Sexually dimorphic stress and pro-inflammatory cytokine responses to an intravenous corticotropin-releasing hormone challenge of Brahman cattle following transportation

Abstract

This study was designed to characterize potential sexually dimorphic stress and immunological responses following a corticotropin-releasing hormone (CRH) challenge in beef cattle. Six female (heifers) and six male (bulls) Brahman calves (264 ± 12 d of age) were administered CRH intravenously (0.5 µg of CRH/kg body mass) after which serum concentrations of cortisol increased from 0.5 h to 4 h. From 1 h to 4 h after CRH administration, serum cortisol concentrations were greater in heifers than in bulls. In all cattle, increased serum concentrations of TNF-α, IL-6 and IFN-γ were observed from 2.5 h to 3 h after CRH, with greater concentrations of IFN-γ and IL-6 in heifers than bulls. Heifer total leukocyte counts decreased 1 h after CRH administration, while bull leukocyte counts and percent neutrophils decreased 2 h after CRH administration. Heifers had greater rectal temperatures than bulls, yet rectal temperatures did not change following administration of CRH. There was no effect of CRH administration on heart rate. However, bulls tended to have increased heart rate 2 h after CRH administration than before CRH. Heifer heart rate was greater than bulls throughout the study. These data demonstrate that acute CRH administration can elicit a pro-inflammatory response, and cattle exhibit a sexually dimorphic pro-inflammatory cytokine and cortisol response to acute CRH administration.

Prenatal transportation stress alters temperament and serum cortisol concentrations in suckling Brahman calves12

“…In the present study, PNS females had greater EV through weaning than control females, PNS males, or control males. Other investigators have reported female cattle to be more temperamental (Shrode and Hammack, 1971;Hoppe et al, 2010), with heifers having greater blood concentrations of cortisol compared with bulls (Lay et al, 1992;Hulbert et al, 2012) and steers having greater cortisol compared with bulls (Tennessen et al, 1984). In the present study, female calves had greater serum concentrations of cortisol relative to males.…”

The metabolic, stress axis, and hematology response of zilpaterol hydrochloride supplemented beef heifers when exposed to a dual corticotropin-releasing hormone and vasopressin challenge1,2,3

“…This is in agree ment with a study utilizing a cimaterol treatment in steers, where no difference in cortisol concentrations were ob served 1 and 13 d following initiation of oral dosing (Chikhou et al, 1991). The temporal pattern associated with an acute increase in circulating concentrations of cor tisol followed by a subsequent decline in the current study is similar to that observed in Brahman calves in response to a CRH challenge (Hulbert et al, 2013), although the magnitude of the cortisol response was greater in the cur rent study. Control heifers produced a greater cortisol response to the CRH/VP challenge compared with ZIL heifers, thus suggesting a possible downregulation of as pects associated with HPA axis regulation.…”

“…Although VT remained increased in CON heif ers, a return to baseline and subbaseline values was ob served in ZIL heifers. The temporal VT response to the CRH/VP challenge in the current study has similarities to the response observed in weaned Brahman calves chal lenged with CRH; in that study the authors reported fluc tuations in rectal temperature in the 8h period following CRH administration (Hulbert et al, 2013).…”

A comparison between the equine and bovine hypothalamus-pituitary-adrenocortical axis

“…In comparison, administration of 0.5 mg of bCRF/kg BW intravenous to Brahman calves enhanced serum cortisol concentrations with a peak value at 30 min (approximately 110 nmol/L in heifers (n ¼ 6) compared with 70 nmol/L in bulls (n ¼ 6)) [102]. After administration of 0.03 mg bCRF/kg BW intravenous in Holstein-Friesian heifer calves (n ¼ 20), the plasma cortisol concentration was approximately 28 to 61 nmol/L within about 30 min and the plasma ACTH concentration was approximately 3.3 to 7.7 pmol/L within about 15 min [103].…”