Type

Journal Article

Authors

M A Crowe
N Leonard
S T L Ting
B Earley
S Gupta

Subjects

Veterinary

Topics
body weight random allocation cattle animals corticotropin releasing hormone drug effects adrenocorticotropic hormone blood male hypothalamo hypophyseal system dose response relationship drug pituitary adrenal system physiology pharmacology hydrocortisone

Technical note: effect of corticotropin-releasing hormone on adrenocorticotropic hormone and cortisol in steers. (2004)

Abstract The objective of this study was to determine an appropriate exogenous dose of bovine corticotropin-releasing hormone (bCRH) to stimulate the physiological effects of the hypothalamic-pituitary-adrenal axis in steers as a method to test the sensitivity of the pituitary and adrenal gland. Twenty 14-mo-old Holstein-Friesian steers were blocked by weight (443.7+/-2.5 kg) and randomly allotted to receive either saline (control) or bCRH (0.1, 0.3, 1.0, or 1.5 microg/kg BW). Animals were housed in a slatted-floor facility (n = 5 per pen). Indwelling jugular catheters, for both the administration of bCRH and blood collection, were fitted on d -1 of the experiment. Saline and bCRH were administered i.v. at time 0. Serial blood samples were collected at -15, 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, and 180 min relative to time 0. Following administration of 0.1 microg of bCRH/kg BW, the peak ACTH response was not significantly different from pretreatment baseline concentrations (mean concentrations as measured at -15 and 0 min before bCRH administration). Mean ACTH concentrations from 0 to 180 min following 0.1 microg of bCRH/kg BW were not significantly different (P = 0.177) from controls. Administration of 0.3, 1.0, and 1.5 microg of bCRH/kg BW increased (P < 0.05) peak ACTH above pretreatment concentrations, and mean ACTH from 0 to 180 min for these treatments were greater (P < 0.05) than for controls. Peak cortisol responses to all bCRH treatments were greater (P < 0.05) than those to pretreatment concentrations. Mean cortisol concentrations from 0 to 180 min were greater (P < 0.05) in all bCRH-treated steers than in controls, but there were no significant differences among the bCRH treatments. The ratio of mean cortisol to mean ACTH for all bCRH doses tested differed (P < 0.05) from control values, indicating reactivity of the adrenals. In conclusion, bCRH challenge may be a useful method for testing the sensitivity of the hypothalamic-pituitary-adrenal axis in steers subjected to stressful husbandry conditions, and a minimum dose of 0.3 microg of bCRH/kg BW is required to stimulate physiological effects of stressor hormones.
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Full list of authors on original publication

M A Crowe, N Leonard, S T L Ting, B Earley, S Gupta

Experts in our system

1
M A Crowe
Teagasc
Total Publications: 102
 
2
Bernadette Earley
Teagasc
Total Publications: 120
 
3
S Gupta
Teagasc
Total Publications: 7