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Radojević K, Rakin A, Pilipović I, Kosec D, Djikić J, Bufan B, Vujnović I, Leposavić G. Effects of catecholamines on thymocyte apoptosis and proliferation depend on thymocyte microenvironment. J Neuroimmunol 2014; 272:16-28. [PMID: 24837703 DOI: 10.1016/j.jneuroim.2014.04.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 04/11/2014] [Accepted: 04/17/2014] [Indexed: 01/24/2023]
Abstract
The present study, through quantification of tyrosine hydroxylase (TH) expression and catecholamine (CA) content in the presence and in the absence of α-methyl-p-tyrosine (AMPT), a TH inhibitor, in adult thymic organ (ATOC) and thymocyte culture, demonstrated that thymic cells produce CAs. In addition, in ATOC an increase in β2-adrenoceptor (AR) mRNA expression and β2-AR thymocyte surface density was registered. Furthermore, AMPT (10(-4)M), as propranolol (10(-4)M), augmented thymocyte apoptosis and diminished thymocyte proliferation in ATOC. Propranolol exerted these effects acting on CD3(high) thymocytes. However, in thymocyte cultures, propranolol (10(-6)M) acting on the same thymocyte subset exerted the opposing effect on thymocyte apoptosis and ConA-stimulated proliferation. This suggested that, depending on thymocyte microenvironment, differential effects can be induced through the same type of AR. Additionally, arterenol (10(-8) to 10(-6)M), similar to propranolol, diminished apoptosis, but increased ConA-stimulated thymocyte proliferation in thymocyte culture. However, differently from propranolol, arterenol affected manly CD3- thymocyte subset, which harbors majority of α1-AR+thymocytes. Additionally, arterenol showed a dose-dependent decrease in efficiency of thymocyte apoptosis and proliferation modulation with the rise in its concentration. Considering greater affinity of arterenol for α1-ARs than for β2-ARs, the previous findings could be attributable to increased engagement of β2-ARs with the rise of arterenol concentration. Consistently, in the presence of propranolol (10(-6)M), a β-AR blocker, the arterenol (10(-8)M) effects on thymocytes were augmented. In conclusion, thymic endogenous CAs, acting through distinct AR types and, possible, the same AR type (but in different cell microenvironment) may exert the opposing effects on thymocyte apoptosis/proliferation.
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Affiliation(s)
- Katarina Radojević
- Immunology Research Centre "Branislav Janković", Institute of Virology, Vaccines and Sera "Torlak", 458 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Ana Rakin
- Immunology Research Centre "Branislav Janković", Institute of Virology, Vaccines and Sera "Torlak", 458 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Ivan Pilipović
- Immunology Research Centre "Branislav Janković", Institute of Virology, Vaccines and Sera "Torlak", 458 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Duško Kosec
- Immunology Research Centre "Branislav Janković", Institute of Virology, Vaccines and Sera "Torlak", 458 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Jasmina Djikić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, 450 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Biljana Bufan
- Department of Microbiology and Immunology, Faculty of Pharmacy, University of Belgrade, 450 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Ivana Vujnović
- Immunology Research Centre "Branislav Janković", Institute of Virology, Vaccines and Sera "Torlak", 458 Vojvode Stepe, 11221 Belgrade, Serbia
| | - Gordana Leposavić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, 450 Vojvode Stepe, 11221 Belgrade, Serbia.
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Wooten DW, Hillmer AT, Moirano JM, Tudorascu DL, Ahlers EO, Slesarev MS, Barnhart TE, Mukherjee J, Schneider ML, Christian BT. 5-HT1A sex based differences in Bmax, in vivo KD, and BPND in the nonhuman primate. Neuroimage 2013; 77:125-32. [PMID: 23537936 DOI: 10.1016/j.neuroimage.2013.03.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/27/2013] [Accepted: 03/13/2013] [Indexed: 10/27/2022] Open
Abstract
UNLABELLED Serotonin (5-HT) dysfunction has been implicated in neuropsychiatric illnesses and may play a pivotal role in the differential prevalence of depression between the sexes. Previous PET studies have revealed sex-based differences in 5-HT1A binding potential (BPND). The binding potential is a function of the radioligand-receptor affinity (1/KDapp), and receptor density (Bmax). In this work, we use a multiple-injection (MI) PET protocol and the 5-HT1A receptor antagonist, [(18)F]mefway, to compare sex-based differences of in vivo affinity, Bmax, and BPND in rhesus monkeys. METHODS PET [(18)F]mefway studies were performed on 17 (6m, 11f) rhesus monkeys using a 3-injection protocol that included partial saturation injections of mefway. Compartmental modeling was performed using a model to account for non-tracer doses of mefway for the estimation of KDapp and Bmax. BPND estimates were also acquired from the first injection (high specific activity [(18)F]mefway, 90-minute duration) for comparison using the cerebellum (CB) as a reference region. Regions of interest were selected in 5-HT1A binding regions of the hippocampus (Hp), dorsal anterior cingulate cortex (dACC), amygdala (Am), and raphe nuclei (RN). RESULTS Female subjects displayed significantly (*p<0.05) lower KDapp in the Hp (-32%), Am (-38%), and RN (-37%). Only the Hp displayed significant differences in Bmax with females having a Bmax of -29% compared to males. Male subjects demonstrated significantly lower BPND measurements in the Am (14%) and RN (29%). CONCLUSION These results suggest that the higher BPND values found in females are the result of lower [(18)F]mefway KDapp. Although a more experimentally complex measurement, separate assay of KDapp and Bmax provides a more sensitive measure than BPND to identify the underlying differences between females and males in 5-HT1A function.
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Affiliation(s)
- Dustin W Wooten
- Department of Medical Physics, University of Wisconsin-Madison, WI 53705, USA.
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Salinas C, Weinzimmer D, Searle G, Labaree D, Ropchan J, Huang Y, Rabiner EA, Carson RE, Gunn RN. Kinetic analysis of drug-target interactions with PET for characterization of pharmacological hysteresis. J Cereb Blood Flow Metab 2013; 33:700-7. [PMID: 23385202 PMCID: PMC3652698 DOI: 10.1038/jcbfm.2012.208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In vivo characterization of the brain pharmacokinetics of novel compounds provides important information for drug development decisions involving dose selection and the determination of administration regimes. In this context, the compound-target affinity is the key parameter to be estimated. However, if compounds exhibit a dynamic lag between plasma and target bound concentrations leading to pharmacological hysteresis, care needs to be taken to ensure the appropriate modeling approach is used so that the system is characterized correctly and that the resultant estimates of affinity are correct. This work focuses on characterizing different pharmacokinetic models that relate the plasma concentration to positron emission tomography outcomes measurements (e.g., volume of distribution and target occupancy) and their performance in estimating the true in vivo affinity. Measured (histamine H3 receptor antagonist--GSK189254) and simulated data sets enabled the investigation of different modeling approaches. An indirect pharmacokinetic-receptor occupancy model was identified as a suitable model for the calculation of affinity when a compound exhibits pharmacological hysteresis.
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Affiliation(s)
- Cristian Salinas
- GlaxoSmithKline, Clinical Imaging Centre, Hammersmith Hospital, London, UK
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Wooten DW, Hillmer AT, Moirano JM, Ahlers EO, Slesarev M, Barnhart TE, Mukherjee J, Schneider ML, Christian BT. Measurement of 5-HT(1A) receptor density and in-vivo binding parameters of [(18)F]mefway in the nonhuman primate. J Cereb Blood Flow Metab 2012; 32:1546-58. [PMID: 22472611 PMCID: PMC3421091 DOI: 10.1038/jcbfm.2012.43] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The goal of this work was to characterize the in-vivo behavior of [(18)F]mefway as a suitable positron emission tomography (PET) radiotracer for the assay of 5-hydroxytryptamine(1A) (5-HT(1A)) receptor density (B(max)). Six rhesus monkeys were studied using a multiple-injection (M-I) protocol consisting of three sequential bolus injections of [(18)F]mefway. Injection times and amounts of unlabeled mefway were optimized for the precise measurement of B(max) and specific binding parameters k(off) and k(on) for estimation of apparent K(D). The PET time series were acquired for 180 minutes with arterial sampling performed throughout. Compartmental analysis using the arterial input function was performed to obtain estimates for K(1), k(2), k(off), B(max), and K(Dapp) in the cerebral cortex and raphe nuclei (RN) using a model that accounted for nontracer doses of mefway. Averaged over subjects, highest binding was seen in the mesial temporal and dorsal anterior cingulate cortices with B(max) values of 42±8 and 36±8 pmol/mL, respectively, and lower values in the superior temporal cortex, RN, and parietal cortex of 24±4, 19±4, and 13±2 pmol/mL, respectively. The K(Dapp) of mefway for the 5-HT(1A) receptor sites was 4.3±1.3 nmol/L. In conclusion, these results show that M-I [(18)F]mefway PET experiments can be used for the in-vivo measurement of 5-HT(1A) receptor density.
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Affiliation(s)
- Dustin W Wooten
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.
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Youngquist ST, Shah A, McClung C, Thomas JL, Rosborough JP, Niemann JT. Does prearrest adrenergic integrity affect pressor response? A comparison of epinephrine and vasopressin in a spontaneous ventricular fibrillation swine model. Resuscitation 2011; 82:228-31. [PMID: 21051132 PMCID: PMC3026096 DOI: 10.1016/j.resuscitation.2010.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 09/18/2010] [Accepted: 10/04/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVES Coronary perfusion pressure (CPP) during resuscitation from cardiac arrest has been shown to correlate with return of spontaneous circulation. Adrenergic blockade of beta-1 and alpha-1 receptors is common in the long-term management of ischemic heart disease and congestive heart failure. We sought to compare the CPP response to vasopressin vs. epinephrine in a swine model of cardiac arrest following pre-arrest adrenergic blockade. METHODS Eight anesthetized and instrumented swine were administered 0.1mg epinephrine and arterial pressure and heart rate response were measured. An infusion of labetalol was then initiated and animals periodically challenged with epinephrine until adrenergic blockade was confirmed. The left anterior descending coronary artery was occluded to produce ventricular fibrillation (VF). After 7min of untreated VF, mechanical chest compressions were initiated. After 1min of compressions, 1mg epinephrine was given while CPP was recorded. When CPP values had returned to pre-epinephrine levels, 40U of bolus vasopressin was given. Differences in CPP (post-vasopressor-pre-vasopressor) were compared within animals for the epinephrine and vasopressin response and with eight, non-adrenergically blocked, historical controls using Bayesian statistics with a non-informative prior. RESULTS The CPP response following epinephrine was 15.1mmHg lower in adrenergically blocked animals compared to non-adrenergically blocked animals (95% Highest Posterior Density [HPD] 2.9-27.2mmHg lower). CPP went up 18.4mmHg more following vasopressin when compared to epinephrine (95% HPD 8.2-29.1mmHg). The posterior probability of a higher CPP response from vasopressin (vs. epinephrine) in these animals was 0.999. CONCLUSIONS Pre-arrest adrenergic blockade blunts the CPP response to epinephrine. Superior augmentation of CPP is attained with vasopressin under these conditions.
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Affiliation(s)
- Scott T Youngquist
- Department of Surgery, University of Utah School of Medicine, Salt Lake City, UT, USA.
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Vandehey NT, Moirano JM, Converse AK, Holden JE, Mukherjee J, Murali D, Nickles RJ, Davidson RJ, Schneider ML, Christian BT. High-affinity dopamine D2/D3 PET radioligands 18F-fallypride and 11C-FLB457: a comparison of kinetics in extrastriatal regions using a multiple-injection protocol. J Cereb Blood Flow Metab 2010; 30:994-1007. [PMID: 20040928 PMCID: PMC2897717 DOI: 10.1038/jcbfm.2009.270] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
(18)F-Fallypride and (11)C-FLB457 are commonly used PET radioligands for imaging extrastriatal dopamine D(2)/D(3) receptors, but differences in their in vivo kinetics may affect the sensitivity for measuring subtle changes in receptor binding. Focusing on regions of low binding, a direct comparison of the kinetics of (18)F-fallypride and (11)C-FLB457 was made using a MI protocol. Injection protocols were designed to estimate K(1), k(2), f(ND)k(on), B(max), and k(off) in the midbrain and cortical regions of the rhesus monkey. (11)C-FLB457 cleared from the arterial plasma faster and yielded a ND space distribution volume (K(1)/k(2)) that is three times higher than (18)F-fallypride, primarily due to a slower k(2) (FAL:FLB; k(2)=0.54 min(-1):0.18 min(-1)). The dissociation rate constant, k(off), was slower for (11)C-FLB457, resulting in a lower K(Dapp) than (18)F-fallypride (FAL:FLB; 0.39 nM:0.13 nM). Specific D(2)/D(3) binding could be detected in the cerebellum for (11)C-FLB457 but not (18)F-fallypride. Both radioligands can be used to image extrastriatal D(2)/D(3) receptors, with (11)C-FLB457 providing greater sensitivity to subtle changes in low-receptor-density cortical regions and (18)F-fallypride being more sensitive to endogenous dopamine displacement in medium-to-high-receptor-density regions. In the presence of specific D(2)/D(3) binding in the cerebellum, reference region analysis methods will give a greater bias in BP(ND) with (11)C-FLB457 than with (18)F-fallypride.
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Affiliation(s)
- Nicholas T Vandehey
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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