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Feng Y, Jiang X, Liu W, Lu H. The location, physiology, pathology of hippocampus Melatonin MT 2 receptor and MT 2-selective modulators. Eur J Med Chem 2023; 262:115888. [PMID: 37866336 DOI: 10.1016/j.ejmech.2023.115888] [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: 08/27/2023] [Revised: 10/06/2023] [Accepted: 10/17/2023] [Indexed: 10/24/2023]
Abstract
Melatonin, a neurohormone secreted by the pineal gland and regulated by the suprachiasmatic nucleus (SCN) of the hypothalamus, is synthesized and directly released into the cerebrospinal fluid (CSF) of the third ventricle (3rdv), where it undergoes rapid absorption by surrounding tissues to exert its physiological function. The hippocampus, a vital structure in the limbic system adjacent to the ventricles, plays a pivotal role in emotional response and memory formation. Melatonin MT1 and MT2 receptors are G protein-coupled receptors (GPCRs) that primarily mediate melatonin's receptor-dependent effects. In comparison to the MT1 receptor, the widely expressed MT2 receptor is crucial for mediating melatonin's biological functions within the hippocampus. Specifically, MT2 receptor is implicated in hippocampal synaptic plasticity and memory processes, as well as neurogenesis and axogenesis. Numerous studies have demonstrated the involvement of MT2 receptors in the pathophysiology and pharmacology of Alzheimer's disease, depression, and epilepsy. This review focuses on the anatomical localization of MT2 receptor in the hippocampus, their physiological function in this region, and their signal transduction and pharmacological roles in neurological disorders. Additionally, we conducted a comprehensive review of MT2 receptor ligands used in psychopharmacology and other MT2-selective ligands over recent years. Ultimately, we provide an outlook on future research for selective MT2 receptor drug candidates.
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Affiliation(s)
- Yueqin Feng
- Department of Ultrasound, the First Affiliated Hospital of China Medical University, Shenyang, PR China
| | - Xiaowen Jiang
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, PR China
| | - Wenwu Liu
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, PR China
| | - Hongyuan Lu
- Department of Clinical Pharmacology, China Medical University, Shenyang, PR China.
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2
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Jia S, Guo X, Chen Z, Li S, Liu XA. The roles of the circadian hormone melatonin in drug addiction. Pharmacol Res 2022; 183:106371. [PMID: 35907435 DOI: 10.1016/j.phrs.2022.106371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/19/2022] [Accepted: 07/26/2022] [Indexed: 10/16/2022]
Abstract
Given the devastating social and health consequences of drug addiction and the limitations of current treatments, a new strategy is needed. Circadian system disruptions are frequently associated with drug addiction. Correcting abnormal circadian rhythms and improving sleep quality may thus be beneficial in the treatment of patients with drug addiction. Melatonin, an essential circadian hormone that modulates the biological clock, has anti-inflammatory, analgesic, anti-depressive, and neuroprotective effects via gut microbiota regulation and epigenetic modifications. It has attracted scientists' attention as a potential solution to drug abuse. This review summarized scientific evidence on the roles of melatonin in substance use disorders at the cellular, circuitry, and system levels, and discussed its potential applications as an intervention strategy for drug addiction.
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Affiliation(s)
- Shuhui Jia
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, CAS Key Laboratory of Brain Connectome and Manipulation, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China
| | - Xuantong Guo
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, CAS Key Laboratory of Brain Connectome and Manipulation, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China
| | - Zuxin Chen
- Shenzhen Key Laboratory of Drug Addiction, Shenzhen Neher Neural Plasticity Laboratory, The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Shupeng Li
- State Key Laboratory of Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Xin-An Liu
- Guangdong Provincial Key Laboratory of Brain Connectome and Behavior, CAS Key Laboratory of Brain Connectome and Manipulation, Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China.
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3
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Grasing KW, Burnell K, De A. Biphasic reward effects are characteristic of both lorcaserin and drugs of abuse: implications for treatment of substance use disorders. Behav Pharmacol 2022; 33:238-248. [PMID: 35324488 PMCID: PMC9149059 DOI: 10.1097/fbp.0000000000000672] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Lorcaserin is a modestly selective agonist for 2C serotonin receptors (5-HT2CR). Despite early promising data, it recently failed to facilitate cocaine abstinence in patients and has been compared with dopamine antagonist medications (antipsychotics). Here, we review the effects of both classes on drug reinforcement. In addition to not being effective treatments for cocaine use disorder, both dopamine antagonists and lorcaserin can have biphasic effects on dopamine and reward behavior. Lower doses can cause enhanced drug taking with higher doses causing reductions. This biphasic pattern is shared with certain stimulants, opioids, and sedative-hypnotics, as well as compounds without abuse potential that include agonists for muscarinic and melatonin receptors. Additional factors associated with decreased drug taking include intermittent dosing for dopamine antagonists and use of progressive-ratio schedules for lorcaserin. Clinically relevant doses of lorcaserin were much lower than those that inhibited cocaine-reinforced behavior and can also augment this same behavior in different species. Diminished drug-reinforced behavior only occurred in animals after higher doses that are not suitable for use in patients. In conclusion, drugs of abuse and related compounds often act as biphasic modifiers of reward behavior, especially when evaluated over a broad range of doses. This property may reflect the underlying physiology of the reward system, allowing homeostatic influences on behavior.
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Affiliation(s)
- Ken W Grasing
- Substance Use Research Laboratory, Research Service, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri
- Division of Clinical Pharmacology, Department of Medicine, University of Kansas School of Medicine, Kansas City, Kansas, USA
| | - Kim Burnell
- Substance Use Research Laboratory, Research Service, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri
| | - Alok De
- Substance Use Research Laboratory, Research Service, Kansas City Veterans Affairs Medical Center, Kansas City, Missouri
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Alshehri FS, Alghamdi BS, Hakami AY, Alshehri AA, Althobaiti YS. Melatonin attenuates morphine-induced conditioned place preference in Wistar rats. Brain Behav 2021; 11:e2397. [PMID: 34710287 PMCID: PMC8671767 DOI: 10.1002/brb3.2397] [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: 06/12/2021] [Revised: 08/04/2021] [Accepted: 09/06/2021] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Morphine is the predominantly used drug for postoperative and cancer pain management. However, the abuse potential of morphine is the primary disadvantage of using opioids in pain management. Melatonin is a neurohormone synthesized in the pineal gland and is involved in circadian rhythms in mammals, as well as other physiological functions. Melatonin provenly attenuates alcohol-seeking and relapse behaviors in rats. Therefore, we aimed to investigate the involvement of the melatonergic system in attenuating morphine dependence. MATERIALS AND METHODS Male Wistar rats were divided into three groups: control, morphine, and morphine + melatonin. Animals were habituated for 3 days, and the initial preference was evaluated. Following the initial preference, the control group received the vehicle and was placed for a 45-min session in the assigned chamber every day, alternating between the two chambers, for 8 days. The morphine group received a morphine injection (5 mg/kg, IP) and was placed for a 45-min session in the white chamber, for a total of four sessions. The morphine + melatonin group received the morphine injection (5 mg/kg, IP) for a total of four sessions over an 8-day period. In the posttest session, the control and morphine groups received a vehicle injection 30 min before placement in the conditioned place preference (CPP). The morphine + melatonin group received a single injection of melatonin (50 mg/kg, IP) 30 min before the preference test. RESULTS Statistical analysis revealed that repeated administration of morphine for four sessions produced a significant increase in the CPP score in the morphine group compared to the control group. However, a single melatonin injection administered 30 min before the posttest attenuated morphine-seeking behavior and reduced morphine-induced place preference. CONCLUSION These findings provide novel evidence for the role of the melatonergic system as a potential target in modulating morphine-seeking behavior.
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Affiliation(s)
- Fahad S Alshehri
- Department of Pharmacology and Toxicology, College of Pharmacy, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Badrah S Alghamdi
- Department of Physiology, Neuroscience Unit, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.,Pre-Clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Alqassem Y Hakami
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia.,King Abdullah International Medical Research Center, Jeddah, Saudi Arabia
| | - Abdullah A Alshehri
- Pre-Clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Yusuf S Althobaiti
- Department of Pharmacology and Toxicology, College of Pharmacy, Taif University, P.O. Box 11099, Taif, 21944, Saudi Arabia.,College of Pharmacy, Addiction and Neuroscience Research Unit, Taif University, Taif, 21944, Saudi Arabia
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Su LY, Liu Q, Jiao L, Yao YG. Molecular Mechanism of Neuroprotective Effect of Melatonin on Morphine Addiction and Analgesic Tolerance: an Update. Mol Neurobiol 2021; 58:4628-4638. [PMID: 34148215 DOI: 10.1007/s12035-021-02448-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 06/07/2021] [Indexed: 12/22/2022]
Abstract
Drug addiction is a global health problem and continues to place an enormous financial burden on society. This addiction is characterized by drug dependence sensitization and craving. Morphine has been widely used for pain relief, but chronic administration of morphine causes analgesic tolerance, hyperalgesia, and addiction, all of which limit its clinical usage. Alterations of multiple molecular pathways have been reported to be involved in the development of drug addiction, including mitochondrial dysfunction, excessive oxidative stress and nitric oxide stress, and increased levels of apoptosis, autophagy, and neuroinflammation. Preclinical and clinical studies have shown that the co-administration of melatonin with morphine leads to a reversal of these affected pathways. In addition, murine models have shown that melatonin improves morphine-induced analgesic tolerance and addictive behaviors, such as behavioral sensitization, reward effect, and physical dependence. In this review, we attempt to summarize the recent findings about the beneficial effect and molecular mechanism of melatonin on mitochondrial dysfunction, uncontrolled autophagy, and neuroinflammation in morphine addiction and morphine analgesic tolerance. We propose that melatonin might be a useful supplement in the treatment opiate abuse.
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Affiliation(s)
- Ling-Yan Su
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China. .,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China. .,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China.
| | - Qianjin Liu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China.,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China
| | - Lijin Jiao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China.,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China
| | - Yong-Gang Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China. .,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China. .,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China. .,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
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Akyuz E, Kullu I, Arulsamy A, Shaikh MF. Melatonin as an Antiepileptic Molecule: Therapeutic Implications via Neuroprotective and Inflammatory Mechanisms. ACS Chem Neurosci 2021; 12:1281-1292. [PMID: 33813829 DOI: 10.1021/acschemneuro.1c00083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Epilepsy is a result of unprovoked, uncontrollable, and repetitive outburst of abnormal and excessive electrical discharges, known as seizures, in the neurons. Epilepsy is a devastating neurological condition that affects 70 million people globally. Unfortunately, only two-thirds of epilepsy patients respond to antiepileptic drugs while others become drug resistant and may be more prone to epilepsy comorbidities such as SUDEP. Oxidative stress, mitochondrial dysfunction, imbalance in the excitatory and inhibitory neurotransmitters, and neuroinflammation are some of the common pathologies of neurological disorders and epilepsy. Studies suggests that melatonin, a pineal hormone that governs sleep-wake cycles, may be neuroprotective against neurological disorders and thus may be translated as an antiepileptic as well. Melatonin has been shown to be an antioxidant, antiexcitotoxic, and anti-inflammatory hormone/molecule in neurodegenerative diseases, which may contribute to its antiepileptic and neuroprotective properties in epilepsy as well. In addition, melatonin has evidently been shown to play a regulatory role in the cardiorespiratory system and sleep-wake cycles, which may have positive implications toward epilepsy associated comorbidities, such as SUDEP. However, studies investigating the changes in melatonin release due to epilepsy and melatonin's antiepileptic role have been inconclusive and scarce, respectively. Thus, this comprehensive review aims to summarize and elucidate the potential role of melatonin in the pathogenesis of epilepsy and its comorbidities, in hopes to develop new diagnostic and therapeutic approaches that will improve the lives of epileptic patients, particularly those who are drug resistant.
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Affiliation(s)
- Enes Akyuz
- University of Health Sciences, International Medicine Faculty, Department of Biophysics, Istanbul, Turkey
| | - Irem Kullu
- Medical School, Yozgat Bozok University, 66100 Yozgat, Turkey
| | - Alina Arulsamy
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Selangor, Malaysia
| | - Mohd. Farooq Shaikh
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Selangor, Malaysia
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Wiesner CD, Davoli V, Schürger D, Prehn-Kristensen A, Baving L. Melatonin Secretion during a Short Nap Fosters Subsequent Feedback Learning. Front Hum Neurosci 2018; 11:648. [PMID: 29375345 PMCID: PMC5767728 DOI: 10.3389/fnhum.2017.00648] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/19/2017] [Indexed: 01/11/2023] Open
Abstract
Sleep helps to protect and renew hippocampus-dependent declarative learning. Less is known about forms of learning that mainly engage the dopaminergic reward system. Animal studies showed that exogenous melatonin modulates the responses of the dopaminergic reward system and acts as a neuroprotectant promoting memory. In humans, melatonin is mainly secreted in darkness during evening hours supporting sleep. In this study, we investigate the effects of a short period of daytime sleep (nap) and endogenous melatonin on reward learning. Twenty-seven healthy, adult students took part in an experiment, either taking a 90-min afternoon nap or watching videos (within-subject design). Before and after the sleep vs. wake interval, saliva melatonin levels and reward learning were measured, and in the nap condition, a polysomnogram was obtained. Reward learning was assessed using a two-alternative probabilistic reinforcement-learning task. Sleep itself and subjective arousal or valence had no significant effects on reward learning. However, this study showed for the first time that an afternoon nap can elicit a small but significant melatonin response in about 41% of the participants and that the magnitude of the melatonin response predicts subsequent reward learning. Only in melatonin responders did a short nap improve reward learning. The difference between melatonin-responders and non-responders occurred very early during learning indicating that melatonin might have improved working memory rather than reward learning. Future studies should use paradigms differentiating working memory and reward learning to clarify which aspect of human feedback learning might profit from melatonin.
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Affiliation(s)
- Christian D. Wiesner
- Department of Clinical Psychology and Psychotherapy, Institute of Psychology, Christian-Albrechts-University zu Kiel, Kiel, Germany
| | - Valentia Davoli
- Department of Child and Adolescent Psychiatry and Psychotherapy, School of Medicine, Christian-Albrechts-University zu Kiel, Kiel, Germany
| | - David Schürger
- Department of Child and Adolescent Psychiatry and Psychotherapy, School of Medicine, Christian-Albrechts-University zu Kiel, Kiel, Germany
| | - Alexander Prehn-Kristensen
- Department of Child and Adolescent Psychiatry and Psychotherapy, School of Medicine, Christian-Albrechts-University zu Kiel, Kiel, Germany
| | - Lioba Baving
- Department of Child and Adolescent Psychiatry and Psychotherapy, School of Medicine, Christian-Albrechts-University zu Kiel, Kiel, Germany
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Shin EJ, Chung YH, Le HLT, Jeong JH, Dang DK, Nam Y, Wie MB, Nah SY, Nabeshima YI, Nabeshima T, Kim HC. Melatonin attenuates memory impairment induced by Klotho gene deficiency via interactive signaling between MT2 receptor, ERK, and Nrf2-related antioxidant potential. Int J Neuropsychopharmacol 2015; 18:pyu105. [PMID: 25550330 PMCID: PMC4438546 DOI: 10.1093/ijnp/pyu105] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/29/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND We demonstrated that oxidative stress plays a crucial role in cognitive impairment in klotho mutant mice, a genetic model of aging. Since down-regulation of melatonin due to aging is well documented, we used this genetic model to determine whether the antioxidant property of melatonin affects memory impairment. METHODS First, we examined the effects of melatonin on hippocampal oxidative parameters and the glutathione/oxidized glutathione (GSH/GSSG) ratio and memory dysfunction of klotho mutant mice. Second, we investigated whether a specific melatonin receptor is involved in the melatonin-mediated pharmacological response by application with melatonin receptor antagonists. Third, we examined phospho-extracellular-signal-regulated kinase (ERK) expression, nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, Nrf2 DNA binding activity, and glutamate-cysteine ligase (GCL) mRNA expression. Finally, we examined effects of the ERK inhibitor SL327 in response to antioxidant efficacy and memory enhancement mediated by melatonin. RESULTS Treatment with melatonin resulted in significant attenuations of oxidative damage, a decrease in the GSH/GSSG ratio, and a significant amelioration of memory impairment in this aging model. These effects of melatonin were significantly counteracted by the selective MT2 receptor antagonist 4-P-PDOT. Importantly, 4-P-PDOT or SL327 also counteracted melatonin-mediated attenuation in response to the decreases in phospho-ERK expression, Nrf2 nuclear translocation, Nrf2 DNA-binding activity, and GCL mRNA expression in the hippocampi of klotho mutant mice. SL327 also counteracted the up-regulation of the GSH/GSSG ratio and the memory enhancement mediated by melatonin in klotho mutant mice. CONCLUSIONS Melatonin attenuates oxidative stress and the associated memory impairment induced by klotho deficiency via signaling interaction between the MT2 receptor and ERK- and Nrf2-related antioxidant potential.
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Velarde E, Alonso-Gómez AL, Azpeleta C, Isorna E, De Pedro N, Delgado MJ. Melatonin effects on gut motility are independent of the relaxation mediated by the nitrergic system in the goldfish. Comp Biochem Physiol A Mol Integr Physiol 2011; 159:367-71. [PMID: 21539928 DOI: 10.1016/j.cbpa.2011.01.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/27/2010] [Accepted: 01/17/2011] [Indexed: 11/19/2022]
Abstract
Melatonin is a key neuroendocrine transducer in the circadian organization of vertebrates. However, its role in gastrointestinal physiology has not been explored in depth. In goldfish, a role for melatonin as a modulator of intestinal motility has been reported, whereby it attenuates the cholinergic contraction. The aim of the present work was to investigate this relaxation induced by melatonin in the gut smooth muscle of the goldfish, studying the possible involvement of nitric oxide. An in vitro model of isolated goldfish intestine was used to test the effects on intestinal motility. The addition of melatonin (10 pM-100 μM) to the organ bath relaxed acetylcholine- and serotonin-stimulated gut strips, but no effect was observed on KCl-contracted preparations. The addition of L-NAME (nitric oxide synthase inhibitor) increased the amplitude of the spontaneous slow waves, while sodium nitroprusside (SNP, nitric oxide donor) abolished them. All these results support a role for the nitrergic system in goldfish gut motility. However, neither L-NAME, nor SNP nor the nitric oxide precursor, l-arginine, modified the melatonin relaxing effect. These results highlight the existence of a basal nitrergic tone in the gut of goldfish, where melatonin would exert a calcium-dependent, nitric oxide-independent relaxing effect on serotonergic and cholinergic contraction.
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Affiliation(s)
- Elena Velarde
- Department of Physiology (Animal Physiology II), Faculty of Biology, Complutense University of Madrid, Madrid, Spain
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10
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Li SX, Liu LJ, Jiang WG, Sun LL, Zhou SJ, Le Foll B, Zhang XY, Kosten TR, Lu L. Circadian alteration in neurobiology during protracted opiate withdrawal in rats. J Neurochem 2010; 115:353-62. [PMID: 20738730 DOI: 10.1111/j.1471-4159.2010.06941.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Protracted opiate withdrawal can extend for months of disrupted hormonal circadian rhythms. We examined rodent behaviors and these circadian disturbances in hormone and peptide levels as well as brain clock gene expression during 60 days of protracted withdrawal. Our behavioral tests included open field, elevated plus maze, and sucrose preference tests at 36 h, 10, 30, and 60 days after stopping chronic morphine. At these four assessment points, we collected samples every 4 h for 24 h to examine circadian rhythms in blood hormone and peptide levels and brain expression of rPER1, rPER2, and rPER3 clock genes. Decreased locomotor activity and elevated adrenocorticotropic hormone and melatonin levels persisted for 2 months after morphine withdrawal, but corticosterone was elevated only at 36 h and 10 days after withdrawal. Orexin levels were high at 36 h after withdrawal, but then reversed during protracted withdrawal to abnormally low levels. Beta-endorphin (β-EP) levels showed no differences from normal. However, circadian rhythms were blunted for all of these hormones. Corticosterone, adrenocorticotropic hormone, and orexin blunting persisted at least for 60 days. The blunted circadian rhythm of β-EP and melatonin recovered by day 60, but the peak phase of β-EP was delayed about 8 h. Blunted circadian rhythms and reduced expression of rPER1, rPER2, and rPER3 persisted at least for 60 days in the suprachiasmatic nucleus, prefrontal cortex, nucleus accumbens core, central nucleus of the amygdala, Hippocampus, and ventral tegmental area. Circadian rhythms of rPER1 in the nucleus accumbens shell and basolateral nucleus of the amygdala and of rPER2 in the central nucleus of the amygdala were reversed. Disrupted circadian rhythms of rPER1, rPER 2, and rPER3 expression in reward-related brain circuits and blunted circadian rhythms in peripheral hormones and peptides may play a role in protracted opiate withdrawal and contribute to relapse.
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Affiliation(s)
- Su-xia Li
- National Institute on Drug Dependence, Peking University, Beijing, China.
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Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
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Han J, Xu Y, Yu CX, Shen J, Wei YM. Melatonin reverses the expression of morphine-induced conditioned place preference through its receptors within central nervous system in mice. Eur J Pharmacol 2008; 594:125-31. [DOI: 10.1016/j.ejphar.2008.07.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Revised: 07/10/2008] [Accepted: 07/23/2008] [Indexed: 11/29/2022]
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