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von Bohlen Und Halbach O. Neurotrophic Factors and Dendritic Spines. ADVANCES IN NEUROBIOLOGY 2023; 34:223-254. [PMID: 37962797 DOI: 10.1007/978-3-031-36159-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Dendritic spines are highly dynamic structures that play important roles in neuronal plasticity. The morphologies and the numbers of dendritic spines are highly variable, and this diversity is correlated with the different morphological and physiological features of this neuronal compartment. Dendritic spines can change their morphology and number rapidly, allowing them to adapt to plastic changes. Neurotrophic factors play important roles in the brain during development. However, these factors are also necessary for a variety of processes in the postnatal brain. Neurotrophic factors, especially members of the neurotrophin family and the ephrin family, are involved in the modulation of long-lasting effects induced by neuronal plasticity by acting on dendritic spines, either directly or indirectly. Thereby, the neurotrophic factors play important roles in processes attributed, for example, to learning and memory.
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Rapamycin Attenuates Anxiety and Depressive Behavior Induced by Helicobacter pylori in Association with Reduced Circulating Levels of Ghrelin. Neural Plast 2022; 2022:2847672. [PMID: 35677839 PMCID: PMC9170403 DOI: 10.1155/2022/2847672] [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: 12/03/2021] [Revised: 04/08/2022] [Accepted: 05/04/2022] [Indexed: 11/17/2022] Open
Abstract
Background. Helicobacter pylori (H. pylori) infection is closely associated with depression and development of neuroinflammation. The aim of this study is to explore the relationship between H. pylori, depression, and circulating levels of ghrelin. Methods. Mice were randomly divided into three groups: healthy control group (gavaged sterile saline and injected with saline,
); H. pylori+saline group (gavaged H. pylori and injected with saline,
); and H. pylori+rapa group (gavaged H. pylori and injected with rapamycin,
). Open field test (OFT), sucrose preference test (SPT), forced swim test (FST), and tail suspension test (TST) were used for anxiety and depressive behavior test. Western blotting was utilized to assess mTOR, p-mTOR, and GSMD expression, and serum ghrelin levels were estimated using ELISA. Results. In the OFT, the control mice moved more and exhibited a increase in crossing number relative to the H. pylori+saline mice (all
). Increased quantity of fecal boli can be indicative of increased anxiety and emotionality of the subject animal. H. pylori+saline mice exhibited an increase in fecal boli when compared to control mice and H. pylori+rapa mice (
). H. pylori infected mice decreasing the expression of ghrelin. The protein levels of p-mTOR/mTOR in the gastric antrum mTOR signaling activation and low-level ghrelin in H. pylori-infect mice compared to those in control mice (all P <0.001). Compared with single H. pylori infection, mTOR inhibitors increased the ghrelin secretion of H. pylori infection to a certain extent (
). The protein levels of GSDMD expression significantly increase in hippocampus of H. pylori-infected mice (
). Rapamycin treatment inhibited expression of GSDMD in H. pylori-infected mice (
). Conclusions. H. pylori infection is associated with increased expression of mTOR and decreased circulating levels of ghrelin. Elevated pyroptosis in the brain and anxiety- and depressed-like behaviors occur when ghrelin levels are suppressed.
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Peris-Sampedro F, Le May MV, Stoltenborg I, Schéle E, Dickson SL. A skeleton in the cupboard in ghrelin research: Where are the skinny dwarfs? J Neuroendocrinol 2021; 33:e13025. [PMID: 34427011 DOI: 10.1111/jne.13025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/09/2021] [Accepted: 08/05/2021] [Indexed: 12/15/2022]
Abstract
Based on studies delivering ghrelin or ghrelin receptor agonists, we have learned a great deal about the importance of the brain ghrelin signalling system for a wide range of physiological processes that include feeding behaviours, growth hormone secretion and glucose homeostasis. Because these processes can be considered as essential to life, the question arises as to why mouse models of depleted ghrelin signalling are not all skinny dwarfs with a host of behavioural and metabolic problems. Here, we provide a systematic detailed review of the phenotype of mice with deficient ghrelin signalling to help better understand the relevance and importance of the brain ghrelin signalling system, with a particular emphasis on those questions that remain unanswered.
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Affiliation(s)
- Fiona Peris-Sampedro
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Marie V Le May
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Iris Stoltenborg
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Schéle
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Suzanne L Dickson
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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Seitz BM, Tomiyama AJ, Blaisdell AP. Eating behavior as a new frontier in memory research. Neurosci Biobehav Rev 2021; 127:795-807. [PMID: 34087276 DOI: 10.1016/j.neubiorev.2021.05.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/15/2021] [Accepted: 05/26/2021] [Indexed: 02/06/2023]
Abstract
The study of memory is commonly associated with neuroscience, aging, education, and eyewitness testimony. Here we discuss how eating behavior is also heavily intertwined-and yet considerably understudied in its relation to memory processes. Both are influenced by similar neuroendocrine signals (e.g., leptin and ghrelin) and are dependent on hippocampal functions. While learning processes have long been implicated in influencing eating behavior, recent research has shown how memory of recent eating modulates future consumption. In humans, obesity is associated with impaired memory performance, and in rodents, dietary-induced obesity causes rapid decrements to memory. Lesions to the hippocampus disrupt memory but also induce obesity, highlighting a cyclic relationship between obesity and memory impairment. Enhancing memory of eating has been shown to reduce future eating and yet, little is known about what influences memory of eating or how memory of eating differs from memory for other behaviors. We discuss recent advancements in these areas and highlight fruitful research pursuits afforded by combining the study of memory with the study of eating behavior.
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Xiao X, Bi M, Jiao Q, Chen X, Du X, Jiang H. A new understanding of GHSR1a--independent of ghrelin activation. Ageing Res Rev 2020; 64:101187. [PMID: 33007437 DOI: 10.1016/j.arr.2020.101187] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/13/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022]
Abstract
Growth hormone secretagogue receptor 1a (GHSR1a), a member of the G protein-coupled receptor (GPCR) family, is a functional receptor of ghrelin. The expression levels and activities of GHSR1a are affected by various factors. In past years, it has been found that the ghrelin-GHSR1a system can perform biological functions such as anti-inflammation, anti-apoptosis, and anti-oxidative stress. In addition to mediating the effect of ghrelin, GHSR1a also has abnormally high constitutive activity; that is, it can still transmit intracellular signals without activation of the ghrelin ligand. This constitutive activity affects brain functions, growth and development of the body; therefore, it has profound impacts on neurodegenerative diseases and some other age-related diseases. In addition, GHSR1a can also form homodimers or heterodimers with other GPCRs, affecting the release of neurotransmitters, appetite regulation, cell proliferation and insulin release. Therefore, further understanding of the constitutive activities and dimerization of GHSR1a will enable us to better clarify the characteristics of GHSR1a and provide more therapeutic targets for drug development. Here, we focus on the roles of GHSR1a in various biological functions and provide a comprehensive summary of the current research on GHSR1a to provide broader therapeutic prospects for age-related disease treatment.
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Affiliation(s)
- Xue Xiao
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Mingxia Bi
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Qian Jiao
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xi Chen
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xixun Du
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China.
| | - Hong Jiang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, School of Basic Medicine, Qingdao University, Qingdao, China.
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Su M, Yan M, Gong Y. Ghrelin fiber projections from the hypothalamic arcuate nucleus into the dorsal vagal complex and the regulation of glycolipid metabolism. Neuropeptides 2019; 78:101972. [PMID: 31610887 DOI: 10.1016/j.npep.2019.101972] [Citation(s) in RCA: 5] [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: 02/20/2019] [Revised: 09/11/2019] [Accepted: 09/14/2019] [Indexed: 12/23/2022]
Abstract
OBJECTIVES This study aimed to explore the involvement of the ghrelin pathway from the arcuate nucleus (ARC) to the dorsal vagal complex (DVC) and to determine its role in the regulation of glycolipid metabolism. METHODS The protein and mRNA expression of ghrelin and growth hormone (GH) secretagogue receptor type 1a (GHSR-1a) were measured using immunohistochemistry and the polymerase chain reaction (PCR) method, respectively. Ghrelin fiber projections arising from the ARC and projecting into the DVC were investigated using retrograde tracing, combined with fluorescence immunohistochemical staining. The effects of electrical stimulation (ES) of the ARC on ghrelin-responsive, glucose-sensitive DVC neurons, glycolipid metabolism, and liver lipid enzymes were determined using electrical physiological method, biochemical analysis, quantitative real-time PCR (qRT-PCR) and Western blot analysis. RESULTS GHSR-1a was expressed in the DVC neurons. Ghrelin fibers originating from the ARC projected into the DVC. ES of the ARC-activated the ghrelin-responsive glucose-excited (GE) and glucose-inhibited (GI) neurons in the DVC. ES of the ARC significantly elevated the serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and glucose levels; it reduced the serum high-density lipoprotein (HDLC) and insulin levels. Moreover, ES of the ARC increased liver acetyl-CoA carboxylase-1 (ACC-1) and decreased carnitine palmitoyltransferase-1 (CPT-1) expression, resulting in lipid accumulation in the liver. All the aforementioned effects were partially blocked by pretreatment with the ghrelin receptor antagonist [D-Lys-3]-GHRP-6 in the DVC and were reduced by vagotomy. ES of the ARC increased agouti-related protein (AgRP)/neuropeptide Y (NPY) expression in the ARC and ghrelin expression in the DVC. CONCLUSION Ghrelin fiber projections arising from the ARC and projecting into the DVC play a role in the regulation of afferent glucose metabolism and glycolipid metabolism via the ghrelin receptor GHSR-1a in the DVC.
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Affiliation(s)
- Manqing Su
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Meixing Yan
- Qingdao Women and Children's Hospital, Qingdao 266042, China
| | - Yanling Gong
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
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Huang HJ, Chen XR, Han QQ, Wang J, Pilot A, Yu R, Liu Q, Li B, Wu GC, Wang YQ, Yu J. The protective effects of Ghrelin/GHSR on hippocampal neurogenesis in CUMS mice. Neuropharmacology 2019; 155:31-43. [PMID: 31103617 DOI: 10.1016/j.neuropharm.2019.05.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 04/27/2019] [Accepted: 05/12/2019] [Indexed: 12/18/2022]
Abstract
Ghrelin is an orexigenic hormone that also plays an important role in mood disorders. Our previous studies demonstrated that ghrelin administration could protect against depression-like behaviors of chronic unpredictable mild stress (CUMS) in rodents. However, the mechanism related to the effect of ghrelin on CUMS mice has yet to be revealed. This article shows that ghrelin (5 nmol/kg/day for 2 weeks, i.p.) decreased depression-like behaviors induced by CUMS and increased hippocampal integrity (neurogenesis and spine density) measured via Ki67, 5-bromo-2-deoxyuridine (BrdU), doublecortin (DCX) labeling and Golgi-cox staining, which were decreased under CUMS. The behavioral phenotypes of Growth hormone secretagogue receptor (Ghsr)-null and wild type (WT) mice were evaluated under no stress condition and after CUMS exposure to determine the effect of Ghsr knockout on the behavioral phenotypes and stress susceptibility of mice. Ghsr-null mice exhibited depression-like behaviors under no stress condition. CUMS induced similar depression- and anxiety-like behavioral manifestations in both Ghsr-null and WT mice. A similar pattern of behavioral changes was observed after hippocampal GHSR knockdown. Additionally, both Ghsr knockout as well as CUMS exhibited deleterious effects on neurogenesis and spine density in the dentate gyrus (DG). Besides, CCK8 assay and 5-Ethynyl-2'-deoxyuridine (EdU) incorporation assay showed that ghrelin has a proliferative effect on primary cultured hippocampal neural stem cells (NSCs) and this proliferation was blocked by D-Lys3-GHRP-6 (DLS, the antagonist of GHSR, 100 μM) pretreatment. Ghrelin-induced proliferation is associated with the inhibition of G1 arrest, and this inhibition was blocked by LY294002 (specific inhibitor of PI3K, 20 μM). Furthermore, the in vivo data displayed that LY294002 (50 nmol, i.c.v.) can significantly block the antidepressant-like action of exogenous ghrelin treatment. All these results suggest that ghrelin/GHSR signaling maintains the integrity of hippocampus and has an inherent neuroprotective effect whether facing stress or not.
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Affiliation(s)
- Hui-Jie Huang
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Xiao-Rong Chen
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Qiu-Qin Han
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Shanghai University of Medicine and Health Sciences, Shanghai, 201318, China
| | - Jing Wang
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Adam Pilot
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Rui Yu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Qiong Liu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai, 200032, China
| | - Bing Li
- Center Laboratories, Jinshan Hospital of Fudan University, Shanghai, 201508, China
| | - Gen-Cheng Wu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Yan-Qing Wang
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Jin Yu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
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Suarez AN, Noble EE, Kanoski SE. Regulation of Memory Function by Feeding-Relevant Biological Systems: Following the Breadcrumbs to the Hippocampus. Front Mol Neurosci 2019; 12:101. [PMID: 31057368 PMCID: PMC6482164 DOI: 10.3389/fnmol.2019.00101] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/03/2019] [Indexed: 12/15/2022] Open
Abstract
The hippocampus (HPC) controls fundamental learning and memory processes, including memory for visuospatial navigation (spatial memory) and flexible memory for facts and autobiographical events (declarative memory). Emerging evidence reveals that hippocampal-dependent memory function is regulated by various peripheral biological systems that are traditionally known for their roles in appetite and body weight regulation. Here, we argue that these effects are consistent with a framework that it is evolutionarily advantageous to encode and recall critical features surrounding feeding behavior, including the spatial location of a food source, social factors, post-absorptive processing, and other episodic elements of a meal. We review evidence that gut-to-brain communication from the vagus nerve and from feeding-relevant endocrine systems, including ghrelin, insulin, leptin, and glucagon-like peptide-1 (GLP-1), promote hippocampal-dependent spatial and declarative memory via neurotrophic and neurogenic mechanisms. The collective literature reviewed herein supports a model in which various stages of feeding behavior and hippocampal-dependent memory function are closely linked.
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Affiliation(s)
- Andrea N Suarez
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Emily E Noble
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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Martínez Damonte V, Rodríguez SS, Raingo J. Growth hormone secretagogue receptor constitutive activity impairs voltage-gated calcium channel-dependent inhibitory neurotransmission in hippocampal neurons. J Physiol 2018; 596:5415-5428. [PMID: 30199095 DOI: 10.1113/jp276256] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 09/06/2018] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Presynaptic CaV 2 voltage-gated calcium channels link action potentials arriving at the presynaptic terminal to neurotransmitter release. Hence, their regulation is essential to fine tune brain circuitry. CaV 2 channels are highly sensitive to G protein-coupled receptor (GPCR) modulation. Our previous data indicated that growth hormone secretagogue receptor (GHSR) constitutive activity impairs CaV 2 channels by decreasing their surface density. We present compelling support for the impact of CaV 2.2 channel inhibition by agonist-independent GHSR activity exclusively on GABA release in hippocampal cultures. We found that this selectivity arises from a high reliance of GABA release on CaV 2.2 rather than on CaV 2.1 channels. Our data provide new information on the effects of the ghrelin-GHSR system on synaptic transmission, suggesting a putative physiological role of the constitutive signalling of a GPCR that is expressed at high levels in brain areas with restricted access to its natural agonist. ABSTRACT Growth hormone secretagogue receptor (GHSR) displays high constitutive activity, independent of its endogenous ligand, ghrelin. Unlike ghrelin-induced GHSR activity, the physiological role of GHSR constitutive activity and the mechanisms that underlie GHSR neuronal modulation remain elusive. We previously demonstrated that GHSR constitutive activity modulates presynaptic CaV 2 voltage-gated calcium channels. Here we postulate that GHSR constitutive activity-mediated modulation of CaV 2 channels could be relevant in the hippocampus since this brain area has high GHSR expression but restricted access to ghrelin. We performed whole-cell patch-clamp in hippocampal primary cultures from E16- to E18-day-old C57BL6 wild-type and GHSR-deficient mice after manipulating GHSR expression with lentiviral transduction. We found that GHSR constitutive activity impairs CaV 2.1 and CaV 2.2 native calcium currents and that CaV 2.2 basal impairment leads to a decrease in GABA but not glutamate release. We postulated that this selective effect is related to a higher CaV 2.2 over CaV 2.1 contribution to GABA release (∼40% for CaV 2.2 in wild-type vs. ∼20% in wild-type GHSR-overexpressing cultures). This effect of GHSR constitutive activity is conserved in hippocampal brain slices, where GHSR constitutive activity reduces local GABAergic transmission of the granule cell layer (intra-granule cell inhibitory postsynaptic current (IPSC) size ∼-67 pA in wild-type vs. ∼-100 pA in GHSR-deficient mice), whereas the glutamatergic output from the dentate gyrus to CA3 remains unchanged. In summary, we found that GHSR constitutive activity impairs IPSCs both in hippocampal primary cultures and in brain slices through a CaV 2-dependent mechanism without affecting glutamatergic transmission.
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Affiliation(s)
- Valentina Martínez Damonte
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
| | - Silvia Susana Rodríguez
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
| | - Jesica Raingo
- Multidisciplinary Institute of Cell Biology (IMBICE), National Council of Science and Technology (CONICET), Buenos Aires Comision of Science (CIC) and La Plata University (UNLP), La Plata, Argentina
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Seminara RS, Jeet C, Biswas S, Kanwal B, Iftikhar W, Sakibuzzaman M, Rutkofsky IH. The Neurocognitive Effects of Ghrelin-induced Signaling on the Hippocampus: A Promising Approach to Alzheimer's Disease. Cureus 2018; 10:e3285. [PMID: 30443455 PMCID: PMC6235652 DOI: 10.7759/cureus.3285] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 09/11/2018] [Indexed: 12/17/2022] Open
Abstract
The communication between the gastrointestinal tract and the central nervous system (CNS) allows for certain peptide hormones to influence neurocognitive function. Ghrelin, also known as the 'hunger hormone,' has the unique ability to enter the CNS and interact with the growth hormone secretagogue receptor (GHS-R) within the hippocampus. Upon interaction with ghrelin, a conformational change in the receptor causes an increase in transcription factors to foster a wide array of physiologic changes in response to caloric deprivation. With the GHS-R in a relatively high concentration within the hippocampus, ghrelin can promote memory, spatial, learning, and behavioral effects. In fact, ghrelin appears to also have a neuroprotective and neuromodulatory response once active within the hippocampal dentate gyrus. Through the GHS-R, higher levels of ghrelin may alter cognitive circuitry and offer a possible link to the treatment of some pathologies implicated in neurological dysfunction. Alzheimer's disease (AD) is already becoming a significant target for ghrelin neuroreceptor therapy. In such experimental models, ghrelin has been shown to combat this degenerative process by eliciting an ameliorative and regenerative response. Although trials and research are still ongoing, further studies are indicated as early research into this adjuvant therapy is promising. The research team explored the effects of ghrelin by reviewing the downstream signaling modifications of ghrelin's interaction with a specific CNS receptor, the GHS-R. Although the GHS-R is found in multiple locations within the CNS, the team investigated the role of the GHS-R within the hippocampus to focus solely on the neurocognitive implications of ghrelin. The team noted which signaling pathways in particular that ghrelin initiated and used this approach to determine whether ghrelin may have any therapeutic benefits. The team explored the possible therapeutic indications of ghrelin by looking at studies conducted with a specific neurodegenerative disease known to target the hippocampus.
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Affiliation(s)
- Robert S Seminara
- Neuroscience, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Charan Jeet
- Research, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Sharmi Biswas
- Pediatrics, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Bushra Kanwal
- Department of Research, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Waleed Iftikhar
- Internal Medicine, CMH Lahore Medical College and Institute of Dentistry, Lahore, PAK
| | - Md Sakibuzzaman
- Neuroscience, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Ian H Rutkofsky
- Medicine, International American University College of Medicine, Washington, D.C., USA
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11
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Fitting S, McLaurin KA, Booze RM, Mactutus CF. Dose-dependent neurocognitive deficits following postnatal day 10 HIV-1 viral protein exposure: Relationship to hippocampal anatomy parameters. Int J Dev Neurosci 2018; 65:66-82. [PMID: 29111178 PMCID: PMC5889695 DOI: 10.1016/j.ijdevneu.2017.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 10/16/2017] [Accepted: 10/23/2017] [Indexed: 11/25/2022] Open
Abstract
Despite the availability of antiretroviral prophylactic treatment, pediatric human immunodeficiency virus type 1 (HIV-1) continues to be a significant risk factor in the post-cART era. The time of infection (i.e., during pregnancy, delivery or breastfeeding) may play a role in the development of neurocognitive deficits in pediatric HIV-1. HIV-1 viral protein exposure on postnatal day (P)1, preceding the postnatal brain growth spurt in rats, had deleterious effects on neurocognitive development and anatomical parameters of the hippocampus (Fitting et al., 2008a,b). In the present study, rats were stereotaxically injected with HIV-1 viral proteins, including Tat1-86 and gp120, on P10 to further examine the role of timing on neurocognitive development and anatomical parameters of the hippocampus (Fitting et al., 2010). The dose-dependent virotoxin effects observed across development following P10 Tat1-86 exposure were specific to spatial learning and absent from prepulse inhibition and locomotor activity. A relationship between alterations in spatial learning and/or memory and hippocampal anatomical parameters was noted. Specifically, the estimated number of neurons and astrocytes in the hilus of the dentate gyrus explained 70% of the variance of search behavior in Morris water maze acquisition training for adolescents and 65% of the variance for adults; a brain-behavior relationship consistent with observations following P1 viral protein exposure. Collectively, late viral protein exposure (P10) results in selective alterations in neurocognitive development without modifying measures of somatic growth, preattentive processing, or locomotor activity, as characterized by early viral protein exposure (P1). Thus, timing may be a critical factor in disease progression, with children infected with HIV earlier in life being more vulnerable to CNS disease.
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Affiliation(s)
- Sylvia Fitting
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA; University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Kristen A McLaurin
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Rosemarie M Booze
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA
| | - Charles F Mactutus
- University of South Carolina, Behavioral Neuroscience Program, Department of Psychology, Columbia, SC 29208, USA.
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12
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Santos VV, Stark R, Rial D, Silva HB, Bayliss JA, Lemus MB, Davies JS, Cunha RA, Prediger RD, Andrews ZB. Acyl ghrelin improves cognition, synaptic plasticity deficits and neuroinflammation following amyloid β (Aβ1-40) administration in mice. J Neuroendocrinol 2017; 29. [PMID: 28380673 DOI: 10.1111/jne.12476] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 03/16/2017] [Accepted: 04/03/2017] [Indexed: 12/24/2022]
Abstract
Ghrelin is a metabolic hormone that has neuroprotective actions in a number of neurological conditions, including Parkinson's disease (PD), stroke and traumatic brain injury. Acyl ghrelin treatment in vivo and in vitro also shows protective capacity in Alzheimer's disease (AD). In the present study, we used ghrelin knockout (KO) and their wild-type littermates to test whether or not endogenous ghrelin is protective in a mouse model of AD, in which human amyloid β peptide 1-40 (Aβ1-40 ) was injected into the lateral ventricles i.c.v. Recognition memory, using the novel object recognition task, was significantly impaired in ghrelin KO mice and after i.c.v. Aβ1-40 treatment. These deficits could be prevented by acyl ghrelin injections for 7 days. Spatial orientation, as assessed by the Y-maze task, was also significantly impaired in ghrelin KO mice and after i.c.v. Aβ1-40 treatment. These deficits could be prevented by acyl ghrelin injections for 7 days. Ghrelin KO mice had deficits in olfactory discrimination; however, neither i.c.v. Aβ1-40 treatment, nor acyl ghrelin injections affected olfactory discrimination. We used stereology to show that ghrelin KO and Aβ1-40 increased the total number of glial fibrillary acidic protein expressing astrocytes and ionised calcium-binding adapter expressing microglial in the rostral hippocampus. Finally, Aβ1-40 blocked long-term potentiation induced by high-frequency stimulation and this effect could be acutely blocked with co-administration of acyl ghrelin. Collectively, our studies demonstrate that ghrelin deletion affects memory performance and also that acyl ghrelin treatment may delay the onset of early events of AD. This supports the idea that acyl ghrelin treatment may be therapeutically beneficial with respect to restricting disease progression in AD.
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Affiliation(s)
- V V Santos
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - R Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - D Rial
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina UFSC, Florianópolis, SC, Brazil
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - H B Silva
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - J A Bayliss
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - M B Lemus
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - J S Davies
- Molecular Neurobiology, Institute of Life Science, Swansea University, Swansea, UK
| | - R A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - R D Prediger
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina UFSC, Florianópolis, SC, Brazil
| | - Z B Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
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13
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Kim C, Kim S, Park S. Neurogenic Effects of Ghrelin on the Hippocampus. Int J Mol Sci 2017; 18:ijms18030588. [PMID: 28282857 PMCID: PMC5372604 DOI: 10.3390/ijms18030588] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 02/24/2017] [Accepted: 03/03/2017] [Indexed: 01/25/2023] Open
Abstract
Mammalian neurogenesis continues throughout adulthood in the subventricular zone of the lateral ventricle and in the subgranular zone of the dentate gyrus in the hippocampus. It is well known that hippocampal neurogenesis is essential in mediating hippocampus-dependent learning and memory. Ghrelin, a peptide hormone mainly synthesized in the stomach, has been shown to play a major role in the regulation of energy metabolism. A plethora of evidence indicates that ghrelin can also exert important effects on neurogenesis in the hippocampus of the adult brain. The aim of this review is to discuss the current role of ghrelin on the in vivo and in vitro regulation of neurogenesis in the adult hippocampus. We will also discuss the possible role of ghrelin in dietary restriction-induced hippocampal neurogenesis and the link between ghrelin-induced hippocampal neurogenesis and cognitive functions.
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Affiliation(s)
- Chanyang Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Sehee Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Seungjoon Park
- Department of Pharmacology and Medical Research Center for Bioreaction to Reactive Oxygen Species and Biomedical Science Institute, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
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14
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Huang HJ, Zhu XC, Han QQ, Wang YL, Yue N, Wang J, Yu R, Li B, Wu GC, Liu Q, Yu J. Ghrelin alleviates anxiety- and depression-like behaviors induced by chronic unpredictable mild stress in rodents. Behav Brain Res 2017; 326:33-43. [PMID: 28245976 DOI: 10.1016/j.bbr.2017.02.040] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/18/2017] [Accepted: 02/22/2017] [Indexed: 12/31/2022]
Abstract
As a regulator of food intake, ghrelin also plays a key role in mood disorders. Previous studies reported that acute ghrelin administration defends against depressive symptoms of chronic stress. However, the effects of long-term ghrelin on rodents under chronic stress hasn't been revealed. In this study, we found chronic peripheral administration of ghrelin (5nmol/kg/day for 2 weeks, i.p.) could alleviate anxiety- and depression-like behaviors induced by chronic unpredictable mild stress (CUMS). The depression-like behaviors were assessed by the forced swimming test (FST), and anxiety-like behaviors were assessed by the open field test (OFT) and the elevated plus maze test (EPM). Meanwhile, we observed that peripheral acylated ghrelin, together with gastral and hippocampal ghrelin prepropeptide mRNA level, were significantly up-regulated in CUMS mice. Besides, the increased protein level of growth hormone secretagogue receptor (GHSR) in hippocampus were also detected. These results suggested that the endogenous ghrelin/GHSR pathway activated by CUMS plays a role in homeostasis. Further results showed that central treatment of ghrelin (10μg/rat/day for 2 weeks, i.c.v.) or GHRP-6 (the agonist of GHSR, 10μg/rat/day for 2 weeks, i.c.v.) significantly alleviated the depression-like behaviors induced by CUMS in FST and sucrose preference test (SPT). Based on these results, we concluded that central GHSR is involved in the antidepressant-like effect of exogenous ghrelin treatment, and ghrelin/GHSR may have the inherent neuromodulatory properties against depressive symptoms.
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Affiliation(s)
- Hui-Jie Huang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Xiao-Cang Zhu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qiu-Qin Han
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Ya-Lin Wang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Na Yue
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Jing Wang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Rui Yu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Bing Li
- Center Laboratory, Jinshan Hospital of Fudan University, Shanghai 201508, China
| | - Gen-Cheng Wu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qiong Liu
- Department of Anatomy, Histology and Embryology, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai 200032, China.
| | - Jin Yu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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15
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Rats with a truncated ghrelin receptor (GHSR) do not respond to ghrelin, and show reduced intake of palatable, high-calorie food. Physiol Behav 2016; 163:88-96. [DOI: 10.1016/j.physbeh.2016.04.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/29/2016] [Accepted: 04/25/2016] [Indexed: 11/19/2022]
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16
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Kunath N, Müller NCJ, Tonon M, Konrad BN, Pawlowski M, Kopczak A, Elbau I, Uhr M, Kühn S, Repantis D, Ohla K, Müller TD, Fernández G, Tschöp M, Czisch M, Steiger A, Dresler M. Ghrelin modulates encoding-related brain function without enhancing memory formation in humans. Neuroimage 2016; 142:465-473. [PMID: 27402596 DOI: 10.1016/j.neuroimage.2016.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/07/2016] [Accepted: 07/06/2016] [Indexed: 01/24/2023] Open
Abstract
Ghrelin regulates energy homeostasis in various species and enhances memory in rodent models. In humans, the role of ghrelin in cognitive processes has yet to be characterized. Here we show in a double-blind randomized crossover design that acute administration of ghrelin alters encoding-related brain activity, however does not enhance memory formation in humans. Twenty-one healthy young male participants had to memorize food- and non-food-related words presented on a background of a virtual navigational route while undergoing fMRI recordings. After acute ghrelin administration, we observed decreased post-encoding resting state fMRI connectivity between the caudate nucleus and the insula, amygdala, and orbitofrontal cortex. In addition, brain activity related to subsequent memory performance was modulated by ghrelin. On the next day, however, no differences were found in free word recall or cued location-word association recall between conditions; and ghrelin's effects on brain activity or functional connectivity were unrelated to memory performance. Further, ghrelin had no effect on a cognitive test battery comprising tests for working memory, fluid reasoning, creativity, mental speed, and attention. In conclusion, in contrast to studies with animal models, we did not find any evidence for the potential of ghrelin acting as a short-term cognitive enhancer in humans.
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Affiliation(s)
- N Kunath
- Max Planck Institute of Psychiatry, Munich, Germany
| | - N C J Müller
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - M Tonon
- Max Planck Institute of Psychiatry, Munich, Germany
| | - B N Konrad
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - M Pawlowski
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A Kopczak
- Max Planck Institute of Psychiatry, Munich, Germany
| | - I Elbau
- Max Planck Institute of Psychiatry, Munich, Germany
| | - M Uhr
- Max Planck Institute of Psychiatry, Munich, Germany
| | - S Kühn
- Max Planck Institute for Human Development, Berlin, Germany
| | - D Repantis
- Charité - Universitätsmedizin Berlin, Department of Psychiatry and Psychotherapy, CBF, Berlin, Germany
| | - K Ohla
- German Institute for Human Nutrition, Potsdam-Rehbrücke, Germany
| | - T D Müller
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Munich, Germany; Department of Medicine, Technische Universität München, Munich, Germany
| | - G Fernández
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - M Tschöp
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Munich, Germany; Department of Medicine, Technische Universität München, Munich, Germany
| | - M Czisch
- Max Planck Institute of Psychiatry, Munich, Germany
| | - A Steiger
- Max Planck Institute of Psychiatry, Munich, Germany
| | - M Dresler
- Max Planck Institute of Psychiatry, Munich, Germany; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands.
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17
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Palleria C, Leporini C, Maida F, Succurro E, De Sarro G, Arturi F, Russo E. Potential effects of current drug therapies on cognitive impairment in patients with type 2 diabetes. Front Neuroendocrinol 2016; 42:76-92. [PMID: 27521218 DOI: 10.1016/j.yfrne.2016.07.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/13/2016] [Accepted: 07/22/2016] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus is a complex metabolic disease that can cause serious damage to various organs. Among the best-known complications, an important role is played by cognitive impairment. Impairment of cognitive functioning has been reported both in type 1 and 2 diabetes mellitus. While this comorbidity has long been known, no major advances have been achieved in clinical research; it is clear that appropriate control of blood glucose levels represents the best current (although unsatisfactory) approach in the prevention of cognitive impairment. We have focused our attention on the possible effect on the brain of antidiabetic drugs, despite their effects on blood glucose levels, giving a brief rationale on the mechanisms (e.g. GLP-1, BDNF, ghrelin) that might be involved. Indeed, GLP-1 agonists are currently clinically studied in other neurodegenerative diseases (i.e. Parkinson's and Alzheimer's disease); furthermore, also other antidiabetic drugs have proven efficacy in preclinical studies. Overall, promising results are already available and finding new intervention strategies represents a current need in this field of research.
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Affiliation(s)
- Caterina Palleria
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Christian Leporini
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Francesca Maida
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Elena Succurro
- Department of Medical and Surgical Sciences, Internal Medicine Unit of "Mater Domini", University Hospital, University "Magna Graecia" of Catanzaro, Policlinico "Mater Domini", Campus Universitario, Viale Europa, 88100 Catanzaro, Italy
| | - Giovambattista De Sarro
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy
| | - Franco Arturi
- Department of Medical and Surgical Sciences, Internal Medicine Unit of "Mater Domini", University Hospital, University "Magna Graecia" of Catanzaro, Policlinico "Mater Domini", Campus Universitario, Viale Europa, 88100 Catanzaro, Italy
| | - Emilio Russo
- Science of Health Department, School of Medicine, University "Magna Graecia" of Catanzaro, Italy.
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18
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Edwards A, Abizaid A. Driving the need to feed: Insight into the collaborative interaction between ghrelin and endocannabinoid systems in modulating brain reward systems. Neurosci Biobehav Rev 2016; 66:33-53. [PMID: 27136126 DOI: 10.1016/j.neubiorev.2016.03.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 01/29/2023]
Abstract
Independent stimulation of either the ghrelin or endocannabinoid system promotes food intake and increases adiposity. Given the similar distribution of their receptors in feeding associated brain regions and organs involved in metabolism, it is not surprising that evidence of their interaction and its importance in modulating energy balance has emerged. This review documents the relationship between ghrelin and endocannabinoid systems within the periphery and hypothalamus (HYP) before presenting evidence suggesting that these two systems likewise work collaboratively within the ventral tegmental area (VTA) to modulate non-homeostatic feeding. Mechanisms, consistent with current evidence and local infrastructure within the VTA, will be proposed.
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Affiliation(s)
- Alexander Edwards
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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19
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Chebani Y, Marion C, Zizzari P, Chettab K, Pastor M, Korostelev M, Geny D, Epelbaum J, Tolle V, Morisset-Lopez S, Pantel J. Enhanced responsiveness of Ghsr Q343X rats to ghrelin results in enhanced adiposity without increased appetite. Sci Signal 2016; 9:ra39. [PMID: 27095593 DOI: 10.1126/scisignal.aae0374] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The ability of the gut hormone ghrelin to promote positive energy balance is mediated by the growth hormone secretagogue receptor (GHSR). GHSR is a G protein-coupled receptor (GPCR) that is found centrally and peripherally and that can signal in a ligand-independent manner basally or when heterodimerized with other GPCRs. However, current Ghsr knockout models cannot dissect ghrelin-dependent and ghrelin-independent signaling, precluding assessment of the physiological importance of these signaling pathways. An animal model carrying a Ghsr mutation that preserves GHSR cell surface abundance, but selectively alters GHSR signaling, would be a useful tool to decipher GHSR signaling in vivo. We used rats with the Ghsr(Q343X) mutation (Ghsr(M/M)), which is predicted to delete the distal part of the GHSR carboxyl-terminal tail, a domain critical for the signal termination processes of receptor internalization and β-arrestin recruitment. In cells, the GHSR-Q343X mutant showed enhanced ligand-induced G protein-dependent signaling and blunted activity of processes involved in GPCR signal termination. Ghsr(M/M)rats displayed enhanced responses to submaximal doses of ghrelin or GHSR agonist. Moreover, Ghsr(M/M)rats had a more stable body weight under caloric restriction, a condition that increases endogenous ghrelin tone, whereas under standard housing conditions,Ghsr(M/M)rats showed increased body weight and adiposity and reduced glucose tolerance. Overall, our data stress the physiological role of the distal domain of GHSR carboxyl terminus as a suppressor of ghrelin sensitivity, and we propose using the Ghsr(M/M)rat as a physiological model of gain of function in Ghsr to identify treatments for obesity-related conditions.
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Affiliation(s)
- Yacine Chebani
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Candice Marion
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Philippe Zizzari
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Khadidja Chettab
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Marie Pastor
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Marie Korostelev
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - David Geny
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Jacques Epelbaum
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France. CNRS, Muséum national d'Histoire naturelle, UMR 7179, Mécanismes adaptatifs et évolution, 91800 Brunoy, France
| | - Virginie Tolle
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Séverine Morisset-Lopez
- Centre de Biophysique Moléculaire, CNRS, UPR 4301, Université d'Orléans, 45071 Orléans, France
| | - Jacques Pantel
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France. Department of Molecular Physiology and Biophysics, Vanderbilt School of Medicine, Nashville, TN 37232, USA
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20
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St-Onge V, Watts A, Abizaid A. Ghrelin enhances cue-induced bar pressing for high fat food. Horm Behav 2016; 78:141-9. [PMID: 26592452 DOI: 10.1016/j.yhbeh.2015.11.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 11/05/2015] [Accepted: 11/20/2015] [Indexed: 01/23/2023]
Abstract
Ghrelin is an orexigenic hormone produced by the stomach that acts on growth hormone secretagogue receptors (GHSRs) both peripherally and centrally. The presence of GHSRs in the ventral tegmental area (VTA) suggests that ghrelin signaling at this level may increase the incentive value of palatable foods as well as other natural and artificial rewards. The present investigation sought to determine if ghrelin plays a role in relapse to such foods following a period of abstinence. To achieve this, thirty-six male Long Evans rats were trained to press a lever to obtain a high fat chocolate food reward on a fixed ratio schedule of 1. Following an extinction period during which lever presses were not reinforced, rats were implanted with a cannula connected to a minipump that continuously delivered ghrelin, a GHSR antagonist ([d-Lys-3]-GHRP-6), or saline in the VTA for 14days. One week later, food reward-associated cues, food reward priming, and an overnight fast were used to induce reinstatement of the lever pressing response. Our results indicate that intra-VTA ghrelin enhances cue-induced reinstatement of responses for palatable food pellets. To the extent that the reinstatement paradigm is considered a valid model of relapse in humans, this suggests that ghrelin signaling facilitates relapse to preferred foods in response to food cues through GHSR signaling in the VTA.
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Affiliation(s)
- Veronique St-Onge
- Carleton University, Department of Neuroscience, 1125 Colonel By drive, Ottawa, Ontario K1S 5B6, Canada
| | - Alexander Watts
- Carleton University, Department of Neuroscience, 1125 Colonel By drive, Ottawa, Ontario K1S 5B6, Canada
| | - Alfonso Abizaid
- Carleton University, Department of Neuroscience, 1125 Colonel By drive, Ottawa, Ontario K1S 5B6, Canada.
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