1
|
Krajewski S, Steczek L, Gotowicz K, Karczmarczyk U, Towpik J, Witkowska-Patena E, Łyczko K, Mazur M, Kozanecki P, Włostowska J, Knuuti J, Dziuk M, Garnuszek P, Kozanecki C. Preclinical evaluation of [ 18F]SYN1 and [ 18F]SYN2, novel radiotracers for PET myocardial perfusion imaging. EJNMMI Res 2024; 14:63. [PMID: 38976101 PMCID: PMC11231114 DOI: 10.1186/s13550-024-01122-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 06/20/2024] [Indexed: 07/09/2024] Open
Abstract
BACKGROUND Positron emission tomography (PET) is now an established diagnostic method for myocardial perfusion imaging (MPI) in coronary artery disease, which is the main cause of death globally. The available tracers show several limitations, therefore, the 18F-labelled tracer is in high demand nowadays. The preclinical studies on normal Wistar rats aimed to characterise two potential, novel radiotracers, [18F]SYN1 and [18F]SYN2, to evaluate which is a better candidate for PET MPI cardiotracer. RESULTS The dynamic microPET images showed rapid myocardial uptake for both tracers. However, the uptake was higher and also stable for [18F]SYN2, with an average standardized uptake value of 3.8. The biodistribution studies confirmed that [18F]SYN2 uptake in the cardiac muscle was high and stable (3.02%ID/g at 15 min and 2.79%ID/g at 6 h) compared to [18F]SYN1 (1.84%ID/g at 15 min and 0.32%ID/g at 6 h). The critical organs determined in dosimetry studies were the small intestine and the kidneys. The estimated effective dose for humans was 0.00714 mSv/MBq for [18F]SYN1 and 0.0109 mSv/MBq for [18F]SYN2. The tested dose level of 2 mg/kg was considered to be the No Observed Adverse Effect Level (NOAEL) for both candidates. The better results were achieved for [18F]SYN2, therefore, further preclinical studies were conducted only for this tracer. Radioligand binding assays showed significant responses in 3 from 68 assays: muscarinic acetylcholine M1 and M2 receptors and potassium channel hERG. The compound was mostly metabolised via an oxidative N-dealkylation, while the fluor substituent was not separated from the molecule. CONCLUSION [18F]SYN2 showed a favourable pharmacodynamic and pharmacokinetic profile, which enabled a clear visualization of the heart in microPET. The compound was well-tolerated in studies in normal rats with moderate radiation exposure. The results encourage further exploration of [18F]SYN2 in clinical studies.
Collapse
Affiliation(s)
| | - Lukasz Steczek
- Research & Development Centre, Synektik SA, Warsaw, Poland
| | - Karina Gotowicz
- Research & Development Centre, Synektik SA, Warsaw, Poland
- Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Urszula Karczmarczyk
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland
| | - Joanna Towpik
- Research & Development Centre, Synektik SA, Warsaw, Poland
| | - Ewa Witkowska-Patena
- Nuclear Medicine Department, Military Institute of Medicine - National Research Institute, Warsaw, Poland
- Affidea Poland, Warsaw, Poland
| | | | - Maciej Mazur
- Department of Chemistry, University of Warsaw, Warsaw, Poland
| | | | | | - Juhani Knuuti
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland
- Department of Clinical Physiology, Nuclear Medicine, and PET, Turku University Hospital, Turku, Finland
| | - Mirosław Dziuk
- Nuclear Medicine Department, Military Institute of Medicine - National Research Institute, Warsaw, Poland
- Affidea Poland, Warsaw, Poland
| | - Piotr Garnuszek
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland
| | | |
Collapse
|
2
|
Myslivecek J. Multitargeting nature of muscarinic orthosteric agonists and antagonists. Front Physiol 2022; 13:974160. [PMID: 36148314 PMCID: PMC9486310 DOI: 10.3389/fphys.2022.974160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/16/2022] Open
Abstract
Muscarinic receptors (mAChRs) are typical members of the G protein-coupled receptor (GPCR) family and exist in five subtypes from M1 to M5. Muscarinic receptor subtypes do not sufficiently differ in affinity to orthosteric antagonists or agonists; therefore, the analysis of receptor subtypes is complicated, and misinterpretations can occur. Usually, when researchers mainly specialized in CNS and peripheral functions aim to study mAChR involvement in behavior, learning, spinal locomotor networks, biological rhythms, cardiovascular physiology, bronchoconstriction, gastrointestinal tract functions, schizophrenia, and Parkinson's disease, they use orthosteric ligands and they do not use allosteric ligands. Moreover, they usually rely on manufacturers' claims that could be misleading. This review aimed to call the attention of researchers not deeply focused on mAChR pharmacology to this fact. Importantly, limited selective binding is not only a property of mAChRs but is a general attribute of most neurotransmitter receptors. In this review, we want to give an overview of the most common off-targets for established mAChR ligands. In this context, an important point is a mention the tremendous knowledge gap on off-targets for novel compounds compared to very well-established ligands. Therefore, we will summarize reported affinities and give an outline of strategies to investigate the subtype's function, thereby avoiding ambiguous results. Despite that, the multitargeting nature of drugs acting also on mAChR could be an advantage when treating such diseases as schizophrenia. Antipsychotics are a perfect example of a multitargeting advantage in treatment. A promising strategy is the use of allosteric ligands, although some of these ligands have also been shown to exhibit limited selectivity. Another new direction in the development of muscarinic selective ligands is functionally selective and biased agonists. The possible selective ligands, usually allosteric, will also be listed. To overcome the limited selectivity of orthosteric ligands, the recommended process is to carefully examine the presence of respective subtypes in specific tissues via knockout studies, carefully apply "specific" agonists/antagonists at appropriate concentrations and then calculate the probability of a specific subtype involvement in specific functions. This could help interested researchers aiming to study the central nervous system functions mediated by the muscarinic receptor.
Collapse
Affiliation(s)
- Jaromir Myslivecek
- Institute of Physiology, 1 Faculty of Medicine, Charles University, Prague, Czechia
| |
Collapse
|
3
|
Fridjonsdottir E, Vallianatou T, Mantas I, Shariatgorji R, Nilsson A, Schembri LS, Odell LR, Svenningsson P, Andrén PE. Region-Specific and Age-Dependent Multitarget Effects of Acetylcholinesterase Inhibitor Tacrine on Comprehensive Neurotransmitter Systems. ACS Chem Biol 2022; 17:147-158. [PMID: 34932310 PMCID: PMC8787750 DOI: 10.1021/acschembio.1c00803] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Regional brain distribution and
metabolism of neurotransmitters
and their response to drug treatment are fundamentally important for
understanding the central effects of neuroactive substances. We used
matrix-assisted laser desorption/ionization mass spectrometry imaging
in
combination with multivariate analysis to visualize in anatomical
detail metabolic effects of aging and tacrine-mediated acetylcholinesterase
inhibition on comprehensive neurotransmitter systems in multiple mouse
brain regions of 12-week-old and 14-month-old mice. We detected age-related
increases in 3,4-dihydroxyphenylacetaldehyde and histamine, indicating
oxidative stress and aging deficits in astrocytes. Tacrine had a significant
impact on the metabolism of neurotransmitters in both age groups;
predominantly, there was an increased norepinephrine turnover throughout
the brain and decreased 3-methoxy tyramine, a marker for dopamine
release,
in the striatum. The striatal levels of histamine were only elevated
after tacrine administration in the older animals. Our results demonstrated
that tacrine is a multitarget and region-specific neuroactive agent,
inducing age-specific responses. Although well-studied, the complete
mechanisms of the action of tacrine are not fully understood, and
the current findings reveal features that may help explain its treatment-related
effectiveness and central side effects.
Collapse
Affiliation(s)
- Elva Fridjonsdottir
- Department of Pharmaceutical Biosciences, Medical Mass Spectrometry Imaging, Uppsala University, SE-75124 Uppsala, Sweden
| | - Theodosia Vallianatou
- Department of Pharmaceutical Biosciences, Medical Mass Spectrometry Imaging, Uppsala University, SE-75124 Uppsala, Sweden
| | - Ioannis Mantas
- Department of Clinical Neuroscience, Section of Neurology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Reza Shariatgorji
- Department of Pharmaceutical Biosciences, Medical Mass Spectrometry Imaging, Uppsala University, SE-75124 Uppsala, Sweden
- Science for Life Laboratory, Spatial Mass Spectrometry, Uppsala University, SE-75124 Uppsala, Sweden
| | - Anna Nilsson
- Department of Pharmaceutical Biosciences, Medical Mass Spectrometry Imaging, Uppsala University, SE-75124 Uppsala, Sweden
- Science for Life Laboratory, Spatial Mass Spectrometry, Uppsala University, SE-75124 Uppsala, Sweden
| | - Luke S. Schembri
- Department of Medicinal Chemistry, Uppsala University, SE-75123 Uppsala, Sweden
| | - Luke R. Odell
- Department of Medicinal Chemistry, Uppsala University, SE-75123 Uppsala, Sweden
| | - Per Svenningsson
- Department of Clinical Neuroscience, Section of Neurology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Per E. Andrén
- Department of Pharmaceutical Biosciences, Medical Mass Spectrometry Imaging, Uppsala University, SE-75124 Uppsala, Sweden
- Science for Life Laboratory, Spatial Mass Spectrometry, Uppsala University, SE-75124 Uppsala, Sweden
| |
Collapse
|
4
|
Myslivecek J. Social Isolation: How Can the Effects on the Cholinergic System Be Isolated? Front Pharmacol 2021; 12:716460. [PMID: 34916930 PMCID: PMC8670609 DOI: 10.3389/fphar.2021.716460] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 11/15/2021] [Indexed: 01/31/2023] Open
Abstract
Social species form organizations that support individuals because the consequent social behaviors help these organisms survive. The isolation of these individuals may be a stressor. We reviewed the potential mechanisms of the effects of social isolation on cholinergic signaling and vice versa how changes in cholinergic signaling affect changes due to social isolation.There are two important problems regarding this topic. First, isolation schemes differ in their duration (1–165 days) and initiation (immediately after birth to adulthood). Second, there is an important problem that is generally not considered when studying the role of the cholinergic system in neurobehavioral correlates: muscarinic and nicotinic receptor subtypes do not differ sufficiently in their affinity for orthosteric site agonists and antagonists. Some potential cholinesterase inhibitors also affect other targets, such as receptors or other neurotransmitter systems. Therefore, the role of the cholinergic system in social isolation should be carefully considered, and multiple receptor systems may be involved in the central nervous system response, although some subtypes are involved in specific functions. To determine the role of a specific receptor subtype, the presence of a specific subtype in the central nervous system should be determined using search in knockout studies with the careful application of specific agonists/antagonists.
Collapse
Affiliation(s)
- Jaromir Myslivecek
- Institute of Physiology, First Faculty of Medicine, Charles University, Prague, Czechia
| |
Collapse
|
5
|
Vakalopoulos C. The EEG as an index of neuromodulator balance in memory and mental illness. Front Neurosci 2014; 8:63. [PMID: 24782698 PMCID: PMC3986529 DOI: 10.3389/fnins.2014.00063] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 03/18/2014] [Indexed: 11/24/2022] Open
Abstract
There is a strong correlation between signature EEG frequency patterns and the relative levels of distinct neuromodulators. These associations become particularly evident during the sleep-wake cycle. The monoamine-acetylcholine balance hypothesis is a theory of neurophysiological markers of the EEG and a detailed description of the findings that support this proposal are presented in this paper. According to this model alpha rhythm reflects the relative predominance of cholinergic muscarinic signals and delta rhythm that of monoaminergic receptor effects. Both high voltage synchronized rhythms are likely mediated by inhibitory Gαi/o-mediated transduction of inhibitory interneurons. Cognitively, alpha and delta EEG measures are proposed to indicate automatic and flexible strategies, respectively. Sleep is associated with marked changes in relative neuromodulator levels corresponding to EEG markers of distinct stages. Sleep studies on memory consolidation present some of the strongest evidence yet for the respective roles of monoaminergic and cholinergic projections in declarative and non-declarative memory processes, a key theoretical premise for understanding the data. Affective dysregulation is reflected in altered EEG patterns during sleep.
Collapse
|
6
|
Çetinkaya MA, Baydan E. Investigation of in vitro effects of ethephon and chlorpyrifos, either alone or in combination, on rat intestinal muscle contraction. Interdiscip Toxicol 2010; 3:35-9. [PMID: 21217869 PMCID: PMC2984123 DOI: 10.2478/v10102-010-0002-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 02/20/2010] [Accepted: 03/01/2010] [Indexed: 11/20/2022] Open
Abstract
A range of pesticides is widely used in pest management and the chances of exposure to multiple organophosphorus (OP) compounds simultaneously are high, especially from dietary and other sources. Although health hazards of individual OP insecticides have been relatively well characterized, there is lesser information on the interactive toxicity of multiple OP insecticides. The aim of this study is to elicit the possible interactions in case combined exposure of an OP pesticide chlorpyrifos (CPF) and a plant growth regulator ethephon (ETF) which are used worldwide. The ileum segments of 3 months old Wistar Albino male rats were used in isolated organ bath containing Tyrode solution. ETF and CPF were incubated (10(-7) M concentration) separately or in combination with each other to ileum and their effects on acetylcholine-induced contractions were studied. The data obtained from this study show that, single and combined exposure to the agents caused agonistic interactions with regard to potency of ACh whereas they caused a decrease on E(max) value of ACh. These findings suggest that exposure to these agents which have direct and indirect cholinergic effects, may cause developing clinical responses with small doses and earlier but the extent of toxicity will be lower.
Collapse
Affiliation(s)
- Mustafa Alp Çetinkaya
- National Food Reference Laboratory, Turkish Ministry of Agriculture and Rural Affairs, Fatih Sultan Mehmet Bulvari, Yenimahalle, Ankara, Turkey
| | - Emine Baydan
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Ankara, Ankara, Diskapi, Turkey
| |
Collapse
|
7
|
Krustev A, Sirakov V, Turiiski V, Getova D, Velkova K, Prissadova N. Delayed evacuatory function due to specific smooth muscle reactivity in the gastrointestinal tracts of tacrine-treated rats. Pharmacology 2007; 81:50-6. [PMID: 17827979 DOI: 10.1159/000107969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Accepted: 06/11/2007] [Indexed: 11/19/2022]
Abstract
Most of the side effects induced by tacrine are associated with the gastrointestinal (GI) tract. The aim of the study was to analyze the nature of radiographically registered, tacrine-induced changes in evacuatory function, as well as to find a possible correlation with the immediate in vitro action of the drug on smooth muscles from the GI tracts of rats. The tacrine dose we used reliably delayed GI passage: contrast matter was not fully evacuated, predominantly from the stomach and cecum. The delay resulted from changes in tone and peristaltic activity, specific for the various regions of the tract. These changes were associated with a superposing of the responses due to the anticholinesterase and noncholinergic action of tacrine.
Collapse
Affiliation(s)
- A Krustev
- Department of Biophysics, Medical University, Plovdiv, Bulgaria
| | | | | | | | | | | |
Collapse
|
8
|
Krustev AD, Argirova MD, Getova DP, Turiiski VI, Prissadova NA. Calcium-independent tacrine-induced relaxation of rat gastric corpus smooth muscles. Can J Physiol Pharmacol 2006; 84:1133-8. [PMID: 17218977 DOI: 10.1139/y06-059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tacrine, a non-competitive reversible acetylcholinesterase and butyrylcholineserase inhibitor, caused a concentration-dependent tonic contraction of gastric smooth muscle preparations in the concentration range 1 × 10−7 mol/L – 1 × 10−5 mol/L, whereas concentrations higher than 2 × 10−5 mol/L induced a biphasic effect; a short-time contraction was followed by a prolonged relaxation. To shed some light on the mechanism underlying this untypical relaxation, the amplitude of mechanical reactions caused by tacrine were compared with those of tacrine in the presence of atropine, ipratropium, metrifonate, TTX, nifedipine, D-600, caffeine, apamin, and charybdotoxin. The results obtained revealed that the relaxation was neither cholinergic in nature, nor mediated by the influence of the drug on intramural neuronal structures. It was not influenced by processes inducing changes in cytosolic Ca2+ levels. This assumption was confirmed by experiments with permeabilized muscle preparations that were pre-contracted in a solution with pCa 5.5. Tacrine relaxed the smooth muscles in spite of the constant intracellular Ca2+ concentration resulting from the permeabilization. These findings argue that tacrine at concentrations higher than 2 × 10−5 mol/L has a desensitizing effect on the contractile apparatus of gastric corpus smooth muscle preparations towards Ca2+.
Collapse
Affiliation(s)
- Atanas D Krustev
- Department of Physics and Biophysics, Medical University, Plovdiv, Bulgaria
| | | | | | | | | |
Collapse
|