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Sharma S, Akundi RS. Mitochondria: A Connecting Link in the Major Depressive Disorder Jigsaw. Curr Neuropharmacol 2019; 17:550-562. [PMID: 29512466 PMCID: PMC6712299 DOI: 10.2174/1570159x16666180302120322] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 02/02/2018] [Accepted: 02/27/2018] [Indexed: 12/19/2022] Open
Abstract
Background Depression is a widespread phenomenon with varying degrees of pathology in different patients. Various hypotheses have been proposed for the cause and continuance of depression. Some of these include, but not limited to, the monoamine hypothesis, the neuroendocrine hypothesis, and the more recent epigenetic and inflammatory hypotheses. Objective In this article, we review all the above hypotheses with a focus on the role of mitochondria as the connecting link. Oxidative stress, respiratory activity, mitochondrial dynamics and metabolism are some of the mitochondria-dependent factors which are affected during depression. We also propose exogenous ATP as a contributing factor to depression. Result Literature review shows that pro-inflammatory markers are elevated in depressive individuals. The cause for elevated levels of cytokines in depression is not completely understood. We propose exogenous ATP activates purinergic receptors which in turn increase the levels of various pro-inflammatory factors in the pathophysiology of depression. Conclusion Mitochondria are integral to the function of neurons and undergo dysfunction in major depressive disorder patients. This dysfunction is reflected in all the various hypotheses that have been proposed for depression. Among the newer targets identified, which also involve mitochondria, includes the role of exogenous ATP. The diversity of purinergic receptors, and their differential expression among various individuals in the population, due to genetic and environmental (prenatal) influences, may influence the susceptibility and severity of depression. Identifying specific receptors involved and using patient-specific purinergic receptor antagonist may be an appropriate therapeutic course in the future.
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Affiliation(s)
- Shilpa Sharma
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
| | - Ravi S Akundi
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
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Agnihotri SK, Sun L, Yee BK, Shen R, Akundi RS, Zhi L, Duncan MJ, Cass WA, Büeler H. PINK1 deficiency is associated with increased deficits of adult hippocampal neurogenesis and lowers the threshold for stress-induced depression in mice. Behav Brain Res 2019; 363:161-172. [PMID: 30735759 DOI: 10.1016/j.bbr.2019.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 02/04/2019] [Accepted: 02/04/2019] [Indexed: 12/29/2022]
Abstract
Parkinson's disease (PD) is characterized by motor impairments and several non-motor features, including frequent depression and anxiety. Stress-induced deficits of adult hippocampal neurogenesis (AHN) have been linked with abnormal affective behavior in animals. It has been speculated that AHN defects may contribute to affective symptoms in PD, but this hypothesis remains insufficiently tested in animal models. Mice that lack the PD-linked kinase PINK1 show impaired differentiation of adult-born neurons in the hippocampus. Here, we examined the relationship between AHN deficits and affective behavior in PINK1-/- mice under basal (no stress) conditions and after exposure to chronic stress. PINK1 loss and corticosterone negatively and jointly affected AHN, leading to lower numbers of neural stem cells and newborn neurons in the dentate gyrus of corticosterone-treated PINK1-/- mice. Despite increased basal AHN deficits, PINK1-deficient mice showed normal affective behavior. However, lack of PINK1 sensitized mice to corticosterone-induced behavioral despair in the tail suspension test at a dose where wildtype mice were unaffected. Moreover, after two weeks of chronic restraint stress male PINK1-/- mice displayed increased immobility in the forced swim test, and protein expression of the glucocorticoid receptor in the hippocampus was reduced. Thus, while impaired AHN as such is insufficient to cause affective dysfunction in this PD model, PINK1 deficiency may lower the threshold for chronic stress-induced depression in PD. Finally, PINK1-deficient mice displayed reduced basal voluntary wheel running but normal rotarod performance, a finding whose mechanisms remain to be determined.
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Affiliation(s)
- Sandeep K Agnihotri
- School of Life Science and Technology, Harbin Institute of Technology, 150080 Harbin, China
| | - Liuke Sun
- School of Life Science and Technology, Harbin Institute of Technology, 150080 Harbin, China
| | - Benjamin K Yee
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, China
| | - Ruifang Shen
- School of Life Science and Technology, Harbin Institute of Technology, 150080 Harbin, China
| | - Ravi S Akundi
- Department of Neuroscience, University of Kentucky, Lexington KY 40536, USA
| | - Lianteng Zhi
- Department of Neuroscience, University of Kentucky, Lexington KY 40536, USA
| | - Marilyn J Duncan
- Department of Neuroscience, University of Kentucky, Lexington KY 40536, USA
| | - Wayne A Cass
- Department of Neuroscience, University of Kentucky, Lexington KY 40536, USA
| | - Hansruedi Büeler
- School of Life Science and Technology, Harbin Institute of Technology, 150080 Harbin, China.
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Akundi RS, Zhi L, Sullivan PG, Büeler H. Shared and cell type-specific mitochondrial defects and metabolic adaptations in primary cells from PINK1-deficient mice. NEURODEGENER DIS 2012; 12:136-49. [PMID: 23295771 DOI: 10.1159/000345689] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/07/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mutations in PTEN-induced kinase 1 (PINK1) cause early-onset recessive parkinsonism. PINK1 and Parkin regulate mitochondrial quality control. However, PINK1 ablation in Drosophila and cultured mammalian cell lines affected mitochondrial function/dynamics in opposite ways, confounding the elucidation of the role of PINK1 in these processes. OBJECTIVE We recently generated PINK1-deficient (PINK1-/-) mice and reasoned that primary cells from these mice provide a more physiological substrate to study the role of PINK1 in mammals and to investigate metabolic adaptations and neuron-specific vulnerability in PINK1 deficiency. METHODS AND RESULTS Using real-time measurement of oxygen consumption and extracellular acidification, we show that basal mitochondrial respiration is increased, while maximum respiration and spare respiratory capacity are decreased in PINK1-/- mouse embryonic fibroblasts (MEF), as is the membrane potential. In addition, a Warburg-like effect in PINK1-/- MEF promotes survival that is abrogated by inhibition of glycolysis. Expression of uncoupling protein-2 is decreased in PINK1-/- MEF and the striatum of PINK1-/- mice, possibly increasing the sensitivity to oxidative stress. Mitochondria accumulate in large foci in PINK1-/- MEF, indicative of abnormal mitochondrial dynamics and/or transport. Like in PINK1-/- Drosophila, enlarged/swollen mitochondria accumulate in three different cell types from PINK1-/- mice (MEF, primary cortical neurons and embryonic stem cells). However, mitochondrial enlargement is greatest and most prominent in primary cortical neurons that also develop cristae fragmentation and disintegration. CONCLUSION Our results reveal mechanisms of PINK1-related parkinsonism, show that the function of PINK1 is conserved between Drosophila and mammals when studied in primary cells, and demonstrate that the same PINK1 mutation can affect mitochondrial morphology/degeneration in a cell type-specific manner, suggesting that tissue-/cell-specific metabolic capacity and adaptations determine phenotypes and cellular vulnerability in PINK1-/- mice and cells.
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Affiliation(s)
- Ravi S Akundi
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Ky., USA
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Akundi RS, Zhi L, Büeler H. PINK1 enhances insulin-like growth factor-1-dependent Akt signaling and protection against apoptosis. Neurobiol Dis 2011; 45:469-78. [PMID: 21945539 DOI: 10.1016/j.nbd.2011.08.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/23/2011] [Accepted: 08/26/2011] [Indexed: 12/13/2022] Open
Abstract
Mutations in the PARK6 gene coding for PTEN-induced kinase 1 (PINK1) cause recessive early-onset Parkinsonism. Although PINK1 and Parkin promote the degradation of depolarized mitochondria in cultured cells, little is known about changes in signaling pathways that may additionally contribute to dopamine neuron loss in recessive Parkinsonism. Accumulating evidence implicates impaired Akt cell survival signaling in sporadic and familial PD (PD). IGF-1/Akt signaling inhibits dopamine neuron loss in several animal models of PD and both IGF-1 and insulin are neuroprotective in various settings. Here, we tested whether PINK1 is required for insulin-like growth factor 1 (IGF-1) and insulin dependent phosphorylation of Akt and the regulation of downstream Akt target proteins. Our results show that embryonic fibroblasts from PINK1-deficient mice display significantly reduced Akt phosphorylation in response to both IGF-1 and insulin. Moreover, phosphorylation of glycogen synthase kinase-3β (GSK-3β) and nuclear exclusion of FoxO1 are decreased in IGF-1 treated PINK1-deficient cells. In addition, phosphorylation of ribosomal protein S6 is reduced indicating decreased activity of mitochondrial target of rapamycin (mTOR) in IGF-1 treated PINK1(-/-) cells. Importantly, the protection afforded by IGF-1 against staurosporine-induced metabolic dysfunction and apoptosis is abrogated in PINK1-deficient cells. Moreover, IGF-1-induced Akt phosphorylation is impaired in primary cortical neurons from PINK1-deficient mice. Inhibition of cellular Ser/Thr phosphatases did not increase the amount of phosphorylated Akt in PINK1(-/-) cells, suggesting that components upstream of Akt phosphorylation are compromised in PINK1-deficient cells. Our studies show that PINK1 is required for optimal IGF-1 and insulin dependent Akt signal transduction, and raise the possibility that impaired IGF-1/Akt signaling is involved in PINK1-related Parkinsonism by increasing the vulnerability of dopaminergic neurons to stress-induced cell death.
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Affiliation(s)
- Ravi S Akundi
- Department of Anatomy and Neurobiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
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Akundi RS, Huang Z, Eason J, Pandya JD, Zhi L, Cass WA, Sullivan PG, Büeler H. Increased mitochondrial calcium sensitivity and abnormal expression of innate immunity genes precede dopaminergic defects in Pink1-deficient mice. PLoS One 2011; 6:e16038. [PMID: 21249202 PMCID: PMC3020954 DOI: 10.1371/journal.pone.0016038] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 12/05/2010] [Indexed: 11/24/2022] Open
Abstract
Background PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca2+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1−/− mice. Methods and Findings Purified brain mitochondria of Pink1−/− mice showed impaired Ca2+ storage capacity, resulting in increased Ca2+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1−/− mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1−/− mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1−/− mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1−/− embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1−/− mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting. Conclusions Increased mitochondrial Ca2+ sensitivity and JNK activity are early defects in Pink1−/− mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1−/− mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-κB activation may predispose neurons of Pink1−/− mice to inflammation and injury-induced cell death.
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Affiliation(s)
- Ravi S. Akundi
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Zhenyu Huang
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Joshua Eason
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jignesh D. Pandya
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Lianteng Zhi
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Wayne A. Cass
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Patrick G. Sullivan
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Hansruedi Büeler
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- * E-mail:
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Fiebich BL, Akundi RS, Seidel M, Geyer V, Haus U, Müller W, Stratz T, Candelario‐Jalil E. Expression of 5‐HT3Areceptors in cells of the immune system. Scand J Rheumatol 2009. [DOI: 10.1080/03009740410006952] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Fiebich BL, Akundi RS, Lieb K, Candelario‐Jalil E, Gmeiner D, Haus U, Müller W, Stratz T, Muñoz E. Antiinflammatory effects of 5‐HT3receptor antagonists in lipopolysaccharide‐stimulated primary human monocytes. Scand J Rheumatol 2009. [DOI: 10.1080/03009740410006998] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Candelario-Jalil E, Akundi RS, Bhatia HS, Lieb K, Appel K, Muñoz E, Hüll M, Fiebich BL. Ascorbic acid enhances the inhibitory effect of aspirin on neuronal cyclooxygenase-2-mediated prostaglandin E2 production. J Neuroimmunol 2006; 174:39-51. [PMID: 16529823 DOI: 10.1016/j.jneuroim.2006.01.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 12/22/2005] [Accepted: 01/09/2006] [Indexed: 12/31/2022]
Abstract
Inhibition of neuronal cyclooxygenase-2 (COX-2) and hence prostaglandin E2 (PGE2) synthesis by non-steroidal anti-inflammatory drugs has been suggested to protect neuronal cells in a variety of pathophysiological situations including Alzheimer's disease and ischemic stroke. Ascorbic acid (vitamin C) has also been shown to protect cerebral tissue in a variety of experimental conditions, which has been attributed to its antioxidant capacity. In the present study, we show that ascorbic acid dose-dependently inhibited interleukin-1beta (IL-1beta)-mediated PGE2 synthesis in the human neuronal cell line, SK-N-SH. Furthermore, in combination with aspirin, ascorbic acid augmented the inhibitory effect of aspirin on PGE2 synthesis. However, ascorbic acid had no synergistic effect along with other COX inhibitors (SC-58125 and indomethacin). The inhibition of IL-1beta-mediated PGE2 synthesis by ascorbic acid was not due to the inhibition of the expression of COX-2 or microsomal prostaglandin E synthase (mPGES-1). Rather, ascorbic acid dose-dependently (0.1-100 microM) produced a significant reduction in IL-1beta-mediated production of 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha), a reliable indicator of free radical formation, suggesting that the effects of ascorbic acid on COX-2-mediated PGE2 biosynthesis may be the result of the maintenance of the neuronal redox status since COX activity is known to be enhanced by oxidative stress. Our results provide in vitro evidence that the neuroprotective effects of ascorbic acid may depend, at least in part, on its ability to reduce neuronal COX-2 activity and PGE2 synthesis, owing to its antioxidant properties. Further, these experiments suggest that a combination of aspirin with ascorbic acid constitutes a novel approach to render COX-2 more sensitive to inhibition by aspirin, allowing an anti-inflammatory therapy with lower doses of aspirin, thereby avoiding the side effects of the usually high dose aspirin treatment.
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Affiliation(s)
- Eduardo Candelario-Jalil
- Neurochemistry Research Group, Department of Psychiatry, University of Freiburg Medical School, Hauptstrasse 5, D-79104 Freiburg, Germany
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Fiebich BL, Akundi RS, Biber K, Hamke M, Schmidt C, Butcher RD, van Calker D, Willmroth F. IL-6 expression induced by adenosine A2b receptor stimulation in U373 MG cells depends on p38 mitogen activated kinase and protein kinase C. Neurochem Int 2005; 46:501-12. [PMID: 15769552 DOI: 10.1016/j.neuint.2004.11.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 11/26/2004] [Accepted: 11/29/2004] [Indexed: 02/02/2023]
Abstract
Adenosine binds to a class of G-protein coupled receptors, which are further distinguished as A(1), A(2a), A(2b) and A(3) adenosine receptors. As we have shown earlier, the stable adenosine analogue NECA (N6-(R)-phenylisopropyladenosine) stimulates IL-6 expression in the human astrocytoma cell line U373 MG via the A(2b) receptor. The mechanism by which NECA promotes astrocytic IL-6 expression has not been identified. By using various inhibitors of signal transduction, we found that p38 mitogen-activated protein kinases (MAPK) activation (inhibitor SB202190), but not extracellular signal-regulated kinase (ERK) (PD98059) and c-jun N-terminal kinase (JNK)(SP600125), is essential in the NECA-induced signalling cascade that leads to the increase in IL-6 synthesis in U373 MG cells. Results obtained with protein kinase C (PKC) inhibitors that have different substrate specificities, indicated that the PKC delta and epsilon isoforms are also involved in adenosine receptor A(2b) dependent upregulation of IL-6 expression. This is supported by the fact that NECA induced the activation of PKC delta and epsilon in U373 MG cells.
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Affiliation(s)
- Bernd L Fiebich
- University of Freiburg Medical School, Department of Psychiatry and Psychotherapy, Neurochemistry Research Group, Hauptstrasse 5, D-79104 Freiburg, Germany.
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Fiebich BL, Akundi RS, Seidel M, Geyer V, Haus U, Müller W, Stratz T, Candelario-Jalil E. Expression of 5-HT3A receptors in cells of the immune system. Scand J Rheumatol Suppl 2004; 119:9-11. [PMID: 15515405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
There is evidence from both human and animal research that 5-hydroxytryptamine3 (5-HT3) receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects including the expression of 5-HT3 receptors in cells of the immune system have not yet been investigated in detail. Therefore, we investigated the expression of the 5-HT3A receptor in primary human monocytes, chondrocytes, T-cells, dendritic cells, and synovial tissue. We found that 5-HT3A receptors are expressed in monocytes, chondrocytes, T-cells, and synovial tissue but not in dendritic cells. Our data show that 5-HT3A receptors are widely expressed in cells of the immune system and that they might play an important role in inflammatory events and in the observed antiphlogistic effects of 5-HT3 receptor antagonists.
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Affiliation(s)
- B L Fiebich
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical School, Germany.
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Fiebich BL, Akundi RS, Lieb K, Candelario-Jalil E, Gmeiner D, Haus U, Müller W, Stratz T, Muñoz E. Antiinflammatory effects of 5-HT3 receptor antagonists in lipopolysaccharide-stimulated primary human monocytes. Scand J Rheumatol Suppl 2004; 119:28-32. [PMID: 15515409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
There is evidence from both human and animal research that 5-hydroxytryptamine (5-HT)3 receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects have not yet been investigated in detail. Therefore, the antiinflammatory effects of tropisetron and ondansetron were investigated in human monocytes. In human monocytes, both lipopolysaccharide (LPS)-stimulated tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta secretion were dose-dependently inhibited by tropisetron starting at a concentration of 5 microg/mL and reaching maximal levels at 25 microg/mL (IC50: 32 microg/mL and 12 microg/mL, respectively). LPS-induced IL-6 and PGE2 release was only slightly inhibited at high doses, whereas LPS-induced release of IL-8 and matrix metalloprotease (MMP)-9 was not affected. In conclusion, our data show that the binding of tropisetron to 5-HT3 receptors results in antiinflammatory effects through inhibition of TNF-alpha/IL-1beta, which might explain the antiphlogistic effects of 5-HT3 antagonists.
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Affiliation(s)
- B L Fiebich
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical School, Germany.
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