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Raikar P, Bannimath G. Recent Trends in Chiral Separation-A Collective Paradigm of Selected Chiral Impurities. CURR PHARM ANAL 2020. [DOI: 10.2174/1573412915666181219144507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chiral separation plays a very important role in the modern pharmaceutical analysis and will
continue in upcoming years. Separation and identification of chiral impurities are indispensable. According
to ICH guidelines, only the active enantiomer of the drug has to be marketed, so there is a focus
on separation of the inactive enantiomer which acts as a chiral impurity. The impurities present in the
enantiomers also pose various toxic adverse effects on bioavailability and efficacy, hence the need to
separate these impurities will forever be trending. This review primarily focuses on the separation techniques
like Capillary Electrophoresis (CE), High-Performance Liquid Chromatography (HPLC), Gas
Chromatography (GC), and Supercritical Fluid Chromatography (SFC) followed by the year-wise trend
in the separation of selected chiral impurities. In the coming years, researchers should work on using
ultra-fast, selective, and sensitive methods for the effective separation of chiral impurities.
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Affiliation(s)
- Prachi Raikar
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research, SS Nagar, Mysuru 570015, India
| | - Gurupadayya Bannimath
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research, SS Nagar, Mysuru 570015, India
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Weiss T, Bernard R, Bernstein HG, Veh RW, Laube G. Agmatine modulates spontaneous activity in neurons of the rat medial habenular complex-a relevant mechanism in the pathophysiology and treatment of depression? Transl Psychiatry 2018; 8:201. [PMID: 30250120 PMCID: PMC6155246 DOI: 10.1038/s41398-018-0254-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/02/2018] [Accepted: 08/17/2018] [Indexed: 12/15/2022] Open
Abstract
The dorsal diencephalic conduction system connects limbic forebrain structures to monaminergic mesencephalic nuclei via a distinct relay station, the habenular complexes. Both habenular nuclei, the lateral as well as the medial nucleus, are considered to play a prominent role in mental disorders like major depression. Herein, we investigate the effect of the polyamine agmatine on the electrical activity of neurons within the medial habenula in rat. We present evidence that agmatine strongly decreases spontaneous action potential firing of medial habenular neurons by activating I1-type imidazoline receptors. Additionally, we compare the expression patterns of agmatinase, an enzyme capable of inactivating agmatine, in rat and human habenula. In the medial habenula of both species, agmatinase is similarly distributed and observed in neurons and, in particular, in distinct neuropil areas. The putative relevance of these findings in the context of depression is discussed. It is concluded that increased activity of the agmatinergic system in the medial habenula may strengthen midbrain dopaminergic activity. Consequently, the habenular-interpeduncular axis may be dysregulated in patients with major depression.
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Affiliation(s)
- Torsten Weiss
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany.
| | - René Bernard
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Klinik für Neurologie, Department of Experimental Neurology, Berlin, Germany
| | - Hans-Gert Bernstein
- 0000 0001 1018 4307grid.5807.aDepartment of Psychiatry and Psychotherapy, Medical Faculty, University of Magdeburg, Magdeburg, Germany
| | - Rüdiger W. Veh
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany
| | - Gregor Laube
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany
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Kjaerby C, Rasmussen R, Andersen M, Nedergaard M. Does Global Astrocytic Calcium Signaling Participate in Awake Brain State Transitions and Neuronal Circuit Function? Neurochem Res 2017; 42:1810-1822. [PMID: 28210958 DOI: 10.1007/s11064-017-2195-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/31/2022]
Abstract
We continuously need to adapt to changing conditions within our surrounding environment, and our brain needs to quickly shift between resting and working activity states in order to allow appropriate behaviors. These global state shifts are intimately linked to the brain-wide release of the neuromodulators, noradrenaline and acetylcholine. Astrocytes have emerged as a new player participating in the regulation of brain activity, and have recently been implicated in brain state shifts. Astrocytes display global Ca2+ signaling in response to activation of the noradrenergic system, but whether astrocytic Ca2+ signaling is causative or correlative for shifts in brain state and neural activity patterns is not known. Here we review the current available literature on astrocytic Ca2+ signaling in awake animals in order to explore the role of astrocytic signaling in brain state shifts. Furthermore, we look at the development and availability of innovative new methodological tools that are opening up for new ways of visualizing and perturbing astrocyte activity in awake behaving animals. With these new tools at hand, the field of astrocyte research will likely be able to elucidate the causal and mechanistic roles of astrocytes in complex behaviors within a very near future.
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Affiliation(s)
- Celia Kjaerby
- Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Building 24.2, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Rune Rasmussen
- Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Building 24.2, Blegdamsvej 3B, 2200, Copenhagen N, Denmark.,Department of Biomedicine, The Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, 8000, Aarhus C, Denmark
| | - Mie Andersen
- Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Building 24.2, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Maiken Nedergaard
- Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Building 24.2, Blegdamsvej 3B, 2200, Copenhagen N, Denmark. .,Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, USA.
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Briand LA, Gritton H, Howe WM, Young DA, Sarter M. Modulators in concert for cognition: modulator interactions in the prefrontal cortex. Prog Neurobiol 2007; 83:69-91. [PMID: 17681661 PMCID: PMC2080765 DOI: 10.1016/j.pneurobio.2007.06.007] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/06/2007] [Accepted: 06/22/2007] [Indexed: 12/19/2022]
Abstract
Research on the regulation and function of ascending noradrenergic, dopaminergic, serotonergic, and cholinergic systems has focused on the organization and function of individual systems. In contrast, evidence describing co-activation and interactions between multiple neuromodulatory systems has remained scarce. However, commonalities in the anatomical organization of these systems and overlapping evidence concerning the post-synaptic effects of neuromodulators strongly suggest that these systems are recruited in concert; they influence each other and simultaneously modulate their target circuits. Therefore, evidence on the regulatory and functional interactions between these systems is considered essential for revealing the role of neuromodulators. This postulate extends to contemporary neurobiological hypotheses of major neuropsychiatric disorders. These hypotheses have focused largely on aberrations in the integrity or regulation of individual ascending modulatory systems, with little regard for the likely possibility that dysregulation in multiple ascending neuromodulatory systems and their interactions contribute essentially to the symptoms of these disorders. This review will paradigmatically focus on neuromodulator interactions in the PFC and be further constrained by an additional focus on their role in cognitive functions. Recent evidence indicates that individual neuromodulators, in addition to their general state-setting or gating functions, encode specific cognitive operations, further substantiating the importance of research concerning the parallel recruitment of neuromodulator systems and interactions between these systems.
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Affiliation(s)
- Lisa A Briand
- University of Michigan, Department of Psychology and Neuroscience Program, Ann Arbor, MI 48109, USA.
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6
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Lorin M, Delépée R, Morin P, Ribet JP. Quantification of very low enantiomeric impurity of efaroxan using a dual cyclodextrin system by capillary electrophoresis. Anal Chim Acta 2007; 592:139-45. [PMID: 17512818 DOI: 10.1016/j.aca.2007.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 04/02/2007] [Accepted: 04/11/2007] [Indexed: 10/23/2022]
Abstract
A rapid method for the enantiomeric purity determination of efaroxan has been developed by capillary electrophoresis (CE) using a dual cyclodextrin (CD) system. The influence of the nature and the concentration of CDs on separation parameters has been studied. High resolution (R(s)=7) and peak efficiency (104,000-121,000 theoretical plates) values were obtained for efaroxan enantiomers by adding two cyclodextrins, one neutral (7.5 mM DM-beta-CD) and the other negatively charged (3 mM CM-beta-CD) to the running buffer composed of 100 mM phosphoric acid-triethanolamine (pH 3). These resolution and peak efficiencies values allowed the quantitation of the (S)-enantiomer of efaroxan at very low enantiomeric excess even if the minor component migrates after the major one. This method was fully validated for the enantiomeric impurity determination of the (S)-form of efaroxan at the 0.05% level. Calibration curve, expressed by the peak areas ratio versus the enantiomeric purity was linear over the 0.05-1% enantiomeric impurity range (r2=0.9996). Limits of detection (LOD) and quantification (LOQ), expressed in term of (S)-enantiomer impurity were 0.02% and 0.05%, respectively. The accuracy of the method at 0.12%, 0.50% and 0.80% enantiomeric impurity levels for the (S)-form were determined. Recoveries were in 94-102% range for each quality control sample and were determined with good precision (intra-day R.S.D.=3.54%, inter-day R.S.D.=5.33%).
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Affiliation(s)
- Marie Lorin
- Institut de Chimie Organique et Analytique, CNRS FR 2708, UMR 6005, Université d'Orléans, BP 6759, Orléans 45067 Cedex 2, France
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7
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Lorin M, Delépée R, Ribet JP, Morin P. Validation of a method using an achiral liquid chromatography sorbent and a circular dichroism detector. J Chromatogr A 2007; 1141:244-50. [PMID: 17207805 DOI: 10.1016/j.chroma.2006.12.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 12/04/2006] [Accepted: 12/11/2006] [Indexed: 11/27/2022]
Abstract
The known HPLC method using an achiral C8 silica sorbent and a circular dichroism (CD) detector for the determination of efaroxan enantiomeric excess has been validated. After optimization of the mobile phase, the enantiomers were detected at 278 nm offering maximum ellipticity between two optically active forms. The calibration curve of the anisotropy factor (g) versus the enantiomeric excess was linear with a correlation coefficient (r2) of 0.9985. The accuracy of the method was assessed by comparing the enantiomeric excess obtained by measuring the g factor (C8 column, CD and UV detections) with those determined by enantioselective HPLC (Chiralpak AD-H column, UV detection). Statistical tests (level of confidence of 95%) were assessed to compare the two orthogonal methods. The straight line gave a correlation coefficient of 0.9995, an intercept not significantly different from zero (0.0549) and a slope of 1.026. The precision evaluated on retention time (RSD<0.6%), g factor (RSD<8.3%) and CD peak area (RSD<7.5%) was suitable both in term of intra- and inter-day precisions. The proposed method has the advantages of being fast and precise without using expensive chiral column. Non-enantioselective HPLC-CD was suitable for the simultaneous determination of the optical and chemical purity of efaroxan.
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Affiliation(s)
- Marie Lorin
- Institut de Chimie Organique et Analytique, CNRS FR 2708, UMR 6005, Université d'Orléans, B.P. 6759, 45067 Orléans Cedex 2, France
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 389] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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9
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Lorin M, Delepee R, Maurizot JC, Ribet JP, Morin P. Sensitivity improvement of circular dichroism detection in HPLC by using a low-pass electronic noise filter: Application to the enantiomeric determination purity of a basic drug. Chirality 2006; 19:106-13. [PMID: 17096379 DOI: 10.1002/chir.20352] [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] [Indexed: 11/09/2022]
Abstract
The quality control of chiral drugs requires the determination of their enantiomeric purity. Nowadays, circular dichroism (CD) spectroscopy is gaining increasing importance in pharmaceutical analysis because of the commercially available CD detector in liquid chromatography. The separation of the two enantiomers of a basic drug (efaroxan) was achieved by high performance liquid chromatography using an amylose-derivated column with both UV and CD detections. A baseline-resolved separation (resolution: 5) was obtained after optimization of the mobile phase composition with hexane-ethanol-diethylamine (90:10:0.05; v/v/v). The use of a commercial low-pass electronic noise filter of the CD signal has improved the signal-to-noise ratio by a factor twelve and allowed the quantitation of each enantiomer in the 1.25-300 microg ml(-1) concentration range. The CD linear calibration curve, expressed in terms of stereoisomer height ratio versus concentration ratio, was plotted over the 0.4-6% range. A correlation coefficient greater than 0.999 was obtained by least-squares regression and the limit of detection for the distomer/eutomer ratio was estimated at 0.14%. Although the method validation showed good repeatability on the retention times (RSD < 0.9%), on the peak height ratios (RSD < 8.7%) of each enantiomer only up to 99.2% enantiomeric purity was achieved.
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Affiliation(s)
- Marie Lorin
- Institut de Chimie Organique et Analytique (ICOA), CNRS FR 2708, UMR 6005, Université d'Orléans, Orléans, France
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Marien MR, Colpaert FC, Rosenquist AC. Noradrenergic mechanisms in neurodegenerative diseases: a theory. ACTA ACUST UNITED AC 2004; 45:38-78. [PMID: 15063099 DOI: 10.1016/j.brainresrev.2004.02.002] [Citation(s) in RCA: 313] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2004] [Indexed: 11/26/2022]
Abstract
A deficiency in the noradrenergic system of the brain, originating largely from cells in the locus coeruleus (LC), is theorized to play a critical role in the progression of a family of neurodegenerative disorders that includes Parkinson's disease (PD) and Alzheimer's disease (AD). Consideration is given here to evidence that several neurodegenerative diseases and syndromes share common elements, including profound LC cell loss, and may in fact be different manifestations of a common pathophysiological process. Findings in animal models of PD indicate that the modification of LC-noradrenergic activity alters electrophysiological, neurochemical and behavioral indices of neurotransmission in the nigrostriatal dopaminergic system, and influences the response of this system to experimental lesions. In models related to AD, noradrenergic mechanisms appear to play important roles in modulating the activity of the basalocortical cholinergic system and its response to injury, and to modify cognitive functions including memory and attention. Mechanisms by which noradrenaline may protect or promote recovery from neural damage are reviewed, including effects on neuroplasticity, neurotrophic factors, neurogenesis, inflammation, cellular energy metabolism and excitotoxicity, and oxidative stress. Based on evidence for facilitatory effects on transmitter release, motor function, memory, neuroprotection and recovery of function after brain injury, a rationale for the potential of noradrenergic-based approaches, specifically alpha2-adrenoceptor antagonists, in the treatment of central neurodegenerative diseases is presented.
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Affiliation(s)
- Marc R Marien
- Centre de Recherche Pierre Fabre, Neurobiology I, 17 Avenue Jean Moulin, 81106 Castres Cedex, France.
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Abelson KSP, Höglund AU. The Effects of the alpha2-Adrenergic Receptor Agonists Clonidine and Rilmenidine, and Antagonists Yohimbine and Efaroxan, on the Spinal Cholinergic Receptor System in the Rat. ACTA ACUST UNITED AC 2004; 94:153-60. [PMID: 15078339 DOI: 10.1111/j.1742-7843.2004.pto940401.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cholinergic agonists produce spinal antinociception via mechanisms involving an increased release of intraspinal acetylcholine. The cholinergic receptor system interacts with several other receptor types, such as alpha2-adrenergic receptors. To fully understand these interactions, the effects of various receptor ligands on the cholinergic system must be investigated in detail. This study was initiated to investigate the effects of the alpha2-adrenergic receptor agonists clonidine and rilmenidine and the alpha2-adrenergic receptor antagonists yohimbine and efaroxan on spinal cholinergic receptors in the rat. Spinal microdialysis was used to measure in vivo changes of acetylcholine after administration of the ligands, with or without nicotinic receptor blockade. In addition, in vitro binding properties of the ligands on muscarinic and nicotinic receptors were investigated. It was found that clonidine and rilmenidine increased, while yohimbine decreased spinal acetylcholine release. Efaroxan affected acetylcholine release differently depending on concentration. Nicotinic receptor blockade attenuated the effect of all ligands. All ligands showed poor binding affinity for muscarinic receptors. On the other hand, all ligands possessed affinity for nicotinic receptors. Clonidine and yohimbine binding was best fit to a one site binding curve and rilmenidine and efaroxan to a two site binding curve. The present study demonstrates that the tested alpha2-adrenergic receptor ligands affect intraspinal acetylcholine release in the rat evoked by nicotinic receptor mechanisms in vivo, and that they possess binding affinity to nicotinic receptors in vitro. The binding of alpha2-adrenergic receptor ligands to nicotinic receptors might affect the intraspinal release of acetylcholine.
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Affiliation(s)
- Klas S P Abelson
- Department of Neuroscience, Division of Comparative Medicine, Biomedical Centre, Uppsala University, Uppsala, Sweden.
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Ichikawa J, Li Z, Dai J, Meltzer HY. Atypical antipsychotic drugs, quetiapine, iloperidone, and melperone, preferentially increase dopamine and acetylcholine release in rat medial prefrontal cortex: role of 5-HT1A receptor agonism. Brain Res 2002; 956:349-57. [PMID: 12445705 DOI: 10.1016/s0006-8993(02)03570-9] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Preferential increases in both cortical dopamine (DA) and acetylcholine (ACh) release have been proposed to distinguish the atypical antipsychotic drugs (APDs) clozapine, olanzapine, risperidone and ziprasidone from typical APDs such as haloperidol. Although only clozapine and ziprasidone are directly acting 5-HT(1A) agonists, WAY100635, a selective 5-HT(1A) antagonist, partially attenuates these atypical APD-induced increases in cortical DA release that may be due to combined 5-HT(2A) and D(2) blockade. However, WAY100635 does not attenuate clozapine-induced cortical ACh release. The present study determined whether quetiapine, iloperidone and melperone, 5-HT(2A)/D(2) antagonist atypical APDs, also increase cortical DA and ACh release, and whether these effects are related to 5-HT(1A) agonism. Quetiapine (30 mg/kg), iloperidone (1-10 mg/kg), and melperone (3-10 mg/kg) increased DA and ACh release in the medial prefrontal cortex (mPFC). Iloperidone (10 mg/kg) and melperone (10 mg/kg), but not quetiapine (30 mg/kg), produced an equivalent or a smaller increase in DA release in the nucleus accumbens (NAC), respectively, compared to the mPFC, whereas none of them increased ACh release in the NAC. WAY100635 (0.2 mg/kg), which alone did not affect DA or ACh release, partially attenuated quetiapine (30 mg/kg)-, iloperidone (10 mg/kg)- and melperone (10 mg/kg)-induced DA release in the mPFC. WAY100635 also partially attenuated quetiapine (30 mg/kg)-induced ACh release in the mPFC, but not that induced by iloperidone (10 mg/kg) or melperone (10 mg/kg). These results indicate that quetiapine, iloperidone and melperone preferentially increase DA release in the mPFC, compared to the NAC via a 5-HT(1A)-related mechanism. However, 5-HT(1A) agonism may be important only for quetiapine-induced ACh release.
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Affiliation(s)
- Junji Ichikawa
- Division of Psychopharmacology, Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN 37212, USA.
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Dazzi L, Vacca G, Ladu S, Pisu MG, Serra M, Biggio G. Long-term treatment with antidepressant drugs reduces the sensitivity of cortical cholinergic neurons to the activating actions of stress and the anxiogenic drug FG 7142. Neuropharmacology 2001; 41:229-37. [PMID: 11489459 DOI: 10.1016/s0028-3908(01)00064-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Certain antidepressant drugs exert an anxiolytic action in both humans and rodents. The effects of long-term treatment with imipramine or mirtazapine, two antidepressant drugs with different mechanisms of action, on the response of cortical cholinergic neurons to foot-shock stress or to the anxiogenic drug FG 7142 were investigated in freely moving rats. Chronic treatment with imipramine or mirtazapine reduced the increase in cortical acetylcholine output induced by foot-shock stress by approximately 50%. The same treatment also reduced the sensitivity of cortical cholinergic neurons to the stimulatory effect of acute administration of FG 7142. In contrast, the administration of a single dose of either antidepressant 40 min before foot shock or FG 7142 injection failed to increase the threshold of excitability of cortical cholinergic neurons. These results demonstrate that long-term treatment with either imipramine or mirtazapine reduces the sensitivity of cortical cholinergic neurons to stress or to an anxiogenic drug with an efficacy similar to that of acute administration of benzodiazepines. The neurochemical mechanism responsible for regulation of cholinergic neuron sensitivity might contribute to the modulation of cognitive function associated with emotional and affective disorders.
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Affiliation(s)
- L Dazzi
- Department of Experimental Biology B. Loddo and CNR Centre for Neuropharmacology, University of Cagliari, Cagliari 09123, Italy.
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Tellez S, Colpaert F, Marien M. Alpha2-adrenoceptor modulation of cortical acetylcholine release in vivo. Neuroscience 1999; 89:1041-50. [PMID: 10362293 DOI: 10.1016/s0306-4522(98)00392-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Acetylcholine release in the rat cortex in vivo has been shown to be modulated by alpha2-adrenoceptor ligands. We have previously reported that the systemic administration of selective alpha2-antagonists including (+)-efaroxan increase, while alpha2-adrenoceptor agonists such as UK-14304 reduce the release of acetylcholine in the medial prefrontal cortex of conscious rats as measured by microdialysis. To evaluate the extent to which noradrenergic afferent inputs are required for the expression of these different effects, the present study examined the drug-induced changes in cortical acetylcholine release in rats which had undergone prior noradrenergic deafferentation. Rats were pretreated with the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (40 mg/kg, i.p.), which after three days had reduced noradrenaline levels in the medial prefrontal cortex by 84%. At that time, slices of cortex were incubated with [3H]choline, superfused and stimulated by consecutive exposures to increasing concentrations of K+. In N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine pretreated tissue, the [3H] outflows evoked by 20, 35 and 45 mM K+ were lower by 12%, 22% and 43%, respectively, in comparison to slices prepared from vehicle-pretreated control animals. For in vivo microdialysis experiments, rats were pretreated as above with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, or prepared seven to eight days in advance with bilateral 6-hydroxydopamine lesions of the locus coeruleus. Neither of these lesioning procedures significantly affected the basal outflow of endogenous acetylcholine in the cortex. In control rats, cortical acetylcholine outflow was increased by up to 300% of baseline values by (+)-efaroxan (0.63 mg/kg, i.p.), and was reduced to 21% of baseline by UK-14304 (2.5 mg/kg, i.p.), confirming our previous findings. In N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine pretreated rats, the inhibitory effect of UK-14304 on acetylcholine outflow persisted, while the ability of (+)-efaroxan to increase outflow was essentially eliminated. In locus coeruleus-lesioned rats, where cortical noradrenaline levels were reduced by 64%, (+)-efaroxan still increased acetylcholine outflow, but this effect was significantly attenuated and less sustained in comparison to sham-operated control rats. Viewed together with complimentary biochemical, electrophysiological and neuroanatomical evidence in the literature, a model is presented to account for these findings, and indicates that alpha2-adrenoceptors both on noradrenergic neurons (autoreceptors) and on non-noradrenergic cells (heteroreceptors) can participate in mediating drug-induced changes in medial prefrontal cortical acetylcholine release in vivo. The acetylcholine release-enhancing effect of (+)-efaroxan appears to be dependent on at least a partially intact cortical noradrenergic innervation.
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Affiliation(s)
- S Tellez
- Division de Neurobiologie I, Centre de Recherche Pierre Fabre, Castres, France
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15
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Frötschl R, Chichmanov L, Kleeberg U, Hildebrandt AG, Roots I, Brockmöller J. Prediction of aryl hydrocarbon receptor-mediated enzyme induction of drugs and chemicals by mRNA quantification. Chem Res Toxicol 1998; 11:1447-52. [PMID: 9860486 DOI: 10.1021/tx980164h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Enzyme-specific testing for drug interactions by in vitro techniques has become a routine practice in drug development. With many drugs, enzyme induction has similar importance for the prediction of drug-drug interactions. We developed a method for recognizing enzyme induction mediated via the aryl hydrocarbon receptor. This type of induction may be clinically important since experimental data suggest a higher rate of toxification in induced subjects. Twenty-four drugs and environmental chemicals, selected as prototype inducers or being chemically related to known inducers, including HIV protease inhibitors nelfinavir, saquinavir, ritonavir, and indinavir, were tested for their potency to induce cytochrome P450 1A1 mRNA in human Hela cell cultures by a quantitative reverse transcriptase polymerase chain reaction. Known prototype inducers such as beta-naphthoflavone and 3-methylcholanthrene exhibited the highest inducing potency quantified with an Imax value (maximal induction of cytochrome P450 1A1 mRNA synthesis) of 5.48 and 10.7 x 10(6) mRNA molecules per 150 ng of total RNA, respectively. The enzyme-inducing efficacy of some compounds such as resveratrol (2.92 x 10(6)) and the protease inhibitors was not much lower (2.23-3.08 x 10(6)). All compounds that were structurally similar to benzimidazoles exhibited some extent of enzyme induction; e.g., Imax values were 0.86 x 10(6), 0.20 x 10(6), and 0.14 x 10(6) for omeprazole, lansoprazole, and losartan, respectively. To predict the clinical relevance of these inducing effects, the concentration at half-maximal induction IM was estimated; the plasma concentrations of these drug substances were within 1 order of magnitude of the IM values, upon usual dosage. In conclusion, cytochrome P450 1A1 enzyme induction by drugs is a common phenomenon, though there is a great range in the inducing efficacy. In vitro prediction of enzyme induction may be useful for explaining or foreseeing drug interactions, drug side effects, or toxicity by xenobiotics.
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Affiliation(s)
- R Frötschl
- Institute of Clinical Pharmacology, University Hospital Charité, Humboldt-University of Berlin, Schumannstrasse 20/21, D-10098 Berlin, Germany
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16
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Acquas E, Wilson C, Fibiger HC. Pharmacology of sensory stimulation-evoked increases in frontal cortical acetylcholine release. Neuroscience 1998; 85:73-83. [PMID: 9607704 DOI: 10.1016/s0306-4522(97)00546-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent research has demonstrated that a variety of sensory stimuli can increase acetylcholine release in the frontal cortex of rats. The aim of the present experiments was to investigate the pharmacological regulation of sensory stimulation-induced increases in the activity of basal forebrain cholinergic neurons. To this end, the effects of agonists and antagonists at a variety of neurotransmitter receptors on basal and tactile stimulation-evoked increases in frontal cortical acetylcholine release were studied using in vivo brain microdialysis. Tactile stimulation, produced by gently stroking the rat's neck with a nylon brush for 20 min, significantly increased frontal cortical acetylcholine release by more than 100% above baseline. The noradrenergic alpha2 agonist clonidine (0.1 or 0.2 mg/kg) and alpha1 antagonist prazosin (1 mg/kg) failed to affect basal cortical acetylcholine release; however, both compounds significantly reduced the increases evoked by sensory stimulation. In contrast, the alpha2 antagonist yohimbine (3 mg/kg) increased basal cortical acetylcholine release, thereby preventing meaningful investigation of its effects on tactile stimulation-evoked increases. The benzodiazepine agonist diazepam (5 mg/kg) reduced, and the GABA(A) receptor antagonist picrotoxin (2 mg/kg) increased basal cortical acetylcholine release; in addition, diazepam attenuated the increases in cortical acetylcholine release evoked by tactile stimulation. While dopaminergic D1 (SCH 23390, 0.15 mg/kg) and D2 (raclopride, 1 mg/kg) receptor antagonists did not by themselves significantly influence the increases evoked by tactile stimulation, their co-administration produced a significant reduction. The opioid receptor antagonist naltrexone (1.5 mg/kg) failed to affect either basal or tactile stimulation-evoked increases in acetylcholine overflow. Finally, the non-competitive N-methyl-D-aspartate receptor antagonist, dizocilpine maleate (MK-801; 0.025 and 0.05 mg/kg) increased basal cortical acetylcholine release. These results confirm that cortically projecting cholinergic neurons are activated by sensory stimuli, and indicate that the increases in cortical acetylcholine release produced by tactile stimulation are inhibited by stimulation of alpha2 or blockade of alpha1 noradrenergic receptors, and by enhanced GABAergic transmission. In addition, simultaneous blockade of dopamine D1 and D2 receptors appears necessary to achieve a significant reduction of sensory stimulation-evoked acetylcholine release in the frontal cortex. The results are consistent with the hypothesis that cortical acetylcholine release is a component of the neurochemistry of arousal and/or attention and indicate that this is modulated by GABAergic, noradrenergic and dopaminergic systems. In contrast, endogenous opioid actions do not appear to be involved.
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Affiliation(s)
- E Acquas
- Department of Psychiatry, University of British Columbia, Vancouver, Canada
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17
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Mesulam MM. Some cholinergic themes related to Alzheimer's disease: synaptology of the nucleus basalis, location of m2 receptors, interactions with amyloid metabolism, and perturbations of cortical plasticity. JOURNAL OF PHYSIOLOGY, PARIS 1998; 92:293-8. [PMID: 9789826 DOI: 10.1016/s0928-4257(98)80036-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cholinergic neurons in the nucleus basalis of Meynert (nbM) receive cholinergic, GABAergic and monoaminergic synapses. Only few of these neurons display the sort of intense m2 immunoreactivity that would be expected if they were expressing m2 as their presynaptic autoreceptor. The depletion of cortical m2 in Alzheimer's disease (AD) appears to reflect the loss of presynaptic autoreceptors located on incoming axons from the nucleus basalis of Meynert (nbM) and also the loss of postsynaptic receptors located on a novel group of nitric oxide producing interstitial neurons in the cerebral cortex. The defect of cholinergic transmission in AD may enhance the neurotoxicity of amyloid beta, leading to a vicious cycle which can potentially accelerate the pathological process. Because acetylcholine plays a critical role in regulating axonal growth and synaptic remodeling, the cholinergic loss in AD can perturb cortical plasticity so as to undermine the already fragile compensatory reserve of the aging cerebral cortex.
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Affiliation(s)
- M M Mesulam
- Department of Neurology and Psychiatry, Northwestern University Medical School, Chicago, Illinois 60611, USA
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18
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Abstract
Although recently developed drugs have brought significant improvement, the treatment of psychotic disorders still presents serious drawbacks. Because inherent complexity and lack of satisfactory understanding of the underlying pathophysiology impose limits for rational drug design, resourceful approaches in the search for antipsychotics are pertinent. This article reports pharmacological properties of alstonine, a heteroyohimbine-type alkaloid, which exhibited an antipsychotic-like profile, inhibiting amphetamine-induced lethality, apomorphine-induced stereotypy, and potentiating barbiturate-induced sleeping time. Atypical features of alstonine were the prevention of haloperidol-induced catalepsy and lack of direct interaction with D1, D2 and 5-HT2A receptors, classically linked to antipsychotic mechanism of action.
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Somboonthum P, Matsuda T, Asano S, Sakaue M, Baba A. MKC-242, a novel 5-HT1A receptor agonist, facilitates cortical acetylcholine release by a mechanism different from that of 8-OH-DPAT in awake rats. Neuropharmacology 1997; 36:1733-9. [PMID: 9517445 DOI: 10.1016/s0028-3908(97)00174-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have previously reported that 5-¿3-[((2S)-1,4-benzodioxan-2-ylmethyl)amino]propoxy¿-1,3-be nzodioxole (MKC-242), a potent and selective serotonin (5-HT)1A receptor agonist, exerts anxiolytic- and antidepressant-like effects in animal models and that the antidepressant-like effect may be mediated by postsynaptic 5-HT1A receptors. The present study, using a microdialysis technique, was undertaken to characterize in vivo the effect of MKC-242 on cholinergic neurons. Subcutaneous injection of MKC-242 (0.5-1.0 mg/kg), like the typical 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), increased extracellular acetylcholine (ACh) levels in the rat cerebral cortex. The increase in ACh release by MKC-242 was also observed in the hippocampus. The effect of MKC-242 on cortical ACh release was attenuated by pretreatment with the 5-HT1A receptor antagonists (10 mg/kg, s.c.) propranolol and N-tert-butyl-3-(4-(2-methoxyphenyl)piperazin-1-yl)-2-phenylpropana mide. The increase in cortical ACh release by MKC-242 was blocked by lesion of serotonergic neurons with 5,7-dihydroxytryptamine, whereas that by 8-OH-DPAT was not. Lesion of noradrenergic neurons with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine did not affect the MKC-242-induced increase in ACh release. These results suggest that systemic injection of MKC-242 facilitates in vivo ACh release via an activation of somadendritic 5-HT1A autoreceptors, and that MKC-242 and 8-OH-DPAT affect cholinergic neurons in the rat cerebral cortex via different mechanisms.
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Affiliation(s)
- P Somboonthum
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Suita, Japan
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20
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M'Harzi M, Willig F, Bardelay C, Palou AM, Oberlander C. Effects of RU 52583, an alpha 2-antagonist, on memory in rats with excitotoxic damage to the septal area. Pharmacol Biochem Behav 1997; 56:649-55. [PMID: 9130290 DOI: 10.1016/s0091-3057(96)00422-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The anti-amnesic action of RU 52583, an alpha 2-adrenergic receptor antagonist, was evaluated through performance of spatial tasks in a radial maze by rats with N-methyl-D-aspartic acid (NMDA) lesion of the medial septal (MS) nuclei. Memory performance of lesioned or sham-operated rats was evaluated by measuring reference memory as long-term maintenance of an acquired performance and working memory or memory for recent events. The lesion: a produced significant impairments of the animals' memory performance, b) significantly reduced the sodium-dependent high-affinity choline uptake in the hippocampal formation, and c) deeply disrupted cholinergic hippocampal theta waves. Oral administration of RU 52583 at 1 and 2 mg/kg (tested doses: 1-5 mg/kg) prior to performance of the task markedly reduced memory impairments, whereas idazoxan, another alpha 2-adrenergic receptor antagonist, had no effect at tested doses (2-5 mg/kg). Cholinergic drugs--arecoline at 0.1 and 1 mg/kg (tested doses: 0.05-1 mg/kg) and physostigmine at 0.02 and 0.1 mg/kg (tested doses: 1, 2, and 5 mg/kg)-administered intraperitoneally showed a tendency to alleviate memory deficits. The present results show that the alpha 2-adrenergic antagonist RU 52583 possesses cognition-enhancing properties in rats with damage to the septohippocampal system.
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Affiliation(s)
- M M'Harzi
- Centre de Recherches Roussel UCLAF, Romainville, France.
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Smith CP, Woods-Kettelberger AT, Corbett R, Porsolt RD, Roehr JE, Bores GM, Giovanni A, Szewczak MR, Rush DK, Martin LL, Klein JT, Turk DJ, DiLeo EM, Effland RC, Huger FP, Kongsamut S. Anti-Obsessional and Antidepressant Profile of Besipirdine. CNS DRUG REVIEWS 1997. [DOI: 10.1111/j.1527-3458.1997.tb00313.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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