Corticoid concentrations are increased in the plasma and urine of ewes with naturally occurring scrapie

The 24-h pattern of corticoid plasma concetrations was determined in scrapi e-affected ewes during the clinical phase of the disease. Twenty one ewes ( 8 healthy and 13 scrapie-affected ewes) were subjected to 24-h blood sampli ng sessions. Urine samples were simultaneously obtained during the clinical stage of the disease and in healthy ewes. The scrapie diagnosis was perfor med by histopathology. Plasma and urinary corticoids were assayed using HPL C methods. Mean plasma and urinary levels of corticoid (cortisol 20 beta-di hydrocortisol cortisone) of scrapie-affected ewes were greater than those o bserved in healthy ewes. 20 beta-dihydrocortisol appeared to be the main co rtisol metabolite in ewes. The intra-individual variations of 20 beta-dihyd rocortisol plasma concentrations were lower than the corresponding plasma c ortisol concentrations due to the dampening effect of the metabolic process on the short term variations of cortisol secretion. This dampening mechani sm was amplified in urine, the urinary concentrations integrating cortisol production over the period preceding sampling For these reasons, 20 beta-di hydrocortisol could present a potential interest for a non invasive diagnos tic test of transmissible spongiform encephalopathies. The pathophysiologic al consequences of an excessive exposure to cortisol on development of the neurogenerative process are discussed.