Pharmacological effects of cannabinoid ligands are thought to be mediated through cannabinoid CB1 and CB2 receptor subtypes. Sequence analysis revealed that rat and human cannabinoid CB2 receptors ...are divergent and share 81% amino acid homology. Pharmacological analysis of the possible species differences between rat and human cannabinoid CB2 receptors was performed using radioligand binding and functional assays. Pronounced species selectivity at the rat cannabinoid CB2 receptor (50- to 140-fold) was observed with AM-1710 (3-(1,1-Dimethyl-heptyl)-1-hydroxy-9-methoxy-benzocchromen-6-one) and AM-1714 (3-(1,1-Dimethyl-heptyl)-1-9-dihydroxy-benzocchromen-6-one). In contrast, JWH-015 ((2-Methyl-1-propyl-1H-indol-3-yl)-napthalen-1-yl-methanone) was 3- to 10-fold selective at the human cannabinoid CB2 receptor. Endocannabinoid ligands were more human receptor selective. Cannabinoid CB2 receptor antagonist, AM-630 ((6-Iodo-2-methyl-1-(2-morpholin-4-yl-ethyl)-1H-indol-3-yl)-(4-methoxy-phenyl)-methanone) was more potent at the rat receptor in radioligand binding and functional assays than that of the human receptor. The findings of the pharmacological differences between the human and rat cannabinoid CB2 receptors in this study provide critical information for characterizing cannabinoid ligands in in vivo rodent models for drug discovery purpose.
In candidate gene era, dozens of single-nucleotide polymorphisms (SNPs) within renin-angiotensin-aldosterone system (RAAS) have been reported to be significantly associated with hypertension. ...However, the unbiased genome-wide association studies (GWAS) rarely identified the SNPs within RAAS were associated with hypertension or blood pressure (BP) traits. In order to figure out whether genetic polymorphisms of RAAS are really associated with hypertension, we systemically searched the GWAS Catalogue and identified all the known RAAS genes and relevant diseases/traits. After data processing, we found that polymorphisms within REN, AGT, ACE2, CYP11B2, ATP6AP2 and HSD11B2 were not associated with any disease or trait. SNPs within ACE, AGTR1, AGTR2, MAS1, RENBP and NR3C2 were associated with other diseases or traits, but showed no direct connection with hypertension. The only SNP associated with a BP trait, systolic BP was rs17367504. However, it is located in the intronic region of MTHFR near many plausible candidate genes, including CLCN6, NPPA, NPPB and AGTRAP. Therefore, the effect of RAAS polymorphisms may have been overestimated during the 'candidate gene era'. In the time of 'precision medicine', the power of RAAS variants needs to be reconsidered when evaluating one's susceptibility of hypertension.
The transient receptor potential ankyrin-1 (TRPA1) channel has emerged as an attractive target for development of analgesic and anti-inflammatory drugs. However, drug discovery efforts targeting ...TRPA1 have been hampered by differences between human and rodent species. Many compounds have been identified to have antagonist activity at human TRPA1 (hTRPA1), but when tested at rat TRPA1 (rTRPA1) and mouse TRPA1 (mTRPA1), they show reduced potency as antagonists, no effect, or agonist activity. These compounds are excluded from further drug development because they cannot be tested in preclinical studies using conventional rat/mouse models. To broaden our understanding of species-specific differences, we cloned and functionally characterized rhesus monkey TRPA1 (rhTRPA1) and compared its pharmacological profile to hTRPA1, rTRPA1, and mTRPA1 channels. The functional activities of a diverse group of TRPA1 ligands (both reactive and nonreactive) were determined in a fluorescent Ca²⁺ influx assay, using transiently transfected human embryonic kidney 293-F cells. 4-Methyl-N-2,2,2-trichloro-1-(4-nitro-phenylsulfanyl)-ethyl-benzamide, menthol, and caffeine displayed species-specific differential pharmacology at TRPA1. The pharmacological profile of the rhTRPA1 channel was found to be similar to the hTRPA1 channel. In contrast, the rTRPA1 and mTRPA1 channels closely resembled each other but were pharmacologically distinct from either hTRPA1 or rhTRPA1 channels. Our findings reveal that TRPA1 function differs between primate and rodent species and suggest that rhesus monkey could serve as a surrogate species for humans in preclinical studies.
Hypertension is the most significant modifiable risk factor for cerebrovascular disease. It has been estimated that about 54% of strokes worldwide can be attributed to hypertension. However, there ...has not been a systematic study assessing the shared genetic susceptibility to hypertension and stroke on a genome-wide level. In this study, SNPs associated with essential hypertension and stroke were collected from the NHGRI-EBI GWAS catalog, and genotype imputation were conducted using information from the 1000 Genomes Project. Subsequently, the SNPs and the mapped genes were compared between the two diseases. Finally, functional clustering was performed, and the enriched GO terms and KEGG pathways were further compared between hypertension and stroke. Comparison of these two groups of SNPs and genes identified only one shared SNP (rs3184504) and 11 shared genes. After genotype imputation, 129 shared SNPs and 16 shared genes were identified. These genes were significantly enriched in 10 GO terms, which were mainly involved in lipoprotein and triglyceride metabolism. Additionally, KEGG analysis identified one pathway, glycerolipid metabolism, as being significantly enriched in both diseases. The present study strongly suggests that the gene network regulating lipid metabolism and blood circulation is the major shared genetic etiology of hypertension and stroke.
Background and purpose:
The histamine H
4
receptor is widely expressed in cells of immune origin and has been shown to play a role in a variety of inflammatory processes mediated by histamine. In ...this report, we describe the
in vitro
and
in vivo
anti‐inflammatory properties of a potent histamine H
4
receptor antagonist, A‐940894 (4‐piperazin‐1‐yl‐6,7‐dihydro‐5H‐benzo6,7cyclohepta1,2‐dpyrimidin‐2‐ylamine).
Experimental approach:
We have analysed the pharmacological profile of A‐940894 at mouse native, rat recombinant and human recombinant and native, histamine H
4
receptors by radioligand binding, calcium mobilization, mast cell shape change, eosinophil chemotaxis assays and in the mouse model of zymosan‐induced peritonitis.
Key results:
A‐940894 potently binds to both human and rat histamine H
4
receptors and exhibits considerably lower affinity for the human histamine H
1
, H
2
or H
3
receptors. It potently blocked histamine‐evoked calcium mobilization in the fluorometric imaging plate reader assays and inhibited histamine‐induced shape change of mouse bone marrow‐derived mast cells and chemotaxis of human eosinophils
in vitro
. In a mouse mast cell‐dependent model of zymosan‐induced peritonitis, A‐940894 significantly blocked neutrophil influx and reduced intraperitoneal prostaglandin D
2
levels. Finally, A‐940894 has good pharmacokinetic properties, including half‐life and oral bioavailability in rats and mice.
Conclusions and Implications:
These data suggest that A‐940894 is a potent and selective histamine H
4
receptor antagonist with pharmacokinetic properties suitable for long‐term
in vivo
testing and could serve as a useful tool for the further characterization of histamine H
4
receptor pharmacology.
Histamine affects homeostatic mechanisms, including food and water consumption, by acting on central nervous system (CNS) receptors. Presynaptic histamine H
3 receptors regulate release of histamine ...and other neurotransmitters, and histamine H
3 receptor antagonists enhance neurotransmitter release. A-331440 {4′-3-(3(
R)-(dimethylamino)-pyrrolidin-1-yl)-propoxy-biphenyl-4-carbonitrile} is a histamine H
3 receptor antagonist which binds potently and selectively to both human and rat histamine H
3 receptors (
K
i≤25 nM). Mice were stabilized on a high-fat diet (45 kcal % lard) prior to 28-day oral b.i.d. dosing for measurement of obesity-related parameters. A-331440 administered at 0.5 mg/kg had no significant effect on weight, whereas 5 mg/kg decreased weight comparably to dexfenfluramine (10 mg/kg). A-331440 administered at 15 mg/kg reduced weight to a level comparable to mice on the low-fat diet. The two higher doses reduced body fat and the highest dose also normalized an insulin tolerance test. These data show that the histamine H
3 receptor antagonist, A-331440, has potential as an antiobesity agent.
Background and purpose: Activation of cannabinoid (CB) receptors decreases nociceptive transmission in inflammatory or neuropathic pain states. However, the effects of CB receptor agonists in ...post‐operative pain remain to be investigated. Here, we characterized the anti‐allodynic effects of WIN 55,212‐2 (WIN) in a rat model of post‐operative pain.
Experimental approach: WIN 55,212‐2 was characterized in radioligand binding and in vitro functional assays at rat and human CB1 and CB2 receptors. Analgesic activity and site(s) of action of WIN were assessed in the skin incision‐induced post‐operative pain model in rats; receptor specificity was investigated using selective CB1 and CB2 receptor antagonists.
Key results: WIN 55,212‐2 exhibited non‐selective affinity and agonist efficacy at human and rat CB1 versus CB2 receptors. Systemic administration of WIN decreased injury‐induced mechanical allodynia and these effects were reversed by pretreatment with a CB1 receptor antagonist, but not with a CB2 receptor antagonist, given by systemic, intrathecal and supraspinal routes. In addition, peripheral administration of both CB1 and CB2 antagonists blocked systemic WIN‐induced analgesic activity.
Conclusions and implications: Both CB1 and CB2 receptors were involved in the peripheral anti‐allodynic effect of systemic WIN in a pre‐clinical model of post‐operative pain. In contrast, the centrally mediated anti‐allodynic activity of systemic WIN is mostly due to the activation of CB1 but not CB2 receptors at both the spinal cord and brain levels. However, the increased potency of WIN following i.c.v. administration suggests that its main site of action is at CB1 receptors in the brain.
British Journal of Pharmacology (2009) 157, 645–655; doi:10.1111/j.1476‐5381.2009.00184.x; published online 3 April 2009
Presynaptic histamine H
3 receptors (H
3R) regulate neurotransmitter release in the central nervous system, suggesting an important role for H
3 ligands in human diseases such as cognitive disorders, ...sleep disturbances, epilepsy, or obesity. Drug development for many of these human diseases relies upon rodent-based models. Although there is significant sequence homology between the human and rat H
3Rs, some compounds show distinct affinity profiles. To identify the amino acids responsible for these species disparities, various mutant receptors were generated and their pharmacology studied. The N-terminal portion was shown to determine the species differences in ligand binding since a chimeric H
3R containing N-terminal human and C-terminal rat receptor sequences exhibited similar pharmacology to the human receptor. Sequence analysis and molecular modeling studies suggested key amino acids at positions 119 and 122 in transmembrane region 3 play important roles in ligand recognition. Mutant receptors changing amino acids 119 or 122 of the human receptor to those in the rat improved ligand binding affinities and functional potencies of antagonist ligands, confirming the significant role that these amino acids play in species-related pharmacological differences. A model has been developed to elucidate the ligand receptor interactions for H
3Rs, and pharmacological aspects of this model are described.
Histamine H
3 receptors regulate the release of a variety of central neurotransmitters involved in cognitive processes. A-349821 ((4′-(3-((
...R,R)2,5-dimethyl-pyrrolidin-1-yl)-propoxy)-biphenyl-4-yl)-morpholin-4-yl-methanone) is a novel, non-imidazole H
3 receptor ligand, displaying high affinity for recombinant rat and human H
3 receptors, with p
K
i values of 9.4 and 8.8, respectively, and high selectivity for the H
3 receptor versus H
1, H
2, and H
4 histamine receptors. A-349821 is a potent H
3 receptor antagonist in a variety of models using recombinant human and rat receptors, reversing agonist induced changes in cyclic AMP formation (p
K
b = 8.2 and p
K
b = 8.1, respectively),
35
S
-GTPγS binding (p
K
b = 9.3 and p
K
b = 8.6, respectively) and calcium levels (human p
K
b = 8.3). In native systems, A-349821 competitively reversed agonist induced inhibition of electric field stimulated guinea-pig ileum (p
A
2 = 9.5) and histamine-mediated inhibition of
3
H
-histamine release from rat brain cortical synaptosomes (p
K
b = 9.2). Additionally, A-349821 inhibited constitutive GTPγS binding at both rat and human H
3 receptors with respective pEC
50 values of 9.1 and 8.6, demonstrating potent inverse agonist properties. In behavioral studies, A-349821 (0.4
mg/kg—4
mg/kg) potently blocked (
R)-α-methylhistamine-induced dipsogenia in mice. The compound also enhanced cognitive activity in a five-trial inhibitory avoidance model in spontaneously hypertensive rat (SHR) pups at doses of 1–10
mg/kg, with the 1
mg/kg dose showing comparable efficacy to a fully efficacious dose of ciproxifan (3
mg/kg). These doses of A-349821 were without effect on spontaneous locomotor activity. Thus, A-349821 is a novel, selective non-imidazole H
3 antagonist/inverse agonist with balanced high potency across species and favorable cognition enhancing effects in rats.
XML support is being added to existing database management systems (DBMSs) and native XML systems are being developed both in industry and in academia. The individual performance characteristics of ...these approaches as well as the relative performance of various systems is an ongoing concern. In this paper we discuss the XBench XML benchmark and report on the relative performance of various DBMSs. XBench is a family of XML benchmarks which recognizes that the XML data that DBMSs manage are quite varied and no one database schema and workload can properly capture this variety. Thus, the members of this benchmark family have been defined for capturing diverse application domains.
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