Changes in plasma somatotropin, prolactin, glucose, and nonesterified fatty acid concentrations in goats administered an epinephrine challenge

The effect of acute adrenergic stimulation on changes in selected pituitary hormone and energy metabolite concentrations in plasma was investigated in goats administered an i.v. epinephrine challenge test. Two separate experiments were conducted using a crossover design with ten crossbred, non-pregnant goats (average BW 42 ± 5 kg) fitted with jugular vein catheters following a 16h fast. Blood was sampled at 10 min intervals from 60 min before treatment (PRE) to 120 min after treatment. Plasma was analyzed for somatotropin, prolactin, glucose, and nonesterified fatty acids (NEFA). In Experiment 1, goats were given an i.v. dose of saline (CON) or epinephrine HCl in saline (1 μg kg-1 BW). Plasma somatotropin (mean PRE 18.8 ± 2.3 ng ml-1) decreased 10 min after epinephrine administration and then increased 154% above PRE at 50 min after treatment (P \u3c 0.05). Plasma glucose (mean PRE 3.44 ± 0.19 mmoll-1) and NEFA (mean PRE 550 ± 68 μequivl-1) increased (P \u3c 0.05) in epinephrine-treated goats, peaking 10 min after treatment at 14.4% and 10.7% above PRE levels, respectively. In Experiment 2, goats were given an i.v. dose of saline (CON) or epinephrine HCl in saline (2 μg kg-1 BW). There was no effect (P \u3e 0.10) of epinephrine on plasma somatotropin or prolactin concentrations. Plasma glucose (mean PRE 3.03 ± 0.16 mmoll-1) and NEFA (mean PRE 429 ± 40 μequivl-1) increased (P \u3c 0.02) in epinephrine-treated goats, peaking at 30% (20 min POST) and 22% (10 min POST) above PRE levels, respectively. In nonpregnant goats, adrenergic stimulation using an i.v. epinephrine challenge resulted in variable hormonal responses, but rapid and measurable metabolic responses. The metabolic responses to the epinephrine challenge were similar to those reported in other species