HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gupta, S. Articles by Crowe, M. A. Search for Related Content PubMed PubMed Citation Articles by Gupta, S. Articles by Crowe, M. A.

Technical Note: Effect of corticotropin-releasing hormone on adrenocorticotropic hormone and cortisol in steers

S. Gupta^*,, B. Earley^*,1, S. T. L. Ting^*,, N. Leonard and M. A. Crowe^,

^* Teagasc, Grange Research Centre, Dunsany, Co. Meath, Ireland, and Faculty of Veterinary Medicine and and Conway Institute, University College Dublin 04, Dublin, Ireland

¹ Correspondence—phone: +353-46-9061100; fax: +353-46-9026154; e-mail: bearley{at}grange.teagasc.ie.

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 µg/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 µg 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 µg of bCRH/kg BW were not significantly different (P = 0.177) from controls. Administration of 0.3, 1.0, and 1.5 µg 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 µg of bCRH/kg BW is required to stimulate physiological effects of stressor hormones.

Key Words: Adrenocorticotropic Hormone • Corticotropin-Releasing Hormone • Cortisol • Hypothalamic-Pituitary-Adrenal Axis • Stress • Steers

This article has been cited by other articles:

				S. Gupta, B. Earley, S. T. L. Ting, and M. A. Crowe Effect of repeated regrouping and relocation on the physiological, immunological, and hematological variables and performance of steers J Anim Sci, August 1, 2005; 83(8): 1948 - 1958. [Abstract] [Full Text] [PDF]