Cerebrospinal fluid cytokine dynamics differ between Alzheimer disease patients and elderly controls.

The time courses of levels of multiple plasma and cerebrospinal fluid (CSF) cytokines in patients with Alzheimer disease (AD) and in age-matched control subjects were compared. Interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, granulocyte-macrophage colony-stimulating factor, interferon-γ, and tumor necrosis factor alpha levels were measured 7 times over a 24-hour period in plasma and CSF using a lumbar catheter. Baseline plasma and CSF cytokine levels were found to be similar in AD and control subjects.

Comparing levels of biochemical markers in CSF from cannulated and non-cannulated rats.

Cerebrospinal fluid (CSF) is commonly used for assessing biomarkers of drug efficacy or disease progression in the central nervous system. Studies of CSF from pre-clinical species can characterize biomarkers for use in clinical trials. However, obtaining CSF from pre-clinical species, particularly rodents, can be challenging due to small body sizes, and consequently, low volumes of CSF.

Rigidified 2-aminopyrimidines as histamine H4 receptor antagonists: effects of substitution about the rigidifying ring.

Three novel series of histamine H(4) receptor (H(4)R) antagonists containing the 2-aminopyrimidine motif are reported. The best of these compounds display good in vitro potency in both functional and binding assays. In addition, representative compounds are able to completely block itch responses when dosed ip in a mouse model of H(4)-agonist induced scratching, thus demonstrating their activities as H(4)R antagonists.

H4 receptor antagonism exhibits anti-nociceptive effects in inflammatory and neuropathic pain models in rats.

The histamine H(4) receptor (H(4)R) is expressed primarily on cells involved in inflammation and immune responses. To determine the potential role of H(4)R in pain transmission, the effects of JNJ7777120, a potent and selective H(4) antagonist, were characterized in preclinical pain models. Administration of JNJ7777120 fully blocked neutrophil influx observed in a mouse zymosan-induced peritonitis model (ED(50)=17 mg/kg s.

Design of a new histamine H3 receptor antagonist chemotype: (3aR,6aR)-5-alkyl-1-aryl-octahydropyrrolo[3,4-b]pyrroles, synthesis, and structure-activity relationships.

A new histamine H3 receptor (H3R) antagonist chemotype 1 was designed by combining key pharmacophoric elements from two different precursor structural series and then simplifying and optimizing the resulting combined structural features. First, analogues were made based on a previously identified conessine-based H3R antagonist series. While the first analogues 11 and 15 showed no antagonistic activity to H3R, the mere addition of a key moiety found in the reference compound 7 (ABT-239) elevated the series to high potency at H3R.

cis-4-(Piperazin-1-yl)-5,6,7a,8,9,10,11,11a-octahydrobenzofuro[2,3-h]quinazolin-2-amine (A-987306), a new histamine H4R antagonist that blocks pain responses against carrageenan-induced hyperalgesia.

cis-4-(Piperazin-1-yl)-5,6,7a,8,9,10,11,11a-octahydrobenzofuro[2,3-h]quinazolin-2-amine, 4 (A-987306) is a new histamine H(4) antagonist. The compound is potent in H(4) receptor binding assays (rat H(4), K(i) = 3.4 nM, human H(4) K(i) = 5.

Cloning and characterization of the monkey histamine H3 receptor isoforms.

We have recently identified three splice isoforms of the histamine H(3) receptor in multiple brain regions of cynomolgus monkey (Macaca fascicularis). Two of the novel isoforms displayed a deletion in the third intracellular loop (H(3)(413) and H(3)(410)), the third isoform H(3)(335) displayed a deletion in the i3 intracellular loop and a complete deletion of the putative fifth transmembrane domain TM5. We have confirmed by RT-PCR the expression of full-length H(3)(445) mRNA as well as H(3)(413), H(3)(410), and H(3)(335) splice isoform mRNA in multiple monkey brain regions including the frontal, parietal and occipital cortex, parahippocampal gyrus, hippocampus, amygdala, caudate nucleus, putamen, thalamus, hypothalamus, and cerebellum.

Rotationally constrained 2,4-diamino-5,6-disubstituted pyrimidines: a new class of histamine H4 receptor antagonists with improved druglikeness and in vivo efficacy in pain and inflammation models.

A new structural class of histamine H 4 receptor antagonists (6-14) was designed based on rotationally restricted 2,4-diaminopyrimidines. Series compounds showed potent and selective in vitro H 4 antagonism across multiple species, good CNS penetration, improved PK properties compared to reference H 4 antagonists, functional H 4 antagonism in cellular and in vivo pharmacological assays, and in vivo anti-inflammatory and antinociceptive efficacy. One compound, 10 (A-943931), combined the best features of the series in a single molecule and is an excellent tool compound to probe H 4 pharmacology.

Structure-activity studies on a series of a 2-aminopyrimidine-containing histamine H4 receptor ligands.

A series of 2-aminopyrimidines was synthesized as ligands of the histamine H4 receptor (H4R). Working in part from a pyrimidine hit that was identified in an HTS campaign, SAR studies were carried out to optimize the potency, which led to compound 3, 4- tert-butyl-6-(4-methylpiperazin-1-yl)pyrimidin-2-ylamine. We further studied this compound by systematically modifying the core pyrimidine moiety, the methylpiperazine at position 4, the NH2 at position 2, and positions 5 and 6 of the pyrimidine ring.

The alkaloid conessine and analogues as potent histamine H3 receptor antagonists.

The naturally occurring alkaloid, conessine (6), was discovered to bind to histamine H3 receptors in a radioligand-based high-throughput screen. Conessine displayed high affinity at both rat and human H3 receptors (pKi = 7.61 and 8.

A robust and high-capacity [(35)S]GTPgammaS binding assay for determining antagonist and inverse agonist pharmacological parameters of histamine H(3) receptor ligands.

Guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding assays were established and utilized as a reliable and high-capacity functional assay for determining antagonist and inverse agonist pharmacological parameters of novel histamine H(3) ligands, at the recombinant human H(3) receptor. [(35)S]GTPgammaS binding assays were performed with membranes prepared from human embryonic kidney 293 cells stably expressing the full-length (445 amino acids) human H(3) receptor isoform, at approximately 1 pmol/mg of protein. Utilizing robotic liquid handling, assay filtration, and scintillation counting in a 96-well format, concentration-response curves were determined for up to 40 compounds per assay.

An 80-amino acid deletion in the third intracellular loop of a naturally occurring human histamine H3 isoform confers pharmacological differences and constitutive activity.

In this article, we pharmacologically characterized two naturally occurring human histamine H3 receptor (hH3R) isoforms, hH3R(445) and hH3R(365). These abundantly expressed splice variants differ by a deletion of 80 amino acids in the intracellular loop 3. In this report, we show that the hH3R(365) is differentially expressed compared with the hH3R(445) and has a higher affinity and potency for H3R agonists and conversely a lower potency and affinity for H3R inverse agonists.

Novel heterocyclic-substituted benzofuran histamine H3 receptor antagonists: in vitro properties, drug-likeness, and behavioral activity.

Three novel heterocyclic benzofurans A-688057 (1), A-687136 (2), and A-698418 (3) were profiled for their in vitro and in vivo properties as a new series of histamine H(3) receptor antagonists. The compounds were all found to have nanomolar potency in vitro at histamine H(3) receptors, and when profiled in vivo for CNS activity, all were found active in an animal behavioral model of attention. The compound with the most benign profile versus CNS side effects was selected for greater scrutiny of its in vitro properties and overall drug-likeness.

Detection of multiple H3 receptor affinity states utilizing [3H]A-349821, a novel, selective, non-imidazole histamine H3 receptor inverse agonist radioligand.

1. A-349821 is a selective histamine H3 receptor antagonist/inverse agonist. Herein, binding of the novel non-imidazole H3 receptor radioligand [3H]A-349821 to membranes expressing native or recombinant H3 receptors from rat or human sources was characterized and compared with the binding of the agonist [3H]N--methylhistamine ([3H]NMH).

G protein-dependent pharmacology of histamine H3 receptor ligands: evidence for heterogeneous active state receptor conformations.

Previously reported pharmacological studies using the imidazole-containing histamine H3 receptor ligands GT-2331 (Cipralisant) and proxyfan resulted in a range of classifications (antagonist, agonist, and protean) for these compounds. We examined the role that the signaling system, with particular emphasis on the type of G protein, had on the pharmacology observed for H3 ligands. Ligands were assessed using assays measuring neurotransmitter release, cAMP, and guanosine 5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding.

Pharmacological properties of ABT-239 [4-(2-{2-[(2R)-2-Methylpyrrolidinyl]ethyl}-benzofuran-5-yl)benzonitrile]: I. Potent and selective histamine H3 receptor antagonist with drug-like properties.

Histamine H3 receptor antagonists are being developed to treat a variety of neurological and cognitive disorders that may be ameliorated by enhancement of central neurotransmitter release. Here, we present the in vitro pharmacological and in vivo pharmacokinetic profiles for the nonimidazole, benzofuran ligand ABT-239 [4-(2-{2-[(2R)-2-methylpyrrolidinyl]ethyl}-benzofuran-5-yl)benzonitrile] and compare it with several previously described imidazole and nonimidazole H3 receptor antagonists. ABT-239 binds to recombinant human and rat H3 receptors with high affinity, with pK(i) values of 9.

Pharmacological and behavioral properties of A-349821, a selective and potent human histamine H3 receptor antagonist.

Histamine H3 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 H3 receptor ligand, displaying high affinity for recombinant rat and human H3 receptors, with pKi values of 9.4 and 8.

Antiobesity effects of A-331440, a novel non-imidazole histamine H3 receptor antagonist.

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).

Use of a fluorescent imaging plate reader--based calcium assay to assess pharmacological differences between the human and rat vanilloid receptor.

The cloned vanilloid receptor 1 (VR1) is a ligand-gated calcium channel that is believed to be the capsaicin-activated vanilloid receptor found in native tissues, based on similarities regarding molecular mass, tissue distribution, and electrophysiological properties. Using a Fluorescent Imaging Plate Reader (FLIPR), along with Fluo-3 to signal intracellular calcium levels ([Ca(++)](i)), rat VR1 (rVR1) and a human orthologue (hVR1) were pharmacologically characterized with various VR1 ligands. HEK-293 cells, stably expressing rVR1 or hVR1, exhibited dose-dependent increases in [Ca(++)](i) when challenged with capsaicin (EC(50)s congruent with 10 nM).

Differential activation of dual signaling responses by human H1 and H2 histamine receptors.

Stimulation of human H1 and H2-histamine receptors (HRs) primarily activates signaling pathways to increase intracellular calcium [Ca2+]i and cyclic AMP (cAMP), respectively. Activation of H2-HR in human embryonic kidney (HEK) cells by histamine and dimaprit increases both cAMP formation and [Ca2+]i, as determined by cAMP-scintillation proximity assays and fluorescence imaging plate reader (FLIPR) assays. In HEK cells expressing relatively high levels of H2-HR (Bmax=26 pmol/mg protein), histamine and dimaprit are full agonists in eliciting cAMP responses with pEC50 values of 9.

Two novel and selective nonimidazole histamine H3 receptor antagonists A-304121 and A-317920: I. In vitro pharmacological effects.

Histamine H3 receptor (H3R) antagonists enhance neurotransmitter release and are being developed for the treatment of a variety of neurological and cognitive disorders. Many potent histamine H3R antagonists contain an imidazole moiety that limits receptor selectivity and the tolerability of this class of compounds. Here we present the in vitro pharmacological data for two novel piperazine amide ligands, A-304121 [4-(3-((2R)-2-aminopropanoyl-1-piperazinyl)propoxy)phenyl)cyclopropylmethanone] and A-317920 [N-((1R)-2-(4-(3-(4-(cyclopropylcarbonyl)phenoxy)propyl)-1-piperazinyl)-1-methyl-2-oxo-ethyl-)-2-furamide], and compare them with the imidazole H3R antagonists ciproxifan, clobenpropit, and thioperamide.

Modeling of relationships between pharmacokinetics and blockade of agonist-induced elevation of intraurethral pressure and mean arterial pressure in conscious dogs treated with alpha(1)-adrenoceptor antagonists.

Fiduxosin is a new alpha(1)-adrenoceptor antagonist targeted for the treatment of symptomatic benign prostatic hyperplasia. The purpose of this study was to determine and compare the potencies of the alpha(1)-adrenoceptor antagonists terazosin, doxazosin, tamsulosin, and fiduxosin, based on relationships between plasma drug concentrations and blockade of phenylephrine (PE)-induced intraurethral (IUP) and mean arterial pressure (MAP) responses after single oral dosing in conscious male beagle dogs. Magnitude of blockade and plasma concentrations were evaluated at selected time points over 24 h.

Effect of fiduxosin, an antagonist selective for alpha(1A)- and alpha(1D)-adrenoceptors, on intraurethral and arterial pressure responses in conscious dogs.

Fiduxosin is an alpha(1)-adrenoceptor antagonist with higher affinity for alpha(1A)-adrenoceptors and for alpha(1D)-adrenoceptors than for alpha(1B)-adrenoceptors. Our hypothesis is that such a compound with higher affinity for subtypes implicated in the control of lower urinary tract function and lower affinity for a subtype implicated in the control of arterial pressure could result in a superior clinical profile for the treatment of lower urinary tract symptoms suggestive of benign prostatic obstruction. The purpose of this study was to evaluate the potency and selectivity of fiduxosin for effects on prostatic intraurethral pressure (IUP) versus mean arterial pressure (MAP) relative to current clinical standards, terazosin and tamsulosin, in conscious dogs.