title: Endotoxin stimulates secretion of cortisol, but not ACTH in heifers pretreated with suppressive doses of a glucocorticoid.
abstract: The ability of triamcinolone acetonide (TA) to suppress actions of lipopolysaccharide (LPS) in the pituitary-adrenal axis was examined in Holstein heifers. The study was carried out using repeated measure/split plot factorial design involving four heifers which were repeatedly used in four experimental groups thus yielding eight experimental units (EU). Each EU received two treatments, the first at zero hour and the second at 28 h. Heifers in Groups I (n = 2) and II (n = 2) were given sterile saline as treatment (TRT) 1. For TRT 2, group I was given sterile saline, and group II received Escherichia coli lipopolysaccharide (LPS). In group III (n = 2) and group IV (n = 2) triamcinolone acetonide was given as TRT 1. Sterile saline (SAL) was TRT 2 for GP III, and group IV heifers received LPS. Administration of LPS elicited increases in concentrations of the stress hormones ACTH (P < 0.05) and cortisol (P < 0.001) in SAL-pretreated heifers. However, in TA-pretreated animals, the endotoxin could only cause increase (P < 0.001) in concentrations of cortisol, but not ACTH. Therefore, the significant response of cortisol to LPS stimulation suggest that, at doses used in this study, triamcinolone acetonide did not suppress LPS-triggered cortisol secretion from adrenal zonae fasciculata and reticularis cells. The LPS-induced ACTH response appears to have been blunted by prior administration of triamcinolone acetonide.
authors.affiliation: Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706-1100, USA.
authors.forename: W T
authors.initials: WT
authors.lastname: Bosu
authors.forename: L L
authors.initials: LL
authors.lastname: Kujjo
authors.forename: G I
authors.initials: GI
authors.lastname: Perez
mesh_terms: D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D002417:Cattle / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology*; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology; D011897:Random Allocation; D014222:Triamcinolone Acetonide / Q000494:pharmacology*
chemical_list: D005938:Glucocorticoids; D008070:Lipopolysaccharides; D000324:Adrenocorticotropic Hormone; D014222:Triamcinolone Acetonide; D006854:Hydrocortisone