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Cheung G, Lin YC, Papadopoulos V. Translocator protein in the rise and fall of central nervous system neurons. Front Cell Neurosci 2023; 17:1210205. [PMID: 37416505 PMCID: PMC10322222 DOI: 10.3389/fncel.2023.1210205] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/07/2023] [Indexed: 07/08/2023] Open
Abstract
Translocator protein (TSPO), a 18 kDa protein found in the outer mitochondrial membrane, has historically been associated with the transport of cholesterol in highly steroidogenic tissues though it is found in all cells throughout the mammalian body. TSPO has also been associated with molecular transport, oxidative stress, apoptosis, and energy metabolism. TSPO levels are typically low in the central nervous system (CNS), but a significant upregulation is observed in activated microglia during neuroinflammation. However, there are also a few specific regions that have been reported to have higher TSPO levels than the rest of the brain under normal conditions. These include the dentate gyrus of the hippocampus, the olfactory bulb, the subventricular zone, the choroid plexus, and the cerebellum. These areas are also all associated with adult neurogenesis, yet there is no explanation of TSPO's function in these cells. Current studies have investigated the role of TSPO in microglia during neuron degeneration, but TSPO's role in the rest of the neuron lifecycle remains to be elucidated. This review aims to discuss the known functions of TSPO and its potential role in the lifecycle of neurons within the CNS.
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Neuropeptidergic control of neurosteroids biosynthesis. Front Neuroendocrinol 2022; 65:100976. [PMID: 34999057 DOI: 10.1016/j.yfrne.2021.100976] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 12/12/2021] [Accepted: 12/22/2021] [Indexed: 01/14/2023]
Abstract
Neurosteroids are steroids synthesized within the central nervous system either from cholesterol or by metabolic reactions of circulating steroid hormone precursors. It has been suggested that neurosteroids exert pleiotropic activities within the central nervous system, such as organization and activation of the central nervous system and behavioral regulation. It is also increasingly becoming clear that neuropeptides exert pleiotropic activities within the central nervous system, such as modulation of neuronal functions and regulation of behavior, besides traditional neuroendocrinological functions. It was hypothesized that some of the physiological functions of neuropeptides acting within the central nervous system may be through the regulation of neurosteroids biosynthesis. Various neuropeptides reviewed in this study possibly regulate neurosteroids biosynthesis by controlling the activities of enzymes that catalyze the production of neurosteroids. It is now required to thoroughly investigate the neuropeptidergic control mechanisms of neurosteroids biosynthesis to characterize the physiological significance of this new neuroendocrinological phenomenon.
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Qiu ZK, Liu X, Chen Y, Wu RJ, Guan SF, Pan YY, Wang QB, Tang D, Zhu T, Chen JS. Translocator protein 18 kDa: a potential therapeutic biomarker for post traumatic stress disorder. Metab Brain Dis 2020; 35:695-707. [PMID: 32172519 DOI: 10.1007/s11011-020-00548-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 02/10/2020] [Indexed: 11/11/2022]
Abstract
Post traumatic stress disorder (PTSD) is widely regarded as a stress-related and trauma disorder. The symptoms of PTSD are characterized as a spectrum of vulnerabilities after the exposure to an extremely traumatic stressor. Considering as one of complex mental disorders, little progress has been made toward its diagnostic biomarkers, despite the involvement of PTSD has been studied. Many studies into the underlying neurobiology of PTSD implicated the dysfunction of neurosteroids biosynthesis and neuorinflammatory processes. Translocator protein 18 kDa (TSPO) has been considered as one of the promising therapeutic biomarkers for neurological stress disorders (like PTSD, depression, anxiety, et al) without the benzodiazepine-like side effects. This protein participates in the formation of neurosteroids and modulation of neuroinflammation. The review outlines current knowledge involving the role of TSPO in the neuropathology of PTSD and the anti-PTSD-like effects of TSPO ligands.
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Affiliation(s)
- Zhi-Kun Qiu
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Xu Liu
- Pharmacy Department of Medical Supplies Center of General Hospital of Chinese People's Armed Police Forces, Beijing, 100039, People's Republic of China
| | - Yong Chen
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Rong-Jia Wu
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Shi-Feng Guan
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Yun-Yun Pan
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Qian-Bo Wang
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China
| | - Dan Tang
- Guangdong Provincial Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 510632, People's Republic of China
| | - Tao Zhu
- Guangdong Provincial Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, 510632, People's Republic of China
| | - Ji-Sheng Chen
- Pharmaceutical Department of The First Affiliated Hospital of Guangdong Pharmaceutical University, Clinical Pharmacy Department of Guangdong Pharmaceutical University, Guangzhou, 510080, People's Republic of China.
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4
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Lack of effect of the combination of metyrapone and oxazepam on brain dopamine. Brain Res 2019; 1724:146435. [DOI: 10.1016/j.brainres.2019.146435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 08/20/2019] [Accepted: 09/02/2019] [Indexed: 01/04/2023]
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Selvaraj V, Stocco DM, Clark BJ. Current knowledge on the acute regulation of steroidogenesis. Biol Reprod 2018; 99:13-26. [PMID: 29718098 PMCID: PMC6044331 DOI: 10.1093/biolre/ioy102] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/23/2018] [Accepted: 04/26/2018] [Indexed: 12/31/2022] Open
Abstract
How rapid induction of steroid hormone biosynthesis occurs in response to trophic hormone stimulation of steroidogenic cells has been a subject of intensive investigation for approximately six decades. A key observation made very early was that acute regulation of steroid biosynthesis required swift and timely synthesis of a new protein whose role appeared to be involved in the delivery of the substrate for all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane where the process of steroidogenesis begins. It was quickly learned that this transfer of cholesterol to the inner mitochondrial membrane was the regulated and rate-limiting step in steroidogenesis. Following this observation, the quest for this putative regulator protein(s) began in earnest in the late 1950s. This review provides a history of this quest, the candidate proteins that arose over the years and facts surrounding their rise or decline. Only two have persisted-translocator protein (TSPO) and the steroidogenic acute regulatory protein (StAR). We present a detailed summary of the work that has been published for each of these two proteins, the specific data that has appeared in support of their role in cholesterol transport and steroidogenesis, and the ensuing observations that have arisen in recent years that have refuted the role of TSPO in this process. We believe that the only viable candidate that has been shown to be indispensable is the StAR protein. Lastly, we provide our view on what may be the most important questions concerning the acute regulation of steroidogenesis that need to be asked in future.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA
| | - Douglas M Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Barbara J Clark
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, USA
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Keller CM, Breaux KN, Goeders NE. Effects of the combination of metyrapone and oxazepam on cocaine-induced increases in corticosterone in the medial prefrontal cortex and nucleus accumbens. Psychoneuroendocrinology 2017; 77:75-83. [PMID: 28024272 DOI: 10.1016/j.psyneuen.2016.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
We have previously demonstrated that a combination of drugs (i.e., metyrapone and oxazepam) known to attenuate HPA-axis activity effectively decreases cocaine self-administration and cue reactivity in rats. However, we did not find changes in plasma corticosterone that matched the behavioral effects we observed, indicating that a different mechanism of action must be involved. Therefore, we hypothesized that the combination of metyrapone and oxazepam attenuates cocaine taking and seeking by decreasing cocaine-induced increases in corticosterone in the brain. Male rats were implanted with guide cannulae targeting the medial prefrontal cortex or nucleus accumbens. After the rats recovered from surgery, the microdialysis session was conducted. Rats were housed in the experimental chamber and the dialysis probes inserted into the guide cannulae the night before the session. The following day, dialysate samples were collected over a five-hour session. Baseline samples were collected for the first two hours, every 20min. Samples were then collected following administration of cocaine (15mg/kg, ip). Before injections of cocaine, rats were pretreated with either vehicle or the combination of metyrapone (50mg/kg, ip) and oxazepam (10mg/kg, ip). The administration of cocaine resulted in an increase in corticosterone in the medial prefrontal cortex following vehicle pretreatment, which was not observed in the nucleus accumbens. This cocaine-induced increase in corticosterone was attenuated by metyrapone/oxazepam. Reducing cocaine-induced increases in corticosterone in the medial prefrontal cortex might represent a novel mechanism through which the combination of metyrapone/oxazepam produces its behavioral effects.
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Affiliation(s)
- Courtney M Keller
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States.
| | - Kelly N Breaux
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States
| | - Nicholas E Goeders
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States
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Stocco DM, Zhao AH, Tu LN, Morohaku K, Selvaraj V. A brief history of the search for the protein(s) involved in the acute regulation of steroidogenesis. Mol Cell Endocrinol 2017; 441:7-16. [PMID: 27484452 PMCID: PMC5929480 DOI: 10.1016/j.mce.2016.07.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 07/26/2016] [Accepted: 07/26/2016] [Indexed: 12/14/2022]
Abstract
The synthesis of steroid hormones occurs in specific cells and tissues in the body in response to trophic hormones and other signals. In order to synthesize steroids de novo, cholesterol, the precursor of all steroid hormones, must be mobilized from cellular stores to the inner mitochondrial membrane (IMM) to be converted into the first steroid formed, pregnenolone. This delivery of cholesterol to the IMM is the rate-limiting step in this process, and has long been known to require the rapid synthesis of a new protein(s) in response to stimulation. Although several possibilities for this protein have arisen over the past few decades, most of the recent attention to fill this role has centered on the candidacies of the proteins the Translocator Protein (TSPO) and the Steroidogenic Acute Regulatory Protein (StAR). In this review, the process of regulating steroidogenesis is briefly described, the characteristics of the candidate proteins and the data supporting their candidacies summarized, and some recent findings that propose a serious challenge for the role of TSPO in this process are discussed.
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Affiliation(s)
- Douglas M Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
| | - Amy H Zhao
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Lan N Tu
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Kanako Morohaku
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Vimal Selvaraj
- Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA
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Selvaraj V, Tu LN. Current status and future perspectives: TSPO in steroid neuroendocrinology. J Endocrinol 2016; 231:R1-R30. [PMID: 27422254 DOI: 10.1530/joe-16-0241] [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: 07/08/2016] [Accepted: 07/15/2016] [Indexed: 12/21/2022]
Abstract
The mitochondrial translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), has received significant attention both as a diagnostic biomarker and as a therapeutic target for different neuronal disease pathologies. Recently, its functional basis believed to be mediating mitochondrial cholesterol import for steroid hormone production has been refuted by studies examining both in vivo and in vitro genetic Tspo-deficient models. As a result, there now exists a fundamental gap in the understanding of TSPO function in the nervous system, and its putative pharmacology in neurosteroid production. In this review, we discuss several recent findings in steroidogenic cells that are in direct contradiction to previous studies, and necessitate a re-examination of the purported role for TSPO in de novo neurosteroid biosynthesis. We critically examine the pharmacological effects of different TSPO-binding drugs with particular focus on studies that measure neurosteroid levels. We highlight the basis of key misconceptions regarding TSPO that continue to pervade the literature, and the need for interpretation with caution to avoid negative impacts. We also summarize the emerging perspectives that point to new directions that need to be investigated for understanding the molecular function of TSPO, only after which the true potential of this therapeutic target in medicine may be realized.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal ScienceCornell University, Ithaca, New York, USA
| | - Lan N Tu
- Department of Animal ScienceCornell University, Ithaca, New York, USA
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9
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Selvaraj V, Stocco DM, Tu LN. Minireview: translocator protein (TSPO) and steroidogenesis: a reappraisal. Mol Endocrinol 2015; 29:490-501. [PMID: 25730708 DOI: 10.1210/me.2015-1033] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The 18-kDa translocator protein (TSPO), also known as the peripheral benzodiazepine receptor, is a transmembrane protein in the outer mitochondrial membrane. TSPO has long been described as being indispensable for mitochondrial cholesterol import that is essential for steroid hormone production. In contrast to this initial proposition, recent experiments reexamining TSPO function have demonstrated that it is not involved in steroidogenesis. This fundamental change has forced a reexamination of the functional interpretations made for TSPO that broadly impacts both basic and clinical research across multiple fields. In this minireview, we recapitulate the key studies from 25 years of TSPO research and concurrently examine their limitations that perhaps led towards the incorrect association of TSPO and steroid hormone production. Although this shift in understanding raises new questions regarding the molecular function of TSPO, these recent developments are poised to have a significant positive impact for research progress in steroid endocrinology.
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Affiliation(s)
- Vimal Selvaraj
- Department of Animal Science (V.S., L.N.T.), Cornell University, Ithaca, New York 14853; and Department of Cell Biology and Biochemistry (D.M.S.), Texas Tech University Health Sciences Center, Lubbock, Texas 79430
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10
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Aghazadeh Y, Zirkin BR, Papadopoulos V. Pharmacological regulation of the cholesterol transport machinery in steroidogenic cells of the testis. VITAMINS AND HORMONES 2015; 98:189-227. [PMID: 25817870 DOI: 10.1016/bs.vh.2014.12.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Reduced serum testosterone (T), or hypogonadism, is estimated to affect about 5 million American men, including both aging and young men. Low serum T has been linked to mood changes, worsening cognition, fatigue, depression, decreased lean body mass and bone mineral density, increased visceral fat, metabolic syndrome, decreased libido, and sexual dysfunction. Administering exogenous T, known as T-replacement therapy (TRT), reverses many of the symptoms of low T levels. However, this treatment can result in luteinizing hormone suppression which, in turn, can lead to reduced sperm numbers and infertility, making TRT inappropriate for men who wish to father children. Additionally, TRT may result in supraphysiologic T levels, skin irritation, and T transfer to others upon contact; and there may be increased risk of prostate cancer and cardiovascular disease, particularly in aging men. Therefore, the development of alternate therapies for treating hypogonadism would be highly desirable. To do so requires greater understanding of the series of steps leading to T formation and how they are regulated, and the identification of key steps that are amenable to pharmacological modulation so as to induce T production. We review herein our current understanding of mechanisms underlying the pharmacological induction of T formation in hypogonadal testis.
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Affiliation(s)
- Yasaman Aghazadeh
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Barry R Zirkin
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Vassilios Papadopoulos
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada; Department of Biochemistry, McGill University, Montreal, Quebec, Canada; Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada.
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11
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Goeders NE, Guerin GF, Schmoutz CD. The combination of metyrapone and oxazepam for the treatment of cocaine and other drug addictions. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 69:419-79. [PMID: 24484984 DOI: 10.1016/b978-0-12-420118-7.00011-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Although scientists have been investigating the neurobiology of psychomotor stimulant reward for many decades, there is still no FDA-approved treatment for cocaine or methamphetamine abuse. Research in our laboratory has focused on the relationship between stress, the subsequent activation of the hypothalamic-pituitary-adrenal (HPA) axis, and psychomotor stimulant reinforcement for almost 30 years. This research has led to the development of a combination of low doses of the cortisol synthesis inhibitor, metyrapone, and the benzodiazepine, oxazepam, as a potential pharmacological treatment for cocaine and other substance use disorders. In fact, we have conducted a pilot clinical trial that demonstrated that this combination can reduce cocaine craving and cocaine use. Our initial hypothesis underlying this effect was that the combination of metyrapone and oxazepam reduced cocaine seeking and taking by decreasing activity within the HPA axis. Even so, doses of the metyrapone and oxazepam combination that consistently reduced cocaine taking and seeking did not reliably alter plasma corticosterone (or cortisol in the pilot clinical trial). Furthermore, subsequent research has demonstrated that this drug combination is effective in adrenalectomized rats, suggesting that these effects must be mediated above the level of the adrenal gland. Our evolving hypothesis is that the combination of metyrapone and oxazepam produces its effects by increasing the levels of neuroactive steroids, most notably tetrahydrodeoxycorticosterone, in the medial prefrontal cortex and amygdala. Additional research will be necessary to confirm this hypothesis and may lead to the development of improved and specific pharmacotherapies for the treatment of psychomotor stimulant use.
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Affiliation(s)
- Nicholas E Goeders
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, Louisiana, USA.
| | - Glenn F Guerin
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, Louisiana, USA
| | - Christopher D Schmoutz
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, Louisiana, USA
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12
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Hamdi Y, Kaddour H, Vaudry D, Bahdoudi S, Douiri S, Leprince J, Castel H, Vaudry H, Tonon MC, Amri M, Masmoudi-Kouki O. The octadecaneuropeptide ODN protects astrocytes against hydrogen peroxide-induced apoptosis via a PKA/MAPK-dependent mechanism. PLoS One 2012; 7:e42498. [PMID: 22927932 PMCID: PMC3424241 DOI: 10.1371/journal.pone.0042498] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 07/06/2012] [Indexed: 12/18/2022] Open
Abstract
Astrocytes synthesize and release endozepines, a family of regulatory peptides, including the octadecaneuropeptide (ODN) an endogenous ligand of both central-type benzodiazepine (CBR) and metabotropic receptors. We have recently shown that ODN exerts a protective effect against hydrogen peroxide (H2O2)-induced oxidative stress in astrocytes. The purpose of the present study was to determine the type of receptor and the transduction pathways involved in the protective effect of ODN in cultured rat astrocytes. We have first observed a protective activity of ODN at very low concentrations that was abrogated by the metabotropic ODN receptor antagonist cyclo1–8[DLeu5]OP, but not by the CBR antagonist flumazenil. We have also found that the metabotropic ODN receptor is positively coupled to adenylyl cyclase in astrocytes and that the glioprotective action of ODN upon H2O2-induced astrocyte death is PKA- and MEK-dependent, but PLC/PKC-independent. Downstream of PKA, ODN induced ERK phosphorylation, which in turn activated the expression of the anti-apoptotic gene Bcl-2 and blocked the stimulation by H2O2 of the pro-apoptotic gene Bax. The effect of ODN on the Bax/Bcl-2 balance contributed to abolish the deleterious action of H2O2 on mitochondrial membrane integrity and caspase-3 activation. Finally, the inhibitory effect of ODN on caspase-3 activity was shown to be PKA and MEK-dependent. In conclusion, the present results demonstrate that the potent glioprotective action of ODN against oxidative stress involves the metabotropic ODN receptor coupled to the PKA/ERK-kinase pathway to inhibit caspase-3 activation.
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Affiliation(s)
- Yosra Hamdi
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Hadhemi Kaddour
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
| | - David Vaudry
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, University of Rouen, Mont-Saint-Aignan, France
- International Associated Laboratory Samuel de Champlain, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), Institute for Medical Research and Innovation (IRIB), University of Rouen, Mont-Saint-Aignan, France
| | - Seyma Bahdoudi
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Salma Douiri
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Jérôme Leprince
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, University of Rouen, Mont-Saint-Aignan, France
- International Associated Laboratory Samuel de Champlain, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), Institute for Medical Research and Innovation (IRIB), University of Rouen, Mont-Saint-Aignan, France
| | - Helene Castel
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, University of Rouen, Mont-Saint-Aignan, France
| | - Hubert Vaudry
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, University of Rouen, Mont-Saint-Aignan, France
- International Associated Laboratory Samuel de Champlain, Mont-Saint-Aignan, France
- Regional Platform for Cell Imaging of Haute-Normandie (PRIMACEN), Institute for Medical Research and Innovation (IRIB), University of Rouen, Mont-Saint-Aignan, France
- * E-mail: (MA), (HV)
| | - Marie-Christine Tonon
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, University of Rouen, Mont-Saint-Aignan, France
| | - Mohamed Amri
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
- * E-mail: (MA), (HV)
| | - Olfa Masmoudi-Kouki
- Laboratory of Functional Neurophysiology and Pathology, Research Unit UR/11ES09, Department of Biological Sciences, Faculty of Science of Tunis, University Tunis El Manar, Tunis, Tunisia
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13
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Do Rego JL, Seong JY, Burel D, Leprince J, Vaudry D, Luu-The V, Tonon MC, Tsutsui K, Pelletier G, Vaudry H. Regulation of neurosteroid biosynthesis by neurotransmitters and neuropeptides. Front Endocrinol (Lausanne) 2012; 3:4. [PMID: 22654849 PMCID: PMC3356045 DOI: 10.3389/fendo.2012.00004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 01/05/2012] [Indexed: 12/30/2022] Open
Abstract
The enzymatic pathways leading to the synthesis of bioactive steroids in the brain are now almost completely elucidated in various groups of vertebrates and, during the last decade, the neuronal mechanisms involved in the regulation of neurosteroid production have received increasing attention. This report reviews the current knowledge concerning the effects of neurotransmitters, peptide hormones, and neuropeptides on the biosynthesis of neurosteroids. Anatomical studies have been carried out to visualize the neurotransmitter- or neuropeptide-containing fibers contacting steroid-synthesizing neurons as well as the neurotransmitter, peptide hormones, or neuropeptide receptors expressed in these neurons. Biochemical experiments have been conducted to investigate the effects of neurotransmitters, peptide hormones, or neuropeptides on neurosteroid biosynthesis, and to characterize the type of receptors involved. Thus, it has been found that glutamate, acting through kainate and/or AMPA receptors, rapidly inactivates P450arom, and that melatonin produced by the pineal gland and eye inhibits the biosynthesis of 7α-hydroxypregnenolone (7α-OH-Δ(5)P), while prolactin produced by the adenohypophysis enhances the formation of 7α-OH-Δ(5)P. It has also been demonstrated that the biosynthesis of neurosteroids is inhibited by GABA, acting through GABA(A) receptors, and neuropeptide Y, acting through Y1 receptors. In contrast, it has been shown that the octadecaneuropetide ODN, acting through central-type benzodiazepine receptors, the triakontatetraneuropeptide TTN, acting though peripheral-type benzodiazepine receptors, and vasotocin, acting through V1a-like receptors, stimulate the production of neurosteroids. Since neurosteroids are implicated in the control of various neurophysiological and behavioral processes, these data suggest that some of the neurophysiological effects exerted by neurotransmitters and neuropeptides may be mediated via the regulation of neurosteroid production.
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Affiliation(s)
- Jean Luc Do Rego
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
| | - Jae Young Seong
- Laboratory of G Protein-Coupled Receptors, Graduate School of Medicine, Korea University College of MedicineSeoul, Korea
| | - Delphine Burel
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of RouenMont-Saint-Aignan, France
| | - Jerôme Leprince
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of RouenMont-Saint-Aignan, France
| | - David Vaudry
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of RouenMont-Saint-Aignan, France
| | - Van Luu-The
- Research Center in Molecular Endocrinology, Oncology and Genetics, Laval University Hospital CenterQuébec, QC, Canada
| | - Marie-Christine Tonon
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of RouenMont-Saint-Aignan, France
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda UniversityTokyo, Japan
- Center for Medical Life Science of Waseda UniversityTokyo, Japan
| | - Georges Pelletier
- Research Center in Molecular Endocrinology, Oncology and Genetics, Laval University Hospital CenterQuébec, QC, Canada
| | - Hubert Vaudry
- INSERMMont-Saint-Aignan France
- European Institute for Peptide Research, IFRMP 23, Regional Platform for Cell Imaging, PRIMACEN, University of RouenMont-Saint-Aignan, France
- International Associated Laboratory Samuel de ChamplainMont-Saint-Aignan, France
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, INSERM U982, University of RouenMont-Saint-Aignan, France
- *Correspondence: Hubert Vaudry, INSERM U982, European Institute for Peptide Research, IFRMP 23, University of Rouen, 76821 Mont-Saint-Aignan, France. e-mail:
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14
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Hamdi Y, Masmoudi-Kouki O, Kaddour H, Belhadj F, Gandolfo P, Vaudry D, Mokni M, Leprince J, Hachem R, Vaudry H, Tonon MC, Amri M. Protective effect of the octadecaneuropeptide on hydrogen peroxide-induced oxidative stress and cell death in cultured rat astrocytes. J Neurochem 2011; 118:416-28. [DOI: 10.1111/j.1471-4159.2011.07315.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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15
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Midzak A, Rone M, Aghazadeh Y, Culty M, Papadopoulos V. Mitochondrial protein import and the genesis of steroidogenic mitochondria. Mol Cell Endocrinol 2011; 336:70-9. [PMID: 21147195 PMCID: PMC3057322 DOI: 10.1016/j.mce.2010.12.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 12/03/2010] [Accepted: 12/05/2010] [Indexed: 11/23/2022]
Abstract
The principal site of regulation of steroid hormone biosynthesis is the transfer of cholesterol from the outer to inner mitochondrial membrane. Hormonal stimulation of steroidogenic cells promotes this mitochondrial lipid import through a multi-protein complex, termed the transduceosome, spanning the two membranes. The transduceosome complex is assembled from multiple proteins, such as the steroidogenic acute regulatory (STAR) protein and translocator protein (TSPO), and requires their targeting to the mitochondria for transduceosome function. The vast majority of mitochondrial proteins, including those participating in cholesterol import, are encoded in the nucleus. Their subsequent mitochondrial incorporation is performed through a series of protein import machineries located in the outer and inner mitochondrial membranes. Here we review our current knowledge of the mitochondrial cholesterol import machinery of the transduceosome. This is complemented with descriptions of mitochondrial protein import machineries and mechanisms by which these machineries assemble the transduceosome in steroidogenic mitochondria.
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Affiliation(s)
- Andrew Midzak
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
| | - Malena Rone
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
| | - Yassaman Aghazadeh
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
| | - Martine Culty
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, H3G 1A4, Canada
| | - Vassilios Papadopoulos
- Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Medicine, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Department of Biochemistry, McGill University, Montreal, Quebec, H3G 1A4, Canada
- Correspondence at The Research Institute of the McGill University Health Center, Montreal General Hospital, 1650 Cedar Avenue, C10-148, Montreal, Quebec H3G 1A4, Canada. Tel: 514-934-1934 ext. 44580; Fax: 514-934-8261;
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16
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Loomis WF, Behrens MM, Williams ME, Anjard C. Pregnenolone sulfate and cortisol induce secretion of acyl-CoA-binding protein and its conversion into endozepines from astrocytes. J Biol Chem 2010; 285:21359-65. [PMID: 20452969 PMCID: PMC2898429 DOI: 10.1074/jbc.m110.105858] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 05/05/2010] [Indexed: 01/01/2023] Open
Abstract
Acyl-CoA-binding protein (ACBP) functions both intracellularly as part of fatty acid metabolism and extracellularly as diazepam binding inhibitor, the precursor of endozepine peptides. Two of these peptides, ODN and TTN, bind to the GABA(A) receptor and modulate its sensitivity to gamma-aminobutyric acid (GABA). We have found that depolarization of mouse primary astrocytes induces the rapid release and processing of ACBP to the active peptides. We previously showed that ODN can trigger the rapid sporulation of the social amoeba Dictyostelium. Using this bioassay, we now show that astrocytes release the endozepine peptides within 10 min of exposure to the steroids cortisol, pregnenolone, pregnenolone sulfate, or progesterone. ACBP lacks a signal sequence for secretion through the endoplasmic reticulum/Golgi pathway and its secretion is not affected by addition of brefeldin A, a well known inhibitor of the classical secretion pathway, suggesting that it follows an unconventional pathway for secretion. Moreover, induction of autophagy by addition of rapamycin also resulted in rapid release of ACBP indicating that this protein uses components of the autophagy pathway for secretion. Following secretion, ACBP is proteolytically cleaved to the active neuropeptides by protease activity on the surface of astrocytes. Neurosteroids, such as pregnenolone sulfate, were previously shown to modulate the excitatory/inhibitory balance in brain through increased release of glutamate and decreased release of GABA. These effects of steroids in neurons will be reinforced by the release of endozepines from astrocytes shown here, and suggest an orchestrated astrocyte-neuron cross-talk that can affect a broad spectrum of behavioral functions.
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Affiliation(s)
- William F. Loomis
- From the Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0368 and
| | | | - Megan E. Williams
- From the Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0368 and
| | - Christophe Anjard
- From the Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093-0368 and
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17
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Do Rego JL, Seong JY, Burel D, Leprince J, Luu-The V, Tsutsui K, Tonon MC, Pelletier G, Vaudry H. Neurosteroid biosynthesis: enzymatic pathways and neuroendocrine regulation by neurotransmitters and neuropeptides. Front Neuroendocrinol 2009; 30:259-301. [PMID: 19505496 DOI: 10.1016/j.yfrne.2009.05.006] [Citation(s) in RCA: 282] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 05/12/2009] [Accepted: 05/21/2009] [Indexed: 01/09/2023]
Abstract
Neuroactive steroids synthesized in neuronal tissue, referred to as neurosteroids, are implicated in proliferation, differentiation, activity and survival of nerve cells. Neurosteroids are also involved in the control of a number of behavioral, neuroendocrine and metabolic processes such as regulation of food intake, locomotor activity, sexual activity, aggressiveness, anxiety, depression, body temperature and blood pressure. In this article, we summarize the current knowledge regarding the existence, neuroanatomical distribution and biological activity of the enzymes responsible for the biosynthesis of neurosteroids in the brain of vertebrates, and we review the neuronal mechanisms that control the activity of these enzymes. The observation that the activity of key steroidogenic enzymes is finely tuned by various neurotransmitters and neuropeptides strongly suggests that some of the central effects of these neuromodulators may be mediated via the regulation of neurosteroid production.
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Affiliation(s)
- Jean Luc Do Rego
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 413, 76821 Mont-Saint-Aignan, France
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18
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Rone MB, Fan J, Papadopoulos V. Cholesterol transport in steroid biosynthesis: role of protein-protein interactions and implications in disease states. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:646-58. [PMID: 19286473 DOI: 10.1016/j.bbalip.2009.03.001] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 02/28/2009] [Accepted: 03/03/2009] [Indexed: 12/20/2022]
Abstract
The transfer of cholesterol from the outer to the inner mitochondrial membrane is the rate-limiting step in hormone-induced steroid formation. To ensure that this step is achieved efficiently, free cholesterol must accumulate in excess at the outer mitochondrial membrane and then be transferred to the inner membrane. This is accomplished through a series of steps that involve various intracellular organelles, including lysosomes and lipid droplets, and proteins such as the translocator protein (18 kDa, TSPO) and steroidogenic acute regulatory (StAR) proteins. TSPO, previously known as the peripheral-type benzodiazepine receptor, is a high-affinity drug- and cholesterol-binding mitochondrial protein. StAR is a hormone-induced mitochondria-targeted protein that has been shown to initiate cholesterol transfer into mitochondria. Through the assistance of proteins such as the cAMP-dependent protein kinase regulatory subunit Ialpha (PKA-RIalpha) and the PKA-RIalpha- and TSPO-associated acyl-coenzyme A binding domain containing 3 (ACBD3) protein, PAP7, cholesterol is transferred to and docked at the outer mitochondrial membrane. The TSPO-dependent import of StAR into mitochondria, and the association of TSPO with the outer/inner mitochondrial membrane contact sites, drives the intramitochondrial cholesterol transfer and subsequent steroid formation. The focus of this review is on (i) the intracellular pathways and protein-protein interactions involved in cholesterol transport and steroid biosynthesis and (ii) the roles and interactions of these proteins in endocrine pathologies and neurological diseases where steroid synthesis plays a critical role.
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Affiliation(s)
- Malena B Rone
- The Research Institute of the McGill University Health Centre and Department of Medicine, McGill University, 1650 Cedar Avenue, Montreal, Quebec, Canada H3G 1A4
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19
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Oikari S, Ahtialansaari T, Huotari A, Kiehne K, Fölsch UR, Wolffram S, Jänne J, Alhonen L, Herzig KH. Effect of medium- and long-chain fatty acid diets on PPAR and SREBP-1 expression and glucose homeostasis in ACBP-overexpressing transgenic rats. Acta Physiol (Oxf) 2008; 194:57-65. [PMID: 18394026 DOI: 10.1111/j.1748-1716.2008.01860.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM Acyl-CoAs are important intermediates and regulators of lipid metabolism. Binding proteins like acyl-CoA binding protein (ACBP) can influence their regulatory functions. ACBP has also been shown to exert direct effects on gene regulation in vitro. As the physiological relevance of ACBP in the regulation of lipid metabolism under high fat diets is unclear, we investigated the influence of such diets on the metabolic responses in ACBP-overexpressing rats. METHODS A transgenic rat line overexpressing the ACBP gene was used to study the effects of 4 weeks of feeding with medium- (MC) or long-chain (LC) fatty acid-containing diets. Glucose tolerance tests were performed. Expression of transcription factors was measured by quantitative RT-PCR and protein levels of AMP-activated protein kinase were determined by western blotting. RESULTS Transgenic animals fed the MC diet had an improved glucose tolerance and lower serum insulin levels compared with controls. Their liver PPARgamma (by 43%) and SREBP-1 (by 35%) mRNA levels were found to be decreased, while adipose tissue PPARgamma expression was increased by 31%. Tg animals fed the LC diet did not exhibit changes in glucose or insulin levels but exhibited increased mRNA levels of liver PPARs and SREBP-1 (1.5-3.5 times) and decreased protein levels of AMPKalpha (by 48%). CONCLUSIONS Our results demonstrate that ACBP overexpression affects metabolic responses to diets with distinct difference in their fatty acid chain lengths. The molecular regulatory mechanism behind these effects seems to be an ACBP-induced tissue-specific regulation of expression of PPARs and SREBP.
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Affiliation(s)
- S Oikari
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, Kuopio, Finland
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20
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Rego JLD, Leprince J, Luu-The V, Pelletier G, Tonon MC, Vaudry H. Structure−Activity Relationships of a Series of Analogs of the Endozepine Octadecaneuropeptide (ODN11-18) on Neurosteroid Biosynthesis by Hypothalamic Explants. J Med Chem 2007; 50:3070-6. [PMID: 17550241 DOI: 10.1021/jm0610548] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have previously shown that the endozepine octadecaneuropeptide (ODN) stimulates the biosynthesis of neurosteroids from frog hypothalamic explants. In the present study, we have investigated the structure-activity relationships of a series of analogs of the C-terminal octapeptide of ODN (OP) on neurosteroid formation. We found that OP and its cyclic analog cyclo1-8OP stimulate in a concentration-dependent manner the synthesis of various steroids including 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone and dehydroepiandrosterone. Deletion or Ala-substitution of the Arg1 or Pro2 residues of OP did not affect the activity of the peptide. In contrast, deletion or replacement of any of the amino acids of the C-terminal hexapeptide fragment totally abolished the effect of OP on neurosteroid biosynthesis. The present study indicates that the C-terminal hexapeptide of ODN/OP is the minimal sequence retaining full biological activity on steroid-producing neurons.
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Affiliation(s)
- Jean Luc Do Rego
- INSERM U413, Laboratory of Cellular and Molecular Neuroendocrinology, European Institute for Peptide Research (IFRMP 23), University of Rouen, 76821 Mont-Saint-Aignan, France
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21
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Compère V, Ouellet J, Luu-The V, Dureuil B, Tonon MC, Vaudry H, Labrie F, Pelletier G. Role of androgens and glucocorticoids in the regulation of diazepam-binding inhibitor mRNA levels in male mouse hypothalamus. Brain Res 2006; 1119:50-7. [PMID: 16963002 DOI: 10.1016/j.brainres.2006.08.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 08/11/2006] [Accepted: 08/12/2006] [Indexed: 10/24/2022]
Abstract
In peripheral organs, gonadal and adrenal steroids regulate diazepam-binding inhibitor (DBI) mRNA expression. In order to further investigate the involvement of peripheral steroid hormones in the modulation of brain DBI mRNA expression, we studied by semiquantitative in situ hybridization the effect of adrenalectomy (ADX) and castration (CX) and short-term replacement therapy on DBI mRNA levels in the male mouse hypothalamus. Cells expressing DBI mRNA were mostly observed in the arcuate nucleus, the median eminence and the ependyma bordering the third ventricle. In the median eminence and the ependyma bordering the third ventricule, the DBI gene expression was decreased in ADX rats and a single injection of corticosterone to ADX rats induced a significant increase in DBI gene expression at 3 and 12 h time intervals without completely restoring the basal DBI mRNA expression observed in intact mice. In the arcuate nucleus, ADX and corticosterone administration did not modify DBI mRNA expression. CX down-regulated DBI gene expression in the ependyma bordering the third ventricle. The administration of dihydrotestosterone (3-24 h) completely reversed the inhibitory effect of CX. In the median eminence and arcuate nucleus, neither CX or dihydrotestosterone administration modified DBI mRNA levels. These results suggest that the effects of glucocorticoids on the hypothalamo-pituitary-adrenocortical axis and androgens on the hypothalamo-pituitary-gonadal axis are mediated by DBI.
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Affiliation(s)
- V Compère
- European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen, Mont-Saint-Aignan, France
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22
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Duparc C, Lefebvre H, Tonon MC, Vaudry H, Kuhn JM. Characterization of endozepines in the human testicular tissue: effect of triakontatetraneuropeptide on testosterone secretion. J Clin Endocrinol Metab 2003; 88:5521-8. [PMID: 14602800 DOI: 10.1210/jc.2003-030783] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previous studies have shown that endozepines, i.e. endogenous ligands of benzodiazepine (BZD) receptors, stimulate steroidogenesis in adrenocortical and Leydig cells. In the present report, we have investigated the presence and action of endozepines in the human testis. Immunohistochemical labeling revealed the occurrence of endozepine-like immunoreactivity in Leydig, Sertoli, and germ cells. HPLC analysis combined with a specific RIA resolved two immunoreactive peaks that coeluted with synthetic octadecaneuropeptide (ODN) and triakontatetraneuropeptide (TTN). RT-PCR amplification showed that the mRNA encoding the endozepine precursor diazepam-binding inhibitor is expressed in the human testis. The action of endozepines on testosterone production was studied in vitro using perifused human testicular fragments. Administration of TTN provoked a dose-dependent increase in testosterone secretion, whereas ODN had no effect. The stimulatory action of TTN on testosterone production was totally blocked by flunitrazepam, a peripheral-type BZD receptor antagonist/central-type BZD receptor (CBR) agonist. Conversely, the CBR agonist clonazepam and the CBR antagonist flumazenil did not affect testosterone secretion. Collectively, these results suggest that, in the human testicular tissue, TTN may exert an intracrine and/or paracrine control of steroidogenesis through activation of a peripheral-type BZD receptor.
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Affiliation(s)
- Celine Duparc
- European Institute for Peptide Research, Institut Fédératif de Recherche Multidisciplinaires sur les Peptides 23, Laboratory of Cellular and Molecular Neuroendocrinology, INSERM, Unit 413, CNRS, University of Rouen, Mont-Saint-Aignan, France
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23
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Gesi M, Fornai F, Lenzi P, Ferrucci M, Soldani P, Ruffoli R, Paparelli A. Morphological alterations induced by loud noise in the myocardium: the role of benzodiazepine receptors. Microsc Res Tech 2002; 59:136-46. [PMID: 12373725 DOI: 10.1002/jemt.10186] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Noise represents an environmental stress factor affecting several organs and apparati, including the cardiovascular system. In experimental animals undergoing noise exposure, subcellular myocardial changes have been reported, especially at mitochondrial level; in particular, after 6 hours of exposure only the atrium exhibited significant mitochondrial alterations, whereas after 12 hours as well as subchronic exposure both atrium and ventricle were damaged. The first part of the present article overviews the experimental evidence on effects of noise on the myocardium. In the second part, the review analyzes the role of benzodiazepine receptors and the potential efficacy of benzodiazepine ligands in preventing the mitochondrial damage induced by noise exposure. Drugs acting at both central and peripheral benzodiazepine receptors significantly prevent this damage. Differences in the amount and the duration of the protective effect might depend on variability in the potency and pharmacokinetics of the specific drug. The effects of the combined treatment with selective and non-selective peripheral benzodiazepine ligands on noise stimulation are discussed at biochemical level reviewing studies on the effects of noise exposure on mitochondrial fractions.
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Affiliation(s)
- Marco Gesi
- Department of Human Morphology and Applied Biology, School of Medicine, University of Pisa, 56126 Pisa, Italy.
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24
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Salvetti F, Chelli B, Gesi M, Pellegrini A, Giannaccini G, Lucacchini A, Martini C. Effect of noise exposure on rat cardiac peripheral benzodiazepine receptors. Life Sci 2000; 66:1165-75. [PMID: 10737412 DOI: 10.1016/s0024-3205(00)00422-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Noise is an environmental physical agent, which is regarded as a stressful stimulus: impairment and modifications in biological functions are reported, after loud noise exposure, at several levels in human and animal organs and apparatuses, as well as in the endocrine, cardiovascular and nervous system. In the present study equilibrium binding parameters of peripheral benzodiazepine receptors (PBRs) labelled by the specific radioligand [3H]PK 11195, were evaluated in cardiac tissue of rats submitted to 6 or 12 h noise exposure and of rats treated "in vivo" with PBR ligands such as PK 11195, Ro54864, diazepam and then noise-exposed. Results revealed a statistically significant decrease in the maximum number of binding sites (Bmax) of [3H]PK 11195 in atrial membranes of 6 or 12 h noise exposed rats, compared with sham-exposed animals, without any change in the dissociation constant (Kd). The "in vivo" PBR ligand pre-treatment counteracted the noise-induced modifications of PBR density. As PBRs are mainly located on mitochondria we also investigated whether noise exposure can affect the [3H]PK 11195 binding parameters in isolated cardiac mitochondrial fractions. Results indicated a significant Bmax value decrease in right atrial mitochondrial fractions of rats 6 or 12 h noise-exposed. Furthermore, as PBR has been suggested to be a supramolecular complex that might coincide with the not-yet-established structure of the mitochondrial permeability transition (MPT)-pore, the status of the MPT-pore in isolated heart mitochondria was investigated in noise- and sham-exposed rats. The loss of absorbance associated with the calcium-induced MPT-pore opening was greater in mitochondria isolated from hearts of 6 h noise- than those of sham-exposed rats. In conclusion, these findings represent a further instance for PBR density decrease in response to a stressful stimulus, like noise; in addition they revealed that "in vivo" administration of PBR ligands significantly prevents this decrease. Finally, our data also suggest the involvement of MPT in the response of an organism to noise stress.
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Affiliation(s)
- F Salvetti
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Italy
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25
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Lacor P, Gandolfo P, Tonon MC, Brault E, Dalibert I, Schumacher M, Benavides J, Ferzaz B. Regulation of the expression of peripheral benzodiazepine receptors and their endogenous ligands during rat sciatic nerve degeneration and regeneration: a role for PBR in neurosteroidogenesis. Brain Res 1999; 815:70-80. [PMID: 9974124 DOI: 10.1016/s0006-8993(98)01105-6] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Peripheral benzodiazepine receptors (PBR) and their endogenous ligands, the diazepam-binding inhibitor derived-peptides, are present in Schwann cells in the peripheral nervous system. The aim of this study was to determine the influence of reversible (freeze-injury) and permanent (transection and ligature) nerve lesion on PBR density and on the levels of their endogenous ligands, by autoradiography (using [3H]PK11195) and radioimmunoassay (using antisera directed against the octadecaneuropeptide (ODN), a diazepam-binding inhibitor fragment). The potential role of PBR on peripheral nerve steroidogenesis, was studied by investigating the effect of specific PBR agonists and antagonists on pregnenolone levels in the sciatic nerve. Sixteen to 30 days after nerve lesion, PBR density and ODN-LI level were highly increased. Their expression returned to normal level when regeneration was completed 60 days after freeze-injury, but remained elevated when regeneration did not occur in transected distal stumps. Reverse-phase HPLC analysis of ODN-LI showed that in control nerve extracts, the major immunoreactive peak co-elutes with triakontatetraneuropeptide (TTN). After freeze-injury, intermediate molecular forms eluting between ODN and TTN were predominant and remained elevated at day 60. The greater accumulation of intermediate forms when regeneration is allowed to occur may indicate a particular role of these forms in axonal elongation and myelination. Ro5-4864, a high affinity PBR agonist increased pregnenolone concentration in the sciatic nerve. This effect was antagonised by PK11195, a high affinity PBR antagonist, which had no effect on pregnenolone basal level, indicating a specific action of PBR in neurosteroid production. These results suggest a role for PBR and their endogenous ligands in peripheral nerve regeneration. A trophic effect could be exerted via stimulation of steroid synthesis.
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Affiliation(s)
- P Lacor
- Synthelabo Recherche, CNS Research Department, Bagneux, France
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26
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Bitran D, Carlson D, Leschiner S, Gavish M. Ovarian steroids and stress produce changes in peripheral benzodiazepine receptor density. Eur J Pharmacol 1998; 361:235-42. [PMID: 9865513 DOI: 10.1016/s0014-2999(98)00708-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Although past research has described changes in the density of the peripheral benzodiazepine receptor in brain and in peripheral organs in response to stressors and steroid hormone exposure, their combined influence had yet to be determined. This study examined the effect of swim-stress as a function of ovarian hormone administration on the binding of an isoquinoline carboxamide derivative, [3H]PK 11195, in brain and peripheral tissues. In olfactory bulb and adrenal gland, stress increased peripheral benzodiazepine receptor density in ovariectomized rats with and without estradiol and progesterone replacement injection, even when compared with unstressed animals treated with hormones, where estradiol + progesterone decreased peripheral benzodiazepine receptor number in olfactory bulb, but estradiol and estradiol + progesterone increased it in adrenal gland. In frontal cortex, stress decreased peripheral benzodiazepine receptor number, an effect that was reversed by estradiol. In hippocampus estradiol decreased peripheral benzodiazepine receptor density in unstressed animals and estradiol + progesterone decreased peripheral benzodiazepine receptor number in unstressed and stressed animals. In cerebellum, stress, estradiol and estradiol + progesterone alone decreased peripheral benzodiazepine receptor density. In uterus of unstressed controls, estradiol + progesterone increased peripheral benzodiazepine receptor density, and stress produced a further increase in steroid-treated females. Stress did not affect peripheral benzodiazepine receptor density in kidney, except in animals that received estradiol + progesterone injections, where swim-stress produced a significant decrease in peripheral benzodiazepine receptor density. Thus, steroid hormones regulate peripheral benzodiazepine receptor density in endocrine organs and brain, and the hormonal state of the organism modifies the peripheral benzodiazepine receptor response to stress in a tissue- and brain region-specific manner, suggesting that the peripheral benzodiazepine receptor may play a pivotal role in an integrated response to stress.
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Affiliation(s)
- D Bitran
- Department of Psychology, College of the Holy Cross, Worcester, MA, USA.
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27
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Do-Rego JL, Mensah-Nyagan AG, Feuilloley M, Ferrara P, Pelletier G, Vaudry H. The endozepine triakontatetraneuropeptide diazepam-binding inhibitor [17-50] stimulates neurosteroid biosynthesis in the frog hypothalamus. Neuroscience 1998; 83:555-70. [PMID: 9460762 DOI: 10.1016/s0306-4522(97)00362-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neurons and glial cells are capable of synthesizing various bioactive steroids, but the neuronal mechanisms controlling neurosteroid-secreting cells are poorly understood. In the present study, we have investigated the possible effect of an endogenous ligand of benzodiazepine receptors, the triakontatetraneuropeptide [17-50] (TTN), on steroid biosynthesis in the frog hypothalamus. Immunohistochemical studies revealed that most hypothalamic neurons expressing 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase also contained peripheral-type benzodiazepine receptor-like immunoreactivity. Confocal laser scanning microscopic analysis revealed that the peripheral-type benzodiazepine receptor-immunoreactive material was located both in the cytoplasm and at the periphery of the cell bodies. By using the pulse-chase technique, TTN was found to stimulate the conversion of [3H]pregnenolone into various steroids, including 17-hydroxypregnenolone, 5 alpha-dihydrotestosterone and 17-hydroxyprogesterone, in a dose-dependent manner. The peripheral-type benzodiazepine receptor agonist Ro5-4864 mimicked the stimulatory effect of TTN on the formation of neurosteroids. The peripheral-type benzodiazepine receptor antagonist PK11195 significantly reduced the effect of TTN on neurosteroid synthesis, while the central-type benzodiazepine receptor antagonist flumazenil did not affect the formation of neurosteroids evoked by TTN. These data indicate that TTN stimulates the biosynthesis of 3-keto-17 alpha-hydroxysteroids in frog hypothalamic neurons through activation of peripheral-type benzodiazepine receptors likely located at the plasma membrane level.
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Affiliation(s)
- J L Do-Rego
- European Institute for Peptide Research (IFRMP no 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U 413, UA CNRS, University of Rouen, Mont-Saint-Aignan, France
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28
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De Mateos-Verchere JG, Leprince J, Tonon MC, Vaudry H, Costentin J. The octadecaneuropeptide ODN induces anxiety in rodents: possible involvement of a shorter biologically active fragment. Peptides 1998; 19:841-8. [PMID: 9663449 DOI: 10.1016/s0196-9781(98)00037-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The octadecaneuropeptide ODN has been originally characterized as an endogenous ligand of central-type benzodiazepine receptors, on its ability to displace the anxiogenic compound beta-[3H]carboline-3-carboxylate methyl ester from its binding sites. The aim of the present study was to investigate the anxiogenic effects of intracerebroventricular administration of ODN in mice and rats. At doses ranging from 10 to 100 ng, ODN increased in mice the latency to explore a white compartment when the animals were placed in a black one. ODN also reduced the first stay duration in the white compartment. These effects were antagonized by diazepam (0.075 mg/kg, s.c.) as well as flumazenil (1 mg/kg, s.c.), indicating that ODN acts as an inverse agonist on central-type benzodiazepine receptors. In rats, ODN reduced the latency to enter a black compartment when the animals were placed in the white one. In the plus-maze elevated test, ODN reduced, in both mice and rats, the number of entries and the time spent in the open arm. In mice, ODN (100 ng) increased the thigmotaxis index, i.e. the distance traveled in the peripheral zone of the open field. Time-course studies revealed that a significant effect of ODN (100 ng) in the black/white compartment test was only observed 40 min after the injection and lasted between 3 and 6 h. The effect of a 1000-ng dose of ODN appeared more tardily than that of a 10-ng dose. In addition, a 1000-ng dose of ODN occluded the early effect of a 100-ng dose on the white compartment first stay duration. The COOH-terminal octapeptide of ODN was more rapidly effective than ODN in the black/white compartment test, suggesting that the anxiogenic effect of the peptide requires the formation of biologically active proteolytic fragment.
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Affiliation(s)
- J G De Mateos-Verchere
- Institut Fédératif de Recherches Multidisciplinaires sur les Peptides (no. 23), Unité de Neuropsychopharmacologie, CNRS UPRES-A 6036, Faculté de Médecine et Pharmacie de Rouen, Saint-Etienne du Rouvray, France
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29
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Affiliation(s)
- A C Latronico
- Developmental Endocrinology Branch, NIH Clinical Center, Bethesda, MD 20892, USA
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30
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Marín RH, Arce A, Martijena ID. Recruitment of peripheral-type benzodiazepine receptors after acute stress in chick forebrain membranes: action of Triton X-100. Neurochem Int 1996; 28:425-9. [PMID: 8740450 DOI: 10.1016/0197-0186(95)00093-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A significant increase in the number of measurable [3H]Ro 5-4864 receptors was found in forebrain membranes of chicks submitted to 15 min of acute swim stress compared to non-stressed chicks. In addition, low subsolubilizing concentrations of Triton X-100 caused a significant increase in the measurable [3H]Ro 5-4864 receptor number in forebrain membranes from non-stressed chicks. However, this increase caused by Triton X-100 was not observed when tested in forebrain membranes from stressed chicks. In all cases the affinity remained unchanged. These results suggest that: (1) acute stress and Triton X-100 induce receptor increase by enhancing [3H]Ro 5-4864 accessibility to a pool of receptors not detected before stress or in the absence of detergent; (2) the pool of non-measured receptors represents about a third of the total in control chicks; (3) the increments are not additive and could involve receptors coming from the same non-measured pool; (4) the receptor increase during a short time of stress could be explained by recruitment of receptors but not by an increase in the receptor protein biosynthesis; (5) stress induces a maximal recruitment of measurable [-3H]Ro 5-4864 receptors.
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Affiliation(s)
- R H Marín
- Cátedra de Química Biológica, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Argentina
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31
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Stocco DM, Clark BJ. Role of the steroidogenic acute regulatory protein (StAR) in steroidogenesis. Biochem Pharmacol 1996; 51:197-205. [PMID: 8573184 DOI: 10.1016/0006-2952(95)02093-4] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The rate-limiting, hormone-regulated, enzymatic step in steroidogenesis is the conversion of cholesterol to pregnenolone by the cholesterol side-chain cleavage enzyme system (CSCC), which is located on the matrix side of the inner mitochondrial membrane. However, it has long been observed that hydrophilic cholesterol-like substrates capable of traversing the mitochondrial membranes are cleaved to pregnenolone by the CSCC in the absence of any hormone stimulation. Therefore, the true regulated step in the acute response of steroidogenic cells to hormone stimulation is the delivery of cholesterol to the inner mitochondrial membrane and the CSCC. It has been known for greater than three decades that transfer of cholesterol requires de novo protein synthesis; however, prior to this time the regulatory protein(s) had yet to be identified conclusively. It is the purpose of this commentary to briefly review a number of the candidates that have been proposed as the acute regulatory protein. As such, we have summarized the available information that describes the roles of transcription, translation, and phosphorylation in this regulation, and have also reviewed the supporting cases that have been made for several of the proteins put forth as the acute regulator. We close with a comprehensive description of the Steroidogenic Acute Regulatory protein (StAR) that we and others have identified and characterized as a family of proteins that are synthesized and imported into the mitochondria in response to hormone stimulation, and for which strong evidence exists indicating that it is the long sought acute regulatory protein.
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Affiliation(s)
- D M Stocco
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock 79430, USA
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32
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Holmes PV, Drugan RC. Stress-induced regulation of the renal peripheral benzodiazepine receptor: possible role of the renin-angiotensin system. Psychoneuroendocrinology 1994; 19:43-54. [PMID: 9210211 DOI: 10.1016/0306-4530(94)90058-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The etiology of the decrease in renal peripheral benzodiazepine receptor (PBR) binding caused by stress was studied in rats. Prior investigations suggest that the response of the renal PBR to stress occurs independently of the hypothalamo-pituitary-adrenal (HPA) axis and sympathetic nervous system. The present experiments tested the hypothesis that the renin-angiotensin system is involved in regulating the PBR. Eighty min of brief, intermittent tailshocks caused increases in plasma renin activity and decreases in renal PBR binding. The stress-induced decrease in renal PBR binding was reversed by pretreatment with captopril. Acute administration of angiotensin II (ANG II) alone caused reductions in PBR binding in kidney, heart, and cerebral cortex. These data suggest that ANG II may be an endogenous factor responsible for regulating the PBR in several tissues during stress.
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Affiliation(s)
- P V Holmes
- Department of Psychology, Schrier Research Laboratory, Brown University, Providence, Rhode Island 02912, USA
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33
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Alho H, Vaalasti A, Podkletnova I, Rechardt L. Expression of diazepam-binding inhibitor peptide in human skin: an immunohistochemical and ultrastructural study. J Invest Dermatol 1993; 101:800-3. [PMID: 8245508 DOI: 10.1111/1523-1747.ep12371698] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Human diazepam binding inhibitor (DBI) was originally isolated from the brain and subsequently found to be present in several peripheral tissues. The various physiologic effects recently attributed to DBI include acting as an endogenous ligand for the central and peripheral (mitochondrial) benzodiazepine receptors. The present work provides, for the first time, evidence of DBI immunoreactivity in skin. DBI immunoreactivity was found in the epidermis, in the eccrine sweat and in sebaceous glands. Ultrastructurally, DBI was distributed throughout the cytoplasm. Although the physiologic role of DBI in skin is unknown, our results indicate that DBI may serve as an endogenous ligand for mitochondrial benzodiazepine receptors. Its activity could be related to the regulation of lipid and cholesterol synthesis in keratinocytes and sebaceous glands and to the secretion of sweat in sweat glands.
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Affiliation(s)
- H Alho
- Department of Biomedical Sciences, University of Tampere, Finland
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34
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Kolmer M, Alho H, Costa E, Pani L. Cloning and tissue-specific functional characterization of the promoter of the rat diazepam binding inhibitor, a peptide with multiple biological actions. Proc Natl Acad Sci U S A 1993; 90:8439-43. [PMID: 7690962 PMCID: PMC47372 DOI: 10.1073/pnas.90.18.8439] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Diazepam binding inhibitor (DBI) is a 10-kDa polypeptide that regulates mitochondrial steroidogenesis, glucose-induced insulin secretion, metabolism of acyl-CoA esters, and the action of gamma-aminobutyrate on GABAA receptors. To investigate the regulation of DBI gene expression, three positive clones were isolated from a rat genomic library. One of them contained a DBI genomic DNA fragment encompassing 4 kb of the 5' untranslated region, the first two exons, and part of the second intron of the DBI gene. Two other overlapping clones contained a processed DBI pseudogene. Several transcription initiation sites were detected by RNase protection and primer extension assays. Different tissues exhibited clear differences in the efficiencies of transcription startpoint usage. Transient expression experiments using DNA fragments of different length from the 5' untranslated region of the DBI gene showed that basal promoter activity required 146 bp of the proximal DBI sequence, whereas full activation was achieved with 423 bp of the 5' untranslated region. DNase I protection experiments with liver nuclear proteins demonstrated three protected regions at nt -387 to -333, -295 to -271, and -176 to -139 relative to the ATG initiation codon; in other tissues the pattern of protection was different. In gel shift assays the most proximal region (-176 to -139) was found to bind several general transcription factors as well as cell type-restricted nuclear proteins which may be related to specific regulatory patterns in different tissues. Thus, the DBI gene possesses some features of a housekeeping gene but also includes a variable regulation which appears to change with the function that it subserves in different cell types.
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Affiliation(s)
- M Kolmer
- Department of Biomedical Sciences, University of Tampere, Finland
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35
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Holmes PV, Drugan RC. Amygdaloid central nucleus lesions and cholinergic blockade attenuate the response of the renal peripheral benzodiazepine receptor to stress. Brain Res 1993; 621:1-9. [PMID: 8221058 DOI: 10.1016/0006-8993(93)90291-t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous research has demonstrated that the density of peripheral benzodiazepine receptors (PBR) in rat kidney rapidly drops following exposure to 80 min of stress. The present experiments examined the contribution of the central and autonomic nervous systems in mediating this effect. Ibotenic acid lesions of the amygdaloid central nucleus (ACe), but not the lateral and basolateral amygdala, diminished the magnitude of the reduction in renal PBR binding caused by stress. Pretreating rats with methyl-scopolamine also inhibited the response of the PBR to stress. Adrenergic blockade with nadolol was ineffective. In order to test whether the PBR was under direct or indirect neural control during stress, unilateral renal denervation was performed. The stress-induced reduction in PBR binding persisted in denervated kidneys revealing that any neural control over the PBR that might exist must be indirect. Together the results suggest that the CNS may be involved in regulating the PBR during stress through the activation of intermediate, possibly hormonal, factors. The involvement of the central nervous system in the modulation of the PBR indicates the relevance of the PBR to physiological adaptations to stress.
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Affiliation(s)
- P V Holmes
- Schrier Research Laboratory, Department of Psychology, Brown University, Providence, RI 02912
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36
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Knudsen J, Mandrup S, Rasmussen JT, Andreasen PH, Poulsen F, Kristiansen K. The function of acyl-CoA-binding protein (ACBP)/diazepam binding inhibitor (DBI). Mol Cell Biochem 1993; 123:129-38. [PMID: 8232254 DOI: 10.1007/bf01076484] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Acyl-CoA-binding protein has been isolated independently by five different groups based on its ability to (1) displace diazepam from the GABAA receptor, (2) affect cell growth, (3) induce medium-chain acyl-CoA-ester synthesis, (4) stimulate steroid hormone synthesis, and (5) affect glucose-induced insulin secretion. In this survey evidence is presented to show that ACBP is able to act as an intracellular acyl-CoA transporter and acyl-CoA pool former. The rat ACBP genomic gene consists of 4 exons and is actively expressed in all tissues tested with highest concentration being found in liver. ACBP consists of 86 amino acid residues and contains 4 alpha-helices which are folded into a boomerang type of structure with alpha-helices 1, 2 and 4 in the one arm and alpha-helix 3 and an open loop in the other arm of the boomerang. ACBP is able to stimulate mitochondrial acyl-CoA synthetase by removing acyl-CoA esters from the enzyme. ACBP is also able to desorb acyl-CoA esters from immobilized membranes and transport and deliver these for mitochondrial beta-oxidation. ACBP efficiently protects acetyl-CoA carboxylase and the mitochondrial ADP/ATP translocase against acyl-CoA inhibition. Finally, ACBP is shown to be able to act as an intracellular acyl-CoA pool former by overexpression in yeast. The possible role of ACBP in lipid metabolism is discussed.
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Affiliation(s)
- J Knudsen
- Institute of Biochemistry, Odense University, Denmark
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37
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Cavallaro S, Korneyev A, Guidotti A, Costa E. Diazepam-binding inhibitor (DBI)-processing products, acting at the mitochondrial DBI receptor, mediate adrenocorticotropic hormone-induced steroidogenesis in rat adrenal gland. Proc Natl Acad Sci U S A 1992; 89:10598-602. [PMID: 1279686 PMCID: PMC50388 DOI: 10.1073/pnas.89.22.10598] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Diazepam-binding inhibitor (DBI) is a 9-kDa polypeptide that colocalizes in glial, adrenocortical, and Leydig cells with the mitochondrial DBI receptor (MDR). By binding with high affinity to the MDR, DBI and one of its processing products--DBI-(17-50)--regulate pregnenolone synthesis and have been suggested to participate in the immediate activation of adrenal steroidogenesis by adrenocorticotropic hormone (ACTH). In adrenals of hypophysectomized rats (1 day after surgery), ACTH failed to acutely affect the amount of adrenal DBI and the density of MDR but increased the rate of DBI processing, as determined by the HPLC profile of DBI-(17-50)-like immunoreactivity. The similar latency times for this effect and for ACTH stimulation of adrenal steroidogenesis suggest that the two processes are related. The ACTH-induced increase in both adrenal steroidogenesis and rate of DBI processing were completely inhibited by cycloheximide; this result suggests the requirement for the de novo synthesis of a protein with a short half-life, probably an endopeptidase. This enzyme, under the influence of ACTH, may activate formation of a DBI-processing product that stimulates steroidogenesis via the MDR. In support of this hypothesis is the demonstration that in hypophysectomized rats the MDR antagonist PK 11195 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxam ide completely inhibited the adrenal steroidogenesis stimulated by ACTH and by the high-affinity MDR ligand 4'-chlorodiazepam.
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Affiliation(s)
- S Cavallaro
- Fidia-Georgetown Institute for Neurosciences, Georgetown University School of Medicine, Washington, DC 20007
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38
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Affiliation(s)
- M Gavish
- Rappaport Family Institute for Research in the Medical Sciences, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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39
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Alho H, Harjuntausta T, Schultz R, Pelto-Huikko M, Bovolin P. Immunohistochemistry of diazepam binding inhibitor (DBI) in the central nervous system and peripheral organs: its possible role as an endogenous regulator of different types of benzodiazepine receptors. Neuropharmacology 1991; 30:1381-6. [PMID: 1664066 DOI: 10.1016/s0028-3908(11)80005-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The distribution of diazepam binding inhibitor (DBI), a multi-function peptide which has recently been discovered, was studied in the rat and human central nervous system and in peripheral organs of the rat by light and electron microscopical immunohistochemistry. In the central nervous system, DBI-LI was localized in many glial cells and glial tumors, and in some neurons. In the periphery, DBI-LI was found in many tissues but it was expressed selectively in specialized cell types. Intense DBI-LI was observed in some endocrine, steroid-producing cells such as glomerular cells of the adrenal gland and Leydig cells of the of the testis. Different types of epithelial cells, for instance distal convoluted tabular cells of the kidney and mucosal cells of the small intestine, displayed moderate DBI-LI. Some supporting cells, such as Schwann cells and Sertoli cells, were also immunopositive. The frequent localization of DBI in cells, also known to contain large amounts of mitochondrial benzodiazepine receptors, indicates that DBI may play an important role as an endogenous regulator of intracellular metabolic functions via the mitochondrial benzodiazepine receptor.
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Affiliation(s)
- H Alho
- Department of Biomedical Sciences, University of Tampere, Finland
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40
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Guidotti A. Role of DBI in brain and its posttranslational processing products in normal and abnormal behavior. Neuropharmacology 1991; 30:1425-33. [PMID: 1664069 DOI: 10.1016/s0028-3908(11)80012-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Because diazepam binding inhibitor (DBI) and its processing products coexist with gamma-aminobutyric acid (GABA) in several axon terminals, DBI immunoreactivity was measured in the cerebrospinal fluid (CSF) of individuals suffering from various neuropsychiatric disorders, that are believe to be associated with abnormalities of GABAergic transmission. Increased amounts of DBI-like immunoreactivity were found in the CSF of patients suffering from severe depression with a severe anxiety component (Barbaccia, Costa, Ferrero, Guidotti, Roy, Sunderland, Pickar, Paul and Goodwin, 1986). Moreover, the amount of DBI and its processing products was found to be increased in the CSF of patients with hepatic encephalopathy (HE) (Rothstein, McKhann, Guarneri, Barbaccia, Guidotti and Costa, 1989; Guarneri, Berkovich, Guidotti and Costa, 1990). The clinical rating of HE correlated with the extent of the increase in DBI in CSF. Other lines of research suggest that DBI and DBI processing products may be important factors in behavioral adaptation to stress, acting via benzodiazepine (BZD) binding sites, located on mitochondria. DBI and its processing products, ODN and TTN, are present in high concentrations in the hypothalamus and in the amygdala, two areas of the brain that are important in regulating behavioral patterns associated with conflict situations, anxiety and stress. In CSF, the content of DBI changes in association with corticotropin releasing factor (CRF) (Roy, Pickar, Gold, Barbaccia, Guidotti, Costa and Linnoila, 1989). Finally DBI is preferentially concentrated in steroidogenic tissues and cells (adrenal cortical cells, Leydig cells of the testes and glial cells of the brain).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Guidotti
- Fidia-Georgetown Institute for the Neurosciences, Georgetown University School of Medicine, Washington, DC 20007
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41
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Abstract
Diazepam binding inhibitor (DBI) is a peptide, initially identified for its ability of displacing the binding of diazepam. The screening of lambda gt 10 cDNA libraries from rat brain with a 47merdeoxyoligonucleotide probe, complementary to a small portion of DBI coding region, allowed the isolation of cDNA clones encoding the entire aminoacid sequence of DBI. This sequence, when compared to that of mouse, human and bovine, revealed that DBI is a well conserved peptide, suggesting a similar function in different species. In order to characterize the function of DBI, studies on the regulation of DBI gene expression were undertaken. The expression of DBI mRNA occurs unevenly in the brain, as well as in peripheral tissues. Moreover, the biosynthesis of DBI is up-regulated in the cerebellum and cerebral cortex of rats made tolerant to diazepam, suggesting that changes in the biosynthesis of DBI might be one of the mechanisms eliciting tolerance to benzodiazepine. In peripheral tissues, the expression of DBI mRNA changes during development. In liver, the content of DBI mRNA was found maximal at postnatal day 1. In contrast, in kidney and heart a linear increase in levels of DBI mRNA was observed from postnatal day 1 to the adult stage, where it reached its maximum level. The tissue specific regulation of DBI mRNA expression, both pharmacologically or developmentally, leads to the hypothesis that DBI might have different functions in different tissues. This would be in line with recent findings that DBI might be also involved in the regulation of an important step of cell metabolism.
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Affiliation(s)
- I Mocchetti
- Department of Anatomy and Cell Biology, Georgetown University, School of Medicine, Washington, DC 20007
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