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Receptor Binding (receptor + binding)
Kinds of Receptor Binding Terms modified by Receptor Binding Selected AbstractsDopamine D2 Receptor Binding, Drd2 Expression and the Number of Dopamine Neurons in the BXD Recombinant Inbred Series: Genetic Relationships to Alcohol and Other Drug Associated PhenotypesALCOHOLISM, Issue 1 2003Robert Hitzemann Background: It has not been established to what extent the natural variation in dopamine systems contribute to the variation in ethanol response. The current study addresses this issue by measuring D2 dopamine (DA) receptor binding, the expression of Drd2, the number of midbrain DA neurons in the BXD recombinant inbred (RI) series and then compares these strain means with those previously reported for a variety of ethanol and other drug-related phenotypes. Methods: Data were collected for 21 to 23 of the BXD RI strains and the parental strains. D2 DA receptor autoradiography was performed using 125I-epidepride as the ligand [Kanes S, Dains K, Cipp L, Gatley J, Hitzemann B, Rasmussen E, Sanderson S, Silverman S, Hitzemann R (1996) Mapping the genes for haloperidol-induced catalepsy. J Pharmacol Exp Ther 277:1016,1025]. Drd2 expression was measured using the Affymetrix oligoarray system. Immunocytochemical techniques were used to determine the number of midbrain DA neurons [Hitzemann B, Dains K, Hitzemann R (1994) Further studies on the relationship between dopamine cell density and haloperidol response. J Pharmacol Exp Ther 271:969,976]. Results and Conclusions: The range of difference in receptor binding for the RI strains was approximately 2-fold in all regions examined, the core, the shell of the nucleus accumbens (NAc) and the dorsomedial caudate-putamen (CPu); heritability in all regions was moderate,(h 2,0.35). Drd2 expression in forebrain samples from the RI and parental strains ranged 1.5- to 2-fold and h2 was moderate,0.47. Variation in the number of tyrosine hydroxylase (TH) positive neurons was moderate, 41% and 26% and h2 was low,0.19 and 0.15 for the ventral tegmental area (VTA) and substantia nigra compacta (SNc), respectively. Significant correlations were found between D2 DA receptor binding and the low dose (1.33 g/kg) ethanol stimulant response. (p < 0.002) and between Drd2 expression and conditioned place preference (CPP) (p < 0.0005). No significant correlations were detected between ethanol preference and either receptor binding or Drd2 expression; however, a significant correlation was found between preference and Ncam expression. Ncam is approximately 0.2 Mb from Drd2. Overall, the data suggest ethanol preference and CPP are associated with the expression of Drd2 or closely linked genetic loci. [source] Lesioning of Locus coeruleus Projections by DSP-4 Neurotoxin Treatment: Effect on Amphetamine-Induced Hyperlocomotion and Dopamine D2 Receptor Binding in RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2000Jaanus Harro DSP-4 is a neurotoxin highly selective for the noradrenergic nerve terminals of the locus coeruleus projections. Data on the effect of DSP-4 treatment on amphetamine-induced hyperlocomotion are contradictory. In this study, DSP-4 (50 mg/kg) caused reduction of noradrenaline levels by 70% in the cerebral cortex and by 79% in the cerebellum. This treatment resulted in upregulation of dopamine D2 receptors in the striatum as evidenced by [3H]-raclopride binding. In an open field test, DSP-4 reduced locomotor activity. D -Amphetamine (1.5 mg/kg) caused a similar increase in locomotor activity in control and DSP-4-pretreated animals not familiar to the apparatus. However, when the rats were habituated to the test apparatus, the effect of amphetamine on horizontal activity was significantly larger in the DSP-4-pretreated animals. These data suggest that supersensitivity of D2 receptors develops after locus coeruleus denervation, but that the enhanced efficacy of amphetamine in DSP-4-treated rats is masked by neophobia. [source] Pharmacological and Functional Characterization of Novel EP and DP Receptor Agonists: DP1 Receptor Mediates Penile Erection in Multiple SpeciesTHE JOURNAL OF SEXUAL MEDICINE, Issue 2 2008Nadia Brugger PhD ABSTRACT Introduction., Despite the widespread use of prostaglandin E1 as an efficacious treatment for male erectile dysfunction for more than two decades, research on prostanoid function in penile physiology has been limited. Aim., To characterize the pharmacological and physiological activity of novel subtype-selective EP and DP receptor agonists. Methods., Radioligand binding and second messenger assays were used to define receptor subtype specificity of the EP and DP agonists. Functional activity was further characterized using isolated human and rabbit penile cavernosal tissue in organ baths. In vivo activity was assessed in rabbits and rats by measuring changes in cavernous pressure after intracavernosal injection of receptor agonists. Main Outcome Measures., Receptor binding and signal transduction, smooth muscle contractile activity, erectile function. Results., In organ bath preparations of human cavernosal tissue contracted with phenylephrine, EP2- and EP4-selective agonists exhibited variable potency in causing relaxation. One of the compounds caused mild contraction, and none of the compounds was as effective as PGE1 (EC50 = 0.23 µM). There was no consistent correlation between the pharmacological profile (receptor binding and second messenger assays) of the EP agonists and their effect on cavernosal tissue tone. In contrast, the DP1-selective agonist AS702224 (EC50 =29 nM) was more effective in relaxing human cavernosal tissue than either PGE1, PGD2 (EC50 = 58 nM), or the DP agonist BW245C (EC50 =59 nM). In rabbit cavernosal tissue, PGE1 and PGD2 caused only contraction, while AS702224 and BW245C caused relaxation. Intracavernosal administration of AS702224 and BW245C also caused penile tumescence in rabbits and rats. For each compound, the erectile response improved with increasing dose and was significantly higher than vehicle alone. Conclusions., These data suggest that AS702224 is a potent DP1-selective agonist that causes penile erection. The DP1 receptor mediates relaxation in human cavernosal tissue, and stimulates pro-erectile responses in rat and rabbit. Thus, rabbits and rats can be useful models for investigating the physiological function of DP1 receptors. Brugger N, Kim NN, Araldi GL, Traish AM, and Palmer SS. Pharmacological and functional characterization of novel EP and DP receptor agonists: DP1 receptor mediates penile erection in multiple species. J Sex Med 2008;5:344,356. [source] An endogenous regulator of inflammation, resolvin E1, modulates osteoclast differentiation and bone resorptionBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2008B S Herrera Background and purpose: The inflammation-resolving lipid mediator resolvin E1 (RvE1) effectively stops inflammation-induced bone loss in vivo in experimental periodontitis. It was of interest to determine whether RvE1 has direct actions on osteoclast (OC) development and bone resorption. Experimental approach: Primary OC cultures derived from mouse bone marrow were treated with RvE1 and analysed for OC differentiation, cell survival and bone substrate resorption. Receptor binding was measured using radiolabelled RvE1. Nuclear factor (NF)-,B activation and Akt phosphorylation were determined with western blotting. Lipid mediator production was assessed with liquid chromatography tandem mass spectrometry. Key results: OC growth and resorption pit formation were markedly decreased in the presence of RvE1. OC differentiation was inhibited by RvE1 as demonstrated by decreased number of multinuclear OC, a delay in the time course of OC development and attenuation of receptor activator of NF-,B ligand-induced nuclear translocation of the p50 subunit of NF-,B. OC survival and apoptosis were not altered by RvE1. Messenger RNA for both receptors of RvE1, ChemR23 and BLT1 is expressed in OC cultures. Leukotriene B4 (LTB4) competed with [3H]RvE1 binding on OC cell membrane preparations, and the LTB4 antagonist U75302 prevented RvE1 inhibition of OC growth, indicating that BLT1 mediates RvE1 actions on OC. Primary OC synthesized the RvE1 precursor 18R -hydroxy-eicosapentaenoic acid and LTB4. Co-incubation of OC with peripheral blood neutrophils resulted in transcellular RvE1 biosynthesis. Conclusions and implications: These results indicate that RvE1 inhibits OC growth and bone resorption by interfering with OC differentiation. The bone-sparing actions of RvE1 are in addition to inflammation resolution, a direct action in bone remodelling. British Journal of Pharmacology (2008) 155, 1214,1223; doi:10.1038/bjp.2008.367; published online 22 September 2008 [source] Manganese cell labeling of murine hepatocytes using manganese(III)-transferrin,CONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2008Christopher H. Sotak Abstract Manganese(III)-transferrin [Mn(III),Tf] was investigated as a way to accomplish manganese-labeling of murine hepatocytes for MRI contrast. It is postulated that Mn(III),Tf can exploit the same transferrin-receptor-dependent and -independent metabolic pathways used by hepatocytes to transport the iron analog Fe(III),Tf. More specifically, it was investigated whether manganese delivered by transferrin could give MRI contrast in hepatocytes. Comparison of the T1 and T2 relaxation times of Mn(III),Tf and Fe(III),Tf over the same concentration range showed that the r1 relaxivities of the two metalloproteins are the same in vitro, with little contribution from paramagnetic enhancement. The degree of manganese cell labeling following incubation for 2,7,h in 31.5,µm Mn(III),Tf was comparable to that of hepatocytes incubated in 500,µm Mn2+ for 1,h. The intrinsic manganese tissue relaxivity between Mn(III),Tf-labeled and Mn2+ -labeled cells was found to be the same, consistent with Mn(III) being released from transferrin and reduced to Mn2+. For both treatment regimens, manganese uptake by hepatocytes appeared to saturate in the first 1,2,h of the incubation period and may explain why the efficiency of hepatocyte cell labeling by the two methods appeared to be comparable in spite of the ,16-fold difference in effective manganese concentration. Hepatocytes continuously released manganese, as detected by MRI, and this was the same for both Mn2+ - and Mn(III),Tf-labeled cells. Manganese release may be the result of normal hepatocyte function, much in the same way that hepatocytes excrete manganese into the bile in vivo. This approach exploits a biological process,namely receptor binding, endocytosis and endosomal acidification,to initiate the release of an MRI contrast agent, potentially conferring more specificity to the labeling process. The ubiquitous expression of transferrin receptors by eukaryotic cells should make Mn(III),Tf particularly useful for manganese labeling of a wide variety of cells both in culture and in vivo. Published in 2008 by John Wiley & Sons, Ltd. [source] Bioisosterism, enantioselectivity, and molecular modeling of new effective N6 - and/or N(9)-substituted 2-phenyl adenines and 8-aza analogs: Different binding modes to A1 adenosine receptorsDRUG DEVELOPMENT RESEARCH, Issue 2 2001A. Maria Bianucci Abstract Bioisosterism of the adenine and 8-azaadenine nuclei was demonstrated by comparison of A1 adenosine receptor binding affinity of 2-phenyl N6 -substituted adenines and the corresponding 8-azaadenines. Some of these new compounds are very potent A1 adenosine receptor antagonists. This work also describes the synthesis and A1 adenosine receptor binding of the enantiomers of some 2-phenyladenines substituted with a 1-phenylethyl chiral group in N6 and N(9) positions. Biological results, showing the same stereoselectivity for all the couples of enantiomers, may supply proof for the hypothesis of a possible double arrangement of 2-phenylsubstituted adenines inside A1 adenosine receptors. Theoretical studies, based on an improved A1 adenosine receptor model and consisting of evaluation and comparison of interaction energies in complexes involving some selected chiral ligands, support the above hypothesis. Drug Dev. Res. 54:52,65, 2001. © 2001 Wiley-Liss, Inc. [source] Positively Charged Material Surfaces Generated by Plasma Polymerized Allylamine Enhance Vinculin Mobility in Vital Human Osteoblastss,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Henrike Rebl Abstract Several studies suggest that the modification of an implant surface by chemical means plays an important role in bone tissue engineering. Previously we have shown that osteoblast cell adhesion and spreading can strongly be increased by a positively charged surface. Cell adhesion and migration are two vital processes that are completely dependent on coordinated formation of focal adhesions. Changes in the organization of the actin cytoskeleton and the focal adhesions are essential for numerous cellular processes including cell motility and tissue morphogenesis. We examined the mobility of the cytoskeletally associated protein vinculin on functionalized surfaces using plasma polymerized allylamine (PPAAm), a homogenous plasma polymer layer with randomly distributed amino groups. In living, GFP,vinculin transfected osteoblastic cells we determined a significant increase in vinculin mobility and vinculin contact length on PPAAm compared to collagen I coated surfaces during the initial adhesion phase. We suggest that positive charges control the cell physiology which seems to be dominant over the integrin receptor binding to collagen I. The results emphasize the role of the surface charge for the design of artificial scaffolds in bone repair. [source] Decrease of D2 receptor binding but increase in D2 -stimulated G-protein activation, dopamine transporter binding and behavioural sensitization in brains of mice treated with a chronic escalating dose ,binge' cocaine administration paradigmEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2008A. Bailey Abstract Understanding the neurobiology of the transition from initial drug use to excessive drug use has been a challenge in drug addiction. We examined the effect of chronic ,binge' escalating dose cocaine administration, which mimics human compulsive drug use, on behavioural responses and the dopaminergic system of mice and compared it with a chronic steady dose (3 × 15 mg/kg/day) ,binge' cocaine administration paradigm. Male C57BL/6J mice were injected with saline or cocaine in an escalating dose paradigm for 14 days. Locomotor and stereotypy activity were measured and quantitative autoradiographic mapping of D1 and D2 receptors, dopamine transporters and D2 -stimulated [35S]GTP,S binding was performed in the brains of mice treated with this escalating and steady dose paradigm. An initial sensitization to the locomotor effects of cocaine followed by a dose-dependent increase in the duration of the locomotor effect of cocaine was observed in the escalating but not the steady dose paradigm. Sensitization to the stereotypy effect of cocaine and an increase in cocaine-induced stereotypy score was observed from 3 × 20 to 3 × 25 mg/kg/day cocaine. There was a significant decrease in D2 receptor density, but an increase in D2 -stimulated G-protein activity and dopamine transporter density in the striatum of cocaine-treated mice, which was not observed in our steady dose paradigm. Our results document that chronic ,binge' escalating dose cocaine treatment triggers profound behavioural and neurochemical changes in the dopaminergic system, which might underlie the transition from drug use to compulsive drug use associated with addiction, which is a process of escalation. [source] Diurnal regulation of the gastrin-releasing peptide receptor in the mouse circadian clockEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2006Ilia N. Karatsoreos Abstract In mammals, circadian rhythms are generated by the suprachiasmatic nuclei (SCN) of the hypothalamus. SCN neurons are heterogeneous and can be classified according to their function, anatomical connections, morphology and/or peptidergic identity. We focus here on gastrin-releasing peptide- (GRP) and on GRP receptor- (GRPr) expressing cells of the SCN. Pharmacological application of GRP in vivo or in vitro can shift the phase of circadian rhythms, and GRPr-deficient mice show blunted photic phase shifting. Given the in vivo and in vitro effects of GRP on circadian behavior and on SCN neuronal activity, we investigated whether the GRPr might be under circadian and/or diurnal control. Using in situ hybridization and autoradiographic receptor binding, we localized the GRPr in the mouse SCN and determined that GRP binding varies with time of day in animals housed in a light,dark cycle but not in conditions of constant darkness. The latter results were confirmed with Western blots of SCN tissue. Together, the present findings reveal that changes in GRPr are light driven and not endogenously organized. Diurnal variation in GRPr activity probably underlies intra-SCN signaling important for entrainment and phase shifting. [source] Metabotropic glutamate receptor 5 localized in the limbic forebrain is critical for the development of morphine-induced rewarding effect in miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Takeshi Aoki Abstract The aim of the present study was to clarify the role of the metabotropic glutamate 5 (mGlu5) receptor subtype in the development of rewarding effect induced by a prototypical µ-opioid receptor agonist morphine in the mouse. In the conditioned place preference paradigm, intracerebroventricular (i.c.v.) administration of a selective mGlu5 receptor antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP), attenuated the morphine-induced rewarding effects. Using immunoblot analysis, we confirmed that the increased level of protein kinase C, (PKC,) isoform was observed in the limbic forebrain of ICR mice conditioned with morphine. Here we found for the first time that the treatment with MPEP significantly inhibited the up-regulation of PKC, isoform in the limbic forebrain of mice showing the significant place preference. Furthermore, it should be mentioned that the protein level of mGlu5 was significantly increased in membrane preparations of the limbic forebrain obtained from morphine-conditioned mice compared to those from saline-conditioned mice. As well as the result from the immunoblot analysis, we demonstrated using the receptor binding assay that the number of mGlu5 receptors in the mouse limbic forebrain was significantly increased by morphine conditioning. The present data provide direct evidence that the activation of mGlu5 receptor linked to the increased PKC, isoform in the mouse limbic forebrain is implicated in the development of rewarding effect of morphine. [source] ,2A and ,2C -adrenoceptor regulation in the brain: ,2A changes persist after chronic stressEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003G. Flügge Abstract Stress-induced activation of the central nervous noradrenergic system has been suspected to induce depressive disorders. As episodes of depression often occur some time after a stress experience we investigated whether stress-induced changes in the ,2 -adrenoceptor (,2 -AR) system persist throughout a post-stress recovery period. Brains of male tree shrews were analysed after 44 days of chronic psychosocial stress and after a subsequent 10-day recovery period. Expression of RNA for ,2A and ,2C -adrenoceptors was quantified by in situ hybridization, and receptor binding was determined by in vitro receptor autoradiography. Activities of the sympathetic nervous system and of the hypothalamo,pituitary,adrenal axis were increased during chronic stress but normalized during recovery. ,2A -AR RNA in the glutamatergic neurons of the lateral reticular nucleus was elevated significantly after stress and after recovery (by 29% and 17%). In the dorsal motor nucleus of the vagus, subtype A expression was enhanced after recovery (by 33%). In the locus coeruleus, subtype A autoreceptor expression was not changed significantly. Subtype C expression in the caudate nucleus and putamen was elevated by stress (by 5 and 4%, respectively) but normalized during recovery. Quantification of 3H-RX821002 binding revealed receptor upregulation during stress and/or recovery. Our data therefore show: (i) that chronic psychosocial stress differentially regulates expression of ,2 -adrenoceptor subtypes A and C; (ii) that subtype A heteroreceptor expression is persistently upregulated whereas (iii), subtype C upregulation is only transient. The present findings coincide with post mortem studies in depressed patients revealing upregulation of ,2A -ARs. [source] Sweat gland epithelial and myoepithelial cells are vitamin D targetsEXPERIMENTAL DERMATOLOGY, Issue 2 2007Nobuo Koike Abstract:, Nuclear receptor binding of 1,25(OH)2 -vitamin D3 (vitamin D) in skin keratinocytes of epidermis, hair sheaths and sebaceous glands was discovered through receptor microscopic autoradiography. Extended experiments with 3H-1,25(OH)2 -vitamin D3 and its analog 3H-oxacalcitriol (OCT) now demonstrate nuclear receptor binding in sweat gland epithelium of secretory coils and ducts as well as in myoepithelial cells, as studied in paws of nude mice after i.v. injection. The results suggest genomic regulation of cell proliferation and differentiation, as well as of secretory and excretory functions, indicating potential therapies for impaired secretion as in hypohidrosis of aged and diseased skin. [source] Correlation between beta-lipoprotein levels and outcome of hepatitis C treatment,HEPATOLOGY, Issue 2 2006Kavitha Gopal The low-density lipoprotein receptor (LDLR) has been proposed as a candidate receptor for the hepatitis C virus (HCV). Competitive inhibition of HCV binding to the LDLR by low-density lipoprotein (LDL) has been shown in vitro. If similar inhibition occurs in vivo, an elevated serum concentration of beta- lipoproteins may reduce the efficiency of infecting hepatocytes with HCV by competitively inhibiting HCV viral receptor binding. We investigated the role of baseline lipid values in influencing the outcome of HCV treatment. We conducted a retrospective chart review of patients treated with an interferon-based regimen at our liver and gastroenterology clinics between 1998 and 2004. Of 99 patients enrolled in the study, 49 (49.5%) had HCV genotype 1 (LDL 100.2 ± 30.2 mg/dL [mean ± SD]), and 50 patients (50.5%) had genotype 2 or 3 (LDL 110.1 ± 40 mg/dL) infection. Early viral response (EVR), end-of-treatment response (ETR), and sustained viral response (SVR) were documented in 99, 88, and 77 patients, respectively. LDL and cholesterol levels prior to treatment were found to be higher in patients with positive EVR, ETR, and SVR. This difference remained significant independent of age. Multivariate analysis controlling for genotype and age showed that the higher the cholesterol and LDL levels prior to treatment, the greater the odds of responding to treatment. In conclusion, having higher serum LDL and cholesterol levels before treatment may be significant prognostic indicators for treatment outcome of those with chronic hepatitis C infection, particularly in genotypes 1 and 2. (HEPATOLOGY 2006;44:335,340.) [source] Receptor architecture of human cingulate cortex: Evaluation of the four-region neurobiological modelHUMAN BRAIN MAPPING, Issue 8 2009Nicola Palomero-Gallagher Abstract The structural and functional organization of the human cingulate cortex is an ongoing focus; however, human imaging studies continue to use the century-old Brodmann concept of a two region cingulate cortex. Recently, a four-region neurobiological model was proposed based on structural, circuitry, and functional imaging observations. It encompasses the anterior cingulate, midcingulate, posterior cingulate, and retrosplenial cortices (ACC, MCC, PCC, and RSC, respectively). For the first time, this study performs multireceptor autoradiography of 15 neurotransmitter receptor ligands and multivariate statistics on human whole brain postmortem samples covering the entire cingulate cortex. We evaluated the validity of Brodmann's duality concept and of the four-region model using a hierarchical clustering analysis of receptor binding according to the degree of similarity of each area's receptor architecture. We could not find support for Brodmann's dual cingulate concept, because the anterior part of his area 24 has significantly higher AMPA, kainate, GABAB, benzodiazepine, and M3 but lower NMDA and GABAA binding site densities than the posterior part. The hierarchical clustering analysis distinguished ACC, MCC, PCC, and RSC as independent regions. The ACC has highest AMPA, kainate, ,2, 5-HT1A, and D1 but lowest GABAA densities. The MCC has lowest AMPA, kainate, ,2, and D1 densities. Area 25 in ACC is similar in receptor-architecture to MCC, particularly the NMDA, GABAA, GABAB, and M2 receptors. The PCC and RSC differ in the higher M1 and ,1 but lower M3 densities of PCC. Thus, multireceptor autoradiography supports the four-region neurobiological model of the cingulate cortex. Hum Brain Mapp, 2009. © 2008 Wiley-Liss, Inc. [source] Buffalo (Bubalus bubalis) interleukin-2: sequence analysis reveals high nucleotide and amino acid identity with interleukin-2 of cattle and other ruminantsINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 4 2002E. Sreekumar Summary A 4400-bp genomic sequence and a 332-bp truncated cDNA sequence of the interleukin-2 (IL-2) gene of Indian water buffalo (Bubalus bubalis) were amplified by polymerase chain reaction and cloned. The coding sequence of the buffalo IL-2 gene was assembled from the 5, end of the genomic clone and the truncated cDNA clone. This sequence had 98.5% nucleotide identity and 98% amino acid identity with cattle IL-2. Three amino acid substitutions were observed at positions 63, 124 and 135. Comparison of the predicted protein structure of buffalo IL-2 with that of human and cattle IL-2 did not reveal significant differences. The putative amino acids responsible for IL-2 receptor binding were conserved in buffalo, cattle and human IL-2. The amino acid sequence of buffalo IL-2 also showed very high identity with that of other ruminants, indicating functional cross-reactivity. [source] Gene and protein expressions in human cord blood cells after exposure to acrylonitrileJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2005Cristina Diodovich Abstract Acrylonitrile is a very high volume industrial chemical used primarily in the manufacture of plastics and rubber, which displays a pronounced acute toxicity and may be carcinogenic. The damage to the hematopoietic function by acrylonitrile may result from interference with cytokine production and cytokine receptor binding. Our present data show that acrylonitrile modulates the expression of some genes implicated in cell differentiation, cell-cycle progression, and clonogenic potential of human cord blood cells. A macroarray hybridization analysis showed that expression of the CXCR4, MCP-1, and MRP8 genes was modified by acrylonitrile exposure. Moreover, the acrylonitrile cell target seems to be the myeloid compartment, as assessed by a CFU-GM assay. In particular, the downregulation of CXCR4, MCP1, and MRP8 can be responsible for the observed reduction of cell proliferation and clonogenic capability of CFU-GM precursors. A Western blot assay showed an acrylonitrile-dependent induction of Bax, while Bcl-2 expression changed only after 48 h of chemical exposure. Bax was overexpressed in respect to Bcl-2, and this fact can be responsible for the induction in cell death after 24 h of treatment. C-fos and c-jun were also downregulated after 24 h and 6 h of treatment, respectively. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:204,212, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20090 [source] Vitamin D Receptor: Key Roles in Bone Mineral Pathophysiology, Molecular Mechanism of Action, and Novel Nutritional Ligands,JOURNAL OF BONE AND MINERAL RESEARCH, Issue S2 2007Peter W Jurutka Abstract The vitamin D hormone, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], binds with high affinity to the nuclear vitamin D receptor (VDR), which recruits its retinoid X receptor (RXR) heterodimeric partner to recognize vitamin D responsive elements (VDREs) in target genes. 1,25(OH)2D3 is known primarily as a regulator of calcium, but it also controls phosphate (re)absorption at the intestine and kidney. Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone produced in osteoblasts that, like PTH, lowers serum phosphate by inhibiting renal reabsorption through Npt2a/Npt2c. Real-time PCR and reporter gene transfection assays were used to probe VDR-mediated transcriptional control by 1,25(OH)2D3. Reporter gene and mammalian two-hybrid transfections, plus competitive receptor binding assays, were used to discover novel VDR ligands. 1,25(OH)2D3 induces FGF23 78-fold in osteoblasts, and because FGF23 in turn represses 1,25(OH)2D3 synthesis, a reciprocal relationship is established, with FGF23 indirectly curtailing 1,25(OH)2D3 -mediated intestinal absorption and counterbalancing renal reabsorption of phosphate, thereby reversing hyperphosphatemia and preventing ectopic calcification. Therefore, a 1,25(OH)2D3,FGF23 axis regulating phosphate is comparable in importance to the 1,25(OH)2D3,PTH axis that regulates calcium. 1,25(OH)2D3 also elicits regulation of LRP5, Runx2, PHEX, TRPV6, and Npt2c, all anabolic toward bone, and RANKL, which is catabolic. Regulation of mouse RANKL by 1,25(OH)2D3 supports a cloverleaf model, whereby VDR-RXR heterodimers bound to multiple VDREs are juxtapositioned through chromatin looping to form a supercomplex, potentially allowing simultaneous interactions with multiple co-modulators and chromatin remodeling enzymes. VDR also selectively binds certain ,3/,6 polyunsaturated fatty acids (PUFAs) with low affinity, leading to transcriptionally active VDR-RXR complexes. Moreover, the turmeric-derived polyphenol, curcumin, activates transcription of a VDRE reporter construct in human colon cancer cells. Activation of VDR by PUFAs and curcumin may elicit unique, 1,25(OH)2D3 -independent signaling pathways to orchestrate the bioeffects of these lipids in intestine, bone, skin/hair follicle, and other VDR-containing tissues. [source] Reduced alpha adrenergic mediated contraction of renal preglomerular blood vessels as a function of gender and agingJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2005John C. Passmore Abstract As human males age, a decline in baroreflex-mediated elevation of blood pressure occurs due, at least in part, to a reduction in alpha-1 adrenergic vasoconstrictor function. Alpha adrenergic constriction is mediated by guanosine triphosphate binding Protein (G Protein) coupled signaling pathways. Alpha-1 A/C, B, and D adrenergic receptor expressions, measured by GeneChip array, are not reduced during aging in renal blood vessels of male or female rats. Alpha-1 A GeneChip expression is greater, at all ages studied, in females than in males. Prazosin binding by alpha-1 adrenergic receptors is greater in young adult female rats than in young adult male rats; however, it is reduced with aging in both male and female rats. G alpha q GeneChip expression declines while expression of adrenergic receptor kinase (GRK2) and tyrosine phosphatases (TyrP) increase with aging in male rats. The declines in alpha-1 adrenergic receptor binding and G alpha q expression and also the increases in GRK2 and TyrP expression likely relate to the age-related decline of vasoconstriction in male rats. The information that the expression of alpha-1 A adrenergic receptors is greater in female rats and (GRK2) expression does not increase during aging could relate to the gender differences in vasoconstrictor function with aging. Gene therapy to ameliorate the age-related decline in renal function could possibly reduce the need for renal dialysis. Signaling pathways such as those reviewed herein may provide an outline of the molecular pathways needed to move toward successful renal gene therapy for aging individuals. J. Cell. Biochem. © 2005 Wiley-Liss, Inc. [source] Insulin-like growth factor (IGF) binding protein-3 regulation of IGF-I is altered in an acidic extracellular environmentJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2001Kimberly E. Forsten While extracellular acidification within solid tumors is well-documented, how reduced pH impacts regulation of insulin-like growth factor-I (IGF-I) has not been studied extensively. Because IGF-I receptor binding is affected by IGF binding proteins (IGFBPs), we examined how pH impacted IGFBP-3 regulation of IGF-I. IGF-I binding in the absence of IGFBP-3 was diminished at reduced pH. Addition of IGFBP-3 reduced IGF-I cell binding at pH 7.4 but increased surface association at pH 5.8. This increase in IGF-I binding at pH 5.8 corresponded with an increase in IGFBP-3 cell association. This, however, was not due to an increase in affinity of IGFBP-3 for heparin at reduced pH although both heparinase III treatment and heparin addition reduced IGFBP-3 enhancement of IGF-I binding. An increase in IGF-I binding to IGFBP-3, though, was seen at reduced pH using a cell-free assay. We hypothesize that the enhanced binding of IGF-I at pH 5.8 is facilitated by increased association of IGFBP-3 at this pH and that the resulting cell associated IGF-I is IGFBP-3 and not IGF-IR bound. Increased internalization and nuclear association of IGF-I at pH 5.8 in the presence of IGFBP-3 was evident, yet cell proliferation was reduced by IGFBP-3 at both pH 5.8 and 7.4 indicating that IGFBP-3-cell associated IGF-I does not signal the cell to proliferate and that the resulting transfer of bound IGF-I from IGF-IR to IGFBP-3 results in diminished proliferation. Solution binding of IGF-I by IGFBP-3 is one means by which IGF-I-induced proliferation is inhibited. Our work suggests that an alternative pathway exists by which IGF-I and IGFBP-3 both associate with the cell surface and that this association inhibits IGF-I-induced proliferation. © 2001 Wiley-Liss, Inc. [source] Liver disease and the renin,angiotensin system: Recent discoveries and clinical implicationsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 9 2008John S Lubel Abstract The renin,angiotensin system (RAS) is a key regulator of vascular resistance, sodium and water homeostasis and the response to tissue injury. Historically, angiotensin II (Ang II) was thought to be the primary effector peptide of this system. Ang II is produced predominantly by the effect of angiotensin converting enzyme (ACE) on angiotensin I (Ang I). Ang II acts mainly through the angiotensin II type-1 receptor (AT1) and, together with ACE, these components represent the ,classical' axis of the RAS. Drug therapies targeting the RAS by inhibiting Ang II formation (ACE inhibitors) or binding to its receptor (angiotensin receptor blockers) are now in widespread clinical use and have been shown to reduce tissue injury and fibrosis in cardiac and renal disease independently of their effects on blood pressure. In 2000, two groups using different methodologies identified a homolog of ACE, called ACE2, which cleaves Ang II to form the biologically active heptapeptide, Ang-(1,7). Conceptually, ACE2, Ang-(1,7), and its putative receptor, the mas receptor represent an ,alternative' axis of the RAS capable of opposing the often deleterious actions of Ang II. Interestingly, ACE inhibitors and angiotensin receptor blockers increase Ang-(1,7) production and it has been proposed that some of the beneficial effects of these drugs are mediated through upregulation of Ang-(1,7) rather than inhibition of Ang II production or receptor binding. The present review focuses on the novel components and pathways of the RAS with particular reference to their potential contribution towards the pathophysiology of liver disease. [source] Preparation and a simple one-step purification of [His1 -mono- 125I-Tyr10,Nle27]-hGHRH(1-32)-NH2JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2002Janos Gardi Abstract A one-step purification of [His1 -mono- 125I-Tyr10,Nle27]-hGHRH(1-32)-NH2, prepared using chloramine-T, by HPLC with isocratic elution is described. The labeled GHRH analog was suitable for GHRH receptor binding assays. Copyright © 2002 John Wiley & Sons, Ltd. [source] A new practical tritium labelling procedure using sodium borotritide and tetrakis(triphenylphosphine)palladium(0)JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2001Tohru Nagasaki Abstract A simple, mild and versatile new tritium (3H) labelling method on a micro scale using sodium borotritide (NaB3H4) and a transition,metal complex catalyst is described. 3H-labelled compounds were prepared effectively by 3H hydrogenolysis of appendant functional groups in target compounds. The appendant functional group such as bromo, iodo or sulfonate in various target compounds can be replaced by tritium (3H) in moderate yields. The new method was established by optimization of the reaction conditions and examination of its applicability using four types of model substrates in tracer runs. Then, various drug candidates and ligands for drug discovery were labelled with tritium on a micro scale. The specific radioactivity of the 3H-labelled compounds used for the studies on receptor binding ranged from 12 to 20 Ci/mmol. Copyright © 2001 John Wiley & Sons, Ltd. [source] Synthesis and receptor binding of IgG1 peptides derived from the IgG Fc regionJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2004Katalin Uray Abstract The IgG binding Fc, receptors (Fc,Rs) play a key role in defence against pathogens by linking humoral and cell-mediated immune responses. Impaired expression and/or function of Fc,R may result in the development of pathological autoimmunity. Considering the functions of Fc,Rs, they are potential target molecules for drug design to aim at developing novel anti-inflammatory and immunomodulatory therapies. Previous data mostly obtained by X-ray analysis of ligand,receptor complexes indicate the profound role of the CH2 domain in binding to various Fc,Rs. Our aim was to localize linear segments, which are able to bind and also to modulate the function of the low affinity Fc,Rs, like Fc,RIIb and Fc,RIIIa. To this end a set of overlapping octapeptides was prepared corresponding to the 231,298 sequence of IgG1 CH2 domain and tested for binding to human recombinant soluble Fc,RIIb. Based on these results, a second group of peptides was synthesized and their binding properties to recombinant soluble Fc,RIIb, as well as to Fc,Rs expressed on the cell surface, was investigated. Here we report that peptide representing the Arg255,Ser267 sequence of IgG1 is implicated in the binding to Fc,RIIb. In addition we found that peptides corresponding to the Arg255,Ser267, Lys288,Ser298 or Pro230,Val240 when presented in a multimeric form conjugated to branched chain polypeptide in uniformly oriented copies induced the release of TNF,, a pro-inflammatory cytokine from MonoMac monocyte cell line. These findings indicate that these conjugated peptides are able to cluster the activating Fc,Rs, and mediate Fc,R dependent function. Peptide Arg255,Ser267 can also be considered as a lead for further functional studies. Copyright © 2004 John Wiley & Sons, Ltd. [source] The PDZ domain protein CAL interacts with mGluR5a and modulates receptor expressionJOURNAL OF NEUROCHEMISTRY, Issue 3 2010Shan Cheng J. Neurochem. (2010) 112, 588,598. Abstract In this study, we investigated the association of metabotropic glutamate receptor subtype-5a (mGluR5a) with cystic fibrosis transmembrane conductance regulator-associated ligand (CAL). Using glutathione- S -transferase pull-down techniques, we found that mGluR5a directly interacted with CAL, with the C-terminus of the receptor binding to the PSD95/Discslarge/ZO-1 homology domain of CAL. The last four amino acids (S-S-S-L) of the C-terminus of the receptor were essential determinants for the interaction. Co-immunoprecipitation experiments and immunofluorescence assays revealed that full-length mGluR5a also associated with intact CAL in vivo, an observation consistent with the results from studies on fragment interactions in vitro. Functionally, upon co-expression with mGluR5a, CAL profoundly inhibited the ubiquitination of mGluR5a and enhanced receptor expression at the protein level but not at the mRNA level. These findings reveal that mGluR5a protein expression is physiologically regulated via its interaction with CAL. These results also suggest a molecular mechanism by which mGluR5a protein expression may be regulated at the post-translational level by the CAL protein, possibly by blocking ubiquitination-dependent receptor degradation. [source] Regulation of A2A adenosine receptor expression and functioning following permanent focal ischemia in rat brainJOURNAL OF NEUROCHEMISTRY, Issue 2 2008Maria L. Trincavelli Abstract Ischemia, through modulation of adenosine receptors (ARs), may influence adenosine-mediated-cellular responses. In the present study, we investigated the modulation of rat A2A receptor expression and functioning, in rat cerebral cortex and striatum, following in vivo focal ischemia (24 h). In cortex, middle cerebral artery occlusion did not induce any alterations in A2A receptor binding and functioning. On the contrary, in striatum, a significant decrease in A2A ligand affinity, associated with an increase in receptor density, were detected. In striatum, ischemia also induced a significant reduction both in G protein pool and in A2A receptor-G protein coupling. On the contrary, A2A receptor functional responsiveness, measured as stimulation of adenylyl cyclise, was not affected by ischemia, suggesting receptor up-regulation may represent a compensatory mechanism to maintain receptor functioning during cerebral damage. Immunohistochemical study showed that following 24 h middle cerebral artery occlusion, A2A ARs were definitely expressed both on neurons and activated microglia in ischemic striatum and cortex, but were not detected on astrocytes. In the non-ischemic hemisphere and in sham-operated rats A2A ARs were barely detected. Modifications of ARs may play a significant role in determining adenosine effects during ischemia and therefore should be taken into account when evaluating time-dependent protective effects of specific A2A active compounds. [source] Involvement of 5-HT3 receptors in the development and expression of methamphetamine-induced behavioral sensitization: 5-HT3A receptor channel and binding studyJOURNAL OF NEUROCHEMISTRY, Issue 3 2006Ji-Hoon Yoo Abstract Methamphetamine (MAP) is one of the most commonly abused drugs in Asia, and previous studies suggest that serotonin 3 receptors (5-HT3) are involved in MAP-induced locomotion and reward. However, little is known about the role of 5-HT3 receptors in MAP-induced behavioral sensitization. Here, we measured the effects of MDL 72222, a 5-HT3 antagonist, and SR 57227 A, a 5-HT3 agonist, on the development and expression of MAP-induced behavioral sensitization, and alternations of 5-HT3 receptor binding labeled with the 5-HT3 -selective antagonist, [3H]GR65630, in mice. In addition, we investigated the effects of MAP on 5-HT3A receptor channel activity in Xenopus laevis oocytes expressing 5-HT3A receptors. We found that MDL 72222 attenuated both the development and expression of behavioral sensitization to MAP (1.0 mg/kg, i.p.), and that this attenuating effect of MDL 72222 was reversed by pre-treatment with SR 57227 A. In oocytes expressing 5-HT3A receptor, MAP exhibited a dual modulation of 5-HT3A receptor channel activity, i.e. pre-treatment with a low dose of MAP (0.1 µm) enhanced 5-HT-induced inward peak current (I5-HT) but a high dose of MAP (100 µm) inhibited I5-HT. The acute administration of MDL 72222 with MAP decreased [3H]GR65630 binding versus MAP alone in the mouse striatum. Our results suggest that MDL 72222 attenuates MAP-induced behavioral sensitization via 5-HT3 receptors in the caudate putamen, and that 5-HT3 receptor antagonists like MDL 72222 have potential as novel anti-psychotic agents for the treatment of MAP dependence and psychosis. [source] Ginkgo biloba affords dose-dependent protection against 6-hydroxydopamine-induced parkinsonism in rats: neurobehavioural, neurochemical and immunohistochemical evidencesJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Muzamil Ahmad Abstract Ginkgo biloba extract (EGb), a potent antioxidant and monoamine oxidase B (MAO-B) inhibitor, was evaluated for its anti-parkinsonian effects in a 6-hydroxydopamine (6-OHDA) rat model of the disease. Rats were treated with 50, 100, and 150 mg/kg EGb for 3 weeks. On day 21, 2 µL 6-OHDA (10 µg in 0.1% ascorbic acid saline) was injected into the right striatum, while the sham-operated group received 2 µL of vehicle. Three weeks after 6-OHDA injection, rats were tested for rotational behaviour, locomotor activity, and muscular coordination. After 6 weeks, they were killed to estimate the generation of thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) content, to measure activities of glutathione- S -transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), and to quantify catecholamines, dopamine (DA) D2 receptor binding, and tyrosine hydroxylase-immunoreactive (TH-IR) fibre density. The increase in drug-induced rotations and deficits in locomotor activity and muscular coordination due to 6-OHDA injections were significantly and dose-dependently restored by EGb. The lesion was followed by an increased generation of TBARS and significant depletion of GSH content in substantia nigra, which was gradually restored with EGb treatment. EGb also dose-dependently restored the activities of glutathione-dependent enzymes, catalase, and SOD in striatum, which had reduced significantly by lesioning. A significant decrease in the level of DA and its metabolites and an increase in the number of dopaminergic D2 receptors in striatum were observed after 6-OHDA injection, both of which were significantly recovered following EGb treatment. Finally, all of these results were exhibited by an increase in the density of TH-IR fibers in the ipsilateral substantia nigra of the lesioned group following treatment with EGb; the lesioning had induced almost a complete loss of TH-IR fibers. Considering our behavioural studies, biochemical analysis, and immunohistochemical observation, we conclude that EGb can be used as a therapeutic approach to check the neuronal loss following parkinsonism. [source] Characterization of nociceptin binding sites by novel peptide analogs and radioprobesJOURNAL OF NEUROCHEMISTRY, Issue 2003S. Benyhe A number of new synthetic nociceptin ligands were studied in receptor binding and functional tests in rat brain membranes and in cloned systems. Ligand binding experiments were performed with three different radioprobes developed in our lab. The nociceptin derivatives exhibited high affinity in competition experiments. Receptor-mediated G-protein activation was determined in [35S]GTPgS binding assays. Among the new structures examined, Ac-RYYRIK-ol was found to be only a weak stimulator by itself, whereas this compound inhibited receptor-mediated G-protein activation. These data suggest that Ac-RYYRIK-ol is a high affinity peptide antagonist for the nociceptin receptor. Acknowledgements:, Supported by the Hungarian Scientific Research Fund OTKA T-035211, T-033078, T-030841, and the Ministry of Education, NKFP 1/027 Hungary. [source] Adenosine A2a receptor-mediated inhibition of rod opsin mRNA expression in tiger salamanderJOURNAL OF NEUROCHEMISTRY, Issue 3 2002Peter D. Alfinito Abstract The neuromodulator adenosine mediates dark-adaptive changes in retinal photoreceptors through A2a receptors. In cold-blooded vertebrates, opsin mRNA expression is lower at night than during the day. In the present study, we tested whether adenosine could inhibit opsin mRNA expression in cultured rod cells and if endogenous adenosine acts to suppress opsin mRNA in the intact retina at night. Semi-quantitative in situ hybridization showed that treatment with 100 nm of the A2a/A2b agonist N,6 -[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA) reduced opsin mRNA 41% in cultured rod cells. The effect of DPMA was blocked by 10 µm of the A2a antagonist 8-(3-chlorostyryl)caffeine (CSC) but not by 10 µm of the A2b antagonist alloxazine. One micromolar adenosine alone had no effect on opsin mRNA. However, in the presence of the adenosine deaminase inhibitor erythro -9-(2-hydroxy-3-nonyl)adenine hydrochloride (EHNA), 1 µm adenosine reduced opsin mRNA 61%. EHNA alone reduced opsin mRNA by 26%. Consistent with an A2a receptor mechanism, 100 nm forskolin (adenylate cyclase agonist) decreased opsin mRNA 34%. Finally, northern blots showed that intravitreal injection of 10 µm CSC at night increased opsin I mRNA 38%. Thus, endogenous adenosine suppresses rod opsin I mRNA expression at night; in vitro results indicate this reduction occurs through A2a -like receptor binding and stimulation of adenylate cyclase activity. [source] Differential Effects of Stress on Adult Hippocampal Cell Proliferation in Low and High Aggressive MiceJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2007A. H. Veenema Male wild house mice selected for a long (LAL) or a short (SAL) latency to attack a male intruder generally show opposing behavioural coping responses to environmental challenges. LAL mice, unlike SAL mice, adapt to novel challenges with a highly reactive hypothalamic-pituitary-adrenal axis and show an enhanced expression of markers for hippocampal plasticity. The present study aimed to test the hypothesis that these features of the more reactive LAL mice are reflected in parameters of hippocampal cell proliferation. The data show that basal cell proliferation in the subgranular zone (SGZ) of the dentate gyrus, assessed by the endogenous proliferation marker Ki-67, is lower in LAL than in SAL mice. Furthermore, application of bromodeoxyuridine (BrdU) over 3 days showed an almost two-fold lower cell proliferation rate in the SGZ in LAL versus SAL mice. Exposure to forced swimming resulted, 24 h later, in a significant reduction in BrdU + cell numbers in LAL mice, whereas cell proliferation was unaffected by this stressor in SAL mice. Plasma corticosterone and dentate gyrus glucocorticoid receptor levels were higher in LAL than in SAL mice. However, no differences between the SAL and LAL lines were found for hippocampal NMDA receptor binding. In conclusion, the data suggest a relationship between coping responses and hippocampal cell proliferation, in which corticosterone may be one of the determinants of line differences in cell proliferation responses to environmental challenges. 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