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Makai S, Falk E, Morandi B. Direct Synthesis of Unprotected 2-Azidoamines from Alkenes via an Iron-Catalyzed Difunctionalization Reaction. J Am Chem Soc 2020; 142:21548-21555. [DOI: 10.1021/jacs.0c11025] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Szabolcs Makai
- ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Eric Falk
- ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Bill Morandi
- ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
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McDonough W, Rich J, Aragon IV, Abou Saleh L, Boyd A, Richter A, Koloteva A, Richter W. Inhibition of type 4 cAMP-phosphodiesterases (PDE4s) in mice induces hypothermia via effects on behavioral and central autonomous thermoregulation. Biochem Pharmacol 2020; 180:114158. [PMID: 32702371 PMCID: PMC7606724 DOI: 10.1016/j.bcp.2020.114158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 02/07/2023]
Abstract
Inhibitors of Type 4 cAMP-phosphodiesterases (PDE4s) exert a number of promising therapeutic benefits, including potent anti-inflammatory, memory- and cognition-enhancing, metabolic, and antineoplastic effects. We report here that treatment with a number of distinct PDE4 inhibitors, including Rolipram, Piclamilast, Roflumilast and RS25344, but not treatment with the PDE3-selective inhibitor Cilostamide, induces a rapid (10-30 min), substantial (-5 °C) and long-lasting (up to 5 h) decrease in core body temperature of C57BL/6 mice; thus, identifying a critical role of PDE4 also in the regulation of body temperature. As little as 0.04 mg/kg of the archetypal PDE4 inhibitor Rolipram induces hypothermia. As similar or higher doses of Rolipram were used in a majority of published animal studies, most of the reported findings are likely paralleled by, or potentially impacted by hypothermia induced by these drugs. We further show that PDE4 inhibition affects central body temperature regulation and acts by lowering the cold-defense balance point of behavioral (including posture and locomotion) and autonomous (including cutaneous tail vasodilation) cold-defense mechanisms. In line with the idea of an effect on central body temperature regulation, hypothermia is induced by moderate doses of various brain-penetrant PDE4 inhibitors, but not by similar doses of YM976, a PDE4 inhibitor that does not efficiently cross the blood-brain barrier. Finally, to begin delineating the mechanism of drug-induced hypothermia, we show that blockade of D2/3-type dopaminergic, but not β-adrenergic, H1-histaminergic or opiate receptors, can alleviate PDE4 inhibitor-induced hypothermia. We thus propose that increased D2/3-type dopaminergic signaling, triggered by PDE4 inhibitor-induced and cAMP-mediated dopamine release in the thermoregulatory centers of the hypothalamus, is a significant contributor to PDE4 inhibitor-induced hypothermia.
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Affiliation(s)
- Will McDonough
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Justin Rich
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Ileana V Aragon
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Lina Abou Saleh
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Abigail Boyd
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Aris Richter
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Anna Koloteva
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Wito Richter
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States.
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Thomae D, Morley TJ, Lee HS, Barret O, Constantinescu C, Papin C, Baldwin RM, Tamagnan GD, Alagille D. Identification and in vivo evaluation of a fluorine-18 rolipram analogue, [(18) F]MNI-617, as a radioligand for PDE4 imaging in mammalian brain. J Labelled Comp Radiopharm 2016; 59:205-13. [PMID: 27006107 DOI: 10.1002/jlcr.3389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 02/18/2016] [Accepted: 02/22/2016] [Indexed: 12/17/2022]
Abstract
Phosphodiesterase (PDE) 4 is the most prevalent PDE in the central nervous system (CNS) and catalyzes hydrolysis of intracellular cAMP, a secondary messenger. By therapeutic inhibition of PDE4, intracellular cAMP levels can be stabilized, and the symptoms of psychiatric and neurodegenerative disorders including depression, memory loss and Parkinson's disease can be ameliorated. Radiotracers targeting PDE4 can be used to study PDE4 density and function, and evaluate new PDE4 therapeutics, in vivo in a non-invasive way, as has been shown using the carbon-11 labeled PDE4 inhibitor R-(-)-rolipram. Herein we describe a small series of rolipram analogs that contain fluoro- or iodo-substituents that could be used as fluorine-18 PET or iodine-123 SPECT PDE4 radiotracers. This series was evaluated with an in vitro binding assay and a 4-(fluoromethyl) derivative of rolipram, MNI-617, was identified, with a five-fold increase in affinity for PDE4 (Kd = 0.26 nM) over R-(-)-rolipram (Kd = 1.6 nM). A deutero-analogue d2 -[(18) F]MNI-617 was radiolabeled and produced in 23% yield with high (>5 Ci/µmol) specific activity and evaluated in non-human primate, where it rapidly entered the brain, with SUVs between 4 and 5, and with a distribution pattern consistent with that of PDE4.
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Affiliation(s)
- David Thomae
- Molecular NeuroImaging LLC, New Haven, CT, 06510, USA
| | | | - Hsiaoju S Lee
- Molecular NeuroImaging LLC, New Haven, CT, 06510, USA
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Bollen E, Akkerman S, Puzzo D, Gulisano W, Palmeri A, D'Hooge R, Balschun D, Steinbusch HWM, Blokland A, Prickaerts J. Object memory enhancement by combining sub-efficacious doses of specific phosphodiesterase inhibitors. Neuropharmacology 2015; 95:361-6. [PMID: 25896769 DOI: 10.1016/j.neuropharm.2015.04.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 02/13/2015] [Accepted: 04/03/2015] [Indexed: 01/17/2023]
Abstract
The second messengers cGMP and cAMP have a vital role in synaptic plasticity and memory processes. As such, phosphodiesterases inhibitors (PDE-Is), which prevent the breakdown of these cyclic nucleotides, represent a potential treatment strategy in memory decline. Recently it has been demonstrated that cGMP and cAMP signaling act in sequence during memory consolidation, with early cGMP signaling requiring subsequent cAMP signaling. Here, we sought to confirm this relationship, and to evaluate its therapeutic implications. Combining sub-efficacious doses of the cGMP-specific PDE type 5 inhibitor vardenafil (0.1 mg/kg) and cAMP-specific PDE type 4 inhibitor rolipram (0.01 mg/kg) during the early and late memory consolidation phase, respectively, led to improved memory performance in a 24 h interval object recognition task. Similarly, such a sub-efficacious combination treatment enhanced the transition of early-phase long-term potentiation (LTP) to late-phase LTP in hippocampal slices. In addition, both object memory and LTP were improved after administration of two sub-efficacious doses of the dual substrate PDE type 2 inhibitor BAY60 7550 (0.3 mg/kg) at the early and late consolidation phase, respectively. Taken together, combinations of sub-efficacious doses of cAMP- and cGMP-specific PDE-Is have an additive effect on long-term synaptic plasticity and memory formation and might prove a superior alternative to single PDE-I treatment.
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Affiliation(s)
- E Bollen
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - S Akkerman
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - D Puzzo
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - W Gulisano
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - A Palmeri
- Department of Biomedical and Biotechnological Sciences - Section of Physiology, University of Catania, 95125 Catania, Italy
| | - R D'Hooge
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - D Balschun
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - H W M Steinbusch
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - A Blokland
- Department of Neuropsychology and Psychopharmacology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
| | - J Prickaerts
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.
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Nakao R, Halldin C. “Mixed” anionic and non-ionic micellar liquid chromatography for high-speed radiometabolite analysis of positron emission tomography radioligands. J Chromatogr A 2013; 1281:54-9. [DOI: 10.1016/j.chroma.2013.01.071] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/10/2013] [Accepted: 01/15/2013] [Indexed: 10/27/2022]
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Cumming P, Vasdev N. Molecular Imaging Studies of Second Messenger Pathways: Looking Deeper than the Membrane. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_52] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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Whole-body biodistribution and radiation dosimetry in monkeys and humans of the phosphodiesterase 4 radioligand [(11)C](R)-rolipram: comparison of two-dimensional planar, bisected and quadrisected image analyses. Nucl Med Biol 2008; 35:493-500. [PMID: 18482687 DOI: 10.1016/j.nucmedbio.2008.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 01/16/2008] [Accepted: 02/11/2008] [Indexed: 11/22/2022]
Abstract
INTRODUCTION [(11)C](R)-Rolipram is a selective radioligand for positron emission tomography (PET) imaging of phosphodiesterase 4, an enzyme that metabolizes 3',5'-cyclic adenosine monophosphate. The aim of this study was to estimate the human radiation absorbed dose of the radioligand based on its biodistribution in both monkeys and humans. METHODS Whole-body PET images were acquired for 2 h after injecting [(11)C](R)-rolipram in eight healthy humans and three monkeys. The simple method of using a single two-dimensional (2D) planar image was compared to more time-consuming methods that used two (bisected) or four (quadrisected) tomographic images in the anteroposterior direction. RESULTS Effective dose was 4.8 microGy/MBq based on 2D planar images. The effective dose was only slightly lower by 1% and 5% using the bisected and quadrisected images, respectively. Nevertheless, the two tomographic methods may have more accurately estimated the exposure of some organs (e.g., kidneys) that are asymmetrically located in the body or have radioactivity that appears to overlap on 2D planar images. Monkeys had a different biodistribution pattern compared to humans (e.g., greater urinary excretion) such that their data overestimated the effective dose in humans by 40%. CONCLUSIONS The effective dose of [(11)C](R)-rolipram was modest and comparable to that of other (11)C-labeled radioligands. The simple and far less time-consuming 2D planar method provided accurate and somewhat more conservative estimates of effective dose than the two tomographic methods. Although monkeys are commonly used to estimate human radiation exposures, their data gave a considerable overestimation for this radioligand.
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Rationally designed PKA inhibitors for positron emission tomography: Synthesis and cerebral biodistribution of N-(2-(4-bromocinnamylamino)ethyl)-N-[11C]methyl-isoquinoline-5-sulfonamide. Bioorg Med Chem 2008; 16:5277-84. [PMID: 18346896 DOI: 10.1016/j.bmc.2008.03.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 02/27/2008] [Accepted: 03/03/2008] [Indexed: 11/23/2022]
Abstract
Protein kinase A (PKA) is an important signal transduction target for drug development because it influences critical cellular processes implicated in neuropsychiatric illnesses such as major depressive disorder. The goal of the present study was to develop the first imaging agent for measuring the levels of PKA with positron emission tomography (PET). By rational derivatization of 5-isoquinoline sulfonamides, it was found that the introduction of a methyl group to the sulphonamidic nitrogen on the known PKA inhibitors N-(2-aminoethyl)isoquinoline-5-sulfonamide (H-9, 1) and N-(2-(4-bromocinnamylamino)ethyl)isoquinoline-5-sulfonamide (H-89, 2), (yielding N-(2-aminoethyl)-N-methyl-isoquinoline-5-sulfonamide (4) and N-(2-(4-bromocinnamylamino)ethyl)-N-methyl-isoquinoline-5-sulfonamide (5), respectively) does not appreciably reduce in vitro potency toward PKA. We have facilitated the synthesis of 4 by reacting isoquinoline-5-sulfonyl chloride with N-methylethylenediamine (20% yield). Several techniques were used to thoroughly characterize 4 including multi ((1)H, (13)C and (15)N) NMR spectroscopy and X-ray crystallography. Compound 4 and 1-(4-bromophenyl)-1-propen-3-yl bromide were reacted to produce 5 in 16% yield. Compound 2 was reacted with [(11)C]CH(3)I to prepare N-(2-(4-bromocinnamylamino) ethyl)-N-[(11)C]methyl-isoquinoline-5-sulfonamide ([(11)C]5), with a decay-corrected radiochemical yield of 32%, based on [(11)C]CO(2). [(11)C]5 was produced with >98% radiochemical purity and 1130mCi/mumol specific activity after 40min (end of synthesis). Conscious rats were administered [(11)C] 5 and sacrificed at 5, 15, 30 and 60min after injection. Radioactivity from all excised brain regions was <0.2%ID/g at all time points. The modest brain penetration of [(11)C]5 may limit its use for studying PKA in the central nervous system.
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Fujita M, Imaizumi M, D'Sa C, Zoghbi SS, Crescenzo MS, Hong J, Musachio JL, Gee AD, Seidel J, Green MV, Pike VW, Duman RS, Innis RB. In vivo and in vitro measurement of brain phosphodiesterase 4 in rats after antidepressant administration. Synapse 2007; 61:78-86. [PMID: 17117418 DOI: 10.1002/syn.20347] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Based largely on in vitro measurements, the mechanism of several antidepressant treatments is thought to involve upregulation of 3'-5'-cyclic adenosine monophosphate (cAMP) signal transduction cascade and a corresponding increase in phosphodiesterase (PDE) 4, the enzyme that metabolizes cAMP. To assess the in vivo status of PDE4, rats were chronically treated with imipramine and then studied with: (1) in vivo positron emission tomography (PET) measurement of (R)-[(11)C]rolipram binding, (2) in vitro measurement of [(3)H]rolipram binding in brain homogenates, and (3) Western blotting for protein levels of PDE4 isoforms. Imipramine administration caused no significant change in B(max)/K(d), for both in vivo measurements with (R)-[(11)C]rolipram and in vitro measurements with [(3)H]rolipram in frontal cortex, hippocampus, and diencephalon. None of 10 isoforms of PDE4A, B, and D measured with immunoblots of frontal cortex and hippocampus showed a significant change. In summary, using relatively large brain regions for both in vivo imaging and in vitro measures of radiolabeled ligand binding and protein levels, chronic imipramine treatment via continuous mini-pump administration caused no significant change in PDE4 levels. Most, but not all, prior in vitro studies have found increased PDE4 levels after antidepressant administration. The current results raise questions about the in vivo effects of antidepressant treatment on PDE4 and on other potentially important experimental factors (e.g., continuous infusion vs. intermittent injection of antidepressant) in large brain areas. However, the results do not deny possibility of changes in discrete areas, which were not studied in the current study applying PET.
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Affiliation(s)
- Masahiro Fujita
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA.
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Kenk M, Greene M, Thackeray J, deKemp RA, Lortie M, Thorn S, Beanlands RS, DaSilva JN. In vivo selective binding of (R)-[11C]rolipram to phosphodiesterase-4 provides the basis for studying intracellular cAMP signaling in the myocardium and other peripheral tissues. Nucl Med Biol 2006; 34:71-7. [PMID: 17210463 DOI: 10.1016/j.nucmedbio.2006.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 09/25/2006] [Accepted: 10/07/2006] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Phosphodiesterase-4 (PDE4) enzymes specifically break down the second messenger cAMP, thereby terminating the intracellular signaling cascade that plays an essential role in neurohormonal modulation of many physiological systems. PDE4 activity and expression are regulated by cAMP levels, suggesting that measurement of PDE4 provides an index of intracellular cAMP signaling. METHODS Male Sprague-Dawley rats were administered (R)- or the less active enantiomer (S)-[11C]rolipram and sacrificed 30 min later with tracer retention measured in various tissues. Co-injections with saturating doses of unlabeled (R)-rolipram, (S)-rolipram and Ro 20-1724, as well as subtype-selective PDE inhibitors vinpocetine, Bay 60-7550, cilostazol and zaprinast were used to establish binding selectivity for PDE4 over PDE1, PDE2, PDE3 and PDE5 subtypes, respectively. Autoradiography was performed to substantiate results of biodistribution studies in the myocardium. RESULTS In vivo (R)-[11C]rolipram retention was dose-dependently reduced by co-injections of (R)-rolipram and (S)-rolipram (ED50 values of 0.03 mg/kg and 0.2 mg/kg, respectively). Vinpocetine, Bay 60-7550, cilostazol and zaprinast had no effect on (R)-[11C]rolipram binding, while (R)-rolipram and Ro 20-1724 reduced the tracer uptake to nonspecific levels in PDE4-rich tissues. CONCLUSIONS In addition to the brain, (R)-[11C]rolipram binds selectively to PDE4 across all cardiac regions, skeletal muscle, lungs and pancreas, but not in the adipose tissues. In vivo findings were confirmed by in vitro autoradiography studies, suggesting that (R)-[11C]rolipram can be applied to evaluate alterations in central and peripheral PDE4 levels and cAMP-mediated signaling.
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Affiliation(s)
- Miran Kenk
- Cardiac PET Centre, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada K1Y 4W7
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Fujita M, Zoghbi SS, Crescenzo MS, Hong J, Musachio JL, Lu JQ, Liow JS, Seneca N, Tipre DN, Cropley VL, Imaizumi M, Gee AD, Seidel J, Green MV, Pike VW, Innis RB. Quantification of brain phosphodiesterase 4 in rat with (R)-[11C]Rolipram-PET. Neuroimage 2005; 26:1201-10. [PMID: 15961054 DOI: 10.1016/j.neuroimage.2005.03.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 03/11/2005] [Accepted: 03/16/2005] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE Phosphodiesterase 4 (PDE4) catabolizes the second messenger 3', 5'-cyclic adenosine monophosphate and may play a critical role in brain diseases. Our aim was to quantify PDE4 in rats with positron emission tomography (PET). METHODS High (n = 6) and low specific activity (SA) (n = 2) higher affinity ((R)-[(11)C]rolipram) and high SA lower affinity ((S)-[(11)C]rolipram) (n = 2) enantiomers were intravenously administered to Sprague-Dawley rats. Brain data were acquired using the ATLAS PET scanner and reconstructed using the 3D-ordered subset expectation maximization algorithm. Arterial samples were taken to measure unmetabolized [(11)C]rolipram. Total distribution volumes (V(T)') were calculated using a 1-tissue compartment (1C) and an unconstrained 2-tissue compartment (2C) model. RESULTS High SA R experiments showed later and greater brain uptake, and slower washout than low SA R and S experiments. In all regions and in all experiments, the 2C model gave significantly better fitting than the 1C model. The poor fitting by the latter caused underestimation of V(T)' by 19-31%. The 2C model identified V(T)' reasonably well with coefficients of variation less than 10%. V(T)' values by this model were 16.4-29.2 mL/cm(3) in high SA R, 2.9-3.5 in low SA R, and 3.1-3.7 in S experiments. CONCLUSIONS Specific binding of (R)-[(11)C]rolipram was accurately measured in living rats. In high SA R experiments, approximately 86% of V(T)' was specific binding. Distribution and changes of PDE4 in animal models can now be studied by measuring V(T)' of high SA (R)-[(11)C]rolipram.
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Affiliation(s)
- Masahiro Fujita
- Molecular Imaging Branch, National Institute of Mental Health, Building 1, Room B3-10, 1 Center Drive, MSC-0135, Bethesda, MD 20892-0135, USA.
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Abstract
Latent inhibition is used to examine attention and study cognitive deficits associated with schizophrenia. Research using MK-801, an N-methyl-D-aspartate (NMDA) open channel blocker, implicates glutamate receptors in acquisition of latent inhibition of cued fear conditioning. Evidence suggests an important relationship between NMDA-induced increases in cyclic adenosine monophosphate (cAMP) and learning and memory. The authors examine whether amplification of the cAMP signaling pathway by rolipram, a selective Type 4 cAMP phosphodiesterase inhibitor, reverses MK-801-induced impairments in latent inhibition. One day before training, mice were injected with MK-801, rolipram, MK-801 and rolipram, or vehicle and received 20 preexposures or no preexposures to an auditory conditioned stimulus (CS). Training consisted of 2 CS-footshock unconditioned stimulus pairings. Rolipram attenuated the disruptive effect of MK-801 on latent inhibition, which suggests a role for the cAMP signaling pathway in the task and implicates phosphodiesterase inhibition as a target for treating cognitive impairments associated with schizophrenia.
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Affiliation(s)
- Jennifer A Davis
- Temple University, Department of Psychology, Philadelphia, PA 19122, USA
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Parker CA, Matthews JC, Gunn RN, Martarello L, Cunningham VJ, Dommett D, Knibb ST, Bender D, Jakobsen S, Brown J, Gee AD. Behaviour of [11C]R(-)- and [11C]S(+)-rolipram in vitro and in vivo, and their use as PET radiotracers for the quantificative assay of PDE4. Synapse 2005; 55:270-9. [PMID: 15668983 DOI: 10.1002/syn.20114] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cyclic AMP (cAMP) is a continually produced nucleotide which is inactivated by hydrolysis to 5'AMP via phosphodiesterase 4 (PDE4) enzymes. Rolipram is a selective PDE4 inhibitor which exists in two enantiomeric forms, R(-) and S(+). Both of these enantiomers have previously been labelled with carbon-11 and used as positron emission tomography (PET) ligands for measuring PDE4 expression and function, and indirectly to explore the function of the cAMP second messenger, in vivo, using PET. The aim of these studies was to relate the in vitro affinities of the two rolipram enantiomers using standard pharmacological assays with the in vivo behaviour of the two enantiomers using PET. In vitro competition assays were performed using rat cortical membranes and [(3)H]R(-)- and [(3)H]S(+)-rolipram with increasing concentrations of either unlabelled R(-)- or S(+)-rolipram. In vivo, a series of PET studies were performed in the porcine brain using [(11)C]R(-)-rolipram with co-administration of increasing doses of either unlabelled R(-)- or S(+)-rolipram. Additional in vivo PET studies were performed using [(11)C]S(+)-rolipram with saturating doses of rolipram. In all studies, R(-)-rolipram exhibited a higher affinity for the PDE4 enzyme than S(+)-rolipram. The calculated affinity ratios were 7.97 from the in vitro studies; 12.5 from the in vivo studies using [(11)C]R(-)-rolipram; and 14.7 from the in vivo studies using [(11)C]S(+)-rolipram. To conclude, the in vitro affinities of R(-)- and S(+)-rolipram predict their apparent in vivo behaviour in the porcine brain, as measured by PET.
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Affiliation(s)
- Christine A Parker
- GlaxoSmithKline, ACCI Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2GG, UK.
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Scott Mason N, Mathis CA. Positron Emission Tomography Agents for Central Nervous System Drug Development Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Tsukada H, Fukumoto D, Nishiyama S, Sato K, Kakiuchi T. Transient focal ischemia affects the cAMP second messenger system and coupled dopamine D1 and 5-HT1A receptors in the living monkey brain: a positron emission tomography study using microdialysis. J Cereb Blood Flow Metab 2004; 24:898-906. [PMID: 15362720 DOI: 10.1097/01.wcb.0000126974.07553.86] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Using positron emission tomography (PET) and microdialysis, the present study showed that neuronal damages after transient focal ischemia was partly induced by hyperactivation of the cyclic adenosine 3',5'-monophosphate (cAMP) second messenger system through modulations of dopamine D, and serotonin 5-HT1A receptors in the living brains of cynomolgus monkeys. Occlusion of the right middle cerebral artery for 3 hours suppressed CBF in the striatum, and reperfusion induced hyperperfusion in the neocortex and striatum of the occluded side. Six hours after reperfusion, the activity of the cAMP second messenger system assayed with [11C]rolipram was significantly facilitated in the neocortex and striatum where CBF was lowered more than 40% of normal during occlusion ("ischemic" area). Seven days later, impaired dopamine D1 and 5-HT1A receptor binding, measured with [11C]SCH23390 and [carbonyl-11C]WAY-100635, respectively, was observed in the ischemic area. Microdialysis analysis revealed that the striatal dopamine level provided a transient and marked increased during occlusion and after reperfusion, whereas the cortical serotonin level transiently increased only after reperfusion, and was at an undetectable level thereafter. Administration of rolipram (0.1 and 1 mg/kg, intravenously) during occlusion facilitated reduction of dopamine D1 binding, whereas rolipram administration 6 hours after reperfusion induced a further decrease in 5-HT1A receptor binding. These results suggest that the activation of cAMP second messenger system modulated by dopamine D1 and 5-HT1A receptors could be involved in the neuronal degeneration after transient cerebral ischemic insult.
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Affiliation(s)
- Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics K.K., Shizuoka, Japan.
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16
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Abstract
Positron emission tomography (PET) and allied non-invasive imaging techniques are being increasingly embraced by the pharmaceutical industry. These imaging modalities allow the assessment of novel drug action in man at a very early stage of the drug's discovery and development process; in turn, this enables earlier decision making about the developmental potential of novel and potential therapeutics. The in vivo characterisation of novel molecular targets and disease mechanisms in man is intimately connected with future developments in the diagnosis, management and treatment of human disease. The utility of non-invasive imaging modalities within the pharmaceutical industry is discussed with particular reference to the use of PET in drug discovery and development in the 21st century.
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Affiliation(s)
- Antony D Gee
- Translational Medicine and Technologies, GlaxoSmithKline, Clinical Research Unit, ACCI, Addenbrookes Hospital, Cambridge, UK
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17
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Abstract
Over the past 30 years, advances in radiotracer chemistry and positron emission tomography instrumentation have merged to make positron emission tomography a powerful scientific tool in the biomedical sciences. However, despite the increasing reliance of the biomedical sciences on imaging and the new needs for functional information created by the sequencing of the human genome, the development of new radiotracers with the specificity and kinetic characteristics for quantitative analysis in vivo remains a slow process. In this article, we focus on advances in the development of the radiotracers involved in neurotransmission, amino acid transport, protein synthesis, and DNA synthesis. We conclude with a brief section on newer radiotracers that image other molecular targets and conclude with a summary of some of the scientific and infrastructure needs that would expedite the development and introduction of new radiotracers into biomedical research and the practice of medicine.
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Affiliation(s)
- Joanna S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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18
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Harada N, Nishiyama S, Ohba H, Sato K, Kakiuchi T, Tsukada H. Age differences in phosphodiesterase type-IV and its functional response to dopamine D1 receptor modulation in the living brain: a PET study in conscious monkeys. Synapse 2002; 44:139-45. [PMID: 11954045 DOI: 10.1002/syn.10067] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The present study demonstrated the age-related changes in the striatal dopamine D1 receptor binding and its related cAMP second-messenger system in the living brains of conscious young (6.4 +/- 1.8 years old) and aged (19.5 +/- 3.3 years old) monkeys (Macaca mulatta) using positron emission tomography (PET). For quantitative analysis of D1 receptors, [11C]SCH23390 was used and phosphodiesterase type-IV (PDE-IV) activity, as an index of cAMP system, was estimated by two scans with R- and S-[11C]rolipram. Significant age-related decreases in D1 receptor binding were observed in the striatum and frontal cortex. Analysis of uptake of R- and S-[11C]rolipram indicated age-related decreases in PDE-IV activity showing 22.0 and 25.2% decreases in the striatum and frontal cortex, respectively, while no significant changes were observed in the cerebellum. With systemic preadministration of the dopamine D1 receptor antagonist SCH23390 (0.2, 0.6, and 2 mg/kg), the PDE-IV activities in the striatum and frontal cortex were dose-dependently suppressed in both age groups. However, the degree of suppression by SCH23390 was more marked in young than in aged monkeys. These results demonstrate that the striatal cAMP second-messenger system activity as well as its functional response to dopamine D1 antagonist showed age-related impairment in the brain.
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Affiliation(s)
- Norihiro Harada
- Central Research Laboratory, Hamamatsu Photonics K. K., Shizuoka 434-8601, Japan
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19
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Tsukada H, Harada N, Ohba H, Nishiyama S, Kakiuchi T. Facilitation of dopaminergic neural transmission does not affect [(11)C]SCH23390 binding to the striatal D(1) dopamine receptors, but the facilitation enhances phosphodiesterase type-IV activity through D(1) receptors: PET studies in the conscious monkey brain. Synapse 2001; 42:258-65. [PMID: 11746724 DOI: 10.1002/syn.10013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The present study evaluated the effects of methamphetamine and scopolamine on the striatal dopamine D(1) receptor binding, measured by [(11)C]SCH23390, and D(1) receptor-coupled cAMP messenger system, determined as phosphodiesterase type-IV (PDE-IV) activity, were evaluated in the brains of conscious monkeys using positron emission tomography (PET) with microdialysis. When methamphetamine (0.1, 0.3, and 1 mg/kg) or scopolamine (0.01, 0.03, and 0.1 mg/kg) was systemically administered, [(11)C]SCH23390 binding to D(1) receptors was not affected. With administration of methamphetamine, the striatal PDE-IV activity, as measured with R-[(11)C]rolipram (active form) and S-[(11)C]rolipram (inactive form), was dose-dependently facilitated with enhanced dopamine level in the striatal ECF. Administration of scopolamine also induced facilitated PDE-IV activity without any apparent changes in the ECF dopamine. These facilitations of PDE-IV activity were abolished by preadministration of SCH23390, but not by raclopride. These results demonstrate that, as evaluated by PDE-IV activity, the inhibition of muscarinic cholinergic receptors actually facilitated dopamine neuronal signal transduction through D(1) receptors, as observed previously on D(2) receptors with no apparent increase in the striatal ECF dopamine level, but the enhanced dopamine transmission could not detected by [(11)C]SCH23390.
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Affiliation(s)
- H Tsukada
- Central Research Laboratory, Hamamatsu Photonics K.K., Shizuoka 434-8601, Japan.
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20
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Peñuelas Sánchez I. [PET radiopharmaceuticals]. REVISTA ESPANOLA DE MEDICINA NUCLEAR 2001; 20:477-98; quiz 499-501. [PMID: 11578585 DOI: 10.1016/s0212-6982(01)71997-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I Peñuelas Sánchez
- Unidad de Radiofarmacia, Servicio de Medicina Nuclear, Clínica Universitaria de Navarra, Spain.
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21
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Takahashi K, Miura S, Ibaraki M, Hatazawa J, Okane K, Kanno I. Synthesis and biodistribution of [11C]H8, a cyclic AMP dependent protein kinase inhibitor. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.25804401129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Lourenco CM, Houle S, Wilson AA, DaSilva JN. Characterization of r-[11C]rolipram for PET imaging of phosphodieterase-4: in vivo binding, metabolism, and dosimetry studies in rats. Nucl Med Biol 2001; 28:347-58. [PMID: 11395307 DOI: 10.1016/s0969-8051(01)00206-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The high-affinity phosphodiesterase-4 (PDE4) inhibitor R-rolipram and the less potent S-enantiomer, both labeled with (11)C, were evaluated in vivo in rats. Regional brain uptake of R-[(11)C]rolipram was higher than R/S-[(11)C]rolipram, whereas S-[(11)C]rolipram retention subsided rapidly to levels below blood. Binding of R-[(11)C]rolipram was selective for PDE4 over PDE1, since treatment with PDE4 competitors Ro 20-1724, or R-, S- or R/S-rolipram, but not with the PDE1 inhibitor vinpocetine, significantly reduced radioactivity uptake to non-specific levels. R-Rolipram (ED(50) congruent with 0.04 mg/Kg) was approximately 13 fold more potent than S-rolipram at inhibiting R-[(11)C]rolipram binding in all brain regions. Nevertheless, S-[(11)C]rolipram appears to be unsuitable for measuring the non-specific binding of R-[(11)C]rolipram. Only unchanged R-[(11)C]rolipram was detected in rat brain homogenates. Additionally, the estimated absorbed radiation dose extrapolated to humans was low. These results support further investigation of R-[(11)C]rolipram in studying PDE4 in vivo by positron emission tomography imaging.
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Affiliation(s)
- C M Lourenco
- Vivian M. Rakoff Pet Centre, Centre for Addiction and Mental Health, Department of Pharmacology, University of Toronto, 250 College Street, M5T 1R8, Toronto, Ontario, Canada
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DaSilva JN, Lourenco CM, Wilson AA, Houle S. Syntheses of the phosphodiesterase-4 inhibitors [11C]Ro 20-1724, R-, R/S- and S-[11C]rolipram. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.465] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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