1
|
Masuoka T, Kiyoi T, Zheng S, He Q, Liu L, Uwada J, Muramatsu I. Corneal acetylcholine regulates sensory nerve activity via nicotinic receptors. Ocul Surf 2024; 32:60-70. [PMID: 38242319 DOI: 10.1016/j.jtos.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 12/19/2023] [Accepted: 01/16/2024] [Indexed: 01/21/2024]
Abstract
PURPOSE Sensory nerve terminals are highly distributed in the cornea, and regulate ocular surface sensation and homeostasis in response to various endogenous and exogenous stimuli. However, little is known about mediators regulating the physiological and pathophysiological activities of corneal sensory nerves. The aim of this study was to investigate the presence of cholinergic regulation in sensory nerves in the cornea. METHODS Localization of choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (vAChT) was evaluated using western blotting and immunohistochemical analysis. The synthesis and liberation of acetylcholine from the cornea were assessed using corneal segments pre-incubated with [3H]choline. The responsiveness of corneal neurons and nerves to cholinergic drugs was explored using calcium imaging with primary cultures of trigeminal ganglion neurons and extracellular recording from corneal preparations in guinea pigs. RESULTS ChAT, but not vAChT, was highly distributed in the corneal epithelium. In corneal segments, [3H] acetylcholine was synthesized from [3H]choline, and was also released in response to electrical stimuli. In cultured corneal neurons, the population sensitive to a transient receptor potential melastatin 8 (TRPM8) agonist exhibited high probability of responding to nicotine in a calcium imaging experiment. The firing frequency of cold-sensitive corneal nerves was increased by the application of nicotine, but diminished by an α4 nicotinic acetylcholine receptor antagonist. CONCLUSIONS The corneal epithelium can synthesize and release acetylcholine. Corneal acetylcholine can excite sensory nerves via nicotinic receptors containing the α4 subunit. Therefore, corneal acetylcholine may be one of the important regulators of corneal nerve activity arranging ocular surface condition and sensation.
Collapse
Affiliation(s)
- Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan.
| | - Takeshi Kiyoi
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Shijie Zheng
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Qiang He
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Li Liu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Junsuke Uwada
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan; Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, 910-1193, Japan
| |
Collapse
|
2
|
Arakawa I, Muramatsu I, Uwada J, Sada K, Matsukawa N, Masuoka T. Acetylcholine release from striatal cholinergic interneurons is controlled differently depending on the firing pattern. J Neurochem 2023; 167:38-51. [PMID: 37653723 DOI: 10.1111/jnc.15950] [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: 02/18/2023] [Revised: 07/31/2023] [Accepted: 08/11/2023] [Indexed: 09/02/2023]
Abstract
How is the quantal size in neurotransmitter release adjusted for various firing levels? We explored the possible mechanisms that regulate acetylcholine (ACh) release from cholinergic interneurons using an ultra-mini superfusion system. After preloading [3 H]ACh in rat striatal cholinergic interneurons, the release was elicited by electrical stimulation under a condition in which presynaptic cholinergic and dopaminergic feedback was inhibited. [3 H]ACh release was reproducible at intervals of more than 10 min; shorter intervals resulted in reduced levels of ACh release. Upon persistent stimulation for 10 min, ACh release transiently increased, before gradually decreasing. Vesamicol, an inhibitor of the vesicular ACh transporter (VAChT), had no effect on the release induced by the first single pulse, but it reduced the release caused by subsequent pulses. Vesamicol also reduced the [3 H]ACh release evoked by multiple pulses, and the inhibition was enhanced by repetitive stimulation. The decreasing phase of [3 H]ACh release during persistent stimulation was accelerated by vesamicol treatment. Thus, it is likely that releasable ACh was slowly compensated for via VAChT during and after stimulation, changing the vesicular ACh content. In addition, ACh release per pulse decreased under high-frequency stimulation. The present results suggest that ACh release from striatal cholinergic interneurons may be adjusted by changes in the quantal size due to slow replenishment via VAChT, and by a reduction in release probability upon high-frequency stimulation. These two distinct processes likely enable the fine tuning of neurotransmission and neuroprotection/limitation against excessive output and have important physiological roles in the brain.
Collapse
Affiliation(s)
- Itsumi Arakawa
- Department of Neurology, Nagoya City University Graduate School of Medicine, Nagoya, Japan
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Fukui, Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Fukui, Japan
- Kimura Hospital, Fukui, Japan
| | - Junsuke Uwada
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
| | - Kiyonao Sada
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Fukui, Japan
| | - Noriyuki Matsukawa
- Department of Neurology, Nagoya City University Graduate School of Medicine, Nagoya, Japan
| | - Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Japan
| |
Collapse
|
3
|
Role of Cholinergic Signaling in Alzheimer's Disease. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27061816. [PMID: 35335180 PMCID: PMC8949236 DOI: 10.3390/molecules27061816] [Citation(s) in RCA: 128] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/14/2022] [Accepted: 02/22/2022] [Indexed: 12/27/2022]
Abstract
Acetylcholine, a neurotransmitter secreted by cholinergic neurons, is involved in signal transduction related to memory and learning ability. Alzheimer’s disease (AD), a progressive and commonly diagnosed neurodegenerative disease, is characterized by memory and cognitive decline and behavioral disorders. The pathogenesis of AD is complex and remains unclear, being affected by various factors. The cholinergic hypothesis is the earliest theory about the pathogenesis of AD. Cholinergic atrophy and cognitive decline are accelerated in age-related neurodegenerative diseases such as AD. In addition, abnormal central cholinergic changes can also induce abnormal phosphorylation of ttau protein, nerve cell inflammation, cell apoptosis, and other pathological phenomena, but the exact mechanism of action is still unclear. Due to the complex and unclear pathogenesis, effective methods to prevent and treat AD are unavailable, and research to explore novel therapeutic drugs is various and active in the world. This review summaries the role of cholinergic signaling and the correlation between the cholinergic signaling pathway with other risk factors in AD and provides the latest research about the efficient therapeutic drugs and treatment of AD.
Collapse
|
4
|
Muramatsu I, Uwada J, Chihara K, Sada K, Wang MH, Yazawa T, Taniguchi T, Ishibashi T, Masuoka T. Evaluation of radiolabeled acetylcholine synthesis and release in rat striatum. J Neurochem 2021; 160:342-355. [PMID: 34878648 DOI: 10.1111/jnc.15556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 10/18/2021] [Accepted: 11/30/2021] [Indexed: 12/26/2022]
Abstract
Cholinergic transmission underlies higher brain functions such as cognition and movement. To elucidate the process whereby acetylcholine (ACh) release is maintained and regulated in the central nervous system, uptake of [3 H]choline and subsequent synthesis and release of [3 H]ACh were investigated in rat striatal segments. Incubation with [3 H]choline elicited efficient uptake via high-affinity choline transporter-1, resulting in accumulation of [3 H]choline and [3 H]ACh. However, following inhibition of ACh esterase (AChE), incubation with [3 H]choline led predominantly to the accumulation of [3 H]ACh. Electrical stimulation and KCl depolarization selectively released [3 H]ACh but not [3 H]choline. [3 H]ACh release gradually declined upon repetitive stimulation, whereas the release was reproducible under inhibition of AChE. [3 H]ACh release was abolished after treatment with vesamicol, an inhibitor of vesicular ACh transporter. These results suggest that releasable ACh is continually replenished from the cytosol to releasable pools of cholinergic vesicles to maintain cholinergic transmission. [3 H]ACh release evoked by electrical stimulation was abolished by tetrodotoxin, but that induced by KCl was largely resistant. ACh release was Ca2+ dependent and exhibited slightly different sensitivities to N- and P-type Ca2+ channel toxins (ω-conotoxin GVIA and ω-agatoxin IVA, respectively) between both stimuli. [3 H]ACh release was negatively regulated by M2 muscarinic and D2 dopaminergic receptors. The present results suggest that inhibition of AChE within cholinergic neurons and of presynaptic negative regulation of ACh release contributes to maintenance and facilitation of cholinergic transmission, providing a potentially useful clue for the development of therapies for cholinergic dysfunction-associated disorders, in addition to inhibition of synaptic cleft AChE.
Collapse
Affiliation(s)
- Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan.,Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan.,Kimura Hospital, Awara, Fukui, Japan
| | - Junsuke Uwada
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan.,Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Kazuyasu Chihara
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
| | - Kiyonao Sada
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
| | - Mao-Hsien Wang
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan.,Department of Anesthesia, En Chu Kon Hospital, New Taipei City, Taiwan, ROC
| | - Takashi Yazawa
- Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Takanobu Taniguchi
- Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Takaharu Ishibashi
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| |
Collapse
|
5
|
Suzuki E, Momiyama T. M1 muscarinic acetylcholine receptor-mediated inhibition of GABA release from striatal medium spiny neurons onto cholinergic interneurons. Eur J Neurosci 2020; 53:796-813. [PMID: 33270289 DOI: 10.1111/ejn.15074] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/10/2020] [Accepted: 11/24/2020] [Indexed: 11/26/2022]
Abstract
Acetylcholine (ACh) modulates neurotransmitter release in the central nervous system. Although GABAergic transmission onto the striatal cholinergic interneurons (ChIN) is modulated by dopamine receptors, cholinergic modulation of the same synapse is still unknown. In the present study, modulatory roles of ACh in the GABAergic transmission from striatal medium spiny neurons (MSNs) onto ChIN were investigated using optogenetics and whole-cell patch-clamp technique in juvenile and young-adult mice brain slices. GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) were evoked by focal electrical- or blue-light stimulation. Bath application of carbachol, a muscarinic ACh receptor agonist, suppressed the amplitude of IPSCs in a concentration-dependent manner in both age groups. A choline esterase inhibitor, physostigmine, also suppressed the amplitude of IPSCs. In the presence of a membrane permeable M1 muscarine receptor antagonist, pirenzepine, carbachol-induced suppression of IPSCs was antagonized, whereas a M2 muscarine receptor antagonist, a M4 receptor antagonist, or a membrane impermeable M1 receptor antagonist did not antagonize carbachol-induced suppression of IPSCs. Retrograde cannabinoid cascade via cannabinoid receptor 1 was not involved in carbachol-induced inhibition. Furthermore, carbachol did not affect amplitude of inward currents induced by puff application of GABA, whereas coefficient of variation of IPSCs was significantly increased by carbachol. These results suggest that activation of presynaptic M1 muscarine receptors located on the GABAergic terminals including intracellular organelle of MSNs inhibits GABA release onto ChIN.
Collapse
Affiliation(s)
- Etsuko Suzuki
- Department of Pharmacology, Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Toshihiko Momiyama
- Department of Pharmacology, Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| |
Collapse
|
6
|
Chen WN, Yeong KY. Scopolamine, a Toxin-Induced Experimental Model, Used for Research in Alzheimer’s Disease. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2020; 19:85-93. [DOI: 10.2174/1871527319666200214104331] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 02/06/2023]
Abstract
Scopolamine as a drug is often used to treat motion sickness. Derivatives of scopolamine
have also found applications as antispasmodic drugs among others. In neuroscience-related research, it
is often used to induce cognitive disorders in experimental models as it readily permeates the bloodbrain
barrier. In the context of Alzheimer’s disease, its effects include causing cholinergic dysfunction
and increasing amyloid-β deposition, both of which are hallmarks of the disease. Hence, the application
of scopolamine in Alzheimer’s disease research is proven pivotal but seldom discussed. In this review,
the relationship between scopolamine and Alzheimer’s disease will be delineated through an
overall effect of scopolamine administration and its specific mechanisms of action, discussing mainly
its influences on cholinergic function and amyloid cascade. The validity of scopolamine as a model of
cognitive impairment or neurotoxin model will also be discussed in terms of advantages and limitations
with future insights.
Collapse
Affiliation(s)
- Win Ning Chen
- School of Science, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia
| | - Keng Yoon Yeong
- School of Science, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia
| |
Collapse
|
7
|
Muramatsu I, Uwada J, Yoshiki H, Sada K, Lee K, Yazawa T, Taniguchi T, Nishio M, Ishibashi T, Masuoka T. Novel regulatory systems for acetylcholine release in rat striatum and anti‐Alzheimer's disease drugs. J Neurochem 2019; 149:605-623. [DOI: 10.1111/jnc.14701] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 02/20/2019] [Accepted: 03/27/2019] [Indexed: 10/27/2022]
Affiliation(s)
- Ikunobu Muramatsu
- Department of Pharmacology School of Medicine Kanazawa Medical University Uchinada, Ishikawa Japan
- Division of Genomic Science and Microbiology School of Medicine University of Fukui Eiheiji Fukui Japan
- Kimura Hospital Awara Fukui Japan
| | - Junsuke Uwada
- Division of Cellular Signal Transduction Department of Biochemistry Asahikawa Medical University Asahikawa Hokkaido Japan
| | - Hatsumi Yoshiki
- Division of Genomic Science and Microbiology School of Medicine University of Fukui Eiheiji Fukui Japan
| | - Kiyonao Sada
- Division of Genomic Science and Microbiology School of Medicine University of Fukui Eiheiji Fukui Japan
| | - Kung‐Shing Lee
- Division of Genomic Science and Microbiology School of Medicine University of Fukui Eiheiji Fukui Japan
- Department of Surgery Kaohsiung Medical University Kaohsiung Taiwan
| | - Takashi Yazawa
- Division of Cellular Signal Transduction Department of Biochemistry Asahikawa Medical University Asahikawa Hokkaido Japan
| | - Takanobu Taniguchi
- Division of Cellular Signal Transduction Department of Biochemistry Asahikawa Medical University Asahikawa Hokkaido Japan
| | - Matomo Nishio
- Department of Pharmacology School of Medicine Kanazawa Medical University Uchinada, Ishikawa Japan
| | - Takaharu Ishibashi
- Department of Pharmacology School of Medicine Kanazawa Medical University Uchinada, Ishikawa Japan
| | - Takayoshi Masuoka
- Department of Pharmacology School of Medicine Kanazawa Medical University Uchinada, Ishikawa Japan
| |
Collapse
|
8
|
Masuoka T, Uwada J, Kudo M, Yoshiki H, Yamashita Y, Taniguchi T, Nishio M, Ishibashi T, Muramatsu I. Augmentation of Endogenous Acetylcholine Uptake and Cholinergic Facilitation of Hippocampal Long-Term Potentiation by Acetylcholinesterase Inhibition. Neuroscience 2019; 404:39-47. [PMID: 30708046 DOI: 10.1016/j.neuroscience.2019.01.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 10/27/2022]
Abstract
Hippocampal cholinergic activity enhances long-term potentiation (LTP) of synaptic transmission in intrahippocampal circuits and regulates cognitive function. We recently demonstrated intracellular distribution of functional M1-muscarinic acetylcholine receptors (mAChRs) and neuronal uptake of acetylcholine (ACh) in the central nervous system. Here we examined whether endogenous ACh acts on intracellular M1-mAChRs following its uptake and causes cholinergic facilitation of hippocampal LTP. ACh esterase (AChE) activities and [3H]ACh uptake was measured in rat hippocampal segments. LTP of evoked field excitatory postsynaptic potentials at CA1 synapses was induced by high frequency stimulation in hippocampal slices. Pretreatment with diisopropylfluorophosphate (DFP) irreversibly inhibited AChE, augmented ACh uptake, and significantly enhanced the LTP. This cholinergic facilitation was inhibited by pirenzepine, a membrane-permeable M1 antagonist, while only the early stage of cholinergic facilitation was inhibited by a membrane-impermeable M1 antagonist, muscarinic toxin 7. Tetraethylammonium (TEA) inhibited ACh uptake in hippocampal segments and selectively suppressed late stage cholinergic facilitation without changing the early stage. In contrast, LTP in DFP-untreated slices was not affected by the muscarinic antagonists and TEA. Carbachol (CCh; an AChE-resistant muscarinic agonist) competed with ACh for its uptake and produced cholinergic facilitation of LTP in DFP-untreated slices. The late stage of CCh-induced facilitation was also selectively inhibited by TEA. Our results suggest that when AChE is inactivated by inhibitors, LTP in hippocampal slices is significantly enhanced by endogenous ACh and that cholinergic facilitation is caused by direct activation of cell-surface M1-mAChRs and subsequent activation of intracellular M1-mAChRs after ACh uptake.
Collapse
Affiliation(s)
- Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan.
| | - Junsuke Uwada
- Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido, 078-8510, Japan
| | - Makiko Kudo
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Hatsumi Yoshiki
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui 910-1193, Japan
| | - Yuka Yamashita
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Takanobu Taniguchi
- Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido, 078-8510, Japan
| | - Matomo Nishio
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Takaharu Ishibashi
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa, 920-0293, Japan
| |
Collapse
|
9
|
Baig AM, Rana Z, Tariq S, Lalani S, Ahmad HR. Traced on the Timeline: Discovery of Acetylcholine and the Components of the Human Cholinergic System in a Primitive Unicellular Eukaryote Acanthamoeba spp. ACS Chem Neurosci 2018; 9:494-504. [PMID: 29058403 DOI: 10.1021/acschemneuro.7b00254] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Acetylcholine (ACh) is the neurotransmitter of cholinergic signal transduction that affects the target cells via muscarinic (mAChR) and nicotinic (nAChR) cholinergic receptors embedded in the cell membrane. Of the cholinergic receptors that bind to ACh, the mAChRs execute several cognitive and metabolic functions in the human central nervous system (CNS). Very little is known about the origins and autocrine/paracrine roles of the ACh in primitive life forms. With the recent report of the evidence of an ACh binding mAChR1 like receptor in Acanthamoeba spp., it was tempting to investigate the origin and functional roles of cholinergic G-Protein coupled receptors (GPCRs) in the biology of eukaryotes. We inferred the presence of ACh, its synthetic, degradation system, and a signal transduction pathway in an approximately ∼2.0 billion year old primitive eukaryotic cell Acanthamoeba castellanii. Bioinformatics analysis, ligand binding prediction, and docking methods were used to establish the origins of enzymes involved in the synthesis and degradation of ACh. Notably, we provide evidence of the presence of ACh in A. castellanii by colorimetric analysis, which to date is the only report of its presence in this primitive unicellular eukaryote. We show the evidence for the presence of homology of evolutionary conserved key enzymes of the cholinergic system like choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in A. castellanii spp., which were found to be near identical to their human counterparts. Tracing the origin, functions of ACh, and primeval mAChRs in primitive eukaryotic cells has the potential of uncovering covert cholinergic pathways that can be extended to humans in order to understand the states of cholinergic deficiency in neurodegenerative diseases (ND).
Collapse
Affiliation(s)
| | - Zohaib Rana
- The Aga Khan University, Karachi 74800, Pakistan
| | | | | | - H. R. Ahmad
- The Aga Khan University, Karachi 74800, Pakistan
| |
Collapse
|
10
|
van den Brink WJ, Palic S, Köhler I, de Lange ECM. Access to the CNS: Biomarker Strategies for Dopaminergic Treatments. Pharm Res 2018; 35:64. [PMID: 29450650 PMCID: PMC5814527 DOI: 10.1007/s11095-017-2333-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 12/18/2017] [Indexed: 12/26/2022]
Abstract
Despite substantial research carried out over the last decades, it remains difficult to understand the wide range of pharmacological effects of dopaminergic agents. The dopaminergic system is involved in several neurological disorders, such as Parkinson's disease and schizophrenia. This complex system features multiple pathways implicated in emotion and cognition, psychomotor functions and endocrine control through activation of G protein-coupled dopamine receptors. This review focuses on the system-wide effects of dopaminergic agents on the multiple biochemical and endocrine pathways, in particular the biomarkers (i.e., indicators of a pharmacological process) that reflect these effects. Dopaminergic treatments developed over the last decades were found to be associated with numerous biochemical pathways in the brain, including the norepinephrine and the kynurenine pathway. Additionally, they have shown to affect peripheral systems, for example the hypothalamus-pituitary-adrenal (HPA) axis. Dopaminergic agents thus have a complex and broad pharmacological profile, rendering drug development challenging. Considering the complex system-wide pharmacological profile of dopaminergic agents, this review underlines the needs for systems pharmacology studies that include: i) proteomics and metabolomics analysis; ii) longitudinal data evaluation and mathematical modeling; iii) pharmacokinetics-based interpretation of drug effects; iv) simultaneous biomarker evaluation in the brain, the cerebrospinal fluid (CSF) and plasma; and v) specific attention to condition-dependent (e.g., disease) pharmacology. Such approach is considered essential to increase our understanding of central nervous system (CNS) drug effects and substantially improve CNS drug development.
Collapse
Affiliation(s)
- Willem Johan van den Brink
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Semra Palic
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Isabelle Köhler
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Elizabeth Cunera Maria de Lange
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
| |
Collapse
|
11
|
Muramatsu I, Uwada J, Masuoka T, Yoshiki H, Sada K, Lee KS, Nishio M, Ishibashi T, Taniguchi T. Regulation of synaptic acetylcholine concentrations by acetylcholine transport in rat striatal cholinergic transmission. J Neurochem 2017; 143:76-86. [PMID: 28700094 DOI: 10.1111/jnc.14127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/17/2017] [Accepted: 06/29/2017] [Indexed: 11/29/2022]
Abstract
In addition to hydrolysis by acetylcholine esterase (AChE), acetylcholine (ACh) is also directly taken up into brain tissues. In this study, we examined whether the uptake of ACh is involved in the regulation of synaptic ACh concentrations. Superfusion experiments with rat striatal segments pre-incubated with [3 H]choline were performed using an ultra-mini superfusion vessel, which was developed to minimize superfusate retention within the vessel. Hemicholinium-3 (HC-3) at concentrations less than 1 μM, selectively inhibited the uptake of [3 H]choline by the high affinity-choline transporter 1 and had no effect on basal and electrically evoked [3 H]efflux in superfusion experiments. In contrast, HC-3 at higher concentrations, as well as tetraethylammonium (>10 μM), which inhibited the uptake of both [3 H]choline and [3 H]ACh, increased basal [3 H]overflow and potentiated electrically evoked [3 H]efflux. These effects of HC-3 and tetraethylammonium were also observed under conditions where tissue AChE was irreversibly inactivated by diisopropylfluorophosphate. Specifically, the potentiation of evoked [3 H]efflux was significantly higher in AChE-inactivated preparations and was attenuated by atropine. On the other hand, striatal segments pre-incubated with [3 H]ACh failed to increase [3 H]overflow in response to electrical stimulation. These results show that synaptic ACh concentrations are significantly regulated by the postsynaptic uptake of ACh, as well as by AChE hydrolysis and modulation of ACh release mediated through presynaptic muscarinic ACh receptors. In addition, these data suggest that the recycling of ACh-derived choline may be minor in cholinergic terminals. This study reveals a new mechanism of cholinergic transmission in the central nervous system.
Collapse
Affiliation(s)
- Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan.,Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan.,Kimura Hospital, Awara, Fukui, Japan
| | - Junsuke Uwada
- Division of Cellular Signal Transduction, Department of Biochemistry, Asahikawa Medical University, Asahikawa, Hokkaido, Japan
| | - Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Hatsumi Yoshiki
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
| | - Kiyonao Sada
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
| | - Kung-Shing Lee
- Division of Genomic Science and Microbiology, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan.,Department of Surgery, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Matomo Nishio
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Takaharu Ishibashi
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | | |
Collapse
|
12
|
Abstract
As the field of PET has expanded and an ever-increasing number and variety of compounds have been radiolabeled as potential in vivo tracers of biochemistry, transporters have become important primary targets or facilitators of radiotracer uptake and distribution. A transporter can be the primary target through the development of a specific high-affinity radioligand: examples are the multiple high-affinity radioligands for the neuronal membrane neurotransmitter or vesicular transporters, used to image nerve terminals in the brain. The goal of a radiotracer might be to study the function of a transporter through the use of a radiolabeled substrate, such as the application of 3-O-[11C]methyl]glucose to measure rates of glucose transport through the blood-brain barrier. In many cases, transporters are required for radiotracer distributions, but the targeted biochemistries might be unrelated: an example is the use of 2-deoxy-2-[18F]FDG for imaging glucose metabolism, where initial passage of the radiotracer through cell membranes requires the action of specific glucose transporters. Finally, there are transporters such as p-glycoprotein that function to extrude small molecules from tissues, and can effectively work against successful uptake of radiotracers. The diversity of structures and functions of transporters, their importance in human health and disease, and their role in therapeutic drug disposition suggest that in vivo imaging of transporter location and function will continue to be a point of emphasis in PET radiopharmaceutical development. In this review, the variety of transporters and their importance for in vivo PET radiotracer development and application are discussed. Transporters have thus joined the other major protein targets such as G-protein coupled receptors, ligand-gated ion channels, enzymes, and aggregated proteins as of high interest for understanding human health and disease.
Collapse
Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI.
| |
Collapse
|