Document Detail

Sex differences in cortisol secretion after administration of an ACTH analogue in sheep during the breeding and non-breeding season.
MedLine Citation:
PMID:  12853181     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to compare the response of cortisol in sheep of different sex and gonadal status to adrenal cortex stimulation by an ACTH analogue in the breeding and non-breeding season. Twenty-four adult Corriedale sheep were used in the non-breeding season, and 19 in the breeding season. Three weeks prior to the first trial (non-breeding season), six rams and six ewes were gonadectomised. In each trial, blood was obtained every 15min for 9h and the animals received 0.5mg of ACTH (Tetracosactid, Synacthen Depot i.m., after 1.5h of sampling. Sampling began at 10:00a.m. in the non-breeding season and at 9:00a.m. in the breeding season. Three main effects (sex, gonadal status and season) were evaluated, each with two levels (male and female, intact and gonadectomised, breeding and non-breeding season, respectively). In both seasons, the females showed higher cortisol levels after ACTH than males (P<0.001), though the difference seemed less marked in the non-breeding season. The cortisol response in the ewes was not affected by season. The rams, however, showed a lower response in the breeding season (P<0.03). Gonadectomy reduced the response in the ewes (P<0.001) but had no effect in the rams. Nevertheless, gonadectomy also eliminated the differences between the ewes and the rams, such that the intact rams had lower levels of cortisol compared to the intact females, with those of the gonadectomised animals of both sexes being intermediate between the gonad-intact groups. The results of this study confirm sex differences in ACTH induced cortisol secretion in intact sheep in vivo. Furthermore, by applying exogenous ACTH we have directly stimulated the adrenal cortex, indicating the existence of sex differences also at this level. The circulating gonadal steroids, which are responsible at least in part for the sex differences in the responses to stress, may influence cortisol secretion from the adrenal gland by direct action at the cortex.
E van Lier; R Pérez-Clariget; M Forsberg
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Animal reproduction science     Volume:  79     ISSN:  0378-4320     ISO Abbreviation:  Anim. Reprod. Sci.     Publication Date:  2003 Nov 
Date Detail:
Created Date:  2003-07-10     Completed Date:  2003-11-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7807205     Medline TA:  Anim Reprod Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  81-92     Citation Subset:  IM    
Animal and Forage Sciences Department, Faculty of Agriculture, Universidad de la República, Avda. E. Garzón 780, 12900 Montevideo, Uruguay.
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MeSH Terms
Adrenal Cortex / drug effects,  physiology
Adrenocorticotropic Hormone / analogs & derivatives*
Body Weight
Cosyntropin / pharmacology
Hydrocortisone / secretion*
Regression Analysis
Sheep / physiology*
Testosterone / blood
Reg. No./Substance:
16960-16-0/Cosyntropin; 50-23-7/Hydrocortisone; 58-22-0/Testosterone; 9002-60-2/Adrenocorticotropic Hormone

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

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