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Chaney A, Williams SR, Boutin H. In vivo molecular imaging of neuroinflammation in Alzheimer's disease. J Neurochem 2018; 149:438-451. [PMID: 30339715 PMCID: PMC6563454 DOI: 10.1111/jnc.14615] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/24/2018] [Accepted: 09/27/2018] [Indexed: 12/11/2022]
Abstract
It has become increasingly evident that neuroinflammation plays a critical role in the pathophysiology of Alzheimer's disease (AD) and other neurodegenerative disorders. Increased glial cell activation is consistently reported in both rodent models of AD and in AD patients. Moreover, recent genome wide association studies have revealed multiple genes associated with inflammation and immunity are significantly associated with an increased risk of AD development (e.g. TREM2). Non‐invasive in vivo detection and tracking of neuroinflammation is necessary to enhance our understanding of the contribution of neuroinflammation to the initiation and progression of AD. Importantly, accurate methods of quantifying neuroinflammation may aid early diagnosis and serve as an output for therapeutic monitoring and disease management. This review details current in vivo imaging biomarkers of neuroinflammation being explored and summarizes both pre‐clinical and clinical results from molecular imaging studies investigating the role of neuroinflammation in AD, with a focus on positron emission tomography and magnetic resonance spectroscopy (MRS). ![]()
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Affiliation(s)
- Aisling Chaney
- School of Health Sciences, Division of Informatics, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre University of Manchester, Manchester, UK.,Wolfson Molecular Imaging Centre, Faculty of Biology, Medicine and Health and Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Steve R Williams
- School of Health Sciences, Division of Informatics, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre University of Manchester, Manchester, UK
| | - Herve Boutin
- Wolfson Molecular Imaging Centre, Faculty of Biology, Medicine and Health and Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK.,School of Biological Sciences, Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
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2
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Chaney AM, Johnson EM, Cropper HC, James ML. PET Imaging of Neuroinflammation Using [11C]DPA-713 in a Mouse Model of Ischemic Stroke. J Vis Exp 2018. [PMID: 29985311 PMCID: PMC6101726 DOI: 10.3791/57243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Neuroinflammation is central to the pathological cascade following ischemic stroke. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and role of certain neuroimmune interactions in stroke. Specifically, Positron Emission Tomography (PET) imaging of translocator protein 18 kDa (TSPO), a marker of activated microglia and peripheral myeloid-lineage cells, provides a means to detect and track neuroinflammation in vivo. Here, we present a method to accurately quantify neuroinflammation using [11C]N,N-Diethyl-2-[2-(4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl]acetamide ([11C]DPA-713), a promising second generation TSPO-PET radiotracer, in distal middle cerebral artery occlusion (dMCAO) compared to sham-operated mice. MRI was performed 2 days post-dMCAO surgery to confirm stroke and define the infarct location and volume. PET/Computed Tomography (CT) imaging was carried out 6 days post-dMCAO to capture the peak increase in TSPO levels following stroke. Quantitation of PET images was conducted to assess the uptake of [11C]DPA-713 in the brain and spleen of dMCAO and sham mice to assess central and peripheral levels of inflammation. In vivo [11C]DPA-713 brain uptake was confirmed using ex vivo autoradiography.
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Affiliation(s)
| | | | | | - Michelle L James
- Department of Radiology, Stanford University; Department of Neurology and Neurological Sciences, Stanford University;
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4
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Slominski AT, Manna PR, Tuckey RC. On the role of skin in the regulation of local and systemic steroidogenic activities. Steroids 2015; 103:72-88. [PMID: 25988614 PMCID: PMC4631694 DOI: 10.1016/j.steroids.2015.04.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 01/08/2023]
Abstract
The mammalian skin is a heterogeneous organ/tissue covering our body, showing regional variations and endowed with neuroendocrine activities. The latter is represented by its ability to produce and respond to neurotransmitters, neuropeptides, hormones and neurohormones, of which expression and phenotypic activities can be modified by ultraviolet radiation, chemical and physical factors, as well as by cytokines. The neuroendocrine contribution to the responses of skin to stress is served, in part, by local synthesis of all elements of the hypothalamo-pituitary-adrenal axis. Skin with subcutis can also be classified as a steroidogenic tissue because it expresses the enzyme, CYP11A1, which initiates steroid synthesis by converting cholesterol to pregnenolone, as in other steroidogenic tissues. Pregnenolone, or steroidal precursors from the circulation, are further transformed in the skin to corticosteroids or sex hormones. Furthermore, in the skin CYP11A1 acts on 7-dehydrocholesterol with production of 7-dehydropregnolone, which can be further metabolized to other Δ7steroids, which after exposure to UVB undergo photochemical transformation to vitamin D like compounds with a short side chain. Vitamin D and lumisterol, produced in the skin after exposure to UVB, are also metabolized by CYP11A1 to several hydroxyderivatives. Vitamin D hydroxyderivatives generated by action of CYP11A1 are biologically active and are subject to further hydroxylations by CYP27B1, CYP27A1 and CP24A. Establishment of which intermediates are produced in the epidermis in vivo and whether they circulate on the systemic level represent a future research challenge. In summary, skin is a neuroendocrine organ endowed with steroid/secosteroidogenic activities.
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Affiliation(s)
- Andrzej T Slominski
- Department of Dermatology, University of Alabama at Birmingham, VA Medical Center, Birmingham, AL, USA.
| | - Pulak R Manna
- Department of immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Robert C Tuckey
- School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, Australia
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Mattner F, Quinlivan M, Greguric I, Pham T, Liu X, Jackson T, Berghofer P, Fookes CJR, Dikic B, Gregoire MC, Dolle F, Katsifis A. Radiosynthesis, In Vivo Biological Evaluation, and Imaging of Brain Lesions with [123I]-CLINME, a New SPECT Tracer for the Translocator Protein. DISEASE MARKERS 2015; 2015:729698. [PMID: 26199457 PMCID: PMC4496498 DOI: 10.1155/2015/729698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 06/10/2015] [Indexed: 11/17/2022]
Abstract
The high affinity translocator protein (TSPO) ligand 6-chloro-2-(4'-iodophenyl)-3-(N,N-methylethyl)imidazo[1,2-a]pyridine-3-acetamide (CLINME) was radiolabelled with iodine-123 and assessed for its sensitivity for the TSPO in rodents. Moreover neuroinflammatory changes on a unilateral excitotoxic lesion rat model were detected using SPECT imaging. [(123)I]-CLINME was prepared in 70-80% radiochemical yield. The uptake of [(123)I]-CLINME was evaluated in rats by biodistribution, competition, and metabolite studies. The unilateral excitotoxic lesion was performed by injection of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid unilaterally into the striatum. The striatum lesion was confirmed and correlated with TSPO expression in astrocytes and activated microglia by immunohistochemistry and autoradiography. In vivo studies with [(123)I]-CLINME indicated a biodistribution pattern consistent with TPSO distribution and the competition studies with PK11195 and Ro 5-4864 showed that [(123)I]-CLINME is selective for this site. The metabolite study showed that the extractable radioactivity was unchanged [(123)I]-CLINME in organs which expresses TSPO. SPECT/CT imaging on the unilateral excitotoxic lesion indicated that the mean ratio uptake in striatum (lesion:nonlesion) was 2.2. Moreover, TSPO changes observed by SPECT imaging were confirmed by immunofluorescence, immunochemistry, and autoradiography. These results indicated that [(123)I]-CLINME is a promising candidate for the quantification and visualization of TPSO expression in activated astroglia using SPECT.
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Affiliation(s)
- F. Mattner
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
- Department of Molecular Imaging, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - M. Quinlivan
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - I. Greguric
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - T. Pham
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - X. Liu
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - T. Jackson
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - P. Berghofer
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - C. J. R. Fookes
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - B. Dikic
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - M.-C. Gregoire
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - F. Dolle
- CEA, DSV/I2BM, Service Hospitalier Frédéric Joliot, 4 Place du Général Leclerc, 91401 Orsay, France
| | - A. Katsifis
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
- Department of Molecular Imaging, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
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Guerin GF, Schmoutz CD, Goeders NE. The extra-adrenal effects of metyrapone and oxazepam on ongoing cocaine self-administration. Brain Res 2014; 1575:45-54. [PMID: 24887642 DOI: 10.1016/j.brainres.2014.05.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/20/2014] [Accepted: 05/25/2014] [Indexed: 11/30/2022]
Abstract
Investigation of the role of stress in cocaine addiction has yielded an efficacious combination of metyrapone and oxazepam, hypothesized to decrease relapse to cocaine use by reducing stress-induced craving. However, recent data suggest an extra-adrenal role for metyrapone in mediating stress- and addiction-related behaviors. The interactions between the physiological stress response and cocaine self-administration were characterized in rodents utilizing surgical adrenalectomy and pharmacological treatment. Male Wistar rats were trained to self-administer cocaine (0.25mg/kg/infusion) and food pellets under a concurrent alternating fixed-ratio schedule of reinforcement. Surgical removal of the adrenal glands resulted in a significant decrease in plasma corticosterone and a consequent increase in ACTH, as expected. However, adrenalectomy did not significantly affect ongoing cocaine self-administration. Pretreatment with metyrapone, oxazepam and their combinations in intact rats resulted in a significant decrease in cocaine-reinforced responses. These same pharmacological treatments were still effective in reducing cocaine- and food-reinforced responding in adrenalectomized rats. The results of these experiments demonstrate that adrenally-derived steroids are not necessary to maintain cocaine-reinforced responding in cocaine-experienced rats. These results also demonstrate that metyrapone may produce effects outside of the adrenal gland, presumably in the central nervous system, to affect cocaine-related behaviors.
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Affiliation(s)
- Glenn F Guerin
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, 1501 Kings Highway, Box 33932, Shreveport, LA 71130, USA
| | - Christopher D Schmoutz
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, 1501 Kings Highway, Box 33932, Shreveport, LA 71130, USA.
| | - Nicholas E Goeders
- Department of Pharmacology, Toxicology, & Neuroscience, Louisiana State University Health Sciences Center, 1501 Kings Highway, Box 33932, Shreveport, LA 71130, USA
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Progesterone treatment normalizes the levels of cell proliferation and cell death in the dentate gyrus of the hippocampus after traumatic brain injury. Exp Neurol 2011; 231:72-81. [PMID: 21684276 DOI: 10.1016/j.expneurol.2011.05.016] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 05/19/2011] [Accepted: 05/26/2011] [Indexed: 11/21/2022]
Abstract
Traumatic brain injury (TBI) increases cell death in the hippocampus and impairs hippocampus-dependent cognition. The hippocampus is also the site of ongoing neurogenesis throughout the lifespan. Progesterone treatment improves behavioral recovery and reduces inflammation, apoptosis, lesion volume, and edema, when given after TBI. The aim of the present study was to determine whether progesterone altered cell proliferation and short-term survival in the dentate gyrus after TBI. Male Sprague-Dawley rats with bilateral contusions of the frontal cortex or sham operations received progesterone or vehicle at 1 and 6 h post-surgery and daily through post-surgery Day 7, and a single injection of bromodeoxyuridine (BrdU) 48 h after injury. Brains were then processed for Ki67 (endogenous marker of cell proliferation), BrdU (short-term cell survival), doublecortin (endogenous marker of immature neurons), and Fluoro-Jade B (marker of degenerating neurons). TBI increased cell proliferation compared to shams and progesterone normalized cell proliferation in injured rats. Progesterone alone increased cell proliferation in intact rats. Interestingly, injury and/or progesterone treatment did not influence short-term cell survival of BrdU-ir cells. All treatments increased the percentage of BrdU-ir cells that were co-labeled with doublecortin (an immature neuronal marker in this case labeling new neurons that survived 5 days), indicating that cell fate is influenced independently by TBI and progesterone treatment. The number of immature neurons that survived 5 days was increased following TBI, but progesterone treatment reduced this effect. Furthermore, TBI increased cell death and progesterone treatment reduced cell death to levels seen in intact rats. Together these findings suggest that progesterone treatment after TBI normalizes the levels of cell proliferation and cell death in the dentate gyrus of the hippocampus.
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Keitel V, Görg B, Bidmon HJ, Zemtsova I, Spomer L, Zilles K, Häussinger D. The bile acid receptor TGR5 (Gpbar-1) acts as a neurosteroid receptor in brain. Glia 2011; 58:1794-805. [PMID: 20665558 DOI: 10.1002/glia.21049] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
TGR5 (Gpbar-1) is a membrane-bound bile acid receptor in the gastrointestinal tract and immune cells with pleiotropic actions. As shown in the present study, TGR5 is also expressed in astrocytes and neurons. Here, TGR5 may act as a neurosteroid receptor, which is activated by nanomolar concentrations of 5β-pregnan-3α-ol-20-one and micromolar concentrations of 5β-pregnan-3α-17α-21-triol-20-one and 5α-pregnan-3α-ol-20-one (allopregnanolone). TGR5 stimulation in astrocytes and neurons is coupled to adenylate cyclase activation, elevation of intracellular Ca(2+) and the generation of reactive oxygen species. In cultured rat astrocytes, TGR5 mRNA is downregulated in the presence of neurosteroids and ammonia already at concentrations of 0.5 mmol L(-1). Furthermore, TGR5 protein levels are significantly reduced in isolated rat astrocytes after incubation with ammonia. A marked downregulation of TGR5 mRNA is also found in cerebral cortex from cirrhotic patients dying with hepatic encephalopathy (HE) when compared with brains from noncirrhotic control subjects. It is concluded that TGR5 is a novel neurosteroid receptor in brain with implications for the pathogenesis of HE.
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Affiliation(s)
- Verena Keitel
- Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University, Moorenstrasse 5, 40225 Düsseldorf, Germany
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Giatti S, Pesaresi M, Cavaletti G, Bianchi R, Carozzi V, Lombardi R, Maschi O, Lauria G, Garcia-Segura L, Caruso D, Melcangi R. Neuroprotective effects of a ligand of translocator protein-18kDa (Ro5-4864) in experimental diabetic neuropathy. Neuroscience 2009; 164:520-9. [DOI: 10.1016/j.neuroscience.2009.08.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 08/03/2009] [Accepted: 08/03/2009] [Indexed: 12/11/2022]
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Katsifis A, Barlin G, Mattner F, Dikic B. Synthesis of [123I]iodine labelled imidazo[1,2-b] pyridazines as potential probes for the study of peripheral benzodiazepine receptors using SPECT. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.92.4.305.35581] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The pyridazines 3-acetamidomethyl-6-chloro-2-(4´-iodophenyl)imidazo[1,2-b]pyridazine 1 (IC50=1.6 nM) and 3-benzamidomethyl-6-iodo-2-(4´-t-butylphenyl)imidazo[1,2-b] pyridazine 2 (IC50=4.2 nM), are high affinity and selective ligands for the Peripheral Benzodiazepine Receptors (PBR) compared to the Central Benzodiazepine counterparts. The [123I] 1 and [123I] 2 labelled analogues of these compounds were subsequently synthesised for the potential study of the PBR in vivo using SPECT. Radioiodination of [123I] 1 was achieved by iododestannylation of the corresponding tributyl tin precursor with Na[ 123I] in the presence of peracetic acid or chloramine-T and the product isolated by C-18 RP HPLC. Radioiodination of [123I] 2 was achieved by copper assisted bromine [123I]iodine exchange of the corresponding bromo precursor in the presence of acetic acid and sodium bisulfate as reducing agent at 200 °C. Purification of the crude products were achieved by semi-preparative C-18 RP HPLC to give the products in radiochemical yields >90%. The products were obtained in >97% chemical and radiochemical purity and with specific activities >180 GBq/μmol.
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Cosenza-Nashat M, Zhao ML, Suh HS, Morgan J, Natividad R, Morgello S, Lee SC. Expression of the translocator protein of 18 kDa by microglia, macrophages and astrocytes based on immunohistochemical localization in abnormal human brain. Neuropathol Appl Neurobiol 2008; 35:306-28. [PMID: 19077109 DOI: 10.1111/j.1365-2990.2008.01006.x] [Citation(s) in RCA: 338] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
AIMS Microglia are involved in neurodegeneration, are prime targets for anti-inflammatory therapy and are potential biomarkers of disease progression. For example, positron emission tomography imaging employing radioligands for the mitochondrial translocator protein of 18 kDa (TSPO, formerly known as the peripheral benzodiazepine receptor) is being scrutinized to detect neuroinflammation in various diseases. TSPO is presumably present in activated microglia, but may be present in other neural cells. METHODS We sought to elucidate the protein expression in normal human central nervous system, several neurological diseases (HIV encephalitis, Alzheimer's disease, multiple sclerosis and stroke) and simian immunodeficiency virus encephalitis by performing immunohistochemistry with two anti-TSPO antibodies. RESULTS Although the overall parenchymal staining was minimal in normal brain, endothelial and smooth muscle cells, subpial glia, intravascular monocytes and ependymal cells were TSPO-positive. In disease states, elevated TSPO was present in parenchymal microglia, macrophages and some hypertrophic astrocytes, but the distribution of TSPO varied depending on the disease, disease stage and proximity to the lesion or relation to infection. Staining with the two antibodies correlated well in white matter, but one antibody also stained cortical neurones. Quantitative analysis demonstrated a significant increase in TSPO in the white matter of HIV encephalitis compared with brains without encephalitis. TSPO expression was also increased in simian immunodeficiency virus encephalitis. CONCLUSIONS This report provides the first comprehensive immunohistochemical analysis of the expression of TSPO. The results are useful for informing the usage of positron emission tomography as an imaging modality and have an impact on the potential use of TSPO as an anti-inflammatory pharmacological target.
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Affiliation(s)
- M Cosenza-Nashat
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Frye CA, Paris JJ, Rhodes ME. Increasing 3alpha,5alpha-THP following inhibition of neurosteroid biosynthesis in the ventral tegmental area reinstates anti-anxiety, social, and sexual behavior of naturally receptive rats. Reproduction 2008; 137:119-28. [PMID: 18818272 DOI: 10.1530/rep-08-0250] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The progesterone metabolite and neurosteroid, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), has actions in the midbrain ventral tegmental area (VTA) to modulate lordosis, but its effects on other reproductively relevant behaviors are not well understood. Effects on exploration, anxiety, and social behavior resulting from inhibition of 3alpha,5alpha-THP formation, as well as 3alpha,5alpha-THP enhancement, were investigated in the midbrain VTA. Naturally sexually receptive, female rats (n=8-10/group) received infusions aimed at the midbrain VTA of vehicle, PK11195 (an inhibitor of neurosteroidogenesis), and/or indomethacin (an inhibitor of 3alpha,5alpha-THP formation from prohormones), and were subsequently infused with vehicle or FGIN 1-27 (a neurosteroidogenesis enhancer). The rats were then assessed in a behavioral battery that examined exploration (open field), anxiety (elevated plus maze), social (social interaction), and sexual (paced mating) behavior. Inhibition of 3alpha,5alpha-THP formation decreased exploratory, anti-anxiety, social, and sexual behavior, as well as midbrain 3alpha,5alpha-THP levels. Infusions of FGIN 1-27 following 3alpha,5alpha-THP inhibition restored these behaviors and midbrain 3alpha,5alpha-THP levels to those commensurate with control rats that had not been administered inhibitors. These findings suggest that 3alpha,5alpha-THP formation in the midbrain VTA may influence appetitive, as well as consummatory, aspects of mating behavior.
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Affiliation(s)
- Cheryl A Frye
- Department of Psychology, The Centers for Neuroscience Life Sciences Research 1058, The University at Albany-SUNY, Albany, New York 12222, USA.
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Gottfried-Blackmore A, Sierra A, Jellinck PH, McEwen BS, Bulloch K. Brain microglia express steroid-converting enzymes in the mouse. J Steroid Biochem Mol Biol 2008; 109:96-107. [PMID: 18329265 PMCID: PMC2423427 DOI: 10.1016/j.jsbmb.2007.12.013] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the CNS, steroid hormones play a major role in the maintenance of brain homeostasis and it's response to injury. Since activated microglia are the pivotal immune cell involved in neurodegeneration, we investigated the possibility that microglia provide a discrete source for the metabolism of active steroid hormones. Using RT-PCR, our results showed that mouse microglia expressed mRNA for 17beta-hydroxysteroid dehydrogenase type 1 and steroid 5alpha-reductase type 1, which are involved in the metabolism of androgens and estrogens. Microglia also expressed the peripheral benzodiazepine receptor and steroid acute regulatory protein; however, the enzymes required for de novo formation of progesterone and DHEA from cholesterol were not expressed. To test the function of these enzymes, primary microglia cultures were incubated with steroid precursors, DHEA and AD. Microglia preferentially produced delta-5 androgens (Adiol) from DHEA and 5alpha-reduced androgens from AD. Adiol behaved as an effective estrogen receptor agonist in neuronal cells. Activation of microglia with pro-inflammatory factors, LPS and INFgamma did not affect the enzymatic properties of these proteins. However, PBR ligands reduced TNFalpha production signifying an immunomodulatory role for PBR. Collectively, our results suggest that microglia utilize steroid-converting enzymes and related proteins to influence inflammation and neurodegeneration within microenvironments of the brain.
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Affiliation(s)
| | - Amanda Sierra
- Laboratory of Neuroendocrinology, Rockefeller University, 1230 York Ave, New York, NY 10065
| | - Peter H. Jellinck
- Department of Biochemistry, Queen’s University, Kingston, Ontario K7L 3N6 Canada
| | - Bruce S. McEwen
- Laboratory of Neuroendocrinology, Rockefeller University, 1230 York Ave, New York, NY 10065
| | - Karen Bulloch
- Laboratory of Cell Physiology and Immunology, Rockefeller University, 1230 York Ave, New York, NY 10065
- CORRESPONDING AUTHOR: Karen Bulloch, Laboratory of Cell Physiology and Immunology, Rockefeller University (box 165), 1230 York Ave, New York, NY 10065. E-mail:
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Chen MK, Guilarte TR. Translocator protein 18 kDa (TSPO): molecular sensor of brain injury and repair. Pharmacol Ther 2008; 118:1-17. [PMID: 18374421 DOI: 10.1016/j.pharmthera.2007.12.004] [Citation(s) in RCA: 398] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 12/21/2007] [Indexed: 11/25/2022]
Abstract
For over 15 years, the peripheral benzodiazepine receptor (PBR), recently named translocator protein 18 kDa (TSPO) has been studied as a biomarker of reactive gliosis and inflammation associated with a variety of neuropathological conditions. Early studies documented that in the brain parenchyma, TSPO is exclusively localized in glial cells. Under normal physiological conditions, TSPO levels are low in the brain neuropil but they markedly increase at sites of brain injury and inflammation making it uniquely suited for assessing active gliosis. This research has generated significant efforts from multiple research groups throughout the world to apply TSPO as a marker of "active" brain pathology using in vivo imaging modalities such as Positron Emission Tomography (PET) in experimental animals and humans. Further, in the last few years, there has been an increased interest in understanding the molecular and cellular function(s) of TSPO in glial cells. The latest evidence suggests that TSPO may not only serve as a biomarker of active brain disease but also the use of TSPO-specific ligands may have therapeutic implications in brain injury and repair. This review presents an overview of the history and function of TSPO focusing on studies related to its use as a sensor of active brain disease in experimental animals and in human studies.
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Affiliation(s)
- Ming-Kai Chen
- Neurotoxicology & Molecular Imaging Laboratory, Department of Environmental Health Sciences, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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Pharmacological evaluation of [123I]-CLINDE: a radioiodinated imidazopyridine-3-acetamide for the study of peripheral benzodiazepine binding sites (PBBS). Eur J Nucl Med Mol Imaging 2007; 35:779-89. [PMID: 18057934 DOI: 10.1007/s00259-007-0645-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 10/23/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE The study aims to evaluate the iodinated imidazopyridine, N',N'-diethyl-6-Chloro-(4'-[(123)I]iodophenyl)imidazo[1,2-a]pyridine-3-acetamide ([(123)I]-CLINDE) as a tracer for the study of peripheral benzodiazepine binding sites (PBBS). MATERIALS AND METHODS In vitro studies were performed using membrane homogenates and sections from kidney, adrenals, and brain cortex of Sprague-Dawley (SD) rats and incubated with [(123)I]-CLINDE. For in vivo studies, the rats were injected with [(123)I]-CLINDE. In competition studies, PBBS-specific drugs PK11195 and Ro 5-4864 and the CBR specific drug Flumazenil were injected before the radiotracer. RESULTS In vitro binding studies in adrenal, kidney, and cortex mitochondrial membranes indicated that [(123)I]-CLINDE binds with high affinity to PBBS, K(d) = 12.6, 0.20, and 3.84 nM, respectively. The density of binding sites was 163, 5.3, and 0.34 pmol/mg protein, respectively. In vivo biodistribution indicated high uptake in adrenals (5.4), heart (1.5), lungs (1.5), kidney (1.5) %ID/g at 6 h p.i. In the central nervous system (CNS), the olfactory bulbs displayed the highest uptake; up to six times the activity in blood. Pre-administration of unlabeled CLINDE, PK11195 and Ro 5-4864 (1 mg/kg) reduced the uptake of [(123)I]-CLINDE by 70-55% in olfactory bulbs. In the kidney and heart, a reduction of 60-80% ID/g was observed, while an increase was observed in the adrenals requiring 10 mg/kg for significant displacement. Flumazenil had no effect on uptake in peripheral organs and brain. Metabolite analysis indicated >90% of the radioactivity in the above tissues was intact [(123)I]-CLINDE. CONCLUSION [(123)I]-CLINDE displays high and selective uptake for the PBBS and warrants further development as a probe for imaging PBBS using single photon emission computed tomography (SPECT).
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Morris RL, Varnes ME, Kenney ME, Li YS, Azizuddin K, McEnery MW, Oleinick NL. The Peripheral Benzodiazepine Receptor in Photodynamic Therapy with the Phthalocyanine Photosensitizer Pc 4¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2002)0750652tpbrip2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Sakai M, Fonseca ESM, Oloris SCS, Matsuzaki P, Otake AH, Leite KRM, Massoco CO, Dagli MLZ, Palermo-Neto J. Effects of peripheral-type benzodiazepine receptor ligands on Ehrlich tumor cell proliferation. Eur J Pharmacol 2006; 550:8-14. [PMID: 17027961 DOI: 10.1016/j.ejphar.2006.07.057] [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: 11/10/2005] [Revised: 07/11/2006] [Accepted: 07/26/2006] [Indexed: 11/18/2022]
Abstract
Peripheral-type benzodiazepine receptors have been found throughout the body, and particularly, in high numbers, in neoplastic tissues such as the ovary, liver, colon, breast, prostate and brain cancer. Peripheral-type benzodiazepine receptor expression has been associated with tumor malignity, and its subcellular localization is important to define its function in tumor cells. We investigated the presence of peripheral-type benzodiazepine receptors in Ehrlich tumor cells, and the in vitro effects of peripheral-type benzodiazepine receptors ligands on tumor cell proliferation. Our results demonstrate the presence of peripheral-type benzodiazepine receptor in the nucleus of Ehrlich tumor cells (85.53+/-12.60%). They also show that diazepam and Ro5-4864 (peripheral-type benzodiazepine receptor agonists) but not clonazepam (a molecule with low affinity for the peripheral-type benzodiazepine receptor) decreased the percentage of tumor cells in G0-G1 phases and increased that of cells in S-G2-M phases. The effects of those agonists were prevented by PK11195 (a peripheral-type benzodiazepine receptor antagonist) that did not produce effects by itself. Altogether, these data suggest that the presence of peripheral-type benzodiazepine receptor within the nucleus of Ehrlich tumor cells is associated with tumor malignity and proliferation capacity.
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Affiliation(s)
- Mônica Sakai
- Laboratory of Applied Pharmacology and Toxicology, School of Veterinary Medicine, University of São Paulo, São Paulo, SP, Brazil
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Herman M, Kang SS, Lee S, James P, Rivier C. Systemic Administration of Alcohol to Adult Rats Inhibits Leydig Cell Activity: Time Course of Effect and Role of Nitric Oxide. Alcohol Clin Exp Res 2006; 30:1479-91. [PMID: 16930210 DOI: 10.1111/j.1530-0277.2006.00179.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Alcohol has been shown to interfere with testosterone (T) release from Leydig cells. However, the mechanisms responsible for this phenomenon, which may include decreased activity of the luteinizing hormone-releasing hormone (LHRH)-LH axis, as well as a direct influence of the drug on the testes, are not fully understood. In this work, we investigated the influence of alcohol, administered intragastrically (i.g.) or delivered via vapors, on Leydig cell activity and T release. Leydig cell function was studied by measuring changes in the levels of the steroidogenic proteins steroidogenic acute regulatory (StAR), the peripheral-type benzodiazepine receptor (PBR), and the cytochrome P450 side-chain cleavage enzyme (P450scc). Testosterone release was studied under basal conditions or in response to human chorionic gonadotropin (hCG). Finally, to identify potential factors mediating the influence of alcohol, we measured the testicular variant of the neuronal nitric oxide (NO) synthase (NOS), TnNOS, in semipurified Leydig cells. METHODS Adult male Sprague-Dawley rats were either injected with alcohol i.g. once or exposed to alcohol vapors (4 h/d) for 1 or 5 days. Controls received the vehicle (i.g. model) or were kept in boxes through which no vapors were circulated. Following these treatments, one series of experiments was devoted to investigate Leydig cell responsiveness by measuring plasma T levels before or after the intravenous injection of hCG (1 U/kg). In another series of experiments, we used semipurified Leydig cell preparations to measure StAR, PBR, P450scc, and TnNOS by Western blot analysis. RESULTS In the i.g. model, the T response to hCG was blunted for 12 hours following alcohol injection, but showed a rebound at 48 hours. Levels of StAR protein and of PBR, but not of P450scc, were significantly decreased within 10 minutes of drug administration. While StAR then remained depressed for 24 hours, PBR values were variable over this time course. By 48 hours, StAR, PBR, and P450scc levels had increased above control values. Both StAR and PBR levels showed correlations with plasma T levels. In the alcohol vapor models, both regimens of the drug also significantly depressed StAR and PBR protein concentrations, blunted the T response to hCG, and did not alter P450scc. Finally, we observed that alcohol delivered i.g. or via vapors up-regulated TnNOS levels in Leydig cells, but that blockade of NO formation failed to restore a normal T response to hCG. CONCLUSIONS Collectively, these results suggest that (a) the ability of Leydig cells to release T does not show a simple correlation with changes in StAR, PBR, and P450scc levels; (b) the time course of the alcohol-induced changes were protein-specific; and (c) despite the ability of alcohol to stimulate TnNOS expression, NO does not appear to mediate the inhibitory influence of this drug on testicular steroidogenesis in the models that we studied.
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Affiliation(s)
- Melissa Herman
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California 92037, USA
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Abstract
Neurosteroids regulate neuronal excitability and are expressed at particularly high levels in the CNS during the perinatal period. Further, neurosteroid levels are increased by a variety of stressors including hypoxia, asphyxia, parturition, ethanol exposure and infection. One mechanism by which neurosteroids regulate neuronal activity is by negative or positive modulation of GABA(A) receptor function. Perinatal respiration is strongly modulated by GABAergic synaptic drive, and GABA release is increased during hypoxia to contribute to hypoxia-induced depression of neonatal ventilation. Here, we use in vitro and in vivo rat models to test the hypothesis that GABA(A) receptor-mediated modulation of perinatal respiration is markedly influenced by the presence of neurosteroids. The principal finding of this study was that the efficacy of GABA(A) receptor-mediated modulation of respiratory membrane potential and rhythmogenesis is markedly enhanced by allopregnanolone and depressed by dehydroepiandrosterone sulphate. These data demonstrate that the modulation of breathing via GABA(A) receptor activation will be determined by the overall balance of negative and positive neurosteroid modulators within respiratory nuclei. This adds a level of complexity that must be considered when examining the depression of breathing in mammals associated with various behavioural states and pathogenic conditions such as apnoea and sudden death suspected to be associated with central respiratory dysfunction.
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Affiliation(s)
- Jun Ren
- Department of Physiology, Division of Neuroscience, 513 HMRC, University of Alberta, Edmonton Alberta, Canada T6G 2S2
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Chen MK, Guilarte TR. Imaging the peripheral benzodiazepine receptor response in central nervous system demyelination and remyelination. Toxicol Sci 2006; 91:532-9. [PMID: 16554315 DOI: 10.1093/toxsci/kfj172] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We used a rodent model of cuprizone-induced demyelination to examine the peripheral benzodiazepine receptor (PBR) response during remyelination. C57BL/6J mice were fed a 0.2% cuprizone-containing or control diet for 3 weeks and then removed to allow for remyelination. Quantitative autoradiography of 3H-(R)-PK11195 binding to PBR in the corpus callosum showed increased levels at 3 weeks of demyelination and gradually decreased as a function of remyelination. PBR levels were associated with the degree of remyelination and activation of microglia and astrocytes. However, the temporal pattern suggests that the PBR signal during the late stages of remyelination was primarily associated with astrocytes. We also used small-animal positron-emission tomography (PET) imaging to determine if this technique could be used to monitor PBR levels in the brain of living mice. The results indicate that 11C-(R)-PK11195 levels are significantly elevated in the mouse brain during cuprizone-induced demyelination and normalize at a time in which remyelination is complete. These findings support the notion that PBR is a sensitive marker for the visualization and quantification of brain injury and recovery. Further, the in vivo imaging of the PBR response is now possible in the living rodent brain.
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Affiliation(s)
- Ming-Kai Chen
- Molecular Neurotoxicology Laboratory, Department of Environmental Health Sciences, The Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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21
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Lavaque E, Sierra A, Azcoitia I, Garcia-Segura LM. Steroidogenic acute regulatory protein in the brain. Neuroscience 2006; 138:741-7. [PMID: 16338087 DOI: 10.1016/j.neuroscience.2005.05.060] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 05/31/2005] [Indexed: 01/19/2023]
Abstract
The nervous system synthesizes steroids that regulate the development and function of neurons and glia, and have neuroprotective properties. The first step in steroidogenesis involves the delivery of free cholesterol to the inner mitochondrial membrane where it can be converted into pregnenolone by the enzyme cytochrome P450side chain cleavage. The peripheral-type benzodiazepine receptor and the steroidogenic acute regulatory protein are involved in this process and appear to function in a coordinated manner. Steroidogenic acute regulatory protein mRNA and protein are widely expressed throughout the adult brain. Steroidogenic acute regulatory protein expression has been detected in many neuronal populations, in ependymocytes, in some astroglial cells, in Schwann cells from peripheral nerves and in proliferating cells of the developing and adult brain. Steroidogenic acute regulatory protein is colocalized in the same neural cells with P450side chain cleavage and with other steroidogenic enzymes. Steroidogenic acute regulatory protein expression in the brain shows marked changes with development, aging and injury. The steroidogenic acute regulatory protein gene may be under the control of diverse mechanisms in different neural cell types, since its expression is upregulated by cyclic AMP (cAMP) in gliomas and astrocytes in culture and downregulated by cyclic AMP (cAMP) in Schwann cells. In addition, activation of N-methyl-D-aspartate receptors, and the consequent rise in intracellular calcium levels, activates steroidogenic acute regulatory protein and steroidogenesis in hippocampal neurons. In conclusion, steroidogenic acute regulatory protein is regulated in the nervous system by different physiological and pathological conditions and may play an important role during brain development, aging and after injury.
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Affiliation(s)
- E Lavaque
- Instituto Cajal, CSIC, Madrid, Spain
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22
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Herman M, Rivier C. Activation of a neural brain-testicular pathway rapidly lowers Leydig cell levels of the steroidogenic acute regulatory protein and the peripheral-type benzodiazepine receptor while increasing levels of neuronal nitric oxide synthase. Endocrinology 2006; 147:624-33. [PMID: 16239298 DOI: 10.1210/en.2005-0879] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Activation of a neural brain-testicular pathway by the intracerebroventricular injection of the beta-adrenergic agonist isoproterenol (ISO), the hypothalamic peptide corticotropin-releasing factor (CRF), or alcohol (EtOH) rapidly decreases the testosterone (T) response to human chorionic gonadotropin. To elucidate the intratesticular mechanisms responsible for this phenomenon, we investigated the influence of intracerebroventricular-injected ISO, CRF, or EtOH on levels of the steroidogenic acute regulatory (StAR) protein, the peripheral-type benzodiazepine receptor (PBR), and the cytochrome P450 side-chain cleavage enzyme in semipurified Leydig cells. ISO (10 microg), CRF (5 microg), or EtOH (5 microl of 200 proof, a dose that does not induce neuronal damage nor leaks to the periphery) rapidly decreased StAR and PBR but not cytochrome P450 side-chain cleavage enzyme protein levels. Levels of the variant of the neuronal nitric oxide synthase (nNOS) that is restricted to Leydig cells, TnNOS, significantly increased in response to ISO, CRF, and EtOH over the time course of altered StAR/PBR concentrations. However, pretreatment of the rats with N(w)nitro-arginine methylester, which blocked ISO-induced increases in TnNOS, neither restored the T response to human chorionic gonadotropin nor prevented the decreases in StAR and PBR. These results provide evidence of concomitant changes in Leydig cell StAR and PBR levels in live rats. They also indicate that activation of a neural brain-testicular pathway rapidly decreases concentrations of these steroidogenic proteins while up-regulating testicular NO production. However, additional studies are necessary to elucidate the functional role played by this gas in our model.
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Affiliation(s)
- Melissa Herman
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California 92037, USA
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Leonelli E, Yague JG, Ballabio M, Azcoitia I, Magnaghi V, Schumacher M, Garcia-Segura LM, Melcangi RC. Ro5-4864, a synthetic ligand of peripheral benzodiazepine receptor, reduces aging-associated myelin degeneration in the sciatic nerve of male rats. Mech Ageing Dev 2005; 126:1159-63. [PMID: 16045970 DOI: 10.1016/j.mad.2005.06.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 05/31/2005] [Accepted: 06/03/2005] [Indexed: 11/22/2022]
Abstract
The peripheral-type benzodiazepine receptor (PBR) is a protein predominantly located in the mitochondrial outer membrane that plays an important role in the regulation of cell survival and proliferation. Previous studies have shown an enhanced expression of PBR in the regenerating sciatic nerve, suggesting that this protein may be involved in the regenerative response. The rat sciatic nerve suffers important structural alterations with aging, including alterations in the morphology of myelin sheaths and a decrease in the number of myelinated fibers. In this study, we have assessed the effect of two PBR ligands, Ro5-4864 and PK-11195, to determine whether PBR may influence aging-associated morphological changes in the sciatic nerve. The treatment of 23-month-old, Sprague-Dawley male rats for 1 month with Ro5-4864 significantly reduced the percentage of fibers with myelin decompaction and increased the total number of myelinated fibers. In contrast, PK-11195, a PBR ligand that binds to a different site than Ro5-4864 in the PBR molecule, did not significantly affect any of the parameters analyzed. These findings support the potential role of PBR ligands to prevent aging-associated peripheral nerve degeneration.
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Affiliation(s)
- Emanuela Leonelli
- Department of Endocrinology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via G. Balzaretti 9, 20133 Milano, Italy
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Laufer N, Maayan R, Hermesh H, Marom S, Gilad R, Strous R, Weizman A. Involvement of GABAA receptor modulating neuroactive steroids in patients with social phobia. Psychiatry Res 2005; 137:131-6. [PMID: 16226317 DOI: 10.1016/j.psychres.2005.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 05/16/2005] [Accepted: 07/13/2005] [Indexed: 11/17/2022]
Abstract
Dehydroepiandrosterone (DHEA) and its sulfate ester (DHEA-S), neurosteroids synthesized in the brain, are weak gamma-aminobutyric acid (GABA) A receptor allosteric antagonists that may be involved in anxiety disorders. In the present study we measured the circulatory [corrected] levels of DHEA, DHEA-S, pregnenolone and cortisol in [corrected] untreated patients (n=26) diagnosed with social phobia (SP) compared with sex- and age-matched healthy controls (n=21). No significant differences in neurosteroids were observed in [corrected] untreated SP patients and [corrected] compared with healthy controls. The findings may reflect an absence of involvement of the GABA(A) modulators DHEA, DHEA-S and pregnenolone in SP.
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Affiliation(s)
- Neil Laufer
- Laboratory of Biological Psychiatry, Felsenstein Medical Research Center, Beilinson Campus, Petah Tiqva, Israel
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Petralia SM, Jahagirdar V, Frye CA. Inhibiting biosynthesis and/or metabolism of progestins in the ventral tegmental area attenuates lordosis of rats in behavioural oestrus. J Neuroendocrinol 2005; 17:545-52. [PMID: 16101892 DOI: 10.1111/j.1365-2826.2005.01342.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the ventral tegmental area (VTA), lordosis of rats is facilitated by 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP). Central 3alpha,5alpha-THP results from metabolism of peripheral progesterone, from the ovaries and/or adrenals, by sequential enzymatic activity of 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase (3alpha-HSOR). In addition, in glial cells, cholesterol is converted into pregnenolone by the P450 side-chain cleavage enzyme (P450scc), which is then metabolized to progesterone by 3beta-hydroxysteroid dehydrogenase, and subsequently reduced to 3alpha,5alpha-THP. We hypothesize that, in the VTA, formation of 3alpha,5alpha-THP by both metabolism and biosynthesis is necessary for facilitation of lordosis of female rats. In Experiment 1, naturally-receptive rats received bilateral VTA infusions of a P450scc inhibitor, digitoxin (1 microg/side); a 5alpha-reductase inhibitor, finasteride (10 microg/side); digitoxin (1 microg/side)+finasteride (10 microg/side); or vehicle and were tested 3 h later for lordosis. In Experiment 2, the effects of VTA infusions of digitoxin, finasteride, digitoxin+finasteride, or vehicle on lordosis and midbrain and plasma 3alpha,5alpha-THP levels were examined. In Experiment 3, we investigated whether infusions of 3alpha,5alpha-THP to the VTA reinstated lordosis and midbrain 3alpha,5alpha-THP levels following administration of inhibitors. VTA infusions of digitoxin, finasteride, or digitoxin+finasteride, significantly and similarly reduced lordosis and midbrain, but not plasma 3alpha,5alpha-THP levels, compared to vehicle. Following receipt of inhibitor infusions, 3alpha,5alpha-THP to the VTA restored lordosis and midbrain 3alpha,5alpha-THP levels. These data suggest that, in the VTA, both central biosynthesis of progesterone and metabolism of progesterone (from central and/or peripheral sources) to 3alpha,5alpha-THP are important for mediating lordosis of rats.
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Affiliation(s)
- S M Petralia
- Department of Psychology, The University at Albany, SUNY, Albany, NY 12222, USA
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Veiga S, Azcoitia I, Garcia-Segura LM. Ro5-4864, a peripheral benzodiazepine receptor ligand, reduces reactive gliosis and protects hippocampal hilar neurons from kainic acid excitotoxicity. J Neurosci Res 2005; 80:129-37. [PMID: 15696538 DOI: 10.1002/jnr.20430] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The peripheral-type benzodiazepine receptor (PBR) is a critical component of the mitochondrial permeability transition pore, which is involved in the regulation of cell survival. Different forms of brain injury result in induction of the expression of the PBR in the areas of neurodegeneration, mainly in reactive glial cells. The consequences of induction of PBR expression after brain injury are unknown. To test whether PBR may be involved in the regulation of neuronal survival after injury, we have assessed the effect of two PBR ligands, Ro5-4864 and PK11195, on neuronal loss induced by kainic acid in the hippocampus. Systemic administration of kainic acid to male rats resulted in the induction of a reactive phenotype in astrocytes and microglia and in a significant loss of hilar neurons in the dentate gyrus. Administration of Ro5-4864, before the injection of kainic acid, decreased reactive gliosis in the hilus and prevented hilar neuronal loss. In contrast, PK11195 was unable to reduce reactive gliosis and did not protect hilar neurons from kainic acid. These findings suggest that the PBR is involved in control of neuronal survival and gliosis after brain injury and identify this molecule as a potential target for neuroprotective interventions.
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Zimmerberg B, Brunelli SA, Fluty AJ, Frye CA. Differences in affective behaviors and hippocampal allopregnanolone levels in adult rats of lines selectively bred for infantile vocalizations. Behav Brain Res 2005; 159:301-11. [PMID: 15817193 DOI: 10.1016/j.bbr.2004.11.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 11/08/2004] [Accepted: 11/08/2004] [Indexed: 11/21/2022]
Abstract
Allopregnanolone, 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-THP), a progesterone metabolite, is an endogenous neurosteroid mediating affective behaviors via its positive modulation of GABA(A) receptors. In order to better understand the role of this neurosteroid in individual differences in affective behavior, we used an animal model based on selective breeding for an infantile affective trait, ultrasonic vocalizations (USV). Adult male and female (in either proestrus or diestrus) rats that had been bred for low (low line) or high (high line) rates of USV after maternal separation were tested in a series of affective behavioral tests: open field, emergence, social interaction, defensive freezing, and the Porsolt forced swim task. Concentrations of allopregnanolone in combined hippocampus and amygdala tissue were then measured. low line subjects showed significantly lower anxiety and depression responses in the emergence, open field, and Porsolt forced swim tasks than did high line subjects. Proestrus females exhibited less affective behaviors than diestrus females or males. Allopregnanolone levels in hippocampus/amygdala were significantly higher in low line subjects compared to high line subjects, and in proestrus females compared to diestrus females and males. These data indicate that: (1) affective behaviors in lines selectively bred for an infantile anxiety trait exhibit selection persistence into adulthood; and (2) levels of allopregnanolone in the limbic system parallel selected disparities in affective behavior, suggesting a selection for alterations in the neurosteroid/GABA(A) receptor system in these lines.
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Affiliation(s)
- Betty Zimmerberg
- Department of Psychology, Williams College, 18 Hoxsey Street, Williamstown, MA 01267, USA.
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Petralia SM, Frye CA. In the ventral tegmental area picrotoxin blocks FGIN 1-27-induced increases in sexual behavior of rats and hamsters. Psychopharmacology (Berl) 2005; 178:174-82. [PMID: 15338106 DOI: 10.1007/s00213-004-2001-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Accepted: 07/23/2004] [Indexed: 10/26/2022]
Abstract
RATIONALE AND OBJECTIVES There are two types of benzodiazepine receptors, mitochondrial benzodiazepine receptors (MBRs), and gamma-aminobutyric acid (GABA(A))/benzodiazepine receptor complexes (GBRs). MBR activation increases neurosteroidogenesis. Ventral tegmental area (VTA) infusions of the MBR agonist, FGIN 1-27, increase midbrain levels of the progesterone metabolite 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP) and lordosis of rats and hamsters. Activation of GBRs leads to membrane hyperpolarization. In the VTA, infusions of GBR agonists enhance 3alpha,5alpha-THP-facilitated lordosis. Thus, if, in the VTA, MBR-mediated increases in 3alpha,5alpha-THP enhance sexual responses via actions at GBRs, then blocking GBRs with picrotoxin will reduce FGIN 1-27-induced increases in sexual behavior of female rodents. METHODS Ovariectomized rats and hamsters, with unilateral guide cannula to the VTA, received estradiol benzoate (10 mug; EB) at hour 0. Hamsters also received progesterone (100 mug) at hour 44. At hour 47.5, all animals were infused first with 10 ng or 20 ng picrotoxin or saline, vehicle to the VTA and, 30 min later, with 5 mug/11.4 nM FGIN 1-27 or saline, vehicle. Ten minutes later, animals were tested for sex and motor behavior. RESULTS Picrotoxin, but not vehicle, infusions blocked FGIN 1-27-mediated increases in lordosis of rats and hamsters, proceptivity of rats, and sexual responsiveness of hamsters. In addition, midbrain 3alpha,5alpha-THP levels were higher in animals that received VTA infusions of FGIN 1-27, compared to those infused with saline, vehicle. CONCLUSION In the VTA, GBRs are required for MBR-enhanced sexual behavior of EB-primed rats and EB- and progesterone-primed hamsters.
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Affiliation(s)
- Sandra M Petralia
- Department of Psychology, The University at Albany-SUNY, 1400 Washington Avenue, Albany, NY 12222, USA
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Mattner F, Katsifis A, Staykova M, Ballantyne P, Willenborg DO. Evaluation of a radiolabelled peripheral benzodiazepine receptor ligand in the central nervous system inflammation of experimental autoimmune encephalomyelitis: a possible probe for imaging multiple sclerosis. Eur J Nucl Med Mol Imaging 2004; 32:557-63. [PMID: 15875181 DOI: 10.1007/s00259-004-1690-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2004] [Accepted: 08/20/2004] [Indexed: 11/29/2022]
Abstract
PURPOSE Peripheral benzodiazepine receptors (PBRs) are upregulated on macrophages and activated microglia, and radioligands for the PBRs can be used to detect in vivo neuroinflammatory changes in a variety of neurological insults, including multiple sclerosis. Substituted 2-phenyl imidazopyridine-3-acetamides with high affinity and selectivity for PBRs have been prepared that are suitable for radiolabelling with a number of positron emission tomography and single-photon emission computed tomography (SPECT) isotopes. In this investigation, the newly developed high-affinity PBR ligand 6-chloro-2-(4'-iodophenyl)-3-(N,N-diethyl)imidazo[1,2-a]pyridine-3-acetamide, or CLINDE, was radiolabelled with 123I and its biodistribution in the central nervous system (CNS) of rats with experimental autoimmune encephalomyelitis (EAE) evaluated. METHODS EAE was induced in male Lewis rats by injection of an emulsion of myelin basic protein and incomplete Freund's adjuvant containing Mycobacterium butyricum. Biodistribution studies with 123I-CLINDE were undertaken on EAE rats exhibiting different clinical disease severity and compared with results in controls. Disease severity was confirmed by histopathology in the spinal cord of rats. The relationship between inflammatory lesions and PBR ligand binding was investigated using ex vivo autoradiography and immunohistochemistry on rats with various clinical scores. RESULTS 123I-CLINDE uptake was enhanced in the CNS of all rats exhibiting EAE when compared to controls. Binding reflected the ascending nature of EAE inflammation, with lumbar/sacral cord>thoracic cord>cervical cord>medulla. The amount of ligand binding also reflected the clinical severity of disease. Ex vivo autoradiography and immunohistochemistry revealed a good spatial correspondence between radioligand signal and foci of inflammation and in particular ED-1+ cells representing macrophages and microglia. CONCLUSION These results demonstrate the ability of 123I-CLINDE to measure in vivo inflammatory events represented by increased density of PBRs and suggest that 123I-CLINDE warrants further investigation as a potential SPECT marker for imaging of CNS inflammation.
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MESH Headings
- Animals
- Brain/diagnostic imaging
- Brain/metabolism
- Bridged Bicyclo Compounds, Heterocyclic/pharmacokinetics
- Carrier Proteins/metabolism
- Drug Evaluation, Preclinical
- Encephalomyelitis, Autoimmune, Experimental/diagnostic imaging
- Encephalomyelitis, Autoimmune, Experimental/metabolism
- Feasibility Studies
- Freund's Adjuvant
- Inflammation/diagnostic imaging
- Inflammation/metabolism
- Isotope Labeling/methods
- Male
- Metabolic Clearance Rate
- Multiple Sclerosis/diagnostic imaging
- Multiple Sclerosis/metabolism
- Organ Specificity
- Radiopharmaceuticals/pharmacokinetics
- Rats
- Rats, Inbred Lew
- Receptors, GABA-A/metabolism
- Spinal Cord/diagnostic imaging
- Spinal Cord/metabolism
- Tissue Distribution
- Tomography, Emission-Computed, Single-Photon/methods
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Affiliation(s)
- F Mattner
- Radiopharmaceuticals Division, ANSTO, New Illawarra Road, Lucas Heights, 2234, Australia.
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30
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Schumacher M, Guennoun R, Robert F, Carelli C, Gago N, Ghoumari A, Gonzalez Deniselle MC, Gonzalez SL, Ibanez C, Labombarda F, Coirini H, Baulieu EE, De Nicola AF. Local synthesis and dual actions of progesterone in the nervous system: neuroprotection and myelination. Growth Horm IGF Res 2004; 14 Suppl A:S18-S33. [PMID: 15135772 DOI: 10.1016/j.ghir.2004.03.007] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Progesterone (PROG) is synthesized in the brain, spinal cord and peripheral nerves. Its direct precursor pregnenolone is either derived from the circulation or from local de novo synthesis as cytochrome P450scc, which converts cholesterol to pregnenolone, is expressed in the nervous system. Pregnenolone is converted to PROG by 3beta-hydroxysteroid dehydrogenase (3beta-HSD). In situ hybridization studies have shown that this enzyme is expressed throughout the rat brain, spinal cord and dorsal root ganglia (DRG) mainly by neurons. Macroglial cells, including astrocytes, oligodendroglial cells and Schwann cells, also have the capacity to synthesize PROG, but expression and activity of 3beta-HSD in these cells are regulated by cellular interactions. Thus, Schwann cells convert pregnenolone to PROG in response to a neuronal signal. There is now strong evidence that P450scc and 3beta-HSD are expressed in the human nervous system, where PROG synthesis also takes place. Although there are only a few studies addressing the biological significance of PROG synthesis in the brain, the autocrine/paracrine actions of locally synthesized PROG are likely to play an important role in the viability of neurons and in the formation of myelin sheaths. The neuroprotective effects of PROG have recently been documented in a murine model of spinal cord motoneuron degeneration, the Wobbler mouse. The treatment of symptomatic Wobbler mice with PROG for 15 days attenuated the neuropathological changes in spinal motoneurons and had beneficial effects on muscle strength and the survival rate of the animals. PROG may exert its neuroprotective effects by regulating expression of specific genes in neurons and glial cells, which may become hormone-sensitive after injury. The promyelinating effects of PROG were first documented in the mouse sciatic nerve and in co-cultures of sensory neurons and Schwann cells. PROG also promotes myelination in the brain, as shown in vitro in explant cultures of cerebellar slices and in vivo in the cerebellar peduncle of aged rats after toxin-induced demyelination. Local synthesis of PROG in the brain and the neuroprotective and promyelinating effects of this neurosteroid offer interesting therapeutic possibilities for the prevention and treatment of neurodegenerative diseases, for accelerating regenerative processes and for preserving cognitive functions during aging.
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31
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Chen MK, Baidoo K, Verina T, Guilarte TR. Peripheral benzodiazepine receptor imaging in CNS demyelination: functional implications of anatomical and cellular localization. ACTA ACUST UNITED AC 2004; 127:1379-92. [PMID: 15069023 DOI: 10.1093/brain/awh161] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The peripheral benzodiazepine receptor (PBR) has been used as a sensitive marker to visualize and measure glial cell activation associated with various forms of brain injury and inflammation. Previous studies have shown that increased PBR levels following brain injury are specific to areas expressing activated glial cells. However, the contribution of glial cell types responsible for the increases in PBR levels following brain injury is not well defined. In the present study, we used a murine model of cuprizone-induced demyelination to broaden the application of PBR as a marker of brain injury and to validate the relationship between PBR levels and glial cell types. C57BL/6J mice were maintained on a cuprizone-containing or control diet and sacrificed at specific time points after initiation of treatment. Quantitative autoradiography of the PBR-selective ligand [(3)H]-(R)-PK11195 and [(125)I]-(R)-PK11195 showed that increased PBR levels were associated with the degree of demyelination assessed by Black-Gold histochemistry and activation of glial cells assessed by glial fibrillary acidic protein (GFAP) immunohistochemistry for astrocytes and CD11b (Mac-1) for microglia. Our findings indicate that brain PBR levels increased as a function of dose and duration of cuprizone treatment and it was detectable prior to observable demyelination. Increased PBR levels were associated with the degree of demyelination and temporal activation of glial cell types in different anatomical regions. In the corpus striatum, we found a close anatomical correlation between microglial activation and increased PBR levels in demyelinating fibre tracts. In the deep cerebellar nuclei, the temporal increases in PBR paralleled demyelination and microglia and astrocyte activation. On the other hand, in the corpus callosum there was an apparent temporal shift in the increase in PBR levels by different glial cell types from an early and predominantly microglial contribution to a late microglial and astrocytic response. High-resolution emulsion autoradiography of [(3)H]-(R)-PK11195 binding to PBR coupled with GFAP or Mac-1 immunohistochemistry showed that demyelination-induced increases in PBR levels were co-localized to both microglia and astrocytes. These findings support the notion that PBR is a sensitive and specific marker for the in vitro and in vivo visualization and quantification of neuropathological changes in the brain.
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Affiliation(s)
- Ming-Kai Chen
- Department of Environmental Health Sciences, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Room W2001, Baltimore, MD 21205, USA
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32
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Benmessahel Y, Troadec JD, Cadepond F, Guennoun R, Hales DB, Schumacher M, Groyer G. Downregulation of steroidogenic acute regulatory protein (StAR) gene expression by cyclic AMP in cultured Schwann cells. Glia 2004; 45:213-28. [PMID: 14730695 DOI: 10.1002/glia.10326] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Steroidogenic acute regulatory protein (StAR) plays a key role in the availability of cholesterol to the inner mitochondrial membrane, where the first step of steroidogenesis, its conversion to pregnenolone, takes place. Here, we demonstrate for the first time that the StAR gene is also expressed in the rat sciatic nerve and in cultured Schwann cells. The addition to the culture medium of the cAMP-elevating agent forskolin or of the cAMP analogue 8Br-cAMP produced a time-course extinction of StAR gene expression. An inverse relationship was demonstrated between StAR gene expression and the intracellular cAMP content. Accordingly, pharmacological inhibition of the activities of Schwann cell adenylyl cyclase or of phosphodiesterase IV resulted in modifications of StAR gene expression. Since StAR gene expression is stimulated by cAMP in classical steroidogenic cells, our work is the first demonstration of a negative regulation of StAR gene by cAMP.
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Paciga M, McCudden CR, Londos C, DiMattia GE, Wagner GF. Targeting of Big Stanniocalcin and Its Receptor to Lipid Storage Droplets of Ovarian Steroidogenic Cells. J Biol Chem 2003; 278:49549-54. [PMID: 14512426 DOI: 10.1074/jbc.m307302200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stanniocalcin (STC) is a large polypeptide hormone that is widely distributed in tissues such as kidney, adrenal, and ovary. In most tissues, STC exists as a 50-kDa homodimer (STC50). The ovaries produce a higher molecular weight variant (big STC) in androgen-producing theca cell and interstitial cell compartments. Luteal cells, which do not express the STC gene, nonetheless contain high levels of STC protein, suggesting they are targeted by and sequester big STC through a receptor-mediated process. Recently, an STC.alkaline phosphatase fusion protein was used to characterize mitochondrial targeting and sequestration of STC50 and its receptor in liver and kidney. The main objective of the present study was to characterize big STC and its receptor in mammalian ovary and determine whether the ovarian STC variant was similarly targeted to luteal cell mitochondria. By in situ ligand binding, we identified large numbers of STC receptors on corpus luteal cells. However, a more detailed analysis of sub-cellular fractions revealed that both STC and its receptor were not preferentially targeted to mitochondria but instead to cholesterol/lipid storage droplets, which was more indicative of a role in steroidogenesis. Functional studies revealed that additions of big STC had concentration-dependent inhibitory effects on both basal and stimulated progesterone output by primary cultured luteal cells. Furthermore, STC receptor levels were up-regulated in luteal cells in response to protein kinase A activation. Taken together, these findings indicate that theca cell-derived big STC is targeted to the cholesterol/lipid storage droplets of luteal cells to regulate steroidogenesis. This constitutes the first reported description of polypeptide hormone and receptor targeting to cholesterol/lipid droplets and the first biological role for the big STC variant.
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Affiliation(s)
- Mark Paciga
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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34
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Ritsner M, Modai I, Gibel A, Leschiner S, Silver H, Tsinovoy G, Weizman A, Gavish M. Decreased platelet peripheral-type benzodiazepine receptors in persistently violent schizophrenia patients. J Psychiatr Res 2003; 37:549-56. [PMID: 14563387 DOI: 10.1016/s0022-3956(03)00055-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Peripheral-type benzodiazepine receptors (PBR) have been shown to be sensitive to stressful conditions. This study aimed to explore a possible association of platelets PBR binding with aggressive behavior and homicidal history in schizophrenia patients. The authors compared [(3)H] PK 11195 binding to platelet membrane among 11 currently aggressive schizophrenia patients, 15 schizophrenia patients with homicidal history, 14 nonaggressive schizophrenia patients, and 15 healthy volunteers. Subjects were assessed for aggressive behavior, psychopathology, anxiety, anger, and emotional distress using standardized instruments. We found that currently aggressive patients had significantly lower (-30%) platelet PBR density (B(max)), and scored significantly higher on hostility, anxiety, state anger, and emotional distress compared to homicidal and nonaggressive schizophrenia patients and healthy controls. Predominance of positive or negative symptoms, homicidal or suicidal attempt history, emotional distress levels, and conventional or atypical antipsychotic therapy is not associated with the expression of platelet PBR binding sites. Significant negative correlations emerged between PBR density and scores for aggressive behavior, hostility and anxiety. Thus, decreased platelet PBR density in aggressive schizophrenia patients is associated with higher scores for overt aggression, hostility and anxiety, but independent of illness subtype, homicidal and suicidal attempt history, distress level and type of antipsychotic treatment.
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Affiliation(s)
- Michael Ritsner
- Sha'ar Menashe Mental Health Center, Mobile Post Hefer 38814, Israel.
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35
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Shen WJ, Patel S, Natu V, Hong R, Wang J, Azhar S, Kraemer FB. Interaction of hormone-sensitive lipase with steroidogenic acute regulatory protein: facilitation of cholesterol transfer in adrenal. J Biol Chem 2003; 278:43870-6. [PMID: 12925534 DOI: 10.1074/jbc.m303934200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hormone-sensitive lipase (HSL) is responsible for the neutral cholesteryl ester hydrolase activity in steroidogenic tissues. Through its action, HSL is involved in regulating intracellular cholesterol metabolism and making unesterified cholesterol available for steroid hormone production. Steroidogenic acute regulatory protein (StAR) facilitates the movement of cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane and is a critical regulatory step in steroidogenesis. In the current studies we demonstrate a direct interaction of HSL with StAR using in vitro glutathione S-transferase pull-down experiments. The 37-kDa StAR is coimmunoprecipitated with HSL from adrenals of animals treated with ACTH. Deletional mutations show that HSL interacts with the N-terminal as well as a central region of StAR. Coexpression of HSL and StAR in Chinese hamster ovary cells results in higher cholesteryl ester hydrolytic activity of HSL. Transient overexpression of HSL in Y1 adrenocortical cells increases mitochondrial cholesterol content under conditions in which StAR is induced. It is proposed that the interaction of HSL with StAR in cytosol increases the hydrolytic activity of HSL and that together HSL and StAR facilitate cholesterol movement from lipid droplets to mitochondria for steroidogenesis.
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Affiliation(s)
- Wen-Jun Shen
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304-1290, USA
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36
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Lacapère JJ, Papadopoulos V. Peripheral-type benzodiazepine receptor: structure and function of a cholesterol-binding protein in steroid and bile acid biosynthesis. Steroids 2003; 68:569-85. [PMID: 12957662 DOI: 10.1016/s0039-128x(03)00101-6] [Citation(s) in RCA: 252] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Cholesterol transport from the outer to the inner mitochondrial membrane is the rate-determining step in steroid and bile acid biosyntheses. Biochemical, pharmacological and molecular studies have demonstrated that the peripheral-type benzodiazepine receptor (PBR) is a five transmembrane domain mitochondrial protein involved in the regulation of cholesterol transport. PBR gene disruption in Leydig cells completely blocked cholesterol transport into mitochondria and steroid formation, while PBR expression in bacteria, devoid of endogenous PBR and cholesterol, induced cholesterol uptake and transport. Molecular modeling of PBR suggested that cholesterol might cross the membrane through the five helices of the receptor and that synthetic and endogenous ligands might bind to common sites in the cytoplasmic loops. A cholesterol recognition/interaction amino acid consensus (CRAC) sequence in the cytoplasmic carboxy-terminus of the PBR was identified by mutagenesis studies. In vitro reconstitution of PBR into proteoliposomes demonstrated that PBR binds both drug ligands and cholesterol with high affinity. In vivo polymeric forms of PBR were observed and polymer formation was reproduced in vitro, using recombinant PBR protein reconstituted into proteoliposomes, associated with an increase in drug ligand binding and reduction of cholesterol-binding capacity. This suggests that the various polymeric states of PBR might be part of a cycle mediating cholesterol uptake and release into the mitochondria, with PBR functioning as a cholesterol exchanger against steroid product(s) arising from cytochrome P450 action. Taking into account the widespread presence of PBR in many tissues, a more general role of PBR in intracellular cholesterol transport and compartmentalization might be considered.
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Affiliation(s)
- Jean Jacques Lacapère
- Unité INSERM U410, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, 75870 Paris Cedex 18, France.
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37
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Abstract
Certain metabolites of progesterone and deoxycorticosterone are established as potent and selective positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. Upon administration these steroids exhibit clear behavioural effects that include anxiolysis, sedation and analgesia, they are anticonvulsant and at high doses induce a state of general anaesthesia, a profile consistent with an action to enhance neuronal inhibition. Physiologically, peripherally synthesised pregnane steroids derived from endocrine glands such as the adrenals and ovaries function as hormones by crossing the blood brain barrier to influence neuronal signalling. However, the demonstration that certain neurons and glial cells within the central nervous system (CNS) can synthesize these steroids either de novo, or from peripherally derived progesterone, has led to the proposal that these steroids (neurosteroids) can additionally function in a paracrine manner, to locally influence GABAergic transmission. Steroid levels are known to change dynamically, for example in stress and during pregnancy. Given that GABA(A) receptors are ubiquitously expressed throughout the central nervous system, such changes in steroid levels would be predicted to cause a global enhancement of inhibitory neurotransmission throughout the brain, a scenario that would seem incompatible with a physiological role as a selective neuromodulator. Here, we will review emerging evidence that the GABA-modulatory actions of the pregnane steroids are highly selective, with their actions being brain region and indeed neuron dependent. Furthermore, the sensitivity of GABA(A) receptors is not static but can dynamically change. The molecular mechanisms underpinning this neuronal specificity will be discussed with particular emphasis being given to the role of GABA(A) receptor isoforms, protein phosphorylation and local steroid metabolism and synthesis.
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Affiliation(s)
- Jeremy J Lambert
- The Department of Pharmacology and Neuroscience, The Neuroscience Institute, Ninewells Hospital and Medical School, Dundee University, Dundee DD1 9SY, Scotland, UK.
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Frye CA, Petralia SM. Mitochondrial benzodiazepine receptors in the ventral tegmental area modulate sexual behaviour of cycling or hormone-primed hamsters. J Neuroendocrinol 2003; 15:677-86. [PMID: 12787052 DOI: 10.1046/j.1365-2826.2003.01047.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hamsters are highly dependent upon the central actions of progesterone (P4) for facilitation of sexual behaviour. In the ventral tegmental area (VTA), P4 has actions through its neurosteroid metabolite 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP). The effects of enhancing or inhibiting neurosteroidogenesis (and thereby 3alpha,5alpha-THP concentrations), through manipulations of mitochondrial benzodiazepine receptors, in the VTA on socio-sexual behaviour of female hamsters were examined. Intact, naturally receptive hamsters and ovariectomized (OVX), hormone-primed hamsters were unilaterally infused via chronic guide cannula to the VTA with the mitochondrial benzodiazepine receptor antagonist 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboximide (PK-11195) or the mitochondrial benzodiazepine receptor agonist, N,N-dihexyl-2-(4-fluorophenyl)indole-30-acetamide (FGIN 1-27) and tested for sexual responsiveness and lordosis. PK-11195 (5.6, 11.2 or 22.4 nm) to the VTA attenuated sexual responsiveness of naturally receptive or oestradiol benzoate (EB) + P4-primed hamsters compared to vehicle. In addition, FGIN 1-27 (11.4 nm) infusions to the VTA increased sexual responsiveness and lordosis of cycling or OVX, EB + P4-primed hamsters, compared to vehicle infusions. In OVX, EB + P4-primed hamsters, decrements in sexual responsiveness produced by VTA infusions of PK-11195 (5.6 nm) were attenuated by VTA infusions of 3alpha,5alpha-THP. VTA infusions of PK-11195 (5.6 nm) or FGIN 1-27 (11.4 nm), respectively, decreased and increased midbrain levels of 3alpha,5alpha-THP compared to each other. Together, these findings indicate that manipulating actions of mitochondrial benzodiazepine receptors in the VTA can augment and inhibit neurosteroidogenesis and sexual responsiveness of hormone-primed and naturally receptive hamsters.
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Affiliation(s)
- C A Frye
- Departments of Psychology, The University at Albany-SUNY, Albany, NY 12222, USA.
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39
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Azhar S, Reaven E. Scavenger receptor class BI and selective cholesteryl ester uptake: partners in the regulation of steroidogenesis. Mol Cell Endocrinol 2002; 195:1-26. [PMID: 12354669 DOI: 10.1016/s0303-7207(02)00222-8] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The steroidogenic tissues have a special requirement for cholesterol, which is used as a substrate for steroid hormone biosynthesis. In many species this cholesterol is obtained from plasma lipoproteins by a unique pathway in which circulating lipoproteins bind to the surface of the steroidogenic cells and contribute their cholesteryl esters to the cells by a 'selective' process in which the whole lipoprotein particle does not enter the cell. This review describes the lipoprotein selective cholesteryl ester uptake process and its specific partnership with the HDL receptor, scavenger receptor class BI (SR-BI). It describes the characteristics of the selective pathway, and the molecular properties, localization, regulation, anchoring sites and potential mechanisms of action of SR-BI in facilitating cholesteryl ester uptake by steroidogenic cells.
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Affiliation(s)
- Salman Azhar
- Geriatric Research, Education and Clinical Center, GRECC-182B, VA Palo Alto Health Care System, 3801 Miranda Avenue, Palo Alto, CA 94304, USA.
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Faure JP, Hauet T, Han Z, Goujon JM, Petit I, Mauco G, Eugene M, Carretier M, Papadopoulos V. Polyethylene glycol reduces early and long-term cold ischemia-reperfusion and renal medulla injury. J Pharmacol Exp Ther 2002; 302:861-70. [PMID: 12183641 DOI: 10.1124/jpet.102.033688] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ischemia-reperfusion injury (IRI) after transplantation is a major cause of delayed graft function, which has a negative impact on early and late graft function and improve acute rejection. We have previously shown that polyethylene glycol (PEG) and particularly PEG 20M has a protective effect against cold ischemia and reperfusion injury in an isolated perfused pig and rat kidney model. We extended those observations to investigate the role of PEG using different doses (30g or 50g/l) added (ICPEG30 or ICPEG50) or not (IC) to a simplified preservation solution to reduce IRI after prolonged cold storage (48-h) of pig kidneys when compared with Euro-Collins and University of Wisconsin solutions. The study of renal function and medulla injury was performed with biochemical methods and proton NMR spectroscopy. Histological and inflammatory cell studies were performed after reperfusion (30-40 min) and on days 7 and 14 and weeks 4, 8, and 12. Peripheral-type benzodiazepine receptor (PBR), a mitochondrial protein involved in cholesterol homeostasis, was also studied. The results demonstrated that ICPEG30 improved renal function and reduced medulla injury. ICPEG30 also improved tubular function and strongly protect mitochondrial integrity. Post-IRI inflammation was strongly reduced in this group, particularly lymphocytes TCD4(+), PBR expression was influenced by IRI in the early period and during the development of chronic dysfunction. This study clearly shows that PEG has a beneficial effect in renal preservation and suggests a role of PBR as a marker IRI and repair processes.
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Affiliation(s)
- Jean Pierre Faure
- Unité de Transplantation Expérimentale, Département de Génétique Animale, Institut National de Recherche Agronomique, Domaine du Magneraud, Surgères, and Faculté de Médecine (EA 2426), Poitiers and Centre Hospitalier et Universitaire, Poitiers, France
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Song G, Dhodda VK, Blei AT, Dempsey RJ, Rao VLR. GeneChip analysis shows altered mRNA expression of transcripts of neurotransmitter and signal transduction pathways in the cerebral cortex of portacaval shunted rats. J Neurosci Res 2002; 68:730-7. [PMID: 12111833 DOI: 10.1002/jnr.10268] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Identifying the gene expression changes induced by hepatic encephalopathy (HE) leads to a better understanding of the molecular mechanisms of HE-induced neurological dysfunction. Using GeneChip and real-time PCR, the present study evaluated the gene expression profile of rat cerebral cortex at 4 weeks after portacaval shunting. Among 1,263 transcripts represented on the chip, mRNA levels of 31 transcripts were altered (greater than twofold; 16 increased and 15 decreased) in the portacaval shunted (PCS) rat compared to sham control. Changes observed by GeneChip analysis were confirmed for 20 transcripts (8 increased, 7 decreased, and 5 unchanged in PCS rat brain) by real-time PCR. Neurotransmitter receptors, transporters, and members of the second messenger signal transduction are the major groups of genes altered in PCS rat brain. Of importance was that the increased heme oxygenase-1 and decreased Cu,Zn-superoxide dismutase expression observed raise the possibility of oxidative stress playing a pathogenic role in chronic HE.
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Affiliation(s)
- Guoqing Song
- Department of Neurological Surgery, University of Wisconsin, Madison, Wisconsin 53792, USA
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Morris RL, Varnes ME, Kenney ME, Li YS, Azizuddin K, McEnery MW, Oleinick NL. The peripheral benzodiazepine receptor in photodynamic therapy with the phthalocyanine photosensitizer Pc 4. Photochem Photobiol 2002; 75:652-61. [PMID: 12081328 DOI: 10.1562/0031-8655(2002)075<0652:tpbrip>2.0.co;2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The peripheral benzodiazepine receptor (PBR) is an 18 kDa protein of the outer mitochondrial membrane that interacts with the voltage-dependent anion channel and may participate in formation of the permeability transition pore. The physiological role of PBR is reflected in the high-affinity binding of endogenous ligands that are metabolites of both cholesterol and heme. Certain porphyrin precursors of heme can be photosensitizers for photodynamic therapy (PDT), which depends on visible light activation of porphyrin-related macrocycles. Because the apparent binding affinity of a series of porphyrin analogs for PBR paralleled their ability to photoinactivate cells, PBR has been proposed as the molecular target for porphyrin-derived photocytotoxicity. The phthalocyanine (Pc) photosensitizer Pc 4 accumulates in mitochondria and structurally resembles porphyrins. Therefore, we tested the relevance of PBR binding on Pc 4-PDT. Binding affinity was measured by competition with 3H-PK11195, a high-affinity ligand of PBR, for binding to rat kidney mitochondria (RKM) or intact Chinese hamster ovary (CHO) cells. To assess the binding of the Pc directly, we synthesized 14C-labeled Pc 4 and found that whereas Pc 4 was a competitive inhibitor of 3H-PK11195 binding to the PBR, PK11195 did not inhibit the binding of 14C-Pc 4 to RKM. Further, 14C-Pc 4 binding to RKM showed no evidence of saturation up to 10 microM. Finally, when Pc 4-loaded CHO cells were exposed to activating red light, apoptosis was induced; Pc 4-PDT was less effective in causing apoptosis in a companion cell line overexpressing the antiapoptotic protein Bcl-2. For both cell lines, PK11195 inhibited PDT-induced apoptosis; however, the inhibition was transient and did not extend to overall cell death, as determined by clonogenic assay. The results demonstrate (1) the presence of low-affinity binding sites for Pc 4 on PBR; (2) the presence of multiple binding sites for Pc 4 in RKM and CHO cells other than those that influence PK11195 binding; and (3) the ability of high supersaturating levels of PK11195 to transiently inhibit apoptosis initiated by Pc 4-PDT, with less influence on overall cell killing. We conclude that the binding of Pc 4 to PBR is less relevant to the photocytotoxicity of Pc 4-PDT than are other mitochondrial events, such as photodamage to Bcl-2 and that the observed inhibition of Pc 4-PDT-induced apoptosis by PK11195 likely occurs through a mechanism independent of PBR.
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Affiliation(s)
- Rachel L Morris
- Department of Radiation Oncology, Case Western Reserve University, Cleveland, OH 44106-4942, USA
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