title: Bovine acute-phase response after different doses of corticotropin-releasing hormone challenge.
abstract: The objective was to compare the acute-phase response of steers receiving different doses of bovine corticotropin-releasing hormone (CRH). Fourteen weaned Angus steers (BW = 191 ± 2.1 kg, age = 167 ± 4.7 d) fitted with an indwelling jugular catheter and a rectal temperature (RT) monitoring device were assigned to receive 1 of 3 treatments (intravenous infusion): 1) 0.1 μg of CRH/kg of BW (CRH1; n = 5), 2) 0.5 μg of CRH/kg of BW (CRH5; n = 5), and 3) 10 mL of saline (0.9%; n = 4). Blood samples were collected via catheters, relative to treatment infusion (0 h), hourly from -2 to 0 h and 4 to 8 h and every 30 min from 0 to 4 h. Rectal temperatures were recorded every 30 min from -2 to 8 h. Blood samples were also collected via jugular venipuncture and rectal temperatures assessed using a digital thermometer every 6 h from 12 to 72 h and every 24 h from 96 to 168 h. All plasma samples collected during the study were analyzed for concentrations of haptoglobin. All plasma samples collected from -2 to 8 h were analyzed for cortisol concentrations. Serum samples collected hourly from -2 to 8 h were analyzed for concentrations of NEFA, IL-6, tumor necrosis factor (TNF)-α, and interferon-γ. Cortisol peaked at 0.5 h for CRH1 steers but returned to baseline concentrations at 1 h relative to infusion (time effect; P < 0.01). In CRH5 steers, cortisol peaked at 0.5 h and returned to baseline concentrations 3.5 h relative to infusion (time effect; P < 0.01). Cortisol concentrations did not change after treatment infusion for saline steers (time effect; P = 0.42). In CRH1 steers, NEFA concentrations peaked 5 h after treatment infusion (time effect; P = 0.01). Conversely, serum NEFA concentrations did not change for CRH5 and saline steers after treatment infusion (time effect; P > 0.37). Mean serum TNF-α concentrations in CRH1 steers after treatment infusion were greater compared with saline (P = 0.02), tended to be greater (P = 0.08) compared with CRH5, and were similar (P = 0.40) between CRH5 and saline steers. Mean RT in CRH1 steers after treatment infusion were greater (P < 0.04) compared with saline and CRH5 and similar (P = 0.50) between CRH5 and saline steers. Haptoglobin increased and peaked 72 h after treatment infusion for CRH1 steers (time effect; P = 0.01) but did not change for CRH5 and saline steers (time effect; P > 0.45). In conclusion, the bovine acute-phase response stimulated by CRH infusion is dependent on the CRH dose and the subsequent response in circulating cortisol.
authors.affiliation: Oregon State University - Eastern Oregon Agricultural Research Center, Burns 97720.
authors.forename: R F
authors.initials: RF
authors.lastname: Cooke
authors.forename: J A
authors.initials: JA
authors.lastname: Carroll
authors.forename: J
authors.initials: J
authors.lastname: Dailey
authors.forename: B I
authors.initials: BI
authors.lastname: Cappellozza
authors.forename: D W
authors.initials: DW
authors.lastname: Bohnert
mesh_terms: D000818:Animals; D002417:Cattle / Q000097:blood*; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006242:Haptoglobins / Q000378:metabolism; D006854:Hydrocortisone / Q000097:blood; D007371:Interferon-gamma / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D005230:Fatty Acids, Nonesterified; D006242:Haptoglobins; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone