1
|
Cumming P, Abi-Dargham A, Gründer G. Molecular imaging of schizophrenia: Neurochemical findings in a heterogeneous and evolving disorder. Behav Brain Res 2020; 398:113004. [PMID: 33197459 DOI: 10.1016/j.bbr.2020.113004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/22/2020] [Accepted: 10/31/2020] [Indexed: 02/07/2023]
Abstract
The past four decades have seen enormous efforts placed on a search for molecular markers of schizophrenia using positron emission tomography (PET) and single photon emission computed tomography (SPECT). In this narrative review, we cast a broad net to define and summarize what researchers have learned about schizophrenia from molecular imaging studies. Some PET studies of brain energy metabolism with the glucose analogue FDGhave have shown a hypofrontality defect in patients with schizophrenia, but more generally indicate a loss of metabolic coherence between different brain regions. An early finding of significantly increased striatal trapping of the dopamine synthesis tracer FDOPA has survived a meta-analysis of many replications, but the increase is not pathognomonic of the disorder, since one half of patients have entirely normal dopamine synthesis capacity. Similarly, competition SPECT studies show greater basal and amphetamine-evoked dopamine occupancy at post-synaptic dopamine D2/3 receptors in patients with schizophrenia, but the difference is likewise not pathognomonic. We thus propose that molecular imaging studies of brain dopamine indicate neurochemical heterogeneity within the diagnostic entity of schizophrenia. Occupancy studies have established the relevant target engagement by antipsychotic medications at dopamine D2/3 receptors in living brain. There is evidence for elevated frontal cortical dopamine D1 receptors, especially in relation to cognitive deficits in schizophrenia. There is a general lack of consistent findings of abnormalities in serotonin markers, but some evidence for decreased levels of nicotinic receptors in patients. There are sparse and somewhat inconsistent findings of reduced binding of muscarinic, glutamate, and opioid receptors ligands, inconsistent findings of microglial activation, and very recently, evidence of globally reduced levels of synaptic proteins in brain of patients. One study reports a decline in histone acetylase binding that is confined to the dorsolateral prefrontal cortex. In most contexts, the phase of the disease and effects of past or present medication can obscure or confound PET and SPECT findings in schizophrenia.
Collapse
Affiliation(s)
- Paul Cumming
- Department of Nuclear Medicine, Inselspital, Bern University, Bern, Switzerland; School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia.
| | - Anissa Abi-Dargham
- Stony Brook University, Renaissance School of Medicine, Stony Brook, New York, USA
| | - Gerhard Gründer
- Central Institute of Mental Health, Department of Molecular Neuroimaging, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| |
Collapse
|
2
|
Johnson BM, Shu YZ, Zhuo X, Meanwell NA. Metabolic and Pharmaceutical Aspects of Fluorinated Compounds. J Med Chem 2020; 63:6315-6386. [PMID: 32182061 DOI: 10.1021/acs.jmedchem.9b01877] [Citation(s) in RCA: 300] [Impact Index Per Article: 75.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The applications of fluorine in drug design continue to expand, facilitated by an improved understanding of its effects on physicochemical properties and the development of synthetic methodologies that are providing access to new fluorinated motifs. In turn, studies of fluorinated molecules are providing deeper insights into the effects of fluorine on metabolic pathways, distribution, and disposition. Despite the high strength of the C-F bond, the departure of fluoride from metabolic intermediates can be facile. This reactivity has been leveraged in the design of mechanism-based enzyme inhibitors and has influenced the metabolic fate of fluorinated compounds. In this Perspective, we summarize the literature associated with the metabolism of fluorinated molecules, focusing on examples where the presence of fluorine influences the metabolic profile. These studies have revealed potentially problematic outcomes with some fluorinated motifs and are enhancing our understanding of how fluorine should be deployed.
Collapse
Affiliation(s)
- Benjamin M Johnson
- Pharmaceutical Candidate Optimization, Bristol Myers Squibb Company, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Yue-Zhong Shu
- Pharmaceutical Candidate Optimization, Bristol Myers Squibb Company, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| | - Xiaoliang Zhuo
- Pharmaceutical Candidate Optimization, Bristol Myers Squibb Company, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Nicholas A Meanwell
- Discovery Chemistry Platforms, Small Molecule Drug Discovery, Bristol Myers Squibb Company, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| |
Collapse
|
3
|
Lima Neto JX, Bezerra KS, Barbosa ED, Oliveira JIN, Manzoni V, Soares-Rachetti VP, Albuquerque EL, Fulco UL. Exploring the Binding Mechanism of GABAB Receptor Agonists and Antagonists through in Silico Simulations. J Chem Inf Model 2019; 60:1005-1018. [DOI: 10.1021/acs.jcim.9b01025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- José X. Lima Neto
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Katyanna S. Bezerra
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Emmanuel D. Barbosa
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Jonas I. N. Oliveira
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Vinícius Manzoni
- Instituto de Física, Universidade Federal do Alagoas, 57072-970 Maceió-AL, Brazil
| | - Vanessa P. Soares-Rachetti
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Eudenilson L. Albuquerque
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| | - Umberto L. Fulco
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN, Brazil
| |
Collapse
|
4
|
Sowa AR, Brooks AF, Shao X, Henderson BD, Sherman P, Arteaga J, Stauff J, Lee AC, Koeppe RA, Scott PJH, Kilbourn MR. Development of Positron Emission Tomography Radiotracers for the GABA Transporter 1. ACS Chem Neurosci 2018; 9:2767-2773. [PMID: 29763549 DOI: 10.1021/acschemneuro.8b00183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In vivo positron emission tomography (PET) imaging of the γ-aminobutyric acid (GABA) receptor complex has been accomplished using radiolabeled benzodiazepine derivatives, but development of specific presynaptic radioligands targeting the neuronal membrane GABA transporter type 1 (GAT-1) has been less successful. The availability of new structure-activity studies of GAT-1 inhibitors and the introduction of a GAT-1 inhibitor (tiagabine, Gabatril) into clinical use prompted us to reinvestigate the syntheses of PET ligands for this transporter. Initial synthesis and rodent PET studies of N-[11C]methylnipecotic acid confirmed the low brain uptake of that small and polar molecule. The common design approach to improve blood-brain barrier permeability of GAT-1 inhibitors is the attachment of a large lipophilic substituent. We selected an unsymmetrical bis-aromatic residue attached to the ring nitrogen by a vinyl ether spacer from a series recently reported by Wanner and coworkers. Nucleophilic aromatic substitution of an aryl chloride precursor with [18F]fluoride was used to prepare the desired candidate radiotracer ( R, E/ Z)-1-(2-((4-fluoro-2-(4-[18F]fluorobenzoyl)styryl)oxy)ethyl)piperidine-3-carboxylic acid (( R, E/ Z)-[18F]10). PET studies in rats showed no brain uptake, which was not altered by pretreatment of animals with the P-glycoprotein inhibitor cyclosporine A, indicating efflux by Pgp was not responsible. Subsequent PET imaging studies of ( R, E/ Z)-[18F]10 in rhesus monkey brain showed very low brain uptake. Finally, to test if the free carboxylic acid group was the likely cause of poor brain uptake, PET studies were done using the ethyl ester derivative of ( R, E/ Z)-[18F]10. Rapid and significant monkey brain uptake of the ester was observed, followed by a slow washout over 90 min. The blood-brain barrier permeability of the ester supports a hypothesis that the free acid function limits brain uptake of nipecotic acid-based GAT-1 radioligands, and future radiotracer efforts should investigate the use of carboxylic acid bioisosteres.
Collapse
Affiliation(s)
- Alexandra R. Sowa
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Allen F. Brooks
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Xia Shao
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Bradford D. Henderson
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Philip Sherman
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Janna Arteaga
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Jenelle Stauff
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Adam C. Lee
- E.I. du Pont de Nemours and Company, DuPont Haskell Global Center for Health Sciences, P.O. Box 30, Newark, Delaware 19714, United States
| | - Robert A. Koeppe
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Michael R. Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| |
Collapse
|