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Sivcev S, Kudova E, Zemkova H. Neurosteroids as positive and negative allosteric modulators of ligand-gated ion channels: P2X receptor perspective. Neuropharmacology 2023; 234:109542. [PMID: 37040816 DOI: 10.1016/j.neuropharm.2023.109542] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/06/2023] [Accepted: 04/07/2023] [Indexed: 04/13/2023]
Abstract
Neurosteroids are steroids synthesized de novo in the brain from cholesterol in an independent manner from peripheral steroid sources. The term "neuroactive steroid" includes all steroids independent of their origin, and newly synthesized analogs of neurosteroids that modify neuronal activities. In vivo application of neuroactive steroids induces potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the γ-aminobutyric acid type-A receptor (GABAAR). However, neuroactive steroids also act as positive or negative allosteric regulators on several ligand-gated channels including N-methyl-d-aspartate receptors (NMDARs), nicotinic acetylcholine receptors (nAChRs) and ATP-gated purinergic P2X receptors. Seven different P2X subunits (P2X1-7) can assemble to form homotrimeric or heterotrimeric ion channels permeable for monovalent cations and calcium. Among them, P2X2, P2X4, and P2X7 are the most abundant within the brain and can be regulated by neurosteroids. Transmembrane domains are necessary for neurosteroid binding, however, no generic motif of amino acids can accurately predict the neurosteroid binding site for any of the ligand-gated ion channels including P2X. Here, we will review what is currently known about the modulation of rat and human P2X by neuroactive steroids and the possible structural determinants underlying neurosteroid-induced potentiation and inhibition of the P2X2 and P2X4 receptors.
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Affiliation(s)
- Sonja Sivcev
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Zemkova
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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Gild ML, Stuart M, Clifton-Bligh RJ, Kinahan A, Handelsman DJ. Thyroid Hormone Abuse in Elite Sports: The Regulatory Challenge. J Clin Endocrinol Metab 2022; 107:e3562-e3573. [PMID: 35438767 PMCID: PMC9387720 DOI: 10.1210/clinem/dgac223] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Indexed: 11/19/2022]
Abstract
Abuse of androgens and erythropoietin has led to hormones being the most effective and frequent class of ergogenic substances prohibited in elite sports by the World Anti-Doping Agency (WADA). At present, thyroid hormone (TH) abuse is not prohibited, but its prevalence among elite athletes and nonprohibited status remains controversial. A corollary of prohibiting hormones for elite sports is that endocrinologists must be aware of a professional athlete's risk of disqualification for using prohibited hormones and/or to certify Therapeutic Use Exemptions, which allow individual athletes to use prohibited substances for valid medical indications. This narrative review considers the status of TH within the framework of the WADA Code criteria for prohibiting substances, which requires meeting 2 of 3 equally important criteria of potential performance enhancement, harmfulness to health, and violation of the spirit of sport. In considering the valid clinical uses of TH, the prevalence of TH use among young adults, the reason why some athletes seek to use TH, and the pathophysiology of sought-after and adverse effects of TH abuse, together with the challenges of detecting TH abuse, it can be concluded that, on the basis of present data, prohibition of TH in elite sport is neither justified nor feasible.
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Affiliation(s)
- Matti L Gild
- Faculty of Medicine and Health, University of Sydney, Sydney 2006, Australia
- Department of Diabetes and Endocrinology, Royal North Shore Hospital, Sydney 2065, Australia
- Cancer Genetics, Kolling Institute of Medical Research, St Leonards 2065, Australia
| | - Mark Stuart
- Division of Medicine, Centre for Metabolism and Inflammation, University College London, WC1E 6BT, UK
- International Testing Agency Lausanne, Lausanne 1007, Switzerland
| | - Roderick J Clifton-Bligh
- Faculty of Medicine and Health, University of Sydney, Sydney 2006, Australia
- Department of Diabetes and Endocrinology, Royal North Shore Hospital, Sydney 2065, Australia
- Cancer Genetics, Kolling Institute of Medical Research, St Leonards 2065, Australia
| | | | - David J Handelsman
- Correspondence: Professor David Handelsman, ANZAC Research Institute, Department of Andrology, Concord Hospital, Sydney, New South Wales, Australia.
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Grønnestad R, Johanson SM, Müller MHB, Schlenk D, Tanabe P, Krøkje Å, Jaspers VLB, Jenssen BM, Ræder EM, Lyche JL, Shi Q, Arukwe A. Effects of an environmentally relevant PFAS mixture on dopamine and steroid hormone levels in exposed mice. Toxicol Appl Pharmacol 2021; 428:115670. [PMID: 34371090 DOI: 10.1016/j.taap.2021.115670] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 12/13/2022]
Abstract
In the present study, we investigated the dopaminergic and steroid hormone systems of A/J mice fed environmentally relevant concentrations of a perfluoroalkyl substance (PFAS) mixture over a period of 10 weeks. The PFAS mixture was chosen based on measured PFAS concentrations in earthworms at a Norwegian skiing area (Trondheim) and consisted of eight different PFAS. Dietary exposure to PFAS led to lower total brain dopamine (DA) concentrations in male mice, as compared to control. On the transcript level, brain tyrosine hydroxylase (th) of PFAS exposed males was reduced, compared to the control group. No significant differences were observed on the transcript levels of enzymes responsible for DA metabolism, namely - monoamine oxidase (maoa and maob) and catechol-O methyltransferase (comt). We detected increased transcript level for DA receptor 2 (dr2) in PFAS exposed females, while expression of DA receptor 1 (dr1), DA transporter (dat) and vesicular monoamine transporter (vmat) were not affected by PFAS exposure. Regarding the steroid hormones, plasma and muscle testosterone (T), 11-ketotestosterone (11-KT) and 17β-estradiol (E2) levels, as well as transcripts for estrogen receptors (esr1 and esr2), gonadotropin releasing hormone (gnrh) and aromatase (cyp19) were unaltered by the PFAS treatment. These results indicate that exposure to PFAS doses, comparable to previous observation in earthworms at a Norwegian skiing area, may alter the dopaminergic system of mice with overt consequences for health, general physiology, cognitive behavior, reproduction and metabolism.
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Affiliation(s)
- Randi Grønnestad
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Silje Modahl Johanson
- Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Mette H B Müller
- Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, Oslo, Norway; Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Daniel Schlenk
- Department of Environmental Sciences, University of California, Riverside, California, USA
| | - Philip Tanabe
- Department of Environmental Sciences, University of California, Riverside, California, USA
| | - Åse Krøkje
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Veerle L B Jaspers
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Bjørn Munro Jenssen
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway; Department of Biosciences, Aarhus University, Roskilde, Denmark
| | - Erik M Ræder
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Jan L Lyche
- Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway
| | - Qingyang Shi
- Department of Environmental Sciences, University of California, Riverside, California, USA
| | - Augustine Arukwe
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
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Concentrations of estradiol, progesterone and testosterone in sefrum and cerebrospinal fluid of patients with aneurysmal subarachnoid hemorrhage correlate weakly with transcranial Doppler flow velocities. BMC Neurosci 2021; 22:29. [PMID: 33892632 PMCID: PMC8067654 DOI: 10.1186/s12868-021-00634-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 04/13/2021] [Indexed: 12/14/2022] Open
Abstract
Background The implication of the steroids estradiol, progesterone and testosterone in cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) has not been comprehensively assessed. In rodents, studies suggested beneficial effects of steroids on cerebral vasospasm after experimental SAH. Studies in humans are warranted, however, a general dilemma of human studies on neuroactive substances is that the brain is not directly accessible and that concentrations in the periphery may not adequately parallel concentrations in the central compartments. In the present study, concentrations of estradiol, progesterone and testosterone in serum and cerebrospinal fluid (CSF) of patients with aSAH were determined. Blood flow velocities in cerebral arteries were measured by transcranial Doppler sonography (TCD). The aim of this study was to evaluate the correlations between the cerebral blood flow velocities and levels of estradiol, progesterone and testosterone in CSF and serum. Results Samples of serum and CSF of 42 patients with aSAH were collected concomitantly daily or every other day via the arterial line and the external ventricular drainage for two weeks after the hemorrhage. Blood flow velocities in the cerebral arteries were determined by TCD. Total estradiol, progesterone and testosterone concentrations were measured by electro-chemiluminescence immunoassay. The strength of correlation was assessed by Spearman’s rank correlation coefficient. The correlation analysis revealed very weak correlations between cerebral blood flow velocities and concentrations of estradiol, progesterone and testosterone levels in both compartments with correlation coefficients below 0.2. Conclusions In humans with aSAH, merely very weak correlations between flow velocities in cerebral arteries and concentrations of estradiol, progesterone and testosterone in serum and CSF were demonstrated. These results suggest a limited influence of the respective steroids on cerebral vascular tone although vasodilatory effects were described in rodent studies. Thus, the implication of steroids in processes of neurological deterioration warrants further clarification.
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Pataky MW, Young WF, Nair KS. Hormonal and Metabolic Changes of Aging and the Influence of Lifestyle Modifications. Mayo Clin Proc 2021; 96:788-814. [PMID: 33673927 PMCID: PMC8020896 DOI: 10.1016/j.mayocp.2020.07.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/01/2020] [Accepted: 07/02/2020] [Indexed: 02/07/2023]
Abstract
Increased life expectancy combined with the aging baby boomer generation has resulted in an unprecedented global expansion of the elderly population. The growing population of older adults and increased rate of age-related chronic illness has caused a substantial socioeconomic burden. The gradual and progressive age-related decline in hormone production and action has a detrimental impact on human health by increasing risk for chronic disease and reducing life span. This article reviews the age-related decline in hormone production, as well as age-related biochemical and body composition changes that reduce the bioavailability and actions of some hormones. The impact of hormonal changes on various chronic conditions including frailty, diabetes, cardiovascular disease, and dementia are also discussed. Hormone replacement therapy has been attempted in many clinical trials to reverse and/or prevent the hormonal decline in aging to combat the progression of age-related diseases. Unfortunately, hormone replacement therapy is not a panacea, as it often results in various adverse events that outweigh its potential health benefits. Therefore, except in some specific individual cases, hormone replacement is not recommended. Rather, positive lifestyle modifications such as regular aerobic and resistance exercise programs and/or healthy calorically restricted diet can favorably affect endocrine and metabolic functions and act as countermeasures to various age-related diseases. We provide a critical review of the available data and offer recommendations that hopefully will form the groundwork for physicians/scientists to develop and optimize new endocrine-targeted therapies and lifestyle modifications that can better address age-related decline in heath.
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Affiliation(s)
- Mark W Pataky
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
| | - William F Young
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
| | - K Sreekumaran Nair
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN.
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Martin J, Plank E, Jungwirth B, Hapfelmeier A, Podtschaske A, Kagerbauer SM. Weak correlations between serum and cerebrospinal fluid levels of estradiol, progesterone and testosterone in males. BMC Neurosci 2019; 20:53. [PMID: 31619164 PMCID: PMC6794746 DOI: 10.1186/s12868-019-0535-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 10/05/2019] [Indexed: 01/16/2023] Open
Abstract
Background Neuroactive steroids seem to be implicated in a variety of neurophysiological and behavioral processes, such as sleep, learning, memory, stress, feeding and aging. Numerous studies have also addressed this implication in various cerebral disorders and diseases. Yet, the correlation and association between steroids in the periphery, e.g. blood, and the central compartments, e.g. cerebrospinal fluid (CSF), have not yet been comprehensively assessed. As the brain is not directly accessible, and the collection of human CSF usually requires invasive procedures, easier accessible compartments, such as blood, have always attracted attention. However, studies in humans are scarce. In the present study we determined estradiol, progesterone and testosterone levels in CSF and serum of 22 males without cerebral disorders or diseases. Results Samples were taken under conditions corresponding closest to basal conditions with patients expecting only spinal anesthesia and minor surgery. All samples per patient were collected concomitantly. Total estradiol, progesterone and testosterone concentrations were measured by electro-chemiluminescence immunoassay. The strength of correlation was assessed by Spearman’s rank correlation coefficient. Correlation analysis revealed merely weak to very weak correlations for estradiol, progesterone and testosterone respectively between the CSF and serum compartments. Conclusions Total steroid levels of estradiol, progesterone and testosterone in CSF and serum of males without neurological disorders were determined. Weak to very weak correlations between CSF and serum were found thus suggesting that concentrations in the periphery do not parallel concentrations in the central compartments. Further research is needed to clarify to what extent and under which conditions serum levels of estradiol, progesterone and testosterone may possibly serve as a biomarker reflecting the respective concentrations in the CSF or in the brain.
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Affiliation(s)
- Jan Martin
- Department of Anesthesiology and Intensive Care Medicine, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675, Munich, Germany.
| | - Eva Plank
- Department of Anesthesiology and Intensive Care Medicine, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675, Munich, Germany
| | - Bettina Jungwirth
- Department of Anesthesiology and Intensive Care Medicine, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675, Munich, Germany
| | - Alexander Hapfelmeier
- Institute of Medical Informatics, Statistics und Epidemiology, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Str. 22, 81675, Munich, Germany
| | - Armin Podtschaske
- Department of Anesthesiology and Intensive Care Medicine, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675, Munich, Germany
| | - Simone M Kagerbauer
- Department of Anesthesiology and Intensive Care Medicine, Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, 81675, Munich, Germany
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Caldwell JD, Londe K, Ochs SD, Hajdu Z, Rodewald A, Gebhart VM, Jirikowski GF. Three steroid-binding globulins, their localization in the brain and nose, and what they might be doing there. Steroids 2019; 142:48-54. [PMID: 29246492 DOI: 10.1016/j.steroids.2017.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 10/06/2017] [Accepted: 12/07/2017] [Indexed: 12/01/2022]
Abstract
Steroid-binding globulins (SBGs) such as sex hormone binding globulin, corticosteroid binding globulin, and vitamin-D binding protein are receiving increasing notice as being actively involved in steroid actions. This paper reviews data of all three of these SBGs, focusing on their presence and possible activity in the brain and nose. We have found all three proteins in the brain in limbic areas such as the paraventricular (PVN) and supraoptic nuclei (SON) as well as other areas of the hypothalamus, hippocampus, and medial preoptic area. There is also evidence that all three are made in the PVN and SON, in conjunction with the neuropeptides oxytocin and vasopressin. The localization of these three SBGs is more variable within areas of the main olfactory area and the vomeronasal organ. However, all three are found in the mucus of these areas, suggesting that one of their functions is to sequester aerosol steroids, such as pheromones, and deliver them to sensory cells and then to deeper sensory areas. In this manuscript, we present multiple models of SBG action including: A) SBG binding to a membrane receptor, B) this SBG receptor being associated with a larger protein complex including cytoplasmic steroid receptors, C) when the SBGs binds to their SBG receptors, second messengers within the cells respond, D) after SBG binding to its receptor, it releases its associated steroid into the membrane's lipid bilayer, from which it gains access into the cell only when bound by an internal protein, E) the SBG, possibly with its bound SBG receptor, is internalized into the cell from which it can gain access to numerous organelles and possibly the cell's nucleus or F) associate with intracellular steroid receptors, G) SBGs produced in target cells are released from those cells upon specific stimulation, and H) according to the Free Steroid Hypothesis steroids released from the extracellular SBG passively diffuse across the plasma membrane of the cell. These models move the area of steroid endocrinology forward by providing important paths of steroid activity within many steroid target cells.
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Affiliation(s)
- J D Caldwell
- Department of Pharmacology, Edward Via College of Osteopathic Medicine and Gibbs Research Center, 350 Howard Street, Spartanburg, SC, USA.
| | - K Londe
- Department of Pharmacology, Edward Via College of Osteopathic Medicine and Gibbs Research Center, 350 Howard Street, Spartanburg, SC, USA
| | - S D Ochs
- Department of Pharmacology, Edward Via College of Osteopathic Medicine and Gibbs Research Center, 350 Howard Street, Spartanburg, SC, USA
| | - Z Hajdu
- Department of Pharmacology, Edward Via College of Osteopathic Medicine and Gibbs Research Center, 350 Howard Street, Spartanburg, SC, USA
| | - A Rodewald
- Institute of Anatomy, Anatomy II, Jena University Hospital, Jena, Germany
| | - V M Gebhart
- Institute of Anatomy, Anatomy II, Jena University Hospital, Jena, Germany
| | - G F Jirikowski
- Institute of Anatomy, Anatomy II, Jena University Hospital, Jena, Germany
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Verdile G, Asih PR, Barron AM, Wahjoepramono EJ, Ittner LM, Martins RN. The impact of luteinizing hormone and testosterone on beta amyloid (Aβ) accumulation: Animal and human clinical studies. Horm Behav 2015; 76:81-90. [PMID: 26122291 DOI: 10.1016/j.yhbeh.2015.05.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 12/31/2022]
Abstract
This article is part of a Special Issue "SBN 2014". Hormonal changes associated with ageing have been implicated in the pathogenesis of Alzheimer's disease (AD), the most common form of dementia. Reductions in serum testosterone and increases in luteinizing hormone (LH) are established AD risk factors for dementia in men and have important roles in modulating AD pathogenesis. One of the defining features of AD is the accumulation of amyloid-beta (Aβ) in the brain, which has a key role in the neurodegenerative cascade. Both testosterone and LH have been shown to modulate CNS Aβ accumulation in animal studies, and associations with cerebral amyloid load in human studies have supported this. The underlying mechanisms by which these hormones modulate Aβ accumulation and contribute to neurodegeneration are not completely understood, however they have been shown to regulate Aβ metabolism, enhance its clearance and alter the processing of its parent molecule, the amyloid precursor protein. This review will discuss underlying mechanisms by which testosterone and LH modulate Aβ and provide an update on therapeutic approaches targeting these hormones.
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Affiliation(s)
- Giuseppe Verdile
- School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Bentley, Western Australia 6102, Australia; Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia.
| | - Prita R Asih
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Dementia Research Unit, Department of Anatomy, School of Medical Sciences, Faculty of Medicine, University of NSW, Kensington, NSW 2052, Australia
| | - Anna M Barron
- National Institute of Radiological Sciences, Chiba-shi, Chiba 263-8555, Japan
| | - Eka J Wahjoepramono
- Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia; Medical Faculty, Pelita Harapan University - Neuroscience Centre, Siloam Hospital, Lippo Karawaci, Tangerang, Indonesia
| | - Lars M Ittner
- Dementia Research Unit, Department of Anatomy, School of Medical Sciences, Faculty of Medicine, University of NSW, Kensington, NSW 2052, Australia; Neuroscience Research Australia, Randwick, NSW 2036, Australia
| | - Ralph N Martins
- Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Joondalup, Western Australia 6027, Australia; Sir James McCusker Alzheimer's disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Crawley, Western Australia 6009, Australia; School of Biomedical Sciences, CHIRI Biosciences, Curtin University, Bentley, Western Australia 6102, Australia
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Garringer JA, Niyonkuru C, McCullough EH, Loucks T, Dixon CE, Conley YP, Berga S, Wagner AK. Impact of aromatase genetic variation on hormone levels and global outcome after severe TBI. J Neurotrauma 2013; 30:1415-25. [PMID: 23540392 PMCID: PMC3741419 DOI: 10.1089/neu.2012.2565] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Although experimental traumatic brain injury (TBI) studies support estradiol as a neuroprotectant and potent stimulator of neuroplasticity, clinical studies suggest a negative association between endogenous estradiol profiles and mortality/poor outcomes. However, no studies have evaluated associations with cerebral spinal fluid (CSF) hormone profiles and aromatase gene (cytochrome P450 [CYP]19A1) variability on clinical TBI outcomes. We evaluated 110 adults with severe TBI. Average and daily estradiol, testosterone, and estradiol/testosterone ratios (E2:T) were measured using CSF and serum samples and compared to healthy controls. Eighteen tagging and four functional single-nucleotide polymorphisms (SNPs) for CYP19A1 were genotyped and compared to hormones, acute mortality, and Glasgow Outcome Scale (GOS) scores 6 months post-TBI. TBI subjects had lower CSF estradiol over time versus controls. CSF testosterone was initially high, but declined over time. E2/T ratios were initially low, compared to controls, but rose over time. Higher mean E2/T ratio in bivariate analysis was associated with lower mortality (p=0.019) and better GOS-6 scores (p=0.030). rs2470152 influenced CSF E2/T ratio and also serum and CSF testosterone (p≤0.05 all comparisons). Multiple-risk SNPs rs2470152, rs4646, and rs2470144 were associated with worse GOS-6 scores (p≤0.05, all comparisons), and those with>1 risk SNP variant had a higher risk for poor outcome, compared with those with ≤1 risk variant. TBI results in low CSF estradiol and dynamic CSF testosterone and E2/T ratio. In contrast to clinical serum hormone studies, higher CSF E2/T ratio was associated with better outcome. Further, genetic variation in CYP19A1 influences both hormone dynamics and outcome post-TBI.
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Affiliation(s)
| | - Christian Niyonkuru
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Emily H. McCullough
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Tammy Loucks
- Department of Gynecology and Obstetrics, Emory University, Atlanta, Georgia
| | - C. Edward Dixon
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Neurosurgery, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Yvette P. Conley
- School of Nursing, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sarah Berga
- Department of Obstetrics and Gynecology, Wake forest University, Winston-Salem, North Carolina
| | - Amy K. Wagner
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, Pennsylvania
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Banks WA. Brain meets body: the blood-brain barrier as an endocrine interface. Endocrinology 2012; 153:4111-9. [PMID: 22778219 PMCID: PMC3423627 DOI: 10.1210/en.2012-1435] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 06/19/2012] [Indexed: 12/30/2022]
Abstract
The blood-brain barrier (BBB) separates the central nervous system (CNS) from the peripheral tissues. However, this does not prevent hormones from entering the brain, but shifts the main control of entry to the BBB. In general, steroid hormones cross the BBB by transmembrane diffusion, a nonsaturable process resulting in brain levels that reflect blood levels, whereas thyroid hormones and many peptides and regulatory proteins cross using transporters, a saturable process resulting in brain levels that reflect blood levels and transporter characteristics. Protein binding, brain-to-blood transport, and pharmacokinetics modulate BBB penetration. Some hormones have the opposite effect within the CNS than they do in the periphery, suggesting that these hormones cross the BBB to act as their own counterregulators. The cells making up the BBB are also endocrine like, both responding to circulating substances and secreting substances into the circulation and CNS. By dividing a hormone's receptors into central and peripheral pools, the former of which may not be part of the hormone's negative feed back loop, the BBB fosters the development of variable hormone resistance syndromes, as exemplified by evidence that altered insulin action in the CNS can contribute to Alzheimer's disease. In summary, the BBB acts as a regulatory interface in an endocrine-like, humoral-based communication between the CNS and peripheral tissues.
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Affiliation(s)
- William A Banks
- Veterans Affairs Puget Sound Health Care System and Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, Washington, USA.
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11
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Zhang G, Shi G, Tan H, Kang Y, Cui H. Intranasal administration of testosterone increased immobile-sniffing, exploratory behavior, motor behavior and grooming behavior in rats. Horm Behav 2011; 59:477-83. [PMID: 21281642 DOI: 10.1016/j.yhbeh.2011.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Revised: 01/19/2011] [Accepted: 01/21/2011] [Indexed: 11/27/2022]
Abstract
Currently, testosterone (T) replacement therapy is typically provided by oral medication, injectable T esters, surgically implanted T pellets, transdermal patches and gels. However, most of these methods of administration are still not ideal for targeting the central nervous system. Recently, therapeutic intranasal T administration (InT) has been considered as another option for delivering T to the brain. In the present study, the effects of 21-day InT treatment were assessed on open field behavior in gonadectomized (GDX) rats and intact rats. Subcutaneous injections of T at same dose were also tested in GDX rats. A total of 12 behavioral events were examined in GDX groups with or without T and in intact groups with or without InT. Significant decreases in open field activity were observed in rats after GDX without InT compared to sham-operated rats. The open field activity scores for most tests significantly increased with InT treatment in GDX rats and in intact rats compared with the corresponding GDX rats and intact rats. Intranasal administration of T improved the reduced behaviors resulted from T deficiency better than subcutaneous injection of T, demonstrating that T can be delivered to the brain by intranasal administration. Our results suggest that intranasal T delivery is an effective option for targeting the central nervous system.
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Affiliation(s)
- Guoliang Zhang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang, PR China
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Vingren JL, Kraemer WJ, Ratamess NA, Anderson JM, Volek JS, Maresh CM. Testosterone Physiology in Resistance Exercise and Training. Sports Med 2010; 40:1037-53. [PMID: 21058750 DOI: 10.2165/11536910-000000000-00000] [Citation(s) in RCA: 251] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Jakob L Vingren
- Applied Physiology Laboratories, Department of Kinesiology, Health Promotion and Recreation, University of North Texas, Denton, Texas, USA
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13
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Veldhuis JD, Keenan DM, Liu PY, Takahashi PY. Kinetics of removal of intravenous testosterone pulses in normal men. Eur J Endocrinol 2010; 162:787-94. [PMID: 20089549 PMCID: PMC2861557 DOI: 10.1530/eje-09-1085] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Testosterone is secreted into the bloodstream episodically, putatively distributing into total, bioavailable (bio) nonsex hormone-binding globulin (nonSHBG-bound), and free testosterone moieties. The kinetics of total, bio, and free testosterone pulses are unknown. Design Adrenal and gonadal steroidogenesis was blocked pharmacologically, glucocorticoid was replaced, and testosterone was infused in pulses in four distinct doses in 14 healthy men under two different paradigms (a total of 220 testosterone pulses). METHODS Testosterone kinetics were assessed by deconvolution analysis of total, free, bioavailable, SHBG-bound, and albumin-bound testosterone concentration-time profiles. RESULTS Independently of testosterone dose or paradigm, rapid-phase half-lives (min) of total, free, bioavailable, SHBG-bound, and albumin-bound testosterone were comparable at 1.4+/-0.22 min (grand mean+/-S.E.M. of geometric means). Slow-phase testosterone half-lives were highest for SHBG-bound testosterone (32 min) and total testosterone (27 min) with the former exceeding that of free testosterone (18 min), bioavailable testosterone (14 min), and albumin-bound testosterone (18 min; P<0.001). Collective outcomes indicate that i) the rapid phase of testosterone disappearance from point sampling in the circulation is not explained by testosterone dose; ii) SHBG-bound testosterone and total testosterone kinetics are prolonged; and iii) the half-lives of bioavailable, albumin-bound, and free testosterone are short. CONCLUSION A frequent-sampling strategy comprising an experimental hormone clamp, estimation of hormone concentrations as bound and free moieties, mimicry of physiological pulses, and deconvolution analysis may have utility in estimating the in vivo kinetics of other hormones, substrates, and metabolites.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Clinical Translational Science Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
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14
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Parent EE, Dence CS, Sharp TL, Welch MJ, Katzenellenbogen JA. 7α-18F-Fluoromethyl-Dihydrotestosterone and 7α-18F-Fluoromethyl-Nortestosterone: Ligands to Determine the Role of Sex Hormone–Binding Globulin for Steroidal Radiopharmaceuticals. J Nucl Med 2008; 49:987-94. [DOI: 10.2967/jnumed.107.048926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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15
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Parent EE, Carlson KE, Katzenellenbogen JA. Synthesis of 7alpha-(fluoromethyl)dihydrotestosterone and 7alpha-(fluoromethyl)nortestosterone, structurally paired androgens designed to probe the role of sex hormone binding globulin in imaging androgen receptors in prostate tumors by positron emission tomography. J Org Chem 2007; 72:5546-54. [PMID: 17585812 DOI: 10.1021/jo070328b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although prostate cancer growth is regulated by androgens through the androgen receptor (AR), in vitro assays of AR levels in prostate tumors have limited prognostic value. This might be improved by direct measurement of tumor AR in vivo using positron emission tomography (PET) imaging with fluorine-18-labeled androgens. Most AR PET imaging agents have been designed to limit steroid binding to serum proteins, but there is evidence that binding to sex hormone binding globulin (SHBG) might enhance tumor uptake. To probe the role of SHBG in prostate tumor uptake of PET imaging agents, we have synthesized two fluoro steroids, 7alpha-(fluoromethyl)dihydrotestosterone (7alpha-FM-DHT) and 7alpha-(fluoromethyl)nortestosterone (7alpha-FM-norT), by a route amenable to their labeling with [18F]fluoride ion. Both compounds have high affinity for AR, but 7alpha-FM-norT has much lower affinity for SHBG. Thus, these two fluoro steroids are well matched in terms of their site of fluorine labeling, similarity of structure, and equivalent AR binding affinity-but contrasting SHBG binding-and therefore can be used as agents for evaluating the role of SHBG binding in the target tissue uptake of AR PET imaging agents in humans.
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Affiliation(s)
- Ephraim E Parent
- Department of Chemistry, University of Illinois, Urbana, IL 61801, USA
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16
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Jacobs C, Van Den Broeck W, Simoens P. Increased Number of Neurons Expressing Androgen Receptor in the Basolateral Amygdala of Pathologically Aggressive Dogs. ACTA ACUST UNITED AC 2006; 53:334-9. [PMID: 16922829 DOI: 10.1111/j.1439-0442.2006.00840.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study aimed to determine the extent to which the androgen receptor (AR) is directly involved in the hormonal modulation of pathological canine aggressive behaviour in the basolateral nuclear group (BNG) of the amygdaloid body. A stereological quantification of AR-positive neurons was performed in the BNGs of normally behaving and aggressive male dogs. The BNG was selected because it is involved in sexual and behavioural activities that are influenced by androgens. In the aggressive dogs the BNG contained a significantly higher number of AR-positive neurons compared with normally behaving dogs suggesting differences in androgen activity within the BNGs of both the groups. However, additional mechanisms are likely to be involved because the AR-negative fraction of BNG neurons was also increased in the aggressive dogs. It was concluded that most of the AR was unliganded because a cytoplasmic staining pattern of AR positivity was observed in the canine BNG neurons. This indicates that genomic androgen actions, which are mediated through the AR are of minor importance in the testosterone modulation of canine aggression within the BNG. Other non-genomic mechanisms through which androgens may exert their action in the BNG are discussed. The aromatase pathway is suggested to be the main mechanism through which testosterone exerts its action within the BNG.
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Affiliation(s)
- C Jacobs
- University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
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17
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Militello A, Vitello G, Lunetta C, Toscano A, Maiorana G, Piccoli T, La Bella V. The serum level of free testosterone is reduced in amyotrophic lateral sclerosis. J Neurol Sci 2002; 195:67-70. [PMID: 11867076 DOI: 10.1016/s0022-510x(01)00688-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Sporadic amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting upper and lower motoneurons. There is an approximately 2:1 higher incidence of ALS in men compared to women, and this has raised the hypothesis of an involvement of sex hormones in the etiopathogenesis of the disorder. In this work, the serum levels of dehydroepiandrosterone sulphate (DHEAS), 17-betaestradiol, free and total testosterone were measured in 35 patients with defined or probable ALS, according to the El-Escorial/WFN revisited criteria, and compared to those obtained from 57 disease controls, matched for age and gender to the ALS group. We found no differences between ALS cases and disease controls in the serum levels of DHEAS, 17-betaestradiol and total testosterone. Conversely, free testosterone was significantly decreased in the ALS group. Given that testosterone crosses the blood-brain barrier only as unbound form, we suggest a possible involvement of this sex hormone in the pathophysiology of this severe motor neuron disease.
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Affiliation(s)
- Alessandra Militello
- ALS Clinical Research Center, Institute of Neuropsychiatry, University of Palermo, Via G. La Loggia, 1, 90129, Palermo, Italy
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18
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Mankoff DA, Dehdashti F, Shields AF. Characterizing tumors using metabolic imaging: PET imaging of cellular proliferation and steroid receptors. Neoplasia 2000; 2:71-88. [PMID: 10933070 PMCID: PMC1531868 DOI: 10.1038/sj.neo.7900075] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Treatment decisions in oncology are increasingly guided by information on the biologic characteristics of tumors. Currently, patient-specific information on tumor biology is obtained from the analysis of biopsy material. Positron emission tomography (PET) provides quantitative estimates of regional biochemistry and receptor status and can overcome the sampling error and difficulty in performing serial studies inherent with biopsy. Imaging using the glucose metabolism tracer, 2 -deoxy-2- fluoro-D-glucose (FDG), has demonstrated PET's ability to guide therapy in clinical oncology. In this review, we highlight PET approaches to imaging two other aspects of tumor biology: cellular proliferation and tumor steroid receptors. We review the biochemical and biologic processes underlying the imaging, positron-emitting radiopharmaceuticals that have been developed, quantitative image-analysis considerations, and clinical studies to date. This provides a basis for evaluating future developments in these promising applications of PET metabolic imaging.
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Affiliation(s)
- D A Mankoff
- Department of Radiology, University of Washington, Seattle, USA
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19
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Hostetler ED, Jonson SD, Welch MJ, Katzenellenbogen JA. Synthesis of 2-[(18)F]Fluoroestradiol, a Potential Diagnostic Imaging Agent for Breast Cancer: Strategies to Achieve Nucleophilic Substitution of an Electron-Rich Aromatic Ring with [(18)F]F(-). J Org Chem 1999; 64:178-185. [PMID: 11674101 DOI: 10.1021/jo981619a] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To improve the pharmacokinetics of fluorine-18 labeled estrogens to be used as receptor-based imaging agents for the identification and staging of estrogen-receptor-positive breast carcinoma, we wanted to synthesize 2-[(18)F]fluoroestradiol. This compound has high affinity for the estrogen receptor and also binds very well to sex hormone binding globulin, a protein thought to protect estrogens from metabolism and deliver them to target tissues. We anticipated that this compound might have increased tumor uptake and reduced uptake in the liver. The synthesis of a [(18)F]fluoroaryl estrogen at the high specific activity, no-carrier-added level requires the use of [(18)F]F(-) as a precursor. Several strategies were explored for the synthesis of a [(18)F]fluoroaryl estrogen. The synthesis of 2-[(18)F]fluoroestradiol was eventually achieved by [(18)F]fluoride ion displacement of a trimethylammonium leaving group at C-2 of an estrogen, with additional activation being provided by a 6-keto group which was subsequently removed by reduction. Incorporation yields of fluorine-18 were between 20% and 50%. The potential of this new radiopharmaceutical as an imaging agent is being evaluated in an appropriate animal model.
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Affiliation(s)
- Eric D. Hostetler
- Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, Illinois 61801, and Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway, St. Louis, Missouri 63110
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20
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Jonson SD, Bonasera TA, Dehdashti F, Cristel ME, Katzenellenbogen JA, Welch MJ. Comparative breast tumor imaging and comparative in vitro metabolism of 16alpha-[18F]fluoroestradiol-17beta and 16beta-[18F]fluoromoxestrol in isolated hepatocytes. Nucl Med Biol 1999; 26:123-30. [PMID: 10096512 DOI: 10.1016/s0969-8051(98)00079-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
16beta-[18F]Fluoromoxestrol ([18]betaFMOX) is an analog of 16alpha-[18F]fluoroestradiol-17beta ([18F]FES), a radiopharmaceutical known to be an effective positron emission tomography (PET) imaging agent for estrogen receptor-positive (ER+) human breast tumors. Based on comparisons of target tissue uptake efficiency and selectivity in a rat model, [18F]betaFMOX was predicted to be as effective an imaging agent as [18F]FES. However, in a preliminary PET imaging study with [18F]FMOX of 12 patients, 3 of whom had ER+ breast cancer, no tumor localization of [18F]betaFMOX was observed. In search for an explanation for the unsuccessful [18F]betaFMOX clinical trial, we have examined the rate of metabolism of [18F]FMOX and [18F]FES in isolated rat, baboon, and human hepatocytes. We have also studied the effect of the serum protein sex hormone-binding globulin (SHBG), which binds [18F]FES better than [18F]betaFMOX, on these rates of metabolism. Immature rat hepatocytes were found to metabolize [18F]FES 31 times faster than [18F]betaFMOX, whereas mature rat cells metabolized [18F]FES only 3 times faster, and baboon and human hepatocytes only 2 times faster than [18F]betaFMOX. In the presence of SHBG, the metabolic consumption rate for [18F]FES in mature rat hepatocytes decreased by 26%. Thus, the very favorable target tissue uptake characteristics of [18F]betaFMOX determined in the rat probably result from its comparative resistance to metabolism (vis-a-vis [18F]FES) in this species, an advantage that is strongly reflected in comparative metabolism rates in rat hepatocytes. In the baboon and human, [18F]FES is extensively protein bound and protected from metabolism, an effect that may be reflected to a degree as a decrease in the rate of metabolism of this compound in baboon and human hepatocytes relative to [18F]betaFMOX. Thus in primates, SHBG may potentiate the ER-mediated uptake of [18F]FES in ER+ tumors by selectively protecting this ligand from metabolism and ensuring its delivery to receptor-containing cells. In addition to current screening methods for 18F-estrogens that involve evaluating in vivo ER-mediated uptake in the immature female rat, studies comparing the metabolism of the new receptor ligands in isolated hepatocytes, especially those from primates or humans, may assist in predicting the potential of these ligands for human PET imaging.
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Affiliation(s)
- S D Jonson
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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21
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Molnár G, Kassai-Bazsa Z. Gonadotropin, ACTH, prolactin, sexual steroid and cortisol levels in postmenopausal women's cerebrospinal fluid (CSF). Arch Gerontol Geriatr 1997; 24:269-80. [PMID: 15374114 DOI: 10.1016/s0167-4943(96)00764-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/1996] [Revised: 11/08/1996] [Accepted: 11/26/1996] [Indexed: 11/15/2022]
Abstract
In CSF and serum of 24 fertile (34.9 +/- 12.2 years) and 15 postmenopausal (58.9 +/- 6.9 years) female patients with non-inflammatory neurologic diseases, LH, FSH, ACTH, prolactin (Prol), estradiol (E), progesterone (P), testosterone (T), and cortisol (C) levels were determined by RIA. In postmenopause, serum levels of FSH and LH had 8- and 6-fold increases in comparison to those in reproductive age. In postmenopause, serum levels of E, P, ACTH and Prol had 8-, 5-, 3- and 2-fold decreases. Serum levels of T and C remained statistically unchanged during the whole life span. In postmenopause, CSF levels of FSH and LH had 3- and 2-fold increases, while E, P, Prol, ACTH CSF levels remained statistically unchanged compared to those in reproductive age (CSF-C levels were under the test sensitivities). CSF/serum ratio of FSH had a 4-fold decrease while that of E had a 4-fold increase in the postmenopause. CSF and serum levels of estradiol and ACTH as well as the logarithmic values of FSH, Prol and P concentrations correlated significantly regarding the whole reproductive postmenopausal life span, however, the CSF-blood barrier seemed to protect the brain from the effects of peripheral estradiol-progesterone deficiencies.
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Affiliation(s)
- G Molnár
- Department of Neurology, University Medical School, Debrecen, H-4012, Hungary
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22
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Bonasera TA, Jonson SD, Pajeau TS, Katzenellenbogen JA, Welch MJ. Retardation of 17-oxidation of 16 alpha-[18F]fluoroestradiol-17 beta by substitution of deuterium for hydrogen in the 17 alpha position(6). Nucl Med Biol 1997; 24:239-49. [PMID: 9228658 DOI: 10.1016/s0969-8051(97)00057-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We describe the synthesis, in vitro metabolism and biodistribution of [17 alpha-2H]16 alpha-[18F]fluoroestradiol ([18F]DFES). The clinically useful breast cancer imaging agent, 16 alpha-[18F]fluoroestradiol-17 beta ([18F]FES), was deuterated at the C-17 alpha position to lower the rate of C-17 alcohol oxidation. Metabolism studies in immature female rat and mature female baboon isolated hepatocytes showed [18F]DFES being consumed ca. 2.5 times slower than [18F]FES. Biodistribution studies and time-activity curve measurements in female rats showed [18F]DFES to have superior uptake characteristics compared to [18F]FES for imaging estrogen-receptor rich targets.
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Affiliation(s)
- T A Bonasera
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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23
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Abstract
The masculinization of the brain, reproductive tract and many other structures is critically dependent on the testicular hormone, testosterone (T). In many species, T circulates bound with high affinity to sex hormone-binding globulin (SHBG). This protein has a wide phylogenetic distribution and SHBG or SHBG-like proteins are produced by the liver, testes, placenta, brain and other tissues. SHBG activity is detectable during gestation and its expression is both stage- and tissue-dependent. Although SHBG binds circulating androgens, it is argued that the trapping of steroids in the circulation is not the principal function of this protein. The specific binding and uptake of SHBG by various tissues has been observed and suggests that SHBG may directly affect the delivery of androgen signals to target tissues. Effects of SHBG on androgen metabolism, tissue retention, cellular targeting, and action are reviewed. Evidence to date indicates that SHBG is able to enhance or inhibit the uptake of androgens in a cell- and tissue-specific manner. Future work will be necessary to demonstrate whether such actions of SHBG are important for normal male reproductive development.
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Affiliation(s)
- D A Damassa
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA
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