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Reduced CGP12177 binding to cardiac β-adrenoceptors in hyperglycemic high-fat-diet-fed, streptozotocin-induced diabetic rats.
MedLine Citation:
PMID:  21831645     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
INTRODUCTION: Abnormal sympathetic nervous system and β-adrenoceptor (β-AR) signaling is associated with diabetes. [(3)H]CGP12177 is a nonselective β-AR antagonist that can be labeled with carbon-11 for positron emission tomography. The aim of this study was to examine the suitability of this tracer for evaluation of altered β-AR expression in diabetic rat hearts. METHODS: Ex vivo biodistribution with [(3)H]CGP12177 was carried out in normal Sprague-Dawley rats for evaluation of specific binding and response to continuous β-AR stimulation by isoproterenol. In a separate group, high-fat-diet feeding imparted insulin resistance and a single intraperitoneal injection of streptozotocin (STZ) or vehicle evoked hyperglycemia (blood glucose >11 mM). [(3)H]CGP12177 biodistribution was assessed at 2 and 8 weeks post-STZ to measure β-AR binding in heart, 30 min following tracer injection. Western blotting of β-AR subtypes was completed in parallel. RESULTS: Infusion of isoproterenol over 14 days did not affect cardiac binding of [(3)H]CGP12177. Approximately half of rats treated with STZ exhibited sustained hyperglycemia and progressive hypoinsulinemia. Myocardial [(3)H]CGP12177 specific binding was unchanged at 2 weeks post-STZ but significantly reduced by 30%-40% at 8 weeks in hyperglycemic but not euglycemic STZ-treated rats compared with vehicle-treated controls. Western blots supported a significant decrease in β(1)-AR in hyperglycemic rats. CONCLUSIONS: Reduced cardiac [(3)H]CGP12177 specific binding in the presence of sustained hyperglycemia corresponds to a decrease in relative β(1)-AR expression. These data indirectly support the use of [(11)C]CGP12177 for assessment of cardiac dysfunction in diabetes.
Authors:
James T Thackeray; Maryam Parsa-Nezhad; Miran Kenk; Stephanie L Thorn; Maria Kolajova; Rob S B Beanlands; Jean N Dasilva
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-8-8
Journal Detail:
Title:  Nuclear medicine and biology     Volume:  -     ISSN:  1872-9614     ISO Abbreviation:  -     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-8-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9304420     Medline TA:  Nucl Med Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Affiliation:
Molecular Function and Imaging Program, National Cardiac PET Centre, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada K1Y4W7; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Roger Guindon Hall, Ottawa, Ontario, Canada K1H8M5.
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