Document Detail


Naturally occurring scrapie is associated with a lower CBG binding capacity in ewes.
MedLine Citation:
PMID:  10810317     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Naturally scrapie-affected ewes present a syndrome of hypercortisolism as evaluated by measuring total plasma cortisol concentrations. The objective of this study was to investigate the plasma protein binding of cortisol and to evaluate the concentration of the biologically active free fraction of cortisol in scrapie-affected ewes. Corticosteroid binding globulin (CBG) binding parameters were evaluated by equilibrium dialysis in 13 naturally scrapie-affected ewes and nine healthy ewes, during two periods of the clinical evolution of the disease. The hypercortisolism of the scrapie-affected ewes was confirmed by a significant increase of the plasma 20 beta-dihydrocortisol and cortisone concentrations, while total cortisol concentrations, obtained from an isolated sample, did not differ between scrapie-affected and control ewes. The scrapie diagnosis was confirmed by histopathology. The CBG maximal capacity (B(max)) was two times lower in scrapie-affected ewes than in healthy ewes (37+/-32 nM and 73+/-28 nM respectively). The dissociation constant K(d) (8.8+/-3.7 nM and 9.8+/-3.0 nM respectively) and the non-specific constant value of binding to albumin (1.13+/-0.18 and 1.14+/-0.23 respectively) did not differ significantly between diseased and control ewes. The significant increased concentrations of CBG-free cortisol (i.e. both albumin-bound and free cortisol fractions) in scrapie-affected ewes indicates that total plasma cortisol concentration is not an appropriate index of pituitary-adrenocortical hyperactivity. In conclusion, ewes with naturally occurring scrapie display a syndrome of hypercortisolism associated with a lower CBG binding capacity which leads to an overexposure of glucocorticoid-sensitive targets to CBG-free cortisol. The physiopathological consequences of this overexposure on the development of the neurodegenerative process in prion disease are discussed.
Authors:
N Picard-Hagen; V Gayrard; M Alvinerie; V Laroute; C Touron; O Andreoletti; P L Toutain
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of endocrinology     Volume:  165     ISSN:  0022-0795     ISO Abbreviation:  J. Endocrinol.     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-06-21     Completed Date:  2000-06-21     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0375363     Medline TA:  J Endocrinol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  527-32     Citation Subset:  IM    
Affiliation:
Unité Associée INRA de Pathologie et Toxicologie Expérimentales, Ecole Nationale Vétérinaire de Toulouse, France.
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MeSH Terms
Descriptor/Qualifier:
Animals
Hydrocortisone / metabolism*
Protein Binding
Scrapie / metabolism*
Sheep
Transcortin / metabolism*
Chemical
Reg. No./Substance:
50-23-7/Hydrocortisone; 9010-38-2/Transcortin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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