Am. Chapa et al., CHANGES IN PLASMA SOMATOTROPIN, PROLACTIN, GLUCOSE, AND NONESTERIFIEDFATTY-ACID CONCENTRATIONS IN GOATS ADMINISTERED AN EPINEPHRINE CHALLENGE, Small ruminant research, 23(2-3), 1997, pp. 125-133
The effect of acute adrenergic stimulation on changes in selected pitu
itary hormone and energy metabolite concentrations in plasma was inves
tigated 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 jug
ular vein catheters following a 16 h fast. Blood was sampled at 10 min
intervals from 60 min before treatment (PRE) to 120 min after treatme
nt. Plasma was analyzed for somatotropin, prolactin, glucose, and none
sterified fatty acids (NEFA). In Experiment 1, goats were given an i.v
. dose of saline (CON) or epinephrine HCl in saline (1 mu g kg(-1) BW)
, Plasma somatotropin (mean PRE 18.8 +/- 2.3 ng ml(-1)) decreased 10 m
in after epinephrine administration and then increased 154% above PRE
at 50 min after treatment (P < 0.05). Plasma glucose (mean PRE 3.44 +/
- 0.19 mmoll(-1)) and NEFA (mean PRE 550 +/- 68 mu equivl(-1)) increas
ed (P < 0.05) in epinephrine-treated goats, peaking 10 min after treat
ment 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 mu g kg(-1) BW). There was no effect (P > 0.10) of epinephr
ine on plasma somatotropin or prolactin concentrations. Plasma glucose
(mean PRE 3.03 +/- 0.16 mmoll(-1)) and NEFA (mean PRE 429 +/- 40 mu e
quivl(-1)) increased (P < 0.02) in epinephrine-treated goats, peaking
at 30% (20 min POST) and 22% (10 min POST) above PRE levels, respectiv
ely. In nonpregnant goats, adrenergic stimulation using an i.v. epinep
hrine challenge resulted in variable hormonal responses, but rapid and
measurable metabolic responses, The metabolic responses to the epinep
hrine challenge were similar to those reported in other species.