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Bernardus Saayman JL, Harvey BH, Wegener G, Brink CB. Sildenafil, alone and in combination with imipramine or escitalopram, display antidepressant-like effects in an adrenocorticotropic hormone-induced (ACTH) rodent model of treatment-resistant depression. Eur J Pharmacol 2024; 969:176434. [PMID: 38458412 DOI: 10.1016/j.ejphar.2024.176434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 03/10/2024]
Abstract
BACKGROUND Major depressive disorder (MDD) represents a challenge with high prevalence and limited effectiveness of existing treatments, particularly in cases of treatment-resistant depression (TRD). Innovative strategies and alternative drug targets are therefore necessary. Sildenafil, a selective phosphodiesterase type 5 (PDE5) inhibitor, is known to exert neuroplastic, anti-inflammatory, and antioxidant properties, and is a promising antidepressant drug candidate. AIM To investigate whether sildenafil monotherapy or in combination with a known antidepressant, can elicit antidepressant-like effects in an adrenocorticotropic hormone (ACTH)-induced rodent model of TRD. METHODS ACTH-naïve and ACTH-treated male Sprague-Dawley (SD) rats received various sub-acute drug treatments, followed by behavioural tests and biochemical analyses conversant with antidepressant actions. RESULTS Sub-chronic ACTH treatment induced significant depressive-like behaviour in rats, evidenced by increased immobility during the forced swim test (FST). Sub-acute sildenafil (10 mg/kg) (SIL-10) (but not SIL-3), and combinations of imipramine (15 mg/kg) (IMI-15) and sildenafil (3 mg/kg) (SIL-3) or escitalopram (15 mg/kg) (ESC-15) and SIL-3, exhibited significant antidepressant-like effects. ACTH treatment significantly elevated hippocampal levels of brain-derived neurotrophic factor (BDNF), serotonin, norepinephrine, kynurenic acid (KYNUA), quinolinic acid (QUINA), and glutathione. The various mono- and combined treatments significantly reversed some of these changes, whereas IMI-15 + SIL-10 significantly increased glutathione disulfide levels. ESC-15 + SIL-3 significantly reduced plasma corticosterone levels. CONCLUSION This study suggests that sildenafil shows promise as a treatment for TRD, either as a stand-alone therapy or in combination with a traditional antidepressant. The neurobiological mechanism underlying the antidepressant-like effects of the different sildenafil mono- and combination therapies reflects a multimodal action and cannot be explained in full by changes in the individually measured biomarker levels.
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Affiliation(s)
- Juandré Lambertus Bernardus Saayman
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen™), Faculty of Health Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Brian Herbert Harvey
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen™), Faculty of Health Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa; South African Medical Research Council Unit on Risk and Resilience on Mental Disorders, Department of Psychiatry and Neuroscience Institute, University of Cape Town, Rondebosch, 7700, South Africa; The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Deakin University, Geelong, Australia
| | - Gregers Wegener
- Translational Neuropsychiatry Unit (TNU), Department of Clinical Medicine, Aarhus University, DK-8200 Aarhus N, Denmark
| | - Christiaan Beyers Brink
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen™), Faculty of Health Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa.
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Majeed M, Nagabhushanam K, Mundkur L. A standardized Ashwagandha root extract alleviates stress, anxiety, and improves quality of life in healthy adults by modulating stress hormones: Results from a randomized, double-blind, placebo-controlled study. Medicine (Baltimore) 2023; 102:e35521. [PMID: 37832082 PMCID: PMC10578737 DOI: 10.1097/md.0000000000035521] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 09/14/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND The coronavirus disease-2019 (COVID-19) pandemic has resulted in a surge in stress, anxiety, and depression worldwide. Ashwagandha, an ayurvedic adaptogen has been traditionally used to manage stress, anxiety, and general well-being. OBJECTIVE We assessed the effect of Ashwagandha root extract (ARE-500 mg) standardized for 2.5% withanolides as per USP protocol with piperine (5 mg of 95% piperine) once daily for 60 days (12.5 mg withanolides/day) to alleviate stress and anxiety in healthy individuals with mild to moderate symptoms. METHODS A randomized, double-blind, placebo-controlled study was conducted for 60 days using ARE (n = 27) and placebo (n = 27) once daily at night at Narayana Institute of Cardiac Sciences, Bangalore, and Vijaya Super Specialty Hospital, Nellore, in India. The objectives of this study were to assess an improvement in perceived stress scale (PSS), generalized anxiety disorder (GAD-7), quality of life (QOL), cognitive scores in the Cambridge Neuropsychological Test Automated Battery (CANTAB), changes in salivary cortisol, urinary serotonin, dopamine, serum levels of nitric oxide (NO), glutathione (GSH) and malondialdehyde (MDA) from baseline to end of the study. Safety was evaluated by laboratory parameters, and by monitoring any incidence of adverse events. RESULTS 54 individuals were randomized and 50 of them completed the study. The PSS, GAD-7, and QOL scores improved significantly in all the participants taking ARE compared to the placebo. The CANTAB analysis revealed a significant improvement in multitasking, concentration, and decision taking time in ARE compared to placebo. ARE was also associated with a greater reduction in the morning salivary cortisol and an increase in urinary serotonin compared to placebo. Serum levels of NO, GSH, and MDA were not significantly different. Biochemical and hematological parameters remained in the normal range in all participants and ARE was well tolerated during the study. CONCLUSION The results of the study suggest that ARE with 2.5% withanolides can effectively improve stress and anxiety by reducing cortisol and increasing serotonin in healthy individuals with mild to moderate symptoms.
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Affiliation(s)
- Muhammed Majeed
- Sami-Sabinsa Group Limited, Peenya Industrial Area, Bangalore, Karnataka, India
- Sabinsa Corporation, East Windsor, NJ, USA
| | | | - Lakshmi Mundkur
- Sami-Sabinsa Group Limited, Peenya Industrial Area, Bangalore, Karnataka, India
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Shen Y, Lv F, Min S, Hao X, Yu J. Ketamine alleviating depressive-like behaviors is associated with regulation of nNOS–CAPON–Dexras1 complex in chronic unpredictable mild stress rats. Transl Neurosci 2022; 13:309-319. [PMID: 36212606 PMCID: PMC9508647 DOI: 10.1515/tnsci-2022-0245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/24/2022] [Accepted: 08/26/2022] [Indexed: 11/17/2022] Open
Abstract
Background A growing number of studies have demonstrated that ketamine induces rapid and sustained antidepressant action. Neuronal nitric oxide synthase (nNOS) signaling has been explored for the treatment of neuropsychiatric disorders for decades. But the effect of ketamine on nNOS signaling is poorly understood. The aim of the present study was to investigate the effect of ketamine on nNOS signaling in a chronic unpredictable mild stress (CUMS) model of depression. Methods Forty-eight rats were randomly divided into four groups: the control group of healthy rats (group C), the healthy rats treated with ketamine 10 mg/kg for 3 days (group CK), the rats model of stress-induced depression group (group D), and the depressed group treated with ketamine 10 mg/kg for 3 days (group DK). The sucrose preference test and open field test were used to assess behavioral changes. Immunohistochemistry, immunofluorescence, and real-time PCR analysis were carried out to measure the expression of nNOS, CAPON, and Dexras1 in the prefrontal cortex (PFC) of the CUMS rats. Results Compared with healthy rats, the total distance traveled, the rearing counts, the sucrose preference percentage (SPP), and CAPON and Dexras1 expression in the PFC significantly decreased, while nNOS expression increased in CUMS rats. After treating with ketamine, the total distance traveled, the rearing counts, the SPP, and CAPON and Dexras1 expression significantly increased, while nNOS expression significantly decreased. Conclusion The results indicated that ketamine improved the depressive behavior of rats, which may be related to the reduced nNOS expression and enhanced CAPON and Dexras1 expression.
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Affiliation(s)
- Yiwei Shen
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University , No. 1 Youyi Rd , Chongqing 400016 , People’s Republic of China
| | - Feng Lv
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University , No. 1 Youyi Rd , Chongqing 400016 , People’s Republic of China
| | - Su Min
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University , No. 1 Youyi Rd , Chongqing 400016 , People’s Republic of China
| | - Xuechao Hao
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University , No. 1 Youyi Rd , Chongqing 400016 , People’s Republic of China
| | - Jian Yu
- Department of Anesthesiology, The First Affiliated Hospital of Chongqing Medical University , No. 1 Youyi Rd , Chongqing 400016 , People’s Republic of China
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Ghasemi M. Nitric oxide: Antidepressant mechanisms and inflammation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2019; 86:121-152. [PMID: 31378250 DOI: 10.1016/bs.apha.2019.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Millions of individuals worldwide suffers from mood disorders, especially major depressive disorder (MDD), which has a high rate of disease burden in society. Although targeting the biogenic amines including serotonin, and norepinephrine have provided invaluable links with the pharmacological treatment of MDD over the last four decades, a growing body of evidence suggest that other biologic systems could contribute to the pathophysiology and treatment of MDD. In this chapter, we highlight the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby treatment of MDD. This has been investigated over the last four decades by showing that (i) levels of NO are altered in patients with major depression; (ii) modulators of NO signaling exert antidepressant effects in patients with MDD or in the animal studies; (iii) NO signaling could be targeted by a variety of antidepressants in animal models of depression; and (iv) NO signaling can potentially modulate the inflammatory pathways that underlie the pathophysiology of MDD. These findings, which hypothesize an NO involvement in MDD, can provide a new insight into novel therapeutic approaches for patients with MDD in the future.
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Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, United States; Department of Neurology, Massachusetts and General Hospital, Boston, MA, United States.
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Berk M, Loo C, Davey CG, Harvey BH. Ketamine and rapidly acting antidepressants: Breaking the speed of sound or light? Aust N Z J Psychiatry 2018; 52:1026-1029. [PMID: 29952212 DOI: 10.1177/0004867418783567] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
There is an urgent need for rapidly acting antidepressants. Current therapies share a delayed onset of action, contrasting with drugs of abuse that have rapid psychotropic effects but cause tolerance and dependence. A key uncertainty is whether there is a finite speed limit imposed by the critical role of homeostatic adaptive mechanisms that underpin the efficacy and onset of available psychotropic agents and whether this is mutable with emerging agents with potential rapid onset, in particular ketamine.
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Affiliation(s)
- Michael Berk
- 1 Deakin University, IMPACT Strategic Research Centre, School of Medicine, Barwon Health, Geelong, VIC, Australia.,2 Centre for Youth Mental Health, Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, VIC, Australia.,3 Department of Psychiatry, The University of Melbourne, Melbourne, VIC, Australia.,4 The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | - Collen Loo
- 5 School of Psychiatry and Black Dog Institute, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Christopher G Davey
- 2 Centre for Youth Mental Health, Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, VIC, Australia.,3 Department of Psychiatry, The University of Melbourne, Melbourne, VIC, Australia
| | - Brian H Harvey
- 6 Division of Pharmacology, School of Pharmacy and Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
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Ghasemi M, Claunch J, Niu K. Pathologic role of nitrergic neurotransmission in mood disorders. Prog Neurobiol 2018; 173:54-87. [PMID: 29890213 DOI: 10.1016/j.pneurobio.2018.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/30/2018] [Accepted: 06/05/2018] [Indexed: 02/08/2023]
Abstract
Mood disorders are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although over the past 40 years the biogenic amine models have provided meaningful links with the clinical phenomena of, and the pharmacological treatments currently employed in, mood disorders, there is still a need to examine the contribution of other systems to the neurobiology and treatment of mood disorders. This article reviews the current literature describing the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby the treatment of mood disorders. The hypothesis has arisen from several observations including (i) altered NO levels in patients with mood disorders; (ii) antidepressant effects of NO signaling blockers in both clinical and pre-clinical studies; (iii) interaction between conventional antidepressants/mood stabilizers and NO signaling modulators in several biochemical and behavioral studies; (iv) biochemical and physiological evidence of interaction between monoaminergic (serotonin, noradrenaline, and dopamine) system and NO signaling; (v) interaction between neurotrophic factors and NO signaling in mood regulation and neuroprotection; and finally (vi) a crucial role for NO signaling in the inflammatory processes involved in pathophysiology of mood disorders. These accumulating lines of evidence have provided a new insight into novel approaches for the treatment of mood disorders.
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Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, 01655, USA.
| | - Joshua Claunch
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Kathy Niu
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
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Repeated treatment with nitric oxide synthase inhibitor attenuates learned helplessness development in rats and increases hippocampal BDNF expression. Acta Neuropsychiatr 2018; 30:127-136. [PMID: 29151391 DOI: 10.1017/neu.2017.28] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Nitric oxide synthase (NOS) inhibitors induce antidepressant-like effects in animal models sensitive to acute drug treatment such as the forced swimming test. However, it is not yet clear if repeated treatment with these drugs is required to induce antidepressant-like effects in preclinical models. OBJECTIVE The aim of this study was to test the effect induced by acute or repeated (7 days) treatment with 7-nitroindazole (7-NI), a preferential inhibitor of neuronal NOS, in rats submitted to the learned helplessness (LH) model. In addition, we aimed at investigating if 7-NI treatment would increase brain-derived neurotrophic factor (BDNF) protein levels in the hippocampus, similarly to the effect of prototype antidepressants. METHODS Animals were submitted to a pre-test (PT) session with inescapable footshocks or habituation (no shocks) to the experimental shuttle box. Six days later they were exposed to a test with escapable footshocks. Independent groups received acute (a single injection after PT or before test) or repeated (once a day for 7 days) treatment with vehicle or 7-NI (30 mg/kg). RESULTS Repeated, but not acute, treatment with 7-NI attenuated LH development. The effect was similar to repeated imipramine treatment. Moreover, in an independent experimental group, only repeated treatment with 7-NI and imipramine increased BDNF protein levels in the hippocampus. CONCLUSION The results suggest the nitrergic system could be a target for the treatment of depressive-like conditions. They also indicate that, similar to the positive control imipramine, the antidepressant-like effects of NOS inhibition could involve an increase in hippocampal BDNF levels.
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Delport A, Harvey BH, Petzer A, Petzer JP. Methylene blue and its analogues as antidepressant compounds. Metab Brain Dis 2017; 32:1357-1382. [PMID: 28762173 DOI: 10.1007/s11011-017-0081-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 07/21/2017] [Indexed: 12/20/2022]
Abstract
Methylene Blue (MB) is considered to have diverse medical applications and is a well-described treatment for methemoglobinemias and ifosfamide-induced encephalopathy. In recent years the focus has shifted to MB as an antimalarial agent and as a potential treatment for neurodegenerative disorders such as Alzheimer's disease. Of interest are reports that MB possesses antidepressant and anxiolytic activity in pre-clinical models and has shown promise in clinical trials for schizophrenia and bipolar disorder. MB is a noteworthy inhibitor of monoamine oxidase A (MAO-A), which is a well-established target for antidepressant action. MB is also recognized as a non-selective inhibitor of nitric oxide synthase (NOS) and guanylate cyclase. Dysfunction of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) cascade is strongly linked to the neurobiology of mood, anxiety and psychosis, while the inhibition of NOS and/or guanylate cyclase has been associated with an antidepressant response. This action of MB may contribute significantly to its psychotropic activity. However, these disorders are also characterised by mitochondrial dysfunction and redox imbalance. By acting as an alternative electron acceptor/donor MB restores mitochondrial function, improves neuronal energy production and inhibits the formation of superoxide, effects that also may contribute to its therapeutic activity. Using MB in depression co-morbid with neurodegenerative disorders, like Alzheimer's and Parkinson's disease, also represents a particularly relevant strategy. By considering their physicochemical and pharmacokinetic properties, analogues of MB may provide therapeutic potential as novel multi-target strategies in the treatment of depression. In addition, low MAO-A active analogues may provide equal or improved response with a lower risk of adverse effects.
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Affiliation(s)
- Anzelle Delport
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
- Division of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Brian H Harvey
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
- Division of Pharmacology, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Anél Petzer
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
- Division of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa
| | - Jacobus P Petzer
- Centre of Excellence for Pharmaceutical Sciences, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa.
- Division of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa.
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Schoeman JC, Steyn SF, Harvey BH, Brink CB. Long-lasting effects of fluoxetine and/or exercise augmentation on bio-behavioural markers of depression in pre-pubertal stress sensitive rats. Behav Brain Res 2017; 323:86-99. [PMID: 28143768 DOI: 10.1016/j.bbr.2017.01.043] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/13/2017] [Accepted: 01/25/2017] [Indexed: 12/25/2022]
Abstract
Juvenile depression is of great concern with only limited treatment currently approved. Delayed onset of action, low remission and high relapse rates, and potential long-lasting consequences further complicates treatment and highlights the need for new treatment options. Studies reporting on long-lasting effects of early-life treatment have reported conflicting results, with the pre-adolescent period mostly overlooked. The anti-depressive effect of exercise, as a possible treatment option or augmentation strategy, is dependent on age and exercise intensity. We investigated the immediate (i.e. postnatal day 35 (PND35)) and lasting (PND60 to PND61) effects of pre-pubertal (PND21 to PND34) fluoxetine and/or exercise on bio-behavioural markers of depression and oxidative stress in stress sensitive Flinders Sensitive Line rats. Low, but not moderate, intensity exercise or 5, but not 10, mg/kg/day fluoxetine displayed anti-depressant-like properties at PND35. Pre-pubertal treatment with 5mg/kg/day fluoxetine or low intensity exercise exerted lasting anti-depressive-like effects into adulthood, whereas the combination of these two treatments did not. Furthermore, the combination of fluoxetine plus exercise reduced hippocampal BDNF levels as compared to exercise alone, which may explain the latter findings. In all treatment groups hippocampal SOD activity was significantly increased at PND61, suggesting an increased anti-oxidant capacity in adulthood. In conclusion, the data confirm the anti-depressant-like properties of both early-life fluoxetine and exercise in a genetic animal model of depression. However, optimal lasting effects of early-life interventions may require adjustment of antidepressant dose and/or exercise intensity to developmental age, and that a combination of antidepressant and exercise may not necessarily be augmentative.
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Affiliation(s)
- Jacobus C Schoeman
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, North West, South Africa
| | - Stephanus F Steyn
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, North West, South Africa
| | - Brian H Harvey
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, North West, South Africa
| | - Christiaan B Brink
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, North West, South Africa.
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Lyu Z, Jackson T. Acute Stressors Reduce Neural Inhibition to Food Cues and Increase Eating Among Binge Eating Disorder Symptomatic Women. Front Behav Neurosci 2016; 10:188. [PMID: 27790097 PMCID: PMC5061815 DOI: 10.3389/fnbeh.2016.00188] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/23/2016] [Indexed: 11/28/2022] Open
Abstract
Stressors can trigger binge-eating but researchers have yet to consider their effects on both neural responses to food cues and food consumption among those at risk. In this experiment, we examined the impact of acute stressors on neural activation to food images and subsequent food consumption within binge-eating disorder (BED) and non-eating disordered control groups. Eighteen women meeting DSM-IV BED criteria and 26 women serving as non-eating disordered controls were randomly assigned to unpleasant stressor (painful cold pressor test (CPT) followed by negative performance feedback) or less unpleasant stressor (non-painful sensory discrimination task followed by positive performance feedback) conditions. Subsequently, they were scanned with functional magnetic resonance imaging (fMRI) while viewing food and neutral images. After the scans, participants completed a self-report battery in an environment conducive to snacking. During exposure to food images, BED-symptomatic women in the unpleasant stressor condition reported more liking of high calorie food images and showed less activation in one inhibitory area, the hippocampus, compared to controls in this condition. BED-symptomatic women exposed to unpleasant stressors also consumed more chocolate than any other group during the post-scan questionnaire completion. Crucially, reduced hippocampal activation to high calorie food images predicted more chocolate consumption following fMRI scans within the entire sample. This experiment provides initial evidence suggesting unpleasant acute stressors contribute to reduced inhibitory region responsiveness in relation to external food cues and later food consumption among BED-symptomatic women.
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Affiliation(s)
- Zhenyong Lyu
- Key Laboratory of Cognition and Personality, Southwest UniversityChongqing, China
| | - Todd Jackson
- Key Laboratory of Cognition and Personality, Southwest UniversityChongqing, China
- Department of Psychology, University of MacauMacau, China
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Brand SJ, Moller M, Harvey BH. A Review of Biomarkers in Mood and Psychotic Disorders: A Dissection of Clinical vs. Preclinical Correlates. Curr Neuropharmacol 2015; 13:324-68. [PMID: 26411964 PMCID: PMC4812797 DOI: 10.2174/1570159x13666150307004545] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 02/04/2015] [Accepted: 03/06/2015] [Indexed: 11/23/2022] Open
Abstract
Despite significant research efforts aimed at understanding the neurobiological underpinnings of mood (depression, bipolar disorder) and psychotic disorders, the diagnosis and evaluation of treatment of these disorders are still based solely on relatively subjective assessment of symptoms as well as psychometric evaluations. Therefore, biological markers aimed at improving the current classification of psychotic and mood-related disorders, and that will enable patients to be stratified on a biological basis into more homogeneous clinically distinct subgroups, are urgently needed. The attainment of this goal can be facilitated by identifying biomarkers that accurately reflect pathophysiologic processes in these disorders. This review postulates that the field of psychotic and mood disorder research has advanced sufficiently to develop biochemical hypotheses of the etiopathology of the particular illness and to target the same for more effective disease modifying therapy. This implies that a "one-size fits all" paradigm in the treatment of psychotic and mood disorders is not a viable approach, but that a customized regime based on individual biological abnormalities would pave the way forward to more effective treatment. In reviewing the clinical and preclinical literature, this paper discusses the most highly regarded pathophysiologic processes in mood and psychotic disorders, thereby providing a scaffold for the selection of suitable biomarkers for future studies in this field, to develope biomarker panels, as well as to improve diagnosis and to customize treatment regimens for better therapeutic outcomes.
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Affiliation(s)
| | | | - Brian H Harvey
- Division of Pharmacology and Center of Excellence for Pharmaceutical Sciences, School of Pharmacy, North-West University, Potchefstroom, South Africa.
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Harvey BH, Slabbert FN. New insights on the antidepressant discontinuation syndrome. Hum Psychopharmacol 2014; 29:503-16. [PMID: 25111000 DOI: 10.1002/hup.2429] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 06/13/2014] [Accepted: 06/23/2014] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Antidepressants are at best 50–55% effective. Non-compliance and the antidepressant discontinuation syndrome (ADS) are causally related yet poorly appreciated. While ADS is associated with most antidepressants, agomelatine seems to be devoid of such risk. We review the neurobiology and clinical consequences of antidepressant non-compliance and the ADS. Agomelatine is presented as a counterpoint to learn more on how ADS risk is determined by pharmacokinetics and pharmacology. DESIGN The relevant literature is reviewed through a MEDLINE search via PubMed, focusing on agomelatine and clinical and preclinical research on ADS. RESULTS Altered serotonergic dysfunction appears central to ADS so that how an antidepressant targets serotonin will determine its relative risk for inducing ADS and thereby affect later treatment outcome. Low ADS risk with agomelatine versus other antidepressants can be ascribed to its unique pharmacokinetic characteristics as well as its distinctive actions on serotonin, including melatonergic, monoaminergic and glutamatergic-nitrergic systems. CONCLUSIONS This review raises awareness of the long-term negative aspects of non-compliance and inappropriate antidepressant discontinuation, and suggests possible approaches to “design-out” a risk for ADS. It reveals intuitive and rational ideas for antidepressant drug design, and provides new thoughts on antidepressant pharmacology, ADS risk and how these affect long-term outcome.
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Affiliation(s)
- Brian H. Harvey
- Centre of Excellence for Pharmaceutical Sciences; School of Pharmacy, North-West University; Potchefstroom South Africa
| | - Francois N. Slabbert
- Medicines Usage Group (MUSA), School of Pharmacy; North-West University; Potchefstroom South Africa
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Peng YL, Liu YN, Liu L, Wang X, Jiang CL, Wang YX. Inducible nitric oxide synthase is involved in the modulation of depressive behaviors induced by unpredictable chronic mild stress. J Neuroinflammation 2012; 9:75. [PMID: 22531370 PMCID: PMC3390904 DOI: 10.1186/1742-2094-9-75] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 04/25/2012] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Experiences and inflammatory mediators are fundamental in the provocation of major depressive disorders (MDDs). We investigated the roles and mechanisms of inducible nitric oxide synthase (iNOS) in stress-induced depression. METHODS We used a depressive-like state mouse model induced by unpredictable chronic mild stress (UCMS). Depressive-like behaviors were evaluated after 4 weeks of UCMS, in the presence and absence of the iNOS inhibitor N-(3-(aminomethyl)benzyl)acetamidine (1400 W) compared with the control group. Immunohistochemistry was used to check the loss of Nissl bodies in cerebral cortex neurons. The levels of iNOS mRNA expression in the cortex and nitrites in the plasma were measured with real-time reverse transcription PCR (RT-PCR) and Griess reagent respectively. RESULTS Results showed that the 4-week UCMS significantly induced depressive-like behaviors, including decreased sucrose preference in a sucrose preference test, increased duration of immobility in a forced swim test, and decreased hole-searching time in a locomotor activity test. Meanwhile, in the locomotor activity test, UCMS had no effect on normal locomotor activities, such as resting time, active time and total travel distance. Furthermore, the levels of iNOS mRNA expression in the cortex and nitrites in the plasma of UCMS-exposed mice were significantly increased compared with that of the control group. Neurons of cerebral cortex in UCMS-exposed mice were shrunken with dark staining, together with loss of Nissl bodies. The above-mentioned stress-related depressive-like behaviors, increase of iNOS mRNA expression in the cortex and nitrites in the plasma, and neuron damage, could be abrogated remarkably by pretreating the mice with an iNOS inhibitor (1400 W). Moreover, neurons with abundant Nissl bodies were significantly increased in the 1400 W + UCMS group. CONCLUSIONS These results support the notion that stress-related NO (derived from iNOS) may contribute to depressive-like behaviors in a mouse model, potentially concurrent with neurodegenerative effects within the cerebral cortex.
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Affiliation(s)
- Yun-Li Peng
- Department of Nautical Medicine, Second Military Medical University, Shanghai, P R China
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Vismari L, Alves GJ, Muscará MN, Palermo-Neto J. A possible role to nitric oxide in the anti-inflammatory effects of amitriptyline. Immunopharmacol Immunotoxicol 2012; 34:578-85. [PMID: 22208160 DOI: 10.3109/08923973.2011.638305] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Antidepressants are reported to display anti-inflammatory effects. Nitric oxide (NO), in turn, has a key role in inflammation. The objective of the present study was to evaluate the effect of amitriptyline co-administered with L-NAME (a NO synthase inhibitor) on certain parameters of acute inflammatory response in rats, as a form to investigate a possible participation of NO in the anti-inflammatory effects of amitriptyline. For this, two animal models were used: carrageenan-induced paw edema and acute peritonitis. In the last one, peritoneal exudate, adhesion molecules expression by peripheral blood leukocytes and serum cytokines levels were evaluated. In a noninflammatory condition, serum levels of nitrates were determined. L-NAME induced a potentiation of the anti-inflammatory effects of amitriptyline (p < 0.05) in the paw edema model; however, these effects were not abrogated when L-NAME was substituted by L-arginine administration. A decrease in both leukocyte concentration and total number of cells in the peritoneal exudate and a reduction in the total serum levels of nitrates were observed with co-administration of L-NAME and amitriptyline (p < 0.05). No significant differences among groups were found concerning the expression of adhesion molecules by peripheral blood leukocytes (p > 0.05). There was a significant decrease on IL-1β and TNF-α serum levels in the experimental groups when compared to the control animals. Together the present results and the literature suggest that the anti-inflammatory effects of amitriptyline may be due to a decrease in NO production. A decrease in IL-1β/TNF-α serum levels may also be implicated in the results observed.
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Affiliation(s)
- Luciana Vismari
- Department of Pathology, São Paulo University, Av. Prof. Dr. Orlando Marques de Paiva, Cidade Universitária, São Paulo, Brazil
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15
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Abstract
The rapid increase in the number of proposed animal models of depression reflects the dissatisfaction with our current state of knowledge on neurobiology of depression and unsuccessful drug development. Results obtained with even the best validated models can be difficult to compare. Because evidence from epidemiological studies suggests that depression occurs in biologically predisposed subjects under the impact of adverse life events, increasing attempts have been made to use the diathesis-stress concept in animal models. In this way, factors underpinning vulnerability to depression have been identified by measuring behavioural traits analogous to facets of human personality, or created by inducing neurochemical lesions. Stressful interventions administered prenatally, in early life or in adulthood have been combined with other vulnerability factors including genetic changes. As a result, several putative animal models of endophenotypes of depression or depression vulnerability have been proposed. Diathesis-stress models may aid in separating adaptive and maladaptive strategies in coping with stress, and understanding the relevant neurobiology. Studies comparing effects of stress on males and females should reveal to which extent the pathogenetic processes leading to depression can be specific to sex/gender.
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Affiliation(s)
- Jaanus Harro
- Unit of Psychophysiology, Department of Psychology, Estonian Centre of Behavioural and Health Sciences, University of Tartu, Estonia.
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Gualda L, Martins G, Müller B, Guimarães F, Oliveira R. 5-HT1A autoreceptor modulation of locomotor activity induced by nitric oxide in the rat dorsal raphe nucleus. Braz J Med Biol Res 2011; 44:332-6. [DOI: 10.1590/s0100-879x2011007500033] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 02/23/2011] [Indexed: 11/22/2022] Open
Affiliation(s)
| | | | - B. Müller
- Universidade Estadual de Maringá, Brasil
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17
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Role of monoamine oxidase, nitric oxide synthase and regional brain monoamines in the antidepressant-like effects of methylene blue and selected structural analogues. Biochem Pharmacol 2010; 80:1580-91. [DOI: 10.1016/j.bcp.2010.07.037] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/29/2010] [Accepted: 07/29/2010] [Indexed: 02/04/2023]
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Mokoena ML, Harvey BH, Oliver DW, Brink CB. Ozone modulates the effects of imipramine on immobility in the forced swim test, and nonspecific parameters of hippocampal oxidative stress in the rat. Metab Brain Dis 2010; 25:125-33. [PMID: 20455016 DOI: 10.1007/s11011-010-9189-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 02/25/2010] [Indexed: 01/07/2023]
Abstract
Depression has been associated with oxidative stress. There is increased awareness of the role of environmental toxins in the development of mood disorders. Ozone, a pro-oxidant and environmental pollutant, has been noted to have central nervous system effects. We investigated the effects of acute and chronic ozone inhalation on the response of imipramine in the forced-swim test (FST) and on biomarkers of oxidative stress in rat hippocampus. Sprague Dawley rats were exposed to 0, 0.25 or 0.7 ppm ozone per inhalation 4 h daily for either 30 days (chronic) or once (acute). Animals were then injected intraperitoneally with imipramine (10 mg/kg) or saline 24, 5 and 1 h before the forced-swim test. Hippocampal superoxide accumulation and lipid peroxidation were measured. Imipramine evoked an antidepressant-like effect independent of acute or chronic ozone exposure. However, 0.7 ppm acute ozone and 0.25 ppm chronic ozone attenuated the antidepressant-like effects of imipramine. The ozone exposures also elevated hippocampal superoxide accumulation and lipid peroxidation. Importantly, imipramine reversed the lipid peroxidation induced by chronic ozone, thereby preventing cellular damage induced by oxidative stress. Ozone exposure presents a feasible model with etiological validity to investigate oxidative stress in depression and antidepressant action.
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Increased stress-evoked nitric oxide signalling in the Flinders sensitive line (FSL) rat: a genetic animal model of depression. Int J Neuropsychopharmacol 2010; 13:461-73. [PMID: 19627650 DOI: 10.1017/s1461145709990241] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Stress engenders the precipitation and progression of affective disorders, while stress-related release of excitatory mediators is implicated in the degenerative pathology observed especially in the hippocampus of patients with severe depression. Nitric oxide (NO) release following stress-evoked N-methyl-d-aspartate (NMDA) receptor activation modulates neurotransmission, cellular memory and neuronal toxicity. We have investigated the Flinders rat (FSL/FRL), a genetic animal model of depression, regarding the response of the hippocampal nitrergic system following exposure to an escapable stress/inescapable stress (ES-IS) paradigm. Hippocampal tissue from naive FSL/FRL rats and those exposed to ES-IS were studied with respect to constitutive nitric oxide synthase (cNOS) activity and neuronal nitric oxide synthase (nNOS) protein levels, as well as transcript expression of upstream regulatory proteins in the NMDA-NO signalling pathway, including NMDAR1, nNOS, CAPON, PIN and PSD95. Within stress-naive animals, no differences in hippocampal cNOS activity and nNOS expression or PIN were evident in FSL and FRL rats, although transcripts for NMDAR1 and CAPON were increased in FSL rats. Within the group of ES-IS animals, we found an increase in total hippocampal cNOS activity, nNOS protein levels and mRNA expression in FSL vs. FRL rats, together with an increase in PSD95 transcripts, and a reduction in PIN. In conclusion, ES-IS enhanced hippocampal cNOS activity in FSL rats, but not FRL rats, confirming the NMDA-NO cascade as an important vulnerability factor in the depressive phenotype of the FSL rat.
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Liebenberg N, Wegener G, Harvey BH, Brink CB. Investigating the role of protein kinase-G in the antidepressant-like response of sildenafil in combination with muscarinic acetylcholine receptor antagonism. Behav Brain Res 2010; 209:137-41. [PMID: 20117144 DOI: 10.1016/j.bbr.2010.01.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 01/21/2010] [Accepted: 01/21/2010] [Indexed: 11/29/2022]
Abstract
The cGMP/PK-G pathway plays a crucial role in neuroprotection and neurotrophin support, and is possibly involved in antidepressant action. Recently we reported on a novel antidepressant-like response following simultaneous administration of sildenafil (phosphodiesterase 5 (PDE5) inhibitor, thereby increasing cGMP levels), and atropine (muscarinic acetylcholine receptor antagonist) in the rat forced swim test (FST). However, it is unclear whether the antidepressant-like activity of sildenafil+atropine is mediated via the activation of PK-G, an important down-stream effector for cGMP, and whether this may target known pathways in antidepressant action. We investigated whether the antidepressant-like response of sildenafil+/-atropine could be reversed by Rp-8-Br-PET-cGMP, a PK-G inhibitor, and also whether a combination of 8-Br-cGMP (PK-G activator)+/-atropine would likewise be active in the FST, and whether this combination could be attenuated by a PK-G inhibitor. 8-Br-cGMP alone, but not sildenafil alone, reduced immobility and selectively increased swimming in the FST. The antidepressant-like action of sildenafil was only evident following co-administration of atropine, and selectively increased climbing behaviour. Importantly, PK-G inhibition prevented the antidepressant-like effects of both 8-Br-cGMP and the sildenafil/atropine combination. These results confirm cholinergic-cGMP-PK-G interactions in the antidepressant-like effects of sildenafil, putatively acting via noradrenergic mechanisms, whereas direct PK-G activation induces antidepressant-like effects that are associated with enhancement of serotonergic neurotransmission.
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Affiliation(s)
- Nico Liebenberg
- School of Pharmacy, North-West University, Potchefstroom, South Africa
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21
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Bhatnagar M, Sharma D, Salvi M. Neuroprotective effects of Withania somnifera dunal.: A possible mechanism. Neurochem Res 2009; 34:1975-83. [PMID: 19444606 DOI: 10.1007/s11064-009-9987-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2009] [Accepted: 04/25/2009] [Indexed: 10/20/2022]
Abstract
Present study was carried out to understand the possible mechanism of neuroprotective action of the root extract of Withania somnifera Dunal (WS). The study is focused on WS mediated inhibition of nitric oxide production, which is known to mediate neurodegeneration during stress. Adult mice (28 +/- 5 g) were exposed to restraint stress for 30 days. Activity of NADPH diaphorase (NADPH-d) and factors (Acetylcholine, serotonin and corticosterone), which regulates NADPH-d activity were studied. Treatment with WS extract for 30 days during stress, significantly reversed the stress induced NADPH-d activation. Observations suggest that inhibition of NADPH-d by WS is not a direct effect of extract on NADPH-d, instead it inhibits via suppressing corticosterone release and activating cholineacetyltransferase, which in turn increase serotonin level in hippocampus to inhibit NADPH-d. Together, the main mechanism underlying the neuroprotective effects of WS can be attributed to its role in the down regulation of nNOS and neurochemical alterations of specific neurotransmitter systems. These observations thus suggest that WS root extract could be developed as a potential preventive or therapeutic drug for stress induced neurological disorders.
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22
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Zhou L, Zhu DY. Neuronal nitric oxide synthase: structure, subcellular localization, regulation, and clinical implications. Nitric Oxide 2009; 20:223-30. [PMID: 19298861 DOI: 10.1016/j.niox.2009.03.001] [Citation(s) in RCA: 445] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 02/23/2009] [Accepted: 03/10/2009] [Indexed: 01/09/2023]
Abstract
Nitric oxide (NO), a free gaseous signaling molecule, is involved in the regulation of the cardiovascular, nervous and immune system. The neurotransmitter function of nitric oxide is dependent on dynamic regulation of its biosynthetic enzyme, nitric oxide synthase (NOS). There are three types of NOS, neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS). Of the three NOS, we focus on nNOS in the present review. Brain nNOS exists in particulate and soluble forms and the differential subcellular localization of nNOS may contribute to its diverse functions. Proteins bearing PDZ domains can interact directly with the PDZ domain of nNOS, influencing the subcellular distribution and/or activity of the enzyme. During the past several years, an increasing number of reports have demonstrated the importance of nNOS in a variety of synaptic signaling events. nNOS has been implicated in modulating physiological functions such as learning, memory, and neurogenesis, as well as being involved in a number of human diseases. In this review we concentrate on recent findings regarding the structural features, subcellular localization and factors regulating nNOS function. In particular, we conclude with a section discussing the role of nNOS in a wide range of physiological and pathological conditions.
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Affiliation(s)
- Li Zhou
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, China
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23
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Abstract
Metabolic encephalopathy is an acute disturbance in cellular metabolism in the brain evoked by conditions of hypoxia, hypoglycaemia, oxidative stress and/or inflammation. It usually develops acutely or subacutely and is reversible if the systemic disorder is treated. If left untreated, however, metabolic encephalopathy may result in secondary structural damage to the brain. Most encephalopathies are present with neuropsychiatric symptoms, one in particular being depression. However, mood disorders are often co-morbid with cardiovascular, liver, kidney and endocrine disorders, while increasing evidence concurs that depression involves inflammatory and neurodegenerative processes. This would suggest that metabolic disturbances resembling encephalopathy may underscore the basic neuropathology of depression at a far deeper level than currently realized. Viewing depression as a form of encephalopathy, and exploiting knowledge gleaned from our understanding of the neurochemistry and treatment of metabolic encephalopathy, may assist in our understanding of the neurobiology of depression, but also in realizing new ideas in the pharmacotherapy of mood disorders.
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Affiliation(s)
- Brian H Harvey
- Unit for Drug Research and Development, Division of Pharmacology, School of Pharmacy, North-West University, Potchefstroom, South Africa.
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24
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Oliveira R, Guimarães F, Deakin J. Expression of neuronal nitric oxide synthase in the hippocampal formation in affective disorders. Braz J Med Biol Res 2008; 41:333-41. [DOI: 10.1590/s0100-879x2008000400012] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 03/04/2008] [Indexed: 05/25/2023] Open
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25
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Brink CB, Clapton JD, Eagar BE, Harvey BH. Appearance of antidepressant-like effect by sildenafil in rats after central muscarinic receptor blockade: evidence from behavioural and neuro-receptor studies. J Neural Transm (Vienna) 2007; 115:117-25. [PMID: 17823768 DOI: 10.1007/s00702-007-0806-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 08/22/2007] [Indexed: 12/24/2022]
Abstract
The phosphodiesterase (PDE) 5 inhibitor sildenafil has been shown to display psychotropic actions in humans and animals, and has been used for the treatment of antidepressant-associated erectile dysfunction. However, its effects on the neurobiology of depression are unknown. Nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) inhibition is anti-depressant in animals, and increasing cGMP with sildenafil is anxiogenic in rodents. Substantial cholinergic-nitrergic interaction exists in the brain, while sildenafil shows modulatory actions on cholinergic transmission. Depression is also associated with increased cholinergic drive. Here we report that sildenafil increases muscarinic acetylcholine receptor (mAChR) signaling in human neuroblastoma cells. We also show that fluoxetine (20 mg/kg/day x 7 days), as well as a combination of sildenafil (10 mg/kg/day x 7 days) plus the antimuscarinic atropine (1 mg/kg/day x 7 days) demonstrates significant, comparable antidepressant-like effects in the rat forced swim test (FST) and also reduces cortical beta-adrenergic receptor (beta-AR) density, while sildenafil or atropine alone did not. Importantly, sildenafil did not modify fluoxetine's response. Sildenafil thus demonstrates antidepressant-like effects but only after central muscarinic receptor blockade, providing evidence for cholinergic-nitrergic interactions in the neurobiology of depression.
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Affiliation(s)
- C B Brink
- Unit for Drug Research and Development, Division of Pharmacology, North-West University (PUK), Potchefstroom, South Africa.
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