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Voronova IP. 5-HT Receptors and Temperature Homeostasis. Biomolecules 2021; 11:1914. [PMID: 34944557 PMCID: PMC8699715 DOI: 10.3390/biom11121914] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/11/2021] [Accepted: 12/16/2021] [Indexed: 12/28/2022] Open
Abstract
The present review summarizes the data concerning the influence of serotonin (5-HT) receptors on body temperature in warm-blooded animals and on processes associated with its maintenance. This review includes the most important part of investigations from the first studies to the latest ones. The established results on the pharmacological activation of 5-HT1A, 5-HT3, 5-HT7 and 5-HT2 receptor types are discussed. Such activation of the first 3 type of receptors causes a decrease in body temperature, whereas the 5-HT2 activation causes its increase. Physiological mechanisms leading to changes in body temperature as a result of 5-HT receptors' activation are discussed. In case of 5-HT1A receptor, they include an inhibition of shivering and non-shivering thermogenesis, as well simultaneous increase of peripheral blood flow, i.e., the processes of heat production and heat loss. The physiological processes mediated by 5-HT2 receptor are opposite to those of the 5-HT1A receptor. Mechanisms of 5-HT3 and 5-HT7 receptor participation in these processes are yet to be studied in more detail. Some facts indicating that in natural conditions, without pharmacological impact, these 5-HT receptors are important links in the system of temperature homeostasis, are also discussed.
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Affiliation(s)
- Irina P. Voronova
- Department of Thermophysiology, Scientific Research Institute of Neurosciences and Medicine, 630117 Novosibirsk, Russia
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2
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Pereira G, Gillies H, Chanda S, Corbett M, Vernon SD, Milani T, Bateman L. Acute Corticotropin-Releasing Factor Receptor Type 2 Agonism Results in Sustained Symptom Improvement in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Front Syst Neurosci 2021; 15:698240. [PMID: 34539356 PMCID: PMC8441022 DOI: 10.3389/fnsys.2021.698240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/15/2021] [Indexed: 11/13/2022] Open
Abstract
Background Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex multi-symptom disease with widespread evidence of disrupted systems. The authors hypothesize that it is caused by the upregulation of the corticotropin-releasing factor receptor type 2 (CRFR2) in the raphé nuclei and limbic system, which impairs the ability to maintain homeostasis. The authors propose utilizing agonist-mediated receptor endocytosis to downregulate CRFR2. Materials and Methods This open-label trial tested the safety, tolerability and efficacy of an acute dose of CT38s (a short-lived, CRFR2-selective agonist, with no known off-target activity) in 14 ME/CFS patients. CT38s was subcutaneously-infused at one of four dose-levels (i.e., infusion rates of 0.01, 0.03, 0.06, and 0.20 μg/kg/h), for a maximum of 10.5 h. Effect was measured as the pre-/post-treatment change in the mean 28-day total daily symptom score (TDSS), which aggregated 13 individual patient-reported symptoms. Results ME/CFS patients were significantly more sensitive to the transient hemodynamic effects of CRFR2 stimulation than healthy subjects in a prior trial, supporting the hypothesized CRFR2 upregulation. Adverse events were generally mild, resolved without intervention, and difficult to distinguish from ME/CFS symptoms, supporting a CRFR2 role in the disease. The acute dose of CT38s was associated with an improvement in mean TDSS that was sustained (over at least 28 days post-treatment) and correlated with both total exposure and pre-treatment symptom severity. At an infusion rate of 0.03 μg/kg/h, mean TDSS improved by -7.5 ± 1.9 (or -25.7%, p = 0.009), with all monitored symptoms improving. Conclusion The trial supports the hypothesis that CRFR2 is upregulated in ME/CFS, and that acute CRFR2 agonism may be a viable treatment approach warranting further study. Clinical Trial Registration ClinicalTrials.gov, identifier NCT03613129.
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Affiliation(s)
| | | | | | | | | | - Tina Milani
- Bateman Horne Center, Salt Lake City, UT, United States
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Gavel EH, Hawke KV, Bentley DJ, Logan-Sprenger HM. Menthol Mouth Rinsing Is More Than Just a Mouth Wash-Swilling of Menthol to Improve Physiological Performance. Front Nutr 2021; 8:691695. [PMID: 34307438 PMCID: PMC8292615 DOI: 10.3389/fnut.2021.691695] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/10/2021] [Indexed: 01/13/2023] Open
Abstract
Interventions that solely act on the central nervous system (CNS) are gaining considerable interest, particularly products consumed through the oral cavity. The oropharyngeal cavity contains a wide array of receptors that respond to sweet, bitter, and cold tastants, all of which have been shown to improve physiological performance. Of late, the ergogenic benefits of carbohydrate (CHO) and caffeine (CAF) mouth rinsings (MRs) have been widely studied; however, less is known about menthol (MEN). That the physiological state and environmental conditions impact the response each product has is increasingly recognized. While the effects of CHO and CAF MRs have been thoroughly studied in both hot and thermoneutral conditions, less is known about MEN as it has only been studied in hot environments. As such, this review summarizes the current knowledge regarding the MEN MR and exercise modality, frequency of the mouth rinse, and mouth rinse duration and compares two different types of study designs: time trials vs. time to exhaustion (TTE).
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Affiliation(s)
- Erica H Gavel
- Faculty of Science, Ontario Tech University, Oshawa, ON, Canada
| | - Kierstyn V Hawke
- Faculty of Health Science, Ontario Tech University, Oshawa, ON, Canada
| | - David J Bentley
- Faculty of Health Science, Ontario Tech University, Oshawa, ON, Canada
| | - Heather M Logan-Sprenger
- Faculty of Science, Ontario Tech University, Oshawa, ON, Canada.,Faculty of Health Science, Ontario Tech University, Oshawa, ON, Canada.,Canadian Sport Institute Ontario, Toronto, ON, Canada
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Docherty JR, Alsufyani HA. Cardiovascular and temperature adverse actions of stimulants. Br J Pharmacol 2021; 178:2551-2568. [PMID: 33786822 DOI: 10.1111/bph.15465] [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: 12/18/2020] [Revised: 02/22/2021] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
The vast majority of illicit stimulants act at monoaminergic systems, causing both psychostimulant and adverse effects. Stimulants can interact as substrates or antagonists at the nerve terminal monoamine transporter that mediates the reuptake of monoamines across the nerve synaptic membrane and at the vesicular monoamine transporter (VMAT-2) that mediates storage of monoamines in vesicles. Stimulants can act directly at presynaptic or postsynaptic receptors for monoamines or have indirect monoamine-mimetic actions due to the release of monoamines. Cocaine and other stimulants can acutely increase the risk of sudden cardiac death. Stimulants, particularly MDMA, in hot conditions, such as that occurring at a "rave," have caused fatalities from the consequences of hyperthermia, often compounding cardiac adverse actions. This review examines the pharmacology of the cardiovascular and temperature adverse actions of stimulants.
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
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Okada T, Shioda K, Makiguchi A, Suda S. Risperidone and 5-HT2A Receptor Antagonists Attenuate and Reverse Cocaine-Induced Hyperthermia in Rats. Int J Neuropsychopharmacol 2020; 23:811-820. [PMID: 32821948 PMCID: PMC7770520 DOI: 10.1093/ijnp/pyaa065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/13/2020] [Accepted: 08/15/2020] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Cocaine (benzoylmethylecgonine) is one of the most widely used illegal psychostimulant drugs worldwide, and mortality from acute intoxication is increasing. Suppressing hyperthermia is effective in reducing cocaine-related mortality, but a definitive therapy has not yet been found. In this study, we assessed the ability of risperidone to attenuate acute cocaine-induced hyperthermia and delineated the mechanism of its action. METHODS Rats were injected i.p. with saline, risperidone, ketanserin, ritanserin, haloperidol, or SCH 23 390 before and after injection of cocaine (30 mg/kg) or with WAY-00 635, SB 206 553, or sulpiride before cocaine injection; thereafter, the rectal temperature was measured every 30 minutes for up to 4 hours. In vivo microdialysis was used to reveal the effect of risperidone on cocaine-induced elevation of dopamine (DA), serotonin (5-HT), and noradrenaline concentrations in the anterior hypothalamus. For post-administration experiments, saline or risperidone (0.5 mg/kg) were injected into rats, and cocaine (30 mg/kg) was injected 15 minutes later. For every 30 minutes thereafter, DA, 5-HT, and noradrenaline levels were measured for up to 240 minutes after cocaine administration. RESULTS Risperidone, 5-HT2A receptor antagonists, and D1 receptor antagonistic drugs prevented and reversed cocaine-induced hyperthermia. In contrast, receptor antagonists for 5-HT1A, 5-HT2B/2C, and D2 did not alter cocaine-induced hyperthermia. Risperidone treatment further attenuated cocaine-induced elevation of DA. CONCLUSIONS Our results indicate that risperidone attenuates cocaine-induced hyperthermia primarily by blocking the activities of the 5-HT2A and D1 receptors and may be potentially useful for treating cocaine-induced acute hyperthermia in humans.
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Affiliation(s)
- Tsuyoshi Okada
- Department of Psychiatry, Jichi Medical University, Tochigi, Japan
| | | | - Akiko Makiguchi
- Department of Psychiatry, Jichi Medical University, Tochigi, Japan.,Department of Psychiatry, Sano Kosei General Hospital, Tochigi, Japan
| | - Shiro Suda
- Department of Psychiatry, Jichi Medical University, Tochigi, Japan
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Monophasic molybdenum selenide-reduced graphene oxide nanocomposite sheets based immunosensing platform for ultrasensitive serotonin detection. Microchem J 2020. [DOI: 10.1016/j.microc.2020.105344] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Elugoke SE, Adekunle AS, Fayemi OE, Mamba BB, Sherif ESM, Ebenso EE. Carbon-Based Quantum Dots for Electrochemical Detection of Monoamine Neurotransmitters-Review. BIOSENSORS 2020; 10:E162. [PMID: 33142771 PMCID: PMC7693402 DOI: 10.3390/bios10110162] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/09/2020] [Accepted: 08/12/2020] [Indexed: 12/13/2022]
Abstract
Imbalance in the levels of monoamine neurotransmitters have manifested in severe health issues. Electrochemical sensors have been designed for their determination, with good sensitivity recorded. Carbon-based quantum dots have proven to be an important component of electrochemical sensors due to their high conductivity, low cytotoxicity and opto-electronic properties. The quest for more sensitive electrodes with cheaper materials led to the development of electrochemical sensors based on carbon-based quantum dots for the detection of neurotransmitters. The importance of monoamine neurotransmitters (NTs) and the good electrocatalytic activity of carbon and graphene quantum dots (CQDs and GQDs) make the review of the efforts made in the design of such sensors for monoamine NTs of huge necessity. The differences and the similarities between these two quantum dots are highlighted prior to a discussion of their application in electrochemical sensors over the last ten years. Compared to other monoamine NTs, dopamine (DA) was the most studied with GQDs and CQD-based electrochemical sensors.
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Affiliation(s)
- Saheed E. Elugoke
- Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa; (S.E.E.); (A.S.A.); (O.E.F.)
- Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa
| | - Abolanle S. Adekunle
- Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa; (S.E.E.); (A.S.A.); (O.E.F.)
- Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa
- Department of Chemistry, Obafemi Awolowo University, Ile-Ife 220005, Nigeria
| | - Omolola E. Fayemi
- Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa; (S.E.E.); (A.S.A.); (O.E.F.)
- Department of Chemistry, School of Physical and Chemical Sciences, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa
| | - Bhekie B. Mamba
- Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709, South Africa;
| | - El-Sayed M. Sherif
- Center of Excellence for Research in Engineering Materials (CEREM), King Saud University, P.O. Box 800, Al-Riyadh 11421, Saudi Arabia;
- Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre, Cairo 12622, Egypt
| | - Eno E. Ebenso
- Material Science Innovation and Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University (Mafikeng Campus), Mmabatho 2735, South Africa; (S.E.E.); (A.S.A.); (O.E.F.)
- Department of Chemistry, College of Science, Engineering and Technology, University of South Africa, Roodepoort 1710, South Africa
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van Deursen DN, van den Heuvel OA, Booij J, Berendse HW, Vriend C. Autonomic failure in Parkinson's disease is associated with striatal dopamine deficiencies. J Neurol 2020; 267:1922-1930. [PMID: 32162062 PMCID: PMC7320937 DOI: 10.1007/s00415-020-09785-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/03/2020] [Accepted: 03/05/2020] [Indexed: 12/11/2022]
Abstract
Autonomic dysfunction is a common non-motor symptom in Parkinson's disease (PD). Dopamine and serotonin are known to play a role in autonomic regulation, and, therefore, PD-related degeneration of serotonergic and dopaminergic neurons in these regions may be associated with autonomic dysfunction. We sought to clarify the association between extrastriatal serotonergic and striatal dopaminergic degeneration and the severity of autonomic symptoms, including gastrointestinal, pupillomotor, thermoregulatory, cardiovascular, and urinary dysfunction. We performed hierarchical multiple regression analyses to determine the relationships between (extra)striatal serotonergic and dopaminergic degeneration and autonomic dysfunction in 310 patients with PD. We used [123I]FP-CIT SPECT binding to presynaptic serotonin (SERT) and dopamine (DAT) transporters as a measure of the integrity of these neurotransmitter systems, and the SCOPA-AUT (Scales for Outcomes in Parkinson's Disease-Autonomic) questionnaire to evaluate the perceived severity of autonomic dysfunction. Motor symptom severity, medication status, and sex were added to the model as covariates. Additional analyses were also performed using five subdomains of the SCOPA-AUT: cardiovascular, gastrointestinal, urinary, thermoregulatory, and pupillomotor symptoms. We found that autonomic symptoms were most significantly related to lower [123I]FP-CIT binding ratios in the right caudate nucleus and were mainly driven by gastrointestinal and cardiovascular dysfunction. These results provide a first look into the modest role of dopaminergic projections towards the caudate nucleus in the pathophysiology of autonomic dysfunction in PD, but the underlying mechanism warrants further investigation.
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Affiliation(s)
- Dagmar N van Deursen
- Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
| | - Odile A van den Heuvel
- Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
- Department of Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC, Academic Medical Center, Meibergdreef 9, Amsterdam, The Netherlands
| | - Henk W Berendse
- Department of Neurology, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
| | - Chris Vriend
- Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands.
- Department of Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands.
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9
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Nehru L, Chinnathambi S, Fazio E, Neri F, Leonardi SG, Bonavita A, Neri G. Electrochemical Sensing of Serotonin by a Modified MnO 2-Graphene Electrode. BIOSENSORS 2020; 10:bios10040033. [PMID: 32252484 PMCID: PMC7235847 DOI: 10.3390/bios10040033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/23/2020] [Accepted: 03/30/2020] [Indexed: 05/15/2023]
Abstract
The development of MnO2-graphene (MnO2-GR) composite by microwave irradiation method and its application as an electrode material for the selective determination of serotonin (SE), popularly known as "happy chemical", is reported. Anchoring MnO2 nanoparticles on graphene, yielded MnO2-GR composite with a large surface area, improved electron transport, high conductivity and numerous channels for rapid diffusion of electrolyte ions. The composite was characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM) for assessing the actual composition, structure and morphology. The MnO2-GR composite modified glassy carbon electrode (GCE) exhibited an excellent electrochemical activity towards the detection of SE in phosphate buffer saline (PBS) at physiological pH of 7.0. Under optimum conditions, the modified electrode could be applied to the quantification of serotonin by square wave voltammetry over a wide linear range of 0.1 to 800 µM with the lowest detection limit of 10 nM (S/N = 3). The newly fabricated sensor also exhibited attractive features such as good anti-interference ability, high reproducibility and long-term stability.
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Affiliation(s)
- Lavanya Nehru
- Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, India
- Department of Engineering, University of Messina, 98166 Messina, Italy; (S.G.L.); (A.B.); (G.N.)
- Correspondence: (L.N.); (S.C.); Tel.: +91-9442563637 (S.C.)
| | - Sekar Chinnathambi
- Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, India
- Correspondence: (L.N.); (S.C.); Tel.: +91-9442563637 (S.C.)
| | - Enza Fazio
- Department of Mathematical and Computational Sciences, Physics and Earth Physics, University of Messina, 98166 Messina, Italy; (E.F.); (F.N.)
| | - Fortunato Neri
- Department of Mathematical and Computational Sciences, Physics and Earth Physics, University of Messina, 98166 Messina, Italy; (E.F.); (F.N.)
| | | | - Anna Bonavita
- Department of Engineering, University of Messina, 98166 Messina, Italy; (S.G.L.); (A.B.); (G.N.)
| | - Giovanni Neri
- Department of Engineering, University of Messina, 98166 Messina, Italy; (S.G.L.); (A.B.); (G.N.)
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Mobed A, Hasanzadeh M, Ahmadalipour A, Fakhari A. Recent advances in the biosensing of neurotransmitters: material and method overviews towards the biomedical analysis of psychiatric disorders. ANALYTICAL METHODS 2020; 12:557-575. [DOI: 10.1039/c9ay02390a] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Neurotransmitters are the most important messengers of the nervous system, and any changes in their balances and activities can cause serious neurological, psychiatric and cognitive disorders such as schizophrenia, Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Ahmad Mobed
- Research Center of Psychiatry and Behavioral Sciences
- Faculty of Medicine
- Student Research Committee
- Tabriz University of Medical Sciences
- Iran
| | - Mohammad Hasanzadeh
- Pharmaceutical Analysis Research Center
- Tabriz University of Medical Sciences
- Tabriz
- Iran
| | - Ali Ahmadalipour
- Research Center of Psychiatry and Behavioral Sciences
- Faculty of Medicine
- Student Research Committee
- Tabriz University of Medical Sciences
- Iran
| | - Ali Fakhari
- Research Center of Psychiatry and Behavioral Sciences
- Faculty of Medicine
- Student Research Committee
- Tabriz University of Medical Sciences
- Iran
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Liang T, Chen Q, Li Q, Li R, Tang J, Hu R, Zhong J, Ge H, Liu X, Hua F. 5-HT1a activation in PO/AH area induces therapeutic hypothermia in a rat model of intracerebral hemorrhage. Oncotarget 2017; 8:73613-73626. [PMID: 29088731 PMCID: PMC5650286 DOI: 10.18632/oncotarget.20280] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/12/2017] [Indexed: 12/23/2022] Open
Abstract
Therapeutic hypothermia is widely applied as a neuroprotective measure on intracerebral hemorrhage (ICH). However, several clinical trials regarding physical hypothermia encountered successive failures because of its side-effects in recent years. Increasing evidences indicate that chemical hypothermia that targets hypothalamic 5-HT1a has potential to down-regulate temperature set point without major side-effects. Thus, this study examined the efficacy and safety of 5-HT1a stimulation in PO/AH area for treating ICH rats. First, the relationship between head temperature and clinical outcomes was investigated in ICH patients and rat models, respectively. Second, the expression and distribution of 5-HT1a receptor in PO/AH area was explored by using whole-cell patch and confocal microscopy. In the meantime, the whole-cell patch was subsequently applied to investigate the involvement of 5-HT1a receptors in temperature regulation. Third, we compared the efficacy between traditional PH and 5-HT1a activation-induced hypothermia for ICH rats. Our data showed that more severe perihematomal edema (PHE) and neurological deficits was associated with increased head temperature following ICH. 5-HT1a receptor was located on warm-sensitive neurons in PO/AH area and 8-OH-DPAT (5-HT1a receptor agonist) significantly enhanced the firing rate of warm-sensitive neurons. 8-OH-DPAT treatment provided a steadier reduction in brain temperature without a withdrawal rebound, which also exhibited a superior neuroprotective effect on ICH-induced neurological dysfunction, white matter injury and BBB damage compared with physical hypothermia. These findings suggest that chemical hypothermia targeting 5-HT1a receptor in PO/AH area could act as a novel therapeutic manner against ICH, which may provide a breakthrough for therapeutic hypothermia.
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Affiliation(s)
- Tan Liang
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Qianwei Chen
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Qiang Li
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Rongwei Li
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Jun Tang
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Rong Hu
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Jun Zhong
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Hongfei Ge
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Xin Liu
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Feng Hua
- Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, China
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Chronic-Stress-Induced Behavioral Changes Associated with Subregion-Selective Serotonin Cell Death in the Dorsal Raphe. J Neurosci 2017; 37:6214-6223. [PMID: 28546314 DOI: 10.1523/jneurosci.3781-16.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/25/2017] [Accepted: 05/16/2017] [Indexed: 01/18/2023] Open
Abstract
The current study examined the neurochemical mechanisms and neuroanatomical changes underlying coexisting behavioral effects associated with chronic-stress-induced alterations in serotonin (5HT) neurons. Chronic unpredictable stress (CUS) to adult male rats produced depression-like changes with cognitive dysfunction and selective cell death in the interfascicular nucleus of the dorsal raphe (DRif), resulting in decreased 5HTergic innervation of medial prefrontal cortex (mPFC). Twenty-one days of CUS decreased basal plasma levels of corticosterone and produced a shorter latency to immobility and longer durations of immobility in the force-swim test that persisted for 1 month after CUS. Deficits in acquisition, recall, perseveration, and reversal learning were evident 1 month after CUS. MK801 treatment during CUS blocked the changes in the forced-swim test and deficits in memory recall. These behavioral changes were associated with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive soma and the eventual loss of 5HT neurons in the DRif and its projections to the mPFC as evidenced by fewer labeled cells in the DRif after retrograde tracer injections into the mPFC of stressed rats. Similar to the effects of MK801 on behavior, MK801 pretreatment during stress blocked the CUS-induced decreases in 5HT soma within the DRif and its projections to the mPFC. Finally, the depression-like behaviors were blocked by acute injection of the 5HT2A/C agonist (-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride into the mPFC before forced-swim testing. These results identify a cause and mechanism of 5HTergic dysfunction of the mPFC and associated mood and cognitive behaviors.SIGNIFICANCE STATEMENT Chronic stress causes persistent mood and cognitive changes typically associated with dysregulated serotonin (5HT) transmission in the medial prefrontal cortex (mPFC), but the cause of this dysregulation is unknown. Prior studies have focused on 5HTergic terminals in this region, but this study shows that chronic stress causes NMDA-receptor-dependent and subregion-specific cell death of 5HT neurons in the dorsal raphe. The consequent decreased 5HT innervation of the mPFC was associated with mood and cognitive changes that persisted long after the termination of stress. These findings identify a mechanism of subregion-selective death of 5HT neurons in the dorsal raphe, a defined neuroanatomical pathway, and a behavioral phenotype that mirror stress-associated diseases such as major depressive disorder.
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Zhang H, Zhao H, Yang X, Xue Q, Cotten JF, Feng HJ. 5-Hydroxytryptophan, a precursor for serotonin synthesis, reduces seizure-induced respiratory arrest. Epilepsia 2016; 57:1228-35. [PMID: 27302625 DOI: 10.1111/epi.13430] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The DBA/1 mouse is a relevant animal model of sudden unexpected death in epilepsy (SUDEP), as it exhibits seizure-induced respiratory arrest (S-IRA) evoked by acoustic stimulation, followed by cardiac arrhythmia and death. Defects in serotonergic neurotransmission may contribute to S-IRA. The tryptophan hydroxylase-2 (TPH2) enzyme converts L-tryptophan to 5-hydroxytryptophan (5-HTP), a precursor for central nervous system (CNS) serotonin (5-HT) synthesis; and DBA/1 mice have a polymorphism that decreases TPH2 activity. We, therefore, hypothesized that supplementation with 5-HTP may bypass TPH2 and suppress S-IRA in DBA/1 mice. METHODS TPH2 expression was examined by Western blot in the brainstem of DBA/1 and C57BL/6J mice both with and without acoustic stimulation. Changes in breathing and cardiac electrical activity in DBA/1 and C57BL/6J mice that incurred sudden death during generalized seizures evoked by pentylenetetrazole (PTZ) were studied by plethysmography and electrocardiography. The effect of 5-HTP administration on seizure-induced mortality evoked by acoustic stimulation or by PTZ was investigated in DBA/1 mice. RESULTS Repetitive acoustic stimulation resulted in reduced TPH2 protein in the brainstem of DBA/1 mice as compared with C57BL/6J mice. S-IRA evoked by acoustic stimulation in DBA/1 mice was significantly reduced by 5-HTP. Following S-IRA, cardiac electrical activity could be detected for minutes before terminal asystole and death in both DBA/1 and C57BL/6J mice after PTZ treatment. The incidence of S-IRA by PTZ administration was greater in DBA/1 than in C57BL/6J mice, and administration of 5-HTP also significantly reduced S-IRA by PTZ in DBA/1 mice. SIGNIFICANCE Our data suggest that S-IRA is the primary event leading to death incurred in most DBA/1 and some C57BL/6J mice during PTZ-evoked seizures. Suppression of S-IRA by 5-HTP suggests that 5-HT transmission contributes to the pathophysiology of S-IRA, and that 5-HTP, an over-the-counter supplement available for human consumption, may be clinically useful in preventing SUDEP.
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Affiliation(s)
- Honghai Zhang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A.,Department of Anesthesia, Hangzhou First People's Hospital, Nanjing Medical University, Hangzhou, China
| | - Haiting Zhao
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A.,Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, China.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaoxuan Yang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A.,Department of Anesthesiology, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Qingsheng Xue
- Department of Anesthesiology, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Joseph F Cotten
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A
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14
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Abstract
Chronic stress is known to affect serotonin (5HT) neurotransmission in the brain and to alter body temperature. The body temperature is controlled in part, by the medial preoptic area (mPOA) of the hypothalamus. To investigate the effect of chronic stress on 5HT and how it affects body temperature regulation, we examined whether exposure to a chronic unpredictable stress (CUS) paradigm produces long-term alterations in thermoregulatory function of the mPOA through decreased 5HT neurotransmission. Adult male Sprague-Dawley rats underwent 21 d of CUS. Four days after the last stress exposure, basal body temperature in the home cage and body temperature in a cold room maintained at 10 °C were recorded. The CUS rats had significantly higher subcutaneous basal body temperature at 13:00 h compared to unstressed (NoStress) rats. Whereas the NoStress rats were able to significantly elevate body temperature from basal levels at 30 and 60 min of exposure to the cold room, the CUS rats showed a hypothermic response to the cold. Treatment during CUS with metyrapone, a corticosterone synthesis inhibitor, blocked stress-induced decrease in body temperature in response to the cold challenge. CUS also decreased 5HT transporter protein immunoreactivity in the mPOA and 5HT2A/C agonist injection into the mPOA after CUS exposure caused stressed rats to exhibit a sensitized hyperthermic response to cold. These results indicate that the CUS induced changes to the 5HTergic system alter mPOA function in thermoregulation. These findings help us to explain the mechanisms underlying chronic stress-induced disorders such as chronic fatigue syndrome wherein long lasting thermoregulatory deficits are observed.
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Affiliation(s)
- Reka Natarajan
- a Department of Neurosciences , University of Toledo College of Medicine , Toledo , OH , USA
| | - Nicole A Northrop
- a Department of Neurosciences , University of Toledo College of Medicine , Toledo , OH , USA
| | - Bryan K Yamamoto
- a Department of Neurosciences , University of Toledo College of Medicine , Toledo , OH , USA
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15
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Changes in intensity of serotonin syndrome caused by adverse interaction between monoamine oxidase inhibitors and serotonin reuptake blockers. Neuropsychopharmacology 2014; 39:1996-2007. [PMID: 24577320 PMCID: PMC4059910 DOI: 10.1038/npp.2014.49] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/15/2014] [Accepted: 02/17/2014] [Indexed: 11/08/2022]
Abstract
Drug interaction between inhibitors of monoamine oxidase (MAOIs) and selective serotonin (5-hydroxytryptamine, 5-HT) reuptake (SSRIs) induces serotonin syndrome, which is usually mild but occasionally severe in intensity. However, little is known about neural mechanisms responsible for the syndrome induction and intensification. In this study, we hypothesized that the syndrome induction and intensity utilize two different but inter-related mechanisms. Serotonin syndrome is elicited by excessive 5-HT in the brain (presynaptic mechanism), whereas syndrome intensity is attributed to neural circuits involving 5-HT2A and NMDA receptors (postsynaptic mechanism). To test this hypothesis, basal 5-HT efflux and postsynaptic circuits were pharmacologically altered in rats by once daily pretreatment of the MAOI clorgyline for 3, 6, or 13 days. Syndrome intensity was estimated by measuring 5-HT efflux, neuromuscular activity, and body-core temperature in response to challenge injection of clorgyline combined with the SSRI paroxetine. Results showed that the onset of serotonin syndrome is caused by 5-HT efflux exceeding 10-fold above baseline, confirming the presynaptic hypothesis. The neuromuscular and body-core temperature abnormalities, which were otherwise mild in drug-naive rats, were significantly intensified to a severe level in rats pretreated with daily clorgyline for 3 and 6 days but not in rats pretreated for 13 days. The intensified effect was blocked by M100907 and MK-801, suggesting that variation in syndrome intensity was mediated through a 5-HT2A and NMDA receptor-engaged circuit. Therefore, we concluded that pretreatments of MAOI pharmacologically alter the activity of postsynaptic circuits, which is responsible for changes in syndrome intensity.
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16
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Electrocatalytic properties of functionalized carbon nanotubes with titanium dioxide and benzofuran derivative/ionic liquid for simultaneous determination of isoproterenol and serotonin. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.03.063] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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High sensitive sensor based on functionalized carbon nanotube/ionic liquid nanocomposite for simultaneous determination of norepinephrine and serotonin. J Electroanal Chem (Lausanne) 2014. [DOI: 10.1016/j.jelechem.2013.12.034] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Jacobsen JPR, Siesser WB, Sachs BD, Peterson S, Cools MJ, Setola V, Folgering JHA, Flik G, Caron MG. Deficient serotonin neurotransmission and depression-like serotonin biomarker alterations in tryptophan hydroxylase 2 (Tph2) loss-of-function mice. Mol Psychiatry 2012; 17:694-704. [PMID: 21537332 PMCID: PMC3536482 DOI: 10.1038/mp.2011.50] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Probably the foremost hypothesis of depression is the 5-hydroxytryptamine (5-HT, serotonin) deficiency hypothesis. Accordingly, anomalies in putative 5-HT biomarkers have repeatedly been reported in depression patients. However, whether such anomalies in fact reflect deficient central 5-HT neurotransmission remains unresolved. We employed a naturalistic model of 5-HT deficiency, the tryptophan hydroxylase 2 (Tph2) R439H knockin mouse, to address this question. We report that Tph2 knockin mice have reduced basal and stimulated levels of extracellular 5-HT (5-HT(Ext)). Interestingly, cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) and fenfluramine-induced plasma prolactin levels are markedly diminished in the Tph2 knockin mice. These data seemingly confirm that low CSF 5-HIAA and fenfluramine-induced plasma prolactin reflects chronic, endogenous central nervous system (CNS) 5-HT deficiency. Moreover, 5-HT(1A) receptor agonist-induced hypothermia is blunted and frontal cortex 5-HT(2A) receptors are increased in the Tph2 knockin mice. These data likewise parallel core findings in depression, but are usually attributed to anomalies in the respective receptors rather than resulting from CNS 5-HT deficiency. Further, 5-HT(2A) receptor function is enhanced in the Tph2 knockin mice. In contrast, 5-HT(1A) receptor levels and G-protein coupling is normal in Tph2 knockin mice, indicating that the blunted hypothermic response relates directly to the low 5-HT(Ext). Thus, we show that not only low CSF 5-HIAA and a blunted fenfluramine-induced prolactin response, but also blunted 5-HT(1A) agonist-induced hypothermia and increased 5-HT(2A) receptor levels are bona fide biomarkers of chronic, endogenous 5-HT deficiency. Potentially, some of these biomarkers could identify patients likely to have 5-HT deficiency. This could have clinical research utility or even guide pharmacotherapy.
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Affiliation(s)
- JPR Jacobsen
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - WB Siesser
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - BD Sachs
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - S Peterson
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - MJ Cools
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - V Setola
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | | | - G Flik
- BrainsOnline, Groningen, The Netherlands
| | - MG Caron
- Department of Cell Biology, Duke University, Durham, NC, USA,Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
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Soares JG, Cavalcanti JR, Oliveira FG, Pontes AL, Sousa TB, Freitas LM, Cavalcante JS, Nascimento ES, Cavalcante JC, Costa MS. Nuclear organization of the serotonergic system in the brain of the rock cavy (Kerodon rupestris). J Chem Neuroanat 2012; 43:112-9. [DOI: 10.1016/j.jchemneu.2012.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 03/12/2012] [Accepted: 03/12/2012] [Indexed: 11/27/2022]
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20
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Meeusen R, Roelands B. Central fatigue and neurotransmitters, can thermoregulation be manipulated? Scand J Med Sci Sports 2011; 20 Suppl 3:19-28. [PMID: 21029187 DOI: 10.1111/j.1600-0838.2010.01205.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Fatigue is a complex phenomenon that can be evoked by peripheral and central factors. Although it is obvious that fatigue has peripheral causes such as glycogen depletion and cardiovascular strain, recent literature also focuses on the central origin of fatigue. It is clear that different brain neurotransmitters--such as serotonin, dopamine and noradrenaline--are implicated in the occurrence of fatigue, but manipulation of these neurotransmitters produced no conclusive results on performance in normal ambient temperature. Exercise in the heat not only adds an extra challenge to the cardiorespiratory system, but also to the brain. This provides a useful tool to investigate the association between exercise-induced hyperthermia and central fatigue. This review focuses on the effects of pharmacological manipulations on performance and thermoregulation in different ambient temperatures. Dopaminergic reuptake inhibition appears to counteract hyperthermia-induced fatigue in 30 °C, while noradrenergic neurotransmission shows negative effects on performance in both normal and high temperature, and serotonergic manipulations did not lead to significant changes in performance. It is, however, unlikely that one neurotransmitter system is responsible for the delay or onset of fatigue. Further research is required to determine the exact mechanisms of fatigue in different environmental conditions.
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Affiliation(s)
- R Meeusen
- Department of Human Physiology & Sports Medicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium.
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21
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Zhang G, Tao R. Enhanced responsivity of 5-HT(2A) receptors at warm ambient temperatures is responsible for the augmentation of the 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced hyperthermia. Neurosci Lett 2010; 490:68-71. [PMID: 21172407 DOI: 10.1016/j.neulet.2010.12.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 12/10/2010] [Accepted: 12/11/2010] [Indexed: 10/18/2022]
Abstract
Warm ambient temperature facilitates hyperthermia and other neurotoxic responses elicited by psychogenic drugs such as MDMA and methamphetamine. However, little is known about the neural mechanism underlying such effects. In the present study, we tested the hypothesis that a warm ambient temperature may enhance the responsivity of 5-HT(2A) receptors in the central nervous system and thereafter cause an augmented response to 5-HT(₂A) receptor agonists. This hypothesis was tested by measuring changes in body-core temperature in response to the 5-HT(2A) receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) administered at four different ambient temperature levels: 12 °C (cold), 22 °C (standard), 27 °C (thermoneutral zone) and 32 °C (warm). It was found that DOI only evoked a small increase in body-core temperature at the standard (22 °C) or thermoneutral ambient temperature (27 °C). In contrast, there was a large increase in body-core temperature when the experiments were conducted at the warmer ambient temperature (32 °C). Interestingly, the effect of DOI at the cold ambient temperature of 12 °C was significantly reduced. Moreover, the ambient temperature-dependent response to DOI was completely blocked by pretreatment with the 5-HT(₂A) receptor antagonist ketanserin. Taken together, these findings support the hypothesis that 5-HT(₂A) receptors may be responsible for some neurotoxic effects of psychogenic drugs in the central nervous system, the activity of which is functionally inhibited at cold but enhanced at warm ambient temperature in contrast to that at standard experimental conditions.
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Affiliation(s)
- Gongliang Zhang
- Department of Basic Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-3091, USA.
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22
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Johnson BN, Yamamoto BK. Chronic stress enhances the corticosterone response and neurotoxicity to +3,4-methylenedioxymethamphetamine (MDMA): the role of ambient temperature. J Pharmacol Exp Ther 2010; 335:180-9. [PMID: 20634423 DOI: 10.1124/jpet.110.171322] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Stress facilitates drug abuse by humans. In rodents, stress enhances the neurochemical, neuroendocrine, and behavioral responses to psychostimulants. Although chronic unpredictable stress (CUS) enhances the acute hyperthermic and long-term monoamine-depleting effects of the psychostimulant +3,4-methylenedioxymethamphetamine (MDMA), the roles of hyperthermia and corticosterone (CORT) in mediating the stress-induced enhancement of MDMA-induced serotonin (5-HT) and dopamine (DA) depletions are unknown. Rats were exposed to 10 days of CUS and then challenged with MDMA (5 mg/kg i.p. once every 2 h for a total of four injections). Prior exposure to CUS augmented MDMA-induced hyperthermia and plasma CORT secretion and the long-term depletions in 5-HT content in striatum, hippocampus, and frontal cortex and DA content in striatum. A reduced ambient temperature of 21°C attenuated the hyperthermia, CORT secretion, and 5-HT decreases after MDMA in nonstressed rats. The lower ambient temperature also prevented the augmented hyperthermia, CORT secretion, and enhanced 5-HT and DA depletions after MDMA in chronically stressed rats to levels exhibited by nonstressed, MDMA-treated rats. To investigate the role of CORT on monoamine depletions in response to MDMA, stressed and nonstressed rats were treated with the CORT synthesis inhibitor metyrapone during exposure to MDMA. Metyrapone prevented CORT secretion in both stressed and nonstressed rats but did not modify 5-HT or DA depletions in any brain region examined. This study suggests that enhanced CORT is a consequence of enhanced hyperthermia and the CUS-induced enhancements of MDMA-induced monoamine depletions may be mediated by hyperthermia but not CORT.
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Affiliation(s)
- Bethann N Johnson
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts, USA
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23
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Roelands B, Meeusen R. Alterations in central fatigue by pharmacological manipulations of neurotransmitters in normal and high ambient temperature. Sports Med 2010; 40:229-46. [PMID: 20199121 DOI: 10.2165/11533670-000000000-00000] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The scientific evidence is reviewed for the involvement of the brain monoamines serotonin, dopamine and noradrenaline (norepinephrine) in the onset of fatigue, in both normal and high ambient temperatures. The main focus is the pharmacological manipulations used to explore the central fatigue hypothesis. The original central fatigue hypothesis emphasizes that an exercise-induced increase in serotonin is responsible for the development of fatigue. However, several pharmacological studies attempted and failed to alter exercise capacity through changes in serotonergic neurotransmission in humans, indicating that the role of serotonin is often overrated. Recent studies, investigating the inhibition of the reuptake of both dopamine and noradrenaline, were capable of detecting changes in performance, specifically when ambient temperature was high. Dopamine and noradrenaline are prominent in innervated areas of the hypothalamus, therefore changes in the catecholaminergic concentrations may also be expected to be involved with the regulation of body core temperature during exercise in the heat. Evidence from different studies suggests that it is very unlikely that one neurotransmitter system is responsible for the appearance of central fatigue. The exact mechanism of fatigue is not known; presumably a complex interplay between both peripheral and central factors induces fatigue. Central fatigue will be determined by the collaboration of the different neurotransmitter systems, with the most important role possibly being for the catecholamines dopamine and noradrenaline.
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Affiliation(s)
- Bart Roelands
- Department of Human Physiology and Sports Medicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
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24
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Raudensky J, Yamamoto BK. Serotonin 2 receptor modulation of hyperthermia, corticosterone, and hippocampal serotonin depletions following serial exposure to chronic stress and methamphetamine. Psychoneuroendocrinology 2010; 35:629-33. [PMID: 19879056 PMCID: PMC3951178 DOI: 10.1016/j.psyneuen.2009.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 09/16/2009] [Accepted: 10/01/2009] [Indexed: 10/20/2022]
Abstract
Chronic stress precipitates drug seeking behavior and alters the effects of drugs of abuse. Although it is known that chronic stress potentiates acute neurochemical and hyperthermic responses to the drug of abuse methamphetamine, no studies have investigated if and how chronic stress alters other physiological responses to methamphetamine. Therefore the objective of these studies was to determine if 10 days of chronic unpredictable stress modulates corticosterone (CORT) responses to methamphetamine and furthermore how chronic stress may modulate methamphetamine-induced increases in hyperthermia and CORT. As chronic stress potentiates hyperthermic responses to serotonin 2 (5-HT2) stimulation and 5-HT2 receptors are important in mediating both hyperthermic and CORT responses, we also investigated if 5-HT2 antagonism would block hyperthermia and CORT secretion by the serial exposure to stress and methamphetamine (stress/methamphetamine). The results of these studies illustrate that stress potentiates methamphetamine-induced increases in body temperature and CORT secretion and that these increases are blocked by the 5-HT2 antagonist ketanserin. Furthermore, the combination of stress and methamphetamine depletes 5-HT content in the hippocampus 7 days after methamphetamine administration which is blocked by the 5-HT2 antagonist ketanserin. Overall, these results indicate a pharmacological mechanism for the depletion of hippocampal 5-HT by the serial exposure to stress and methamphetamine and further illustrate the deleterious interactions between chronic stress and methamphetamine use.
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Affiliation(s)
- Jamie Raudensky
- McLean Hospital, Harvard Medical School, McLean Hospital MRC 114, 115 Mill St, Belmont, MA 02378
| | - Bryan K. Yamamoto
- University of Toledo Health Sciences Center, Department of Neurosciences, Mail Stop 1007, 3000 Arlington Ave., Toledo, OH 43614
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25
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Zhang G, Krishnamoorthy S, Ma Z, Vukovich NP, Huang X, Tao R. Assessment of 5-hydroxytryptamine efflux in rat brain during a mild, moderate and severe serotonin-toxicity syndrome. Eur J Pharmacol 2009; 615:66-75. [PMID: 19464285 PMCID: PMC2756783 DOI: 10.1016/j.ejphar.2009.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 05/01/2009] [Accepted: 05/14/2009] [Indexed: 11/30/2022]
Abstract
Serotonin (5-hydroxytryptamine; 5-HT)-toxicity syndrome, an iatrogenic brain disorder induced by excessive efflux of 5-HT, has received much attention because of increasing incidents of serotonergic antidepressants. However, the neural mechanism by which extracellular 5-HT is elevated to a toxic level for the syndrome remains to be determined. The goal of the present study was to test the hypothesis that extracellular 5-HT is composed of two component effluxes responsible for distinct aspects of the syndrome. The first set of experiments was to characterize the syndrome by measuring changes in neuromuscular signs, body-core temperature and mortality rate. Our results indicate that the syndrome severity can be categorized into mild, moderate and severe levels. The second set of experiments was to determine a threshold of extracellular 5-HT for induction of each level of the syndrome. Our results demonstrate that there were an 11-fold increase in the mild syndrome and an over 55-fold increase in the severe syndrome. In the last series of experiments, the excessive increases in 5-HT were pharmacologically separated into primary and secondary component effluxes with the 5-HT2A receptor antagonists cyproheptadine and ketanserin and NMDA receptor antagonist (+)-MK-801. Our results suggest that the primary component efflux was caused by direct drug effects on 5-HT biosynthetic and metabolic pathways and secondary efflux ascribed to indirect drug effect on a positive-feedback circuit involving 5-HT2A and NMDA receptors. In summary, the primary efflux could be an initial cause for the induction of the syndrome while the secondary efflux might involve deterioration of the syndrome.
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Affiliation(s)
- Gongliang Zhang
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Swapna Krishnamoorthy
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Zhiyuan Ma
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Nick P. Vukovich
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Xupei Huang
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
| | - Rui Tao
- Charles E. Schmidt College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, U.S.A
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26
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Time trial performance in normal and high ambient temperature: is there a role for 5-HT? Eur J Appl Physiol 2009; 107:119-26. [PMID: 19533165 DOI: 10.1007/s00421-009-1109-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
Abstract
The original central fatigue hypothesis suggested that fatigue during prolonged exercise might be due to higher 5-HT activity. Therefore, we examined the effects of acute administration of a selective 5-HT reuptake inhibitor (SSRI) on performance and thermoregulation. Eleven healthy trained male cyclists completed four experimental trials (two in 18 degrees C, two in 30 degrees C) in a double-blind randomised crossover design. Subjects ingested either a placebo (PLA: lactose 2 x 10 mg) or citalopram (CITAL 2 x 10 mg) on the evening before and the morning of the trial. Subjects cycled for 60 min at 55% W(max), immediately followed by a time trial (TT) to measure performance. The significance level was set at P < 0.05. Acute SSRI did not significantly change performance on the TT (18 degrees C P = 0.518; 30 degrees C P = 0.112). During recovery at 30 degrees C, core temperature was significantly lower in the CITAL trial (P < 0.012). At 30 degrees C heart rate was significantly lower after exercise in CITAL (P = 0.013). CITAL significantly increased cortisol concentrations at rest (P = 0.016), after the TT (P = 0.006) and after 15-min recovery (P = 0.041) at 30 degrees C. 5-HT reuptake inhibition did not cause significant reductions in performance. Core temperature was significantly lower only after the time trial in heat after CITAL administration. The present work failed to prove whether or not 5-HT has an exclusive role in the onset of centrally mediated fatigue during prolonged exercise in both normal and high ambient temperature.
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Johnson BN, Yamamoto BK. Chronic unpredictable stress augments +3,4-methylenedioxymethamphetamine-induced monoamine depletions: the role of corticosterone. Neuroscience 2009; 159:1233-43. [PMID: 19409219 DOI: 10.1016/j.neuroscience.2009.01.067] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 01/14/2009] [Accepted: 01/29/2009] [Indexed: 11/19/2022]
Abstract
Exposure to stress alters the behavioral and neurochemical effects of drugs of abuse. However, it is unknown if chronic stress can affect the serotonergic depletions induced by the psychostimulant drug 3,4-methylenedioxymethamphetamine (MDMA). Rats were exposed to 10 days of chronic unpredictable stress (CUS) which resulted in the predicted elevation of basal plasma corticosterone concentrations. On the 11th day, rats received four challenge doses of MDMA (5 mg/kg every 2 h, i.p.) or saline. Five days later, rats were killed and serotonin (5-HT) and dopamine content were measured in the striatum, hippocampus, and frontal cortex. MDMA produced greater depletions of 5-HT in all three brain regions of rats pre-exposed to CUS compared to rats not exposed to CUS. CUS-exposed rats also had an augmented acute hyperthermic response but a similar increase in plasma corticosterone after challenge injections of MDMA compared with non-stressed rats similarly challenged with MDMA. Moreover, CUS-exposed rats exhibited an MDMA-induced depletion of striatal dopamine that was absent in non-stressed rats that received MDMA. To investigate the role of corticosterone in these effects, the corticosterone synthesis inhibitor, metyrapone (50 mg/kg i.p.), was administered prior to each stressor on each of the 10 days of CUS. Metyrapone blocked the chronic stress-induced elevation in basal plasma corticosterone, prevented the enhancement of MDMA-induced hyperthermia, and blocked the enhanced depletions of 5-HT and dopamine in CUS-exposed rats, but had no effect on the acute MDMA-induced increases in plasma corticosterone. These findings suggest that CUS alone can increase the basal level of corticosterone that in turn, plays an important role in enhancing the sensitivity of both 5-HT and dopamine terminals to the hyperthermic and monoamine depleting effects of MDMA without altering the acute corticosterone response to an MDMA challenge.
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Affiliation(s)
- B N Johnson
- Department of Pharmacology and Experimental Therapeutics, Laboratory of Neurochemistry, Boston University School of Medicine, Boston, MA 02118, USA
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Hadjicharalambous M, Kilduff LP, Pitsiladis YP. Brain serotonin and dopamine modulators, perceptual responses and endurance performance during exercise in the heat following creatine supplementation. J Int Soc Sports Nutr 2008; 5:14. [PMID: 18826587 PMCID: PMC2570654 DOI: 10.1186/1550-2783-5-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 09/30/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The present experiment examined the responses of peripheral modulators and indices of brain serotonin (5-HT) and dopamine (DA) function and their association with perception of effort during prolonged exercise in the heat after creatine (Cr) supplementation. METHODS Twenty one endurance-trained males performed, in a double-blind fashion, two constant-load exercise tests to exhaustion at 63 +/- 5% V(O2) max in the heat (ambient temperature: 30.3 +/- 0.5 degrees C, relative humidity: 70 +/- 2%) before and after 7 days of Cr (20 g.d-1 Cr + 140 g.d-1 glucose polymer) or placebo (Plc) (160 g.d-1 glucose polymer) supplementation. RESULTS 3-way interaction has shown that Cr supplementation reduced rectal temperature, heart rate, ratings of perceived leg fatigue (P < 0.05), plasma free-tryptophan (Trp) (P < 0.01) and free-Trp:tyrosine ratio (P < 0.01) but did not influence the ratio of free-Trp:large neutral amino acids or contribute in improving endurance performance (Plc group, n = 10: 50.4 +/- 8.4 min vs. 51.2 +/- 8.0 min, P > 0.05; Cr group, n = 11: 47.0 +/- 4.7 min vs. 49.7 +/- 7.5 min, P > 0.05). However, after dividing the participants into "responders" and "non-responders" to Cr, based on their intramuscular Cr uptake, performance was higher in the "responders" relative to "non-responders" group (51.7 +/- 7.4 min vs.47.3 +/- 4.9 min, p < 0.05). CONCLUSION Although Cr influenced key modulators of brain 5-HT and DA function and reduced various thermophysiological parameters which all may have contributed to the reduced effort perception during exercise in the heat, performance was improved only in the "responders" to Cr supplementation. The present results may also suggest the demanding of the pre-experimental identification of the participants into "responders" and "non-responders" to Cr supplementation before performing the main experimentation. Otherwise, the possibility of the type II error may be enhanced.
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Pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA). Br J Pharmacol 2008; 154:606-22. [PMID: 18500382 DOI: 10.1038/bjp.2008.124] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This review examines the pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA). Stimulants that increase alertness/reduce fatigue or activate the cardiovascular system can include drugs like ephedrine available in many over-the-counter medicines. Others such as amphetamines, cocaine and hallucinogenic drugs, available on prescription or illegally, can modify mood. A total of 62 stimulants (61 chemical entities) are listed in the WADA List, prohibited in competition. Athletes may have stimulants in their body for one of three main reasons: inadvertent consumption in a propriety medicine; deliberate consumption for misuse as a recreational drug and deliberate consumption to enhance performance. The majority of stimulants on the list act on the monoaminergic systems: adrenergic (sympathetic, transmitter noradrenaline), dopaminergic (transmitter dopamine) and serotonergic (transmitter serotonin, 5-HT). Sympathomimetic describes agents, which mimic sympathetic responses, and dopaminomimetic and serotoninomimetic can be used to describe actions on the dopamine and serotonin systems. However, many agents act to mimic more than one of these monoamines, so that a collective term of monoaminomimetic may be useful. Monoaminomimietic actions of stimulants can include blockade of re-uptake of neurotransmitter, indirect release of neurotransmitter, direct activation of monoaminergic receptors. Many of the stimulants are amphetamines or amphetamine derivatives, including agents with abuse potential as recreational drugs. A number of agents are metabolized to amphetamine or metamphetamine. In addition to the monoaminomimetic agents, a small number of agents with different modes of action are on the list. A number of commonly used stimulants are not considered as Prohibited Substances.
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Rodrigues A, Lima N, Coimbra C, Marubayashi U. Evidence that exercise-induced heat storage is dependent on adrenomedullary secretion. Physiol Behav 2008; 94:463-7. [DOI: 10.1016/j.physbeh.2008.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 02/14/2008] [Accepted: 02/21/2008] [Indexed: 11/25/2022]
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Ma Z, Zhang G, Jenney C, Krishnamoorthy S, Tao R. Characterization of serotonin-toxicity syndrome (toxidrome) elicited by 5-hydroxy-l-tryptophan in clorgyline-pretreated rats. Eur J Pharmacol 2008; 588:198-206. [PMID: 18499101 DOI: 10.1016/j.ejphar.2008.04.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 03/11/2008] [Accepted: 04/01/2008] [Indexed: 12/13/2022]
Abstract
Patients are at high risk of developing serotonin-toxicity syndrome (toxidrome) when they take multiple serotonergic drugs, particularly co-administered with monoamine oxidase inhibitors or 5-hydroxytryptamine (5-HT) reuptake blockers. The toxidrome can vary from mild to severe. The primary goal of the present study was to understand the relationship between behavioral signs and degrees of toxidrome induced by 5-hydroxy-l-tryptophan (5-HTP) in clorgylinized rats. The severity was obtained by scoring behavioral signs including head shakes, penile erection, forepaw treading, hind limb abduction, Straub tail and tremor. It was found that 5-HTP produced a dose-dependent increase in degrees of the toxidrome. Furthermore, correlation between the toxidrome and changes in body-core temperature (delta Tcor) was determined. There was hypothermia in the mild toxidrome (delta Tcor<-1 degrees C), high hyperthermia in the severe toxidrome (delta Tcor>+2 degrees C) and a small change in T(cor) in the moderate toxidrome (-1 degrees C<delta Tcor<+2 degrees C). Thus, delta Tcor in response to drugs can be used to estimate the severity of the toxidrome. The second attempt was to identify the receptors mediating those changes. 5-HT1A receptors were involved in the hypothermic response while 5-HT2A and NMDA receptors mediated head shakes, hyperthermia, forepaw treading and Straub tail. Lastly, antidotal effect of cyproheptadine and (+)-MK-801 was examined. Both drugs blocked hyperthermia and death. However, the effects on mortality became poor when the antidotes were injected 60 min after high hyperthermia had been induced. These findings demonstrate the importance of the time frame using antidotes in the treatment of the 5-HT toxidrome.
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Affiliation(s)
- Zhiyuan Ma
- Department of Basic Science, Florida Atlantic University, Boca Raton, FL 33431, USA
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Dias MB, Nucci TB, Margatho LO, Antunes-Rodrigues J, Gargaglioni LH, Branco LGS. Raphe magnus nucleus is involved in ventilatory but not hypothermic response to CO2. J Appl Physiol (1985) 2007; 103:1780-8. [PMID: 17823301 DOI: 10.1152/japplphysiol.00424.2007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is evidence that serotonin [5-hydroxytryptamine (5-HT)] is involved in the physiological responses to hypercapnia. Serotonergic neurons represent the major cell type (comprising 15-20% of the neurons) in raphe magnus nucleus (RMg), which is a medullary raphe nucleus. In the present study, we tested the hypothesis 1) that RMg plays a role in the ventilatory and thermal responses to hypercapnia, and 2) that RMg serotonergic neurons are involved in these responses. To this end, we microinjected 1) ibotenic acid to promote nonspecific lesioning of neurons in the RMg, or 2) anti-SERT-SAP (an immunotoxin that utilizes a monoclonal antibody to the third extracellular domain of the serotonin reuptake transporter) to specifically kill the serotonergic neurons in the RMg. Hypercapnia caused hyperventilation and hypothermia in all groups. RMg nonspecific lesions elicited a significant reduction of the ventilatory response to hypercapnia due to lower tidal volume (Vt) and respiratory frequency. Rats submitted to specific killing of RMg serotonergic neurons showed no consistent difference in ventilation during air breathing but had a decreased ventilatory response to CO(2) due to lower Vt. The hypercapnia-induced hypothermia was not affected by specific or nonspecific lesions of RMg serotonergic neurons. These data suggest that RMg serotonergic neurons do not participate in the tonic maintenance of ventilation during air breathing but contribute to the ventilatory response to CO(2). Ultimately, this nucleus may not be involved in the thermal responses to CO(2).
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Affiliation(s)
- Mirela B Dias
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil
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Meeusen R, Watson P, Hasegawa H, Roelands B, Piacentini MF. Central fatigue: the serotonin hypothesis and beyond. Sports Med 2007; 36:881-909. [PMID: 17004850 DOI: 10.2165/00007256-200636100-00006] [Citation(s) in RCA: 247] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.
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Affiliation(s)
- Romain Meeusen
- Department Human Physiology and Sportsmedicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium.
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Watson P, Shirreffs SM, Maughan RJ. The effect of acute branched-chain amino acid supplementation on prolonged exercise capacity in a warm environment. Eur J Appl Physiol 2005; 93:306-14. [PMID: 15349784 DOI: 10.1007/s00421-004-1206-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Eight males were recruited to examine the effect of branched-chain amino acid (BCAA) supplementation on exercise capacity in a glycogen-depleted state in a warm environment. Following a exercise and dietary regimen designed to reduce glycogen availability, subjects returned to the laboratory the following morning and remained seated for 2 h, before cycling to volitional exhaustion at 50% VO2 peak in a warm environment [30.0 (0.2) degrees C; mean (SD)]. Four 250 ml aliquots of a 12 g l(-1) BCAA solution or placebo were ingested at 30 min intervals prior to exercise, with an additional 150 ml consumed every 15 min throughout exercise. BCAA ingestion had no effect on exercise capacity [placebo 103.9 (26.9) min; BCAA 111.0 (29.2) min; P = 0.129). No difference in heart rate (P = 0.345), core temperature (P = 0.628), or weighted mean skin temperature (P = 0.114) was apparent between trials. Ingestion of the BCAA solution produced a marked increase in plasma BCAA immediately prior to exercise [+ 1126 (158) micromol l(-1); P < 0.001) with this difference maintained throughout. Consequently, a significant reduction in the plasma concentration ratio of free tryptophan to BCAA was observed during the BCAA trial when compared to the placebo (P < 0.001). Plasma ammonia concentration was significantly elevated during exercise throughout the BCAA trial (P < 0.001), with no change from rest apparent during the placebo trial (P = 0.608). Blood glucose (P = 0.114) and lactate (P = 0.836) concentrations were not different between trials. Ingestion of a BCAA solution prior to, and during, prolonged exercise in glycogen-depleted subjects did not influence exercise capacity in a warm environment.
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Affiliation(s)
- Phillip Watson
- School of Sport and Exercise Sciences, Loughborough University, Leicestershire LE11 3TU, UK
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Ishiwata T, Saito T, Hasegawa H, Yazawa T, Otokawa M, Aihara Y. Changes of body temperature and extracellular serotonin level in the preoptic area and anterior hypothalamus after thermal or serotonergic pharmacological stimulation of freely moving rats. Life Sci 2004; 75:2665-75. [PMID: 15369702 DOI: 10.1016/j.lfs.2004.04.040] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Accepted: 04/29/2004] [Indexed: 11/22/2022]
Abstract
Although many studies has been shown that serotonin (5-HT) in the preoptic area and anterior hypothalamus (PO/AH) is important for regulating body temperature (Tb), the exact role is not established yet due to conflicting results probably related to experimental techniques or conditions such as the use of anesthesia. The purpose of present study was to clarify the role of 5-HT in the PO/AH using the combined methods of telemetry, microdialysis and high performance liquid chromatography (HPLC), with a special emphasis on the regulation of Tb in freely moving rats. Firstly, we measured changes in Tb and levels of extracellular 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the PO/AH during cold (5 degrees C) and heat (35 degrees C) exposure. We also perfused fluoxetine (5-HT re-uptake inhibitor) and 8-hydroxy-2-(Di-n-propylamino)tetralin (8-OH-DPAT: 5-HT1A agonist) into the PO/AH. During both exposures, although Tb changed significantly, no significant changes were noted in extracellular levels of 5-HT and 5-HIAA in the PO/AH. In addition, although perfusion of fluoxetine or 8-OH-DPAT into the PO/AH increased or decreased extracellular 5-HT and 5-HIAA levels in the PO/AH respectively, but Tb did not change at all. Our results suggest that 5-HT in the PO/AH may not mediate acute changes in thermoregulation.
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Affiliation(s)
- Takayuki Ishiwata
- Department of Biology, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan.
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Rodrigues AG, Lima NRV, Coimbra CC, Marubayashi U. Intracerebroventricular physostigmine facilitates heat loss mechanisms in running rats. J Appl Physiol (1985) 2004; 97:333-8. [PMID: 15033963 DOI: 10.1152/japplphysiol.00742.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to evaluate the participation of central cholinergic transmission in the regulation of metabolic rate, core temperature, and heat storage in untrained rats submitted to exercise on a treadmill (20 m/min, 5% inclination) until fatigue. The animals were separated into eight experimental groups, and core temperature or metabolic rate was measured in the rats while they were exercising or while they were at rest after injection of 2 microl of 5 x 10(-3) M physostigmine (Phy) or 0.15 M NaCl solution (Sal) into the lateral cerebral ventricle. Metabolic rate was determined by the indirect calorimetry system, and colonic temperature was recorded as an index of core temperature. In resting animals, Phy induced only a small increase in metabolic rate compared with Sal injection, without having any effect on core temperature. During exercise, the Phy-treated animals showed a lower core heating rate (0.022 +/- 0.003 degrees C/min Phy vs. 0.033 +/- 0.003 degrees C/min Sal; P < 0.02), lower heat storage (285 +/- 37 cal Phy vs. 436 +/- 34 cal Sal; P < 0.02) and lower core temperature at fatigue point than the Sal-treated group (38.5 +/- 0.1 degrees C Phy vs. 39.0 +/- 0.1 degrees C Sal; P < 0.05). However, despite the lower core heating rate, heat storage, and core temperature at fatigue, the Phy-treated rats showed a similar running time compared with the Sal-treated group. We conclude that the activation of the central cholinergic system during exercise increases heat dissipation and attenuates the exercise-induced increase in core temperature without affecting running performance.
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Affiliation(s)
- Alex G Rodrigues
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Minas Gerais, Brazil
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Matuszewich L, Yamamoto BK. Long-lasting effects of chronic stress on DOI-induced hyperthermia in male rats. Psychopharmacology (Berl) 2003; 169:169-75. [PMID: 12768269 DOI: 10.1007/s00213-003-1498-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2002] [Accepted: 03/28/2003] [Indexed: 12/20/2022]
Abstract
RATIONALE Exposure to chronic stress can affect the serotoninergic (5-HT) system and behavioral measures associated with 5-HT. Repeated stress increases 5-HT receptor subtype 2 (5-HT2) mediated behaviors in rodents, such as wet dog shakes and head twitch. OBJECTIVES The current study investigated whether exposure to chronic unpredictable stress would augment 5-HT(2A/C) receptor-mediated hyperthermia. Furthermore, the persistence of these hyperthermic effects was investigated by testing rats up to 60 days after the stress procedure terminated. METHODS For 2 or 10 days, rats were either not stressed (controls) or exposed to chronic unpredictable stress, i.e. two stressors per day of the following: cage rotation, cold exposure, swim, restraint, light cycle manipulations, single housing, and food and water deprivation. After the termination of stress (day 3 or 11), the 5-HT(2A/C) receptor agonist DOI (1.5 mg/kg) or saline, was injected and the rectal temperature of the rats was monitored. In a separate experiment, the 5-HT2 receptor antagonist, LY-53,587, was injected 30 min prior to the injection of DOI or saline. Finally, DOI was injected into rats 8, 30 or 60 days after the 10-day stress procedure ended. RESULTS Rats exposed to 10 days, but not 2 days, of unpredictable stress exhibited higher rectal temperatures following DOI than non-stressed rats. The DOI-induced hyperthermia was attenuated by LY-53,587. The augmentation of DOI-induced hyperthermia in stressed rats persisted when examined 8, 30 and 60 days following the stress procedure. CONCLUSIONS The enhancement of 5-HT receptor function by chronic stress persists even after the environmental stressor is removed. This lasting increase in 5-HT receptor function may have implications for clinical disorders associated with stress, such as depression or post-traumatic stress disorder.
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Affiliation(s)
- Leslie Matuszewich
- Department of Psychiatry, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
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