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Nourazaran M, Yousefi R, Moosavi-Movahedi F, Panahi F, Hong J, Moosavi-Movahedi AA. The structural and functional consequences of melatonin and serotonin on human αB-crystallin and their dual role in the eye lens transparency. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2023:140928. [PMID: 37330131 DOI: 10.1016/j.bbapap.2023.140928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/19/2023]
Abstract
Crystallins are the major soluble lens proteins, and α-crystallin, the most important protective protein of the eye lens, has two subunits (αA and αB) with chaperone activity. αB-crystallin (αB-Cry) with a relatively wide tissue distribution has an innate ability to interact effectively with the misfolded proteins, preventing their aggregation. Melatonin and serotonin have also been identified in relatively high concentrations in the lenticular tissues. This study investigated the effect of these naturally occurring compounds and medications on the structure, oligomerization, aggregation, and chaperone-like activity of human αB-Cry. Various spectroscopic methods, dynamic light scattering (DLS), differential scanning calorimetry (DSC), and molecular docking have been used for this purpose. Based on our results, melatonin indicates an inhibitory effect on the aggregation of human αB-Cry without altering its chaperone-like activity. However, serotonin decreases αB-Cry oligomeric size distribution by creating hydrogen bonds, decreases its chaperone-like activity, and at high concentrations increases protein aggregation.
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Affiliation(s)
- Mona Nourazaran
- Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - Reza Yousefi
- Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran.
| | | | - Farhad Panahi
- Institute of Organic Chemistry, Albert-Ludwigs-University of Freiburg, Albertstrasse 21, Freiburg 79104, Germany
| | - Jun Hong
- School of Life Sciences, Henan University, Kaifeng 475000, People's Republic of China
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Differential effects of acute administration of SCH-23390, a D₁ receptor antagonist, and of ethanol on swimming activity, anxiety-related responses, and neurochemistry of zebrafish. Psychopharmacology (Berl) 2015. [PMID: 26210378 DOI: 10.1007/s00213-015-4030-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE The zebrafish has become an increasingly popular animal model for investigating ethanol's actions in the brain and its effects on behavior. Acute exposure to ethanol in zebrafish has been shown to induce a dose-dependent increase of locomotor activity, to reduce fear- and anxiety-related behavioral responses, and to increase the levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). OBJECTIVES The objective of the present study was to investigate the role of dopamine D1 receptors (D1-R) in ethanol-induced locomotor activity in zebrafish. METHODS Zebrafish were pre-treated with SCH-23390 (0 or 1 mg/L bath concentration), a D1-R antagonist, and subsequently exposed to ethanol (0, 0.25, 0.5, 1.0 % v/v). To explore potential underlying mechanisms, we quantified levels of dopamine, DOPAC, serotonin, and 5-HIAA from whole-brain tissue using high-precision liquid chromatography. RESULTS We found pre-treatment with the D1-R antagonist to attenuate locomotor activity independent of ethanol concentration. Furthermore, unlike ethanol, D1-R antagonism did not alter behavioral responses associated with fear and anxiety. Pre-treatment with SCH-23390 decreased levels of dopamine and DOPAC, but this effect was also independent of ethanol concentration. The D1-R antagonist also reduced serotonin and 5-hydroxyindole acetic acid (5-HIAA) levels. CONCLUSION These results suggest a multifaceted and at least partially independent role of dopamine D1 receptors in ethanol-induced locomotor activity and anxiety-related responses as well as in the functioning of the dopaminergic and serotoninergic neurotransmitter systems in zebrafish.
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Kuo YC, Wang CC. Carmustine-loaded catanionic solid lipid nanoparticles with serotonergic 1B receptor subtype antagonist for in vitro targeted delivery to inhibit brain cancer growth. J Taiwan Inst Chem Eng 2015. [DOI: 10.1016/j.jtice.2014.08.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Kuo YC, Hong TY. Delivering etoposide to the brain using catanionic solid lipid nanoparticles with surface 5-HT-moduline. Int J Pharm 2014; 465:132-42. [DOI: 10.1016/j.ijpharm.2014.02.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/24/2014] [Accepted: 02/07/2014] [Indexed: 11/25/2022]
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Skelin I, Fikre-Merid M, Diksic M. Both acute and subchronic treatments with pindolol, a 5-HT1A and β1 and β2 adrenoceptor antagonist, elevate regional serotonin synthesis in the rat brain: An autoradiographic study. Neurochem Int 2012; 61:1417-23. [DOI: 10.1016/j.neuint.2012.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Revised: 09/24/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
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Skelin I, Kovačević T, Sato H, Diksic M. The opposite effect of a 5-HT1B receptor agonist on 5-HT synthesis, as well as its resistant counterpart, in an animal model of depression. Brain Res Bull 2012; 88:477-86. [PMID: 22542420 DOI: 10.1016/j.brainresbull.2012.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 04/11/2012] [Accepted: 04/11/2012] [Indexed: 01/29/2023]
Abstract
Flinders Sensitive Line (FSL) rat is as an animal model of depression with altered parameters of the serotonergic (5-HT) system function (5-HT synthesis rates, tissue concentrations, release, receptor density and affinity), as well as an altered sensitivity of these parameters to different 5-HT based antidepressants. The effects of acute and chronic treatments with the 5-HT(1B) agonist, CP-94253 on 5-HT synthesis, in the FSL rats and the Flinders Resistant Line (FRL) controls were measured using α-[(14)C]methyl-L-tryptophan (α-MTrp) autoradiography. CP-94253 (5mg/kg), or an adequate volume of saline, was injected i.p. as a single dose in the acute experiment or delivered via the subcutaneously implanted osmotic minipump (5 mg/kg/day for 14 days) in the chronic experiment. The acute treatment with CP-94253 significantly decreased the 5-HT synthesis in both the FRL and FSL rats, with a more widespread effect in the FRL rats. Chronic treatment with CP-94253 significantly decreased 5-HT synthesis in the FRL rats, while 5-HT synthesis in the FSL rats was significantly increased throughout the brain. In both the acute and chronic experiment, the FRL rats had higher brain 5-HT synthesis rates, relative to the FSL rats. The shift in the direction of the treatment effect from acute to chronic, using the 5-HT(1B) agonist, CP-94253, on 5-HT synthesis in the FSL model of depression, with an opposite effect on the control FRL rats, suggests the differential adaptation of the 5-HT system in the FSL and FRL rats to chronic stimulation of 5-HT(1B) receptors.
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Affiliation(s)
- Ivan Skelin
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, and Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Que., Canada H3A 2B4
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Hasegawa S, Fikre-Merid M, Diksic M. 5-HT2A receptor antagonist M100907 reduces serotonin synthesis: an autoradiographic study. Brain Res Bull 2012; 87:44-9. [PMID: 22056993 PMCID: PMC3653840 DOI: 10.1016/j.brainresbull.2011.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 10/19/2011] [Indexed: 11/16/2022]
Abstract
The effects of the administration of the serotonin (5-HT)(2A) antagonist, M100907, on 5-HT synthesis rates, were evaluated using the α-[(14)C]methyl-l-tryptophan (α-MTrp) autoradiographic method. In the treatment study, M100907 (10mg/kg) was injected intraperitoneally 30 min before the α-MTrp injection (30 μCi over 2 min). A single dose of M100907 caused a significant decrease in the synthesis in the anterior olfactory nucleus, accumbens nucleus, frontal cortex, sensory-motor cortex, cingulate cortex, medial caudate-putamen, dorsal thalamus, substantia nigra, inferior collicus, raphe magnus nucleus, superior olive, and raphe pallidus nucleus. These data suggest that the terminal 5-HT(2A) receptors are involved in the regulation of 5-HT synthesis in the entire brain. Further, 5-HT synthesis is likely regulated by the 5-HT(2A) antagonistic property of M100907 in the cortices, anterior olfactory nucleus, caudate putamen, and nucleus accumbens.
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Affiliation(s)
| | - Maraki Fikre-Merid
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
| | - Mirko Diksic
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
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Measuring serotonin synthesis: from conventional methods to PET tracers and their (pre)clinical implications. Eur J Nucl Med Mol Imaging 2010; 38:576-91. [PMID: 21113591 PMCID: PMC3034914 DOI: 10.1007/s00259-010-1663-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 11/01/2010] [Indexed: 12/20/2022]
Abstract
The serotonergic system of the brain is complex, with an extensive innervation pattern covering all brain regions and endowed with at least 15 different receptors (each with their particular distribution patterns), specific reuptake mechanisms and synthetic processes. Many aspects of the functioning of the serotonergic system are still unclear, partially because of the difficulty of measuring physiological processes in the living brain. In this review we give an overview of the conventional methods of measuring serotonin synthesis and methods using positron emission tomography (PET) tracers, more specifically with respect to serotonergic function in affective disorders. Conventional methods are invasive and do not directly measure synthesis rates. Although they may give insight into turnover rates, a more direct measurement may be preferred. PET is a noninvasive technique which can trace metabolic processes, like serotonin synthesis. Tracers developed for this purpose are α-[11C]methyltryptophan ([11C]AMT) and 5-hydroxy-L-[β-11C]tryptophan ([11C]5-HTP). Both tracers have advantages and disadvantages. [11C]AMT can enter the kynurenine pathway under inflammatory conditions (and thus provide a false signal), but this tracer has been used in many studies leading to novel insights regarding antidepressant action. [11C]5-HTP is difficult to produce, but trapping of this compound may better represent serotonin synthesis. AMT and 5-HTP kinetics are differently affected by tryptophan depletion and changes of mood. This may indicate that both tracers are associated with different enzymatic processes. In conclusion, PET with radiolabelled substrates for the serotonergic pathway is the only direct way to detect changes of serotonin synthesis in the living brain.
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Lam DD, Garfield AS, Marston OJ, Shaw J, Heisler LK. Brain serotonin system in the coordination of food intake and body weight. Pharmacol Biochem Behav 2010; 97:84-91. [PMID: 20837046 DOI: 10.1016/j.pbb.2010.09.003] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 08/02/2010] [Accepted: 09/06/2010] [Indexed: 11/30/2022]
Abstract
An inverse relationship between brain serotonin and food intake and body weight has been known for more than 30 years. Specifically, augmentation of brain serotonin inhibits food intake, while depletion of brain serotonin promotes hyperphagia and weight gain. Through the decades, serotonin receptors have been identified and their function in the serotonergic regulation of food intake clarified. Recent refined genetic studies now indicate that a primary mechanism through which serotonin influences appetite and body weight is via serotonin 2C receptor (5-HT(2C)R) and serotonin 1B receptor (5-HT(1B)R) influencing the activity of endogenous melanocortin receptor agonists and antagonists at the melanocortin 4 receptor (MC4R). However, other mechanisms are also possible and the challenge of future research is to delineate them in the complete elucidation of the complex neurocircuitry underlying the serotonergic control of appetite and body weight.
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Affiliation(s)
- Daniel D Lam
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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Şişecioğlu M, Çankaya M, Gülçin İ, Özdemir H. Interactions of melatonin and serotonin with lactoperoxidase enzyme. J Enzyme Inhib Med Chem 2010; 25:779-83. [PMID: 20121623 DOI: 10.3109/14756360903425239] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Melatonin is the chief secretory product of the pineal gland and is synthesized enzymatically from serotonin. These indoleamine derivatives play an important role in the prevention of oxidative damage. Lactoperoxidase (LPO; EC 1.11.1.7) was purified from bovine milk with three purification steps: Amberlite CG-50 resin, CM-Sephadex C-50 ion-exchange, and Sephadex G-100 gel filtration chromatography, respectively. LPO was purified with a yield of 21.6%, a specific activity of 34.0 EU/mg protein, and 14.7-fold purification. To determine the enzyme purity, SDS-PAGE was performed and a single band was observed. The R(z) (A(412)/A(280)) value for LPO was 0.9. The effect of melatonin and serotonin on lactoperoxidase was determined using ABTS as chromogenic substrate. The half-maximal inhibitory concentration (IC(50)) values for melatonin and serotonin were found to be 1.46 and 1.29 μM, respectively. Also, the inhibition constants (K(i)) for melatonin and serotonin were 0.82 ± 0.28 and 0.26 ± 0.04 μM, respectively. Both melatonin and serotonin were found to be competitive inhibitors.
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Affiliation(s)
- Melda Şişecioğlu
- Department of Chemistry, Faculty of Sciences, Atatürk University, Erzurum, Turkey
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11
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Nishi K, Kanemaru K, Diksic M. A genetic rat model of depression, Flinders sensitive line, has a lower density of 5-HT(1A) receptors, but a higher density of 5-HT(1B) receptors, compared to control rats. Neurochem Int 2008; 54:299-307. [PMID: 19121358 DOI: 10.1016/j.neuint.2008.12.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 11/29/2008] [Accepted: 12/08/2008] [Indexed: 11/25/2022]
Abstract
Deficiencies in brain serotonergic neurotransmission, which is in part associated with the alteration of brain serotonin (5-HT) receptors, have been proposed as part of a neurochemical imbalance in affective disorders, including depression. The drugs used for the treatment of these disorders generally act through and/or on the serotonergic system. Different animal models of depression have provided researchers with tools to obtain a better understanding of drug actions and possibilities to obtain insight into the neurochemical bases of these disorders. The measurements of the 5-HT(1A) and 5-HT(1B) receptor densities in a rat model of depression, Flinders sensitive line (FSL) rats, and comparisons with Sprague-Dawley (SPD) and Flinders resistant line (FRL) rats, are reported here. The receptor sites were quantified by autoradiography in more than 25 distinct brain regions known to have relatively large densities of respective sites. Some brain regions (e.g., dental gyrus, septal nucleus) were divided into several parts, according to previously known subdivisions, because of a substantial heterogeneity of these receptors. The densities in the FSL rats ("depressed" rats) were compared statistically to those in the SPD rats. In addition, comparisons were made to the densities in the FRL rats (rats not showing depressive symptoms). Comparisons were performed with the SPD and FRL rats because both of these strains have been used as control animals in studies of FSL rats. The results show that the densities of 5-HT(1A) receptors are not significantly different between the FSL and SPD rats, but they are significantly different from the FRL rats. 5-HT(1A) receptor density is significantly higher in the FRL rats than the SPD rats. The 5-HT(1B) receptors were significantly greater in the FSL rats than in either the SPD or FRL rats. In addition, the FRL rats have 5-HT(1B) receptor densities significantly lower in many brain regions than the SPD rats. The data presented here, in addition to previously reported differences in regional synthesis between these strains and the effect of acute citalopram on synthesis, suggest that SPD rats are likely a more appropriate control than FRL rats, when studies of FSL rats are performed with drugs acting directly or indirectly on, or through, the brain serotonergic system. However, comparisons, particularly of neurochemical and/or biological parameters in FRL rats, may reveal new insight into the alterations of 5-HT neurotransmission in this animal model of depression and possibly human depression, as well as the elevation of symptoms with treatments. The data also suggest that there could be a different fraction of 5-HT(1A) receptors in high and low affinity states in these strains, as well as the possibility of different intracellular signalling.
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Affiliation(s)
- Kyoko Nishi
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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Nguyen KQ, Tohyama Y, Watanabe A, Hasegawa S, Skelin I, Diksic M. Acute effects of combining citalopram and pindolol on regional brain serotonin synthesis in sham operated and olfactory bulbectomized rats. Neurochem Int 2008; 54:161-71. [PMID: 19073228 DOI: 10.1016/j.neuint.2008.08.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Revised: 08/25/2008] [Accepted: 08/26/2008] [Indexed: 10/21/2022]
Abstract
The olfactory bulbectomized (OBX) rat is considered to be a good model of the pathology of human depression and also of the functional actions of antidepressant drug therapy. It has been proposed that antidepressant effects of selective serotonin reuptake inhibitors (SSRIs) can be accelerated by blocking 5-HT(1A/B) autoreceptors with pindolol. The underlying mechanism is thought to involve acute unrestricting of 5-HT release and, consequently, relatively enhanced 5-HT turnover throughout the forebrain serotonergic networks. The effect of this combination on 5-HT turnover in sham operated or OBX rats can be assessed at the level of 5-HT synthesis, a very important presynaptic step in serotonergic neurotransmission, using the alpha-[(14)C]methyl-l-tryptophan autoradiography method. In sham rats, acute citalopram (20mg/kg) treatment increased synthesis at almost all serotonergic terminal regions but slightly decreased synthesis at serotonergic cell body regions (i.e. dorsal and median (not significant) raphe; approximately 16%). Combining pindolol (10mg/kg) with citalopram further increased synthesis at many regions in sham rats (relative to treatment with only citalopram). In OBX rats, citalopram decreased synthesis at a few terminal regions and greatly decreased synthesis at the dorsal and median raphe ( approximately 45%; relative to OBX rats treated with saline). Combining pindolol with citalopram greatly increased synthesis at almost all regions in OBX rats (relative to treatment with only citalopram). These results suggest that acute citalopram effects result in elevated terminal 5-HT synthesis, but these effects are restrained by 5-HT(1A/B) autoreceptor feedback to different degrees in sham and OBX rats. Moreover, 5-HT(1A/B) autoreceptor feedback is stronger in OBX rats and may underlie the delay of SSRI effects in OBX rats and, correspondingly, in human depression. Pindolol acceleration and augmentation of SSRI antidepressant therapy for human depression may be mediated by attenuation of 5-HT(1A/B) autoreceptor feedback, permitting unhindered SSRI effects on serotonergic terminals.
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Affiliation(s)
- Khanh Q Nguyen
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
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Gülçin I. Measurement of antioxidant ability of melatonin and serotonin by the DMPD and CUPRAC methods as trolox equivalent. J Enzyme Inhib Med Chem 2008; 23:871-6. [DOI: 10.1080/14756360701626223] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Ilhami Gülçin
- .Department of Chemistry, Faculty of Science and Arts, Atatürk University, 25240, Erzurum, Turkey
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Acute citalopram has different effects on regional 5-HT synthesis in FSL, FRL, and SDP rats: an autoradiographic evaluation. Brain Res Bull 2008; 77:214-20. [PMID: 18674602 DOI: 10.1016/j.brainresbull.2008.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 07/02/2008] [Accepted: 07/04/2008] [Indexed: 11/21/2022]
Abstract
In this study, we measured the effect of an acute treatment of citalopram on 5-hydroxytryptamine (5-HT) synthesis in a genetic rat model of depression, the Flinders Sensitive Line (FSL) rats, their counterparts, the Flinders Resistant Line (FRL) rats, and outbred Sprague-Dawley (SPD) rats, using the alpha-[(14)C]methyl-l-tryptophan (alpha-MTrp) autoradiographic method. A comparison of 5-HT synthesis in the FSL rats treated with citalopram (FSL-CTP) and those treated with saline (FSL-SAL) indicate that citalopram reduces global 5-HT synthesis in the FSL rats, as well as in all the brain areas investigated. The reduced synthesis was also observed in the dorsal raphe (DR) nucleus and the median raphe (MR) nucleus. The comparison of the synthesis between the citalopram-treated SPD rats (SPD-CTP) and the saline-treated SPD rats (SPD-SAL) revealed a global increase of 5-HT synthesis in the SPD-CTP group, as well as an increase in some terminal areas, but a reduction in the DR and the MR. In contrast to the reduction throughout the brain in the FSL rats, the FRL rats treated with citalopram (FRL-CTP), when compared to the saline group (FRL-SAL), showed a global increase of 5-HT synthesis, as well as in most of the terminal areas and in the DR and the MR. The reduction of 5-HT synthesis throughout the brain in the FSL rats is likely, in part, a result of reported supersensitivity of the 5-HT(1A) receptors. Comparing changes in the SPD, FRL, and FSL rats treated with citalopram to their respective controls (saline-treated rats), the FSL rats treated acutely with citalopram were the only rats that exhibited lower 5-HT synthesis rates in all of the limbic areas, the basal ganglia, and the neocortices. This may be related to the pathophysiological basis of depressive characteristics in FSL rats. The citalopram treatment produced unexpected results in the FRL rats: 5-HT synthesis was elevated not only in most of the terminal areas, but also in the cell body areas, the DR and MR. The increase of 5-HT synthesis throughout the brain in the FRL rats is likely, in part, a result of the reported subsensitivity of the 5-HT(1A) receptors, and possibly other sites through which 5-HT synthesis could be controlled (e.g., 5-HT(1B)). In addition differences in intracellular signaling could be at least in part responsible for these differences.
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Veiga CP, Miczek KA, Lucion AB, Almeida RMMD. Effect of 5-HT1B receptor agonists injected into the prefrontal cortex on maternal aggression in rats. Braz J Med Biol Res 2007; 40:825-30. [PMID: 17581682 DOI: 10.1590/s0100-879x2006005000113] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Accepted: 03/26/2007] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT1B) receptors play an essential role in the inhibition of aggressive behavior in rodents. CP-94,253, a 5-HT1B receptor agonist, can reduce aggression in male mice when administered directly into the ventro-orbitofrontal (VO) prefrontal cortex (PFC). The objective of the current study was to assess the effects of two selective 5-HT1B receptor agonists (CP-94,253 and CP-93,129), microinjected into the VO PFC, on maternal aggressive behavior after social instigation in rats. CP-94,253 (0.56 microg/0.2 microL, N = 8, and 1.0 microg/0.2 microL, N = 8) or CP-93,129 (1.0 microg/0.2 microL, N = 9) was microinjected into the VO PFC of Wistar rats on the 9th day postpartum and 15 min thereafter the aggressive behavior by the resident female against a male intruder was recorded for 10 min. The frequency and duration of aggressive and non-aggressive behaviors were analyzed using ANOVA and post hoc tests. CP-93,129 significantly decreased maternal aggression. The frequency of lateral attacks, bites and pinnings was reduced compared to control, while the non-aggressive behaviors and maternal care were largely unaffected by this treatment. CP-94,253 had no significant effects on aggressive or non-aggressive behaviors when microinjected into the same area of female rats. CP-93,129, a specific 5-HT1B receptor agonist, administered into the VO PFC reduced maternal aggressive behavior, while the CP-94,253 agonist did not significantly affect this behavior after social instigation in female rats. We conclude that only the 5-HT1B receptor agonist CP-93,129 administered into the VO PFC decreased aggression in female rats postpartum after social instigation.
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Affiliation(s)
- C P Veiga
- Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
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Nishi K, Mück-Seler D, Hasegawa S, Watanabe A, Diksic M. Acute effects of moclobemide and deprenyl on 5-HT synthesis rates in the rat brain: An autoradiographic study. Brain Res Bull 2006; 70:368-77. [PMID: 17027772 DOI: 10.1016/j.brainresbull.2006.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2006] [Revised: 05/31/2006] [Accepted: 06/23/2006] [Indexed: 11/25/2022]
Abstract
Serotonin (5-HT), norepinephrine (NE) and dopamine (DA) released from nerve terminals in the brain are primarily removed from the synaptic cleft by a reuptake mechanism. In part, the homeostasis is maintained by monoamine oxidase (MAO) deamination achieved primarily intracellularly. The present study's aim was to examine the effect of the acute administration of the MAO inhibitors, moclobemide (a MAO-A inhibitor) and deprenyl (a MAO-B inhibitor), on 5-HT synthesis rates, measured in discrete regions of the rat brain by an autoradiographic method, using alpha-[14C]methyl-l-tryptophan as a tracer. MAO inhibitors have different effects on 5-HT synthesis rates in the cell bodies and areas of the nerve terminals. Moclobemide (10 mg/kg, i.p. 30 min before the tracer injection) and deprenyl (3 mg/kg, i.p. 2 h before the tracer injection) decreased the 5-HT synthesis rates in the dorsal (-18% and -22%) and median (-22% and -33%) raphe, respectively. Moclobemide also significantly decreased 5-HT synthesis in the entire nerve terminal areas investigated. The reductions were between 23% (cingulate cortex) and 50% (locus coeruleus). Deprenyl did not significantly affect 5-HT synthesis in the nerve terminals. The present results suggest that MAO-A, and to a lesser extent, MAO-B, are involved in the regulation of 5-HT synthesis in the rat brain. The mechanism(s) of MAO inhibitors' action on 5-HT synthesis in the raphe nuclei are probably related to an increase in the extraneuronal 5-HT concentration and also to the interaction between the serotonergic and catecholaminergic neurons. The reduction of 5-HT synthesis in the raphe nuclei likely occurs by an action of extracellular 5-HT via the dendritic autoreceptors with a possible contribution from the action of extracellular DA and NE. In the terminal regions, the most likely mechanism is via the presynaptic autoreceptors through which elevated extraneuronal 5-HT acts on synthesis control. However, there is also a possibility that the elevation in intraneuronal 5-HT directly inhibits its synthesis, especially following deprenyl treatment. A great influence of moclobemide on 5-HT synthesis could be related to its antidepressant action.
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Affiliation(s)
- Kyoko Nishi
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, and Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A2B4
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17
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Lechin F, van der Dijs B, Hernández-Adrián G. Dorsal raphe vs. median raphe serotonergic antagonism. Anatomical, physiological, behavioral, neuroendocrinological, neuropharmacological and clinical evidences: relevance for neuropharmacological therapy. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:565-85. [PMID: 16436311 DOI: 10.1016/j.pnpbp.2005.11.025] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/30/2005] [Indexed: 01/28/2023]
Abstract
Monoaminergic neurons located in the central nervous system (CNS) are organized into complex circuits which include noradrenergic (NA), adrenergic (Ad), dopaminergic (DA), serotonergic (5-HT), histaminergic (H), GABA-ergic and glutamatergic systems. Most of these circuits are composed of more than one and often several types of the above neurons. Such physiologically flexible circuits respond appropriately to both external and internal stimuli which, if not modulated adequately, can trigger pathophysiologic responses. A great deal of research has been devoted to mapping the multiple functions of the CNS circuitry, thereby forming the basis for effective neuropharmacological therapeutic approaches. Such lineal strategies that seek to normalize complex and mixed physiological disorders, however, meet only partial therapeutic success and are often followed by undesirable side effects and/or total failure. In light of these, we have worked to develop possible models of CNS circuitry that are less affected by physiological interaction using the models to design more effective therapeutic approaches. In the present review, we cite and present evidence supporting the dorsal raphe versus median raphe serotonergic circuitry as one model of a reliable paradigm, necessary to the clear understanding and therapy of many psychiatric and even non-psychiatric disturbances.
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Affiliation(s)
- Fuad Lechin
- Department of Physiological Sciences, Section of Neurochemical, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas, Venezuela.
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Watanabe A, Nakai A, Tohyama Y, Nguyen KQ, Diksic M. Effects of anpirtoline on regional serotonin synthesis in the rat brain: an autoradiographic study. Nucl Med Biol 2006; 33:325-32. [PMID: 16631081 DOI: 10.1016/j.nucmedbio.2005.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 08/09/2005] [Accepted: 08/09/2005] [Indexed: 11/23/2022]
Abstract
Anpirtoline has been described as an agonist at 5-HT1B receptors with a relatively high potency. It also acts as an agonist at 5-HT1A receptors, but has a lower potency than at the 5-HT1B sites. There is very little known about the mechanism by which anpirtoline influences regional 5-HT synthesis. The aim of the present study was to investigate the effects of acutely and chronically administered anpirtoline on 5-HT synthesis in the rat brain using the autoradiographic alpha-[14C]methyl-L-tryptophan method. In the acute study, anpirtoline (2.0 mg/kg) was administered intraperitoneally 30 min before the tracer injection. The control rats were injected with the same volume of saline. In the chronic study, anpirtoline (2 mg/kg per day) was injected subcutaneously in saline once a day for 10 days. There were no significant differences between the plasma-free and total tryptophan concentrations between the anpirtoline treatment and the respective control groups. In the acute experiment, 5-HT synthesis rates in all of the brain areas investigated were significantly decreased by anpirtoline when compared to the saline-treated group. In the chronic anpirtoline experiment, 5-HT synthesis rates of almost all of the projection areas, as well as the raphe nuclei, were normalized or had a tendency to be normalized. These results suggest that it is likely that the terminal 5-HT1B receptors are involved in the regulation of 5-HT synthesis in the projection areas and that 5-HT synthesis, in the raphe, is likely influenced by anpirtoline's 5-HT1A and/or 5-HT1B agonistic properties.
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Affiliation(s)
- Arata Watanabe
- Cone Neurological Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada H3A 2B4
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Hasegawa S, Watanabe A, Nguyen KQ, Debonnel G, Diksic M. Chronic administration of citalopram in olfactory bulbectomy rats restores brain 5-HT synthesis rates: an autoradiographic study. Psychopharmacology (Berl) 2005; 179:781-90. [PMID: 15619103 DOI: 10.1007/s00213-004-2122-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 11/16/2004] [Indexed: 12/19/2022]
Abstract
RATIONALE The olfactory bulbectomized (OBX) rat model is widely accepted as an animal model of depression with a proposed serotonergic imbalance in the brain. OBJECTIVE To study the effects of chronic administration of citalopram on serotonin (5-HT) synthesis rates. METHOD Serotonin synthesis was evaluated using the alpha-[(14)C]methyl-L: -tryptophan (alpha-MTrp) autoradiographic method in OBX rats. Citalopram was administered continuously (10 mg kg(-1) day(-1)) for 14 days using a subcutaneous osmotic minipump. RESULTS The OBX rats treated with citalopram (OBX-CTP) have the same 5-HT synthesis rates as the sham-operated rats treated with citalopram (Sham-CTP). The OBX-CTP rats, relative to the OBX rats treated with saline (OBX-SAL), showed a reduction in the majority of the terminal brain structures, suggesting a normalization of 5-HT synthesis in the OBX-CTP rats following treatment. The OBX-SAL rats have significantly greater synthesis than the Sham-SAL rats in a majority of the terminal structures, but lower rates in the dorsal raphe. A few structures in the OBX-CTP group have lower synthesis than in the Sham-SAL group (e.g., dorsal raphe, hippocampus, amygdala). The data suggest that receptors in some brain areas are likely still responsive to the elevated levels of the extracellular 5-HT produced by citalopram. CONCLUSION There is no significant global or individual structure difference in the synthesis between the Sham-CTP and OBX-CTP groups. The similarity in the synthesis between the OBX-CTP, Sham-CTP and Sham-SAL groups is likely a result of changes in the sensitivity of the receptors through which 5-HT synthesis is controlled. Because of some of the differences in the synthesis between the Sham-CTP and Sham-SAL groups, the data suggest that receptors throughout the brain are not fully desensitized.
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Affiliation(s)
- Shu Hasegawa
- Cone Neurosurgical Research Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, Montreal, Quebec, Canada
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