptor stimulation in guinea pigs.

In this study, the activity of the delta-opioid receptor subtype-selective agonist, SB 227122, was investigated in a guinea pig model of citric acid-induced cough. Parenteral administration of selective agonists of the delta-opioid receptor (SB 227122), mu-opioid receptor (codeine and hydrocodone), and kappa-opioid receptor (BRL 52974) produced dose-related inhibition of citric acid-induced cough with ED(50) values of 7.3, 5.2, 5.1, and 5.3 mg/kg, respectively. The nonselective opioid receptor antagonist, naloxone (3 mg/kg, i.m.), attenuated the antitussive effects of codeine or SB 227122, indicating that the antitussive activity of both compounds is opioid receptor-mediated. The delta-receptor antagonist, SB 244525 (10 mg/kg, i.p.), inhibited the antitussive effect of SB 227122 (20 mg/kg, i.p.). In contrast, combined pretreatment with beta-funaltrexamine (mu-receptor antagonist; 20 mg/kg, s.c.) and norbinaltorphimine (kappa-receptor antagonist; 20 mg/kg, s.c.), at doses that inhibited the antitussive activity of mu- and kappa-receptor agonists, respectively, was without effect on the antitussive response of SB 227122 (20 mg/kg, i.p.). The sigma-receptor antagonist rimcazole (3 mg/kg, i.p.) inhibited the antitussive effect of dextromethorphan (30 mg/kg, i.p.), a sigma-receptor agonist, but not that of SB 227122. These studies provide compelling evidence that the antitussive effects of SB 227122 in this guinea pig cough model are mediated by agonist activity at the delta-opioid receptor.

Animals↗

PubMed2000

SB 239063, a potent p38 MAP kinase inhibitor, reduces inflammatory cytokine production, airways eosinophil infiltration, and persistence.

The anti-inflammatory/antiallergic activity of a novel second-generation p38 mitogen-activated protein kinase inhibitor, SB 239063[trans-1-(4-hydroxycyclohexyl) -4-(4-fluorophenyl)-5-(2-methoxypyridimidin-4-yl)imidazole], was investigated in vivo and in vitro. SB 239063 had an IC(50) of 44 nM for inhibition of recombinant purified human p38alpha. In lipopolysaccharide-stimulated human peripheral blood monocytes, SB 239063 inhibited interleukin-1 and tumor necrosis factor-alpha production (IC(50) values = 0.12 and 0.35 microM, respectively). A role for p38 kinase in cytokine-associated inflammation in the mouse was shown by p38 activation in the lung and inhibition of lipopolysaccharide-induced tumor necrosis factor-alpha production by SB 239063 (ED(50) = 5.8 mg/kg p.o.). Antiallergic activity was demonstrated by essential abolition (approximately 93% inhibition) of inhaled ovalbumin (OA)-induced airway eosinophilia by SB 239063 (12 mg/kg p.o.), measured by bronchoalveolar lavage (BAL) in OA-sensitized mice. In addition, p38 kinase was found by Western analysis to be activated in guinea pig lung. Administration of SB 239063 (10 or 30 mg/kg p.o.) in conscious guinea pigs markedly reduced ( approximately 50% inhibition) OA-induced pulmonary eosinophil influx, measured by BAL 24 h after antigen. SB 239063 (10 mg/kg b.i.d. p.o.) administered after leukotriene D(4) inhalation, reduced by 60% the persistent airway eosinophilia seen at 4 days. Apoptosis of cultured eosinophils isolated from guinea pig BAL was increased by SB 239063 (1-10 microM) in the presence of interleukin-5. These results indicate that SB 239063 is a potent inhibitor of inflammatory cytokine production, inhibits eosinophil recruitment, in addition to enhancing apoptosis of these cells. Collectively, the results support the potential utility of p38 kinase inhibitors, such as SB 239063, for the treatment of asthma and other inflammatory disorders.

Administration, Inhalation↗

PubMed2000

Role of neurokinin receptors in the behavioral effect of intravesical antigen infusion in guinea pig bladder.

PURPOSE: To characterize a guinea pig behavior model of bladder pain due to intravesical antigen infusion and to determine the role of neurokinin receptor subtypes in mediating this behavior. MATERIALS AND METHODS: The influence of subtype-selective neurokinin receptor antagonists on increased abdominal licking behavior in response to intravesical antigen infusion in guinea pigs immunized with ovalbumin (OA) was determined. RESULTS: Intravesical OA infusion for 30 minutes induced a significantly greater frequency (about 3-fold) of abdominal licking behavior than during either the 30 minutes pre-challenge or post challenge saline infusions. Treatment with IP capsaicin 7 to 10 days before OA challenge abolished the intravesical antigen-induced behavior. IP injection of the NK1 receptor antagonist CP 99994 (10 mg./kg. or 30 mg./kg.), 30 minutes pretreatment, inhibited the increase in the average number of abdominal licks during antigen infusion. The 30 mg./kg., but not the 10 mg./kg. dose increased the percent of animals showing antinociceptive activity (defined as 4 or less abdominal licks during the antigen infusion). The NK2 receptor antagonist SR 48968 reduced the antigen-induced abdominal licking behavior at IP doses of 3 and 10 mg./kg. but was ineffective at 1 mg./kg. The NK3 receptor antagonist SB 235375 (30 mg./kg., IP) did not reduce this behavior. CONCLUSIONS: These results suggest a role for activation of NK1 and NK2, but not NK3 receptors, by tachykinins released from capsaicin-sensitive nerves, in the increased abdominal licking behavior response of guinea pigs to intravesical antigen infusion.

Administration, Intravesical↗

PubMed2000

Nonpeptide tachykinin receptor antagonists. II. Pharmacological and pharmacokinetic profile of SB-222200, a central nervous system penetrant, potent and selective NK-3 receptor antagonist.

The pharmacological and pharmacokinetic profile of SB-222200 [(S)-(-)-N-(alpha-ethylbenzyl)-3-methyl-2-phenylquinoline-4-car boxami de], a human NK-3 receptor (hNK-3R) antagonist, was determined. SB-222200 inhibited (125)I-[MePhe(7)]neurokinin B (NKB) binding to Chinese hamster ovary (CHO) cell membranes stably expressing the hNK-3 receptor (CHO-hNK-3R) with a K(i) = 4.4 nM and antagonized NKB-induced Ca(2+) mobilization in HEK 293 cells stably expressing the hNK-3 receptor (HEK 293-hNK-3R) with an IC(50) = 18.4 nM. SB-222200 was selective for hNK-3 receptors compared with hNK-1 (K(i) > 100,000 nM) and hNK-2 receptors (K(i) = 250 nM). In HEK 293 cells transiently expressing murine NK-3 receptors (HEK 293-mNK-3R), SB-222200 inhibited binding of (125)I-[MePhe(7)]NKB (K(i) = 174 nM) and antagonized NKB (1 nM)-induced calcium mobilization (IC(50) = 265 nM). In mice oral administration of SB-222200 produced dose-dependent inhibition of behavioral responses induced by i.p. or intracerebral ventricular administration of the NK-3 receptor-selective agonist, senktide, with ED(50) values of approximately 5 mg/kg. SB-222200 effectively crossed the blood-brain barrier in the mouse and rat. The inhibitory effect of SB-222200 against senktide-induced behavioral responses in the mouse correlated significantly with brain, but not plasma, concentrations of the compound. Pharmacokinetic evaluation of SB-222200 in rat after oral administration (8 mg/kg) indicated sustained plasma concentrations (C(max) = about 400 ng/ml) and bioavailability of 46%. The preclinical profile of SB-222200, demonstrating high affinity, selectivity, reversibility, oral activity, and central nervous system penetration, suggests that it will be a useful tool compound to define the physiological and pathophysiological roles of NK-3 receptors, in particular in the central nervous system.

Animals↗

PubMed1999

Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14.

Urotensin-II (U-II) is a vasoactive 'somatostatin-like' cyclic peptide which was originally isolated from fish spinal cords, and which has recently been cloned from man. Here we describe the identification of an orphan human G-protein-coupled receptor homologous to rat GPR14 and expressed predominantly in cardiovascular tissue, which functions as a U-II receptor. Goby and human U-II bind to recombinant human GPR14 with high affinity, and the binding is functionally coupled to calcium mobilization. Human U-II is found within both vascular and cardiac tissue (including coronary atheroma) and effectively constricts isolated arteries from non-human primates. The potency of vasoconstriction of U-II is an order of magnitude greater than that of endothelin-1, making human U-II the most potent mammalian vasoconstrictor identified so far. In vivo, human U-II markedly increases total peripheral resistance in anaesthetized non-human primates, a response associated with profound cardiac contractile dysfunction. Furthermore, as U-II immunoreactivity is also found within central nervous system and endocrine tissues, it may have additional activities.

Amino Acid Sequence↗