TY - JOUR
TI - Pituitary responsiveness to gonadotropin- and thyrotropin-releasing
hormones in goats treated with recombinant bovine somatotropin
AU - Chadio, SE
AU - Menegatos, J
AU - Zervas, G
AU - Goulas, C
AU - Deligeorgis,
AU - S
AU - Kalogiannis, D
JO - Small Ruminant Research
PY - 2002
VL - 46
TODO - 2-3
SP - 149-157
PB - ELSEVIER SCIENCE BV
SN - 0921-4488
TODO - 10.1016/S0921-4488(02)00188-8
TODO - GnRH; TRH; pituitary responsiveness; somatotropin; goat
TODO - Non-lactating, crossbred Alpine goats, of similar age and body weight
were used to evaluate the effects of bovine somatotropin (bST)
administration on pituitary function. Following ovarian synchronization,
treated goats (n = 4) received a subcutaneous injection of 160mg rbST,
three times, at 14-day intervals, while control goats (n = 4) remained
uninjected. The day after the last rbST injection ovarian
synchronization was repeated and the following day all animals were
challenged with 50 mug gonadatropin-releasing hormone (GnRH) and 100 mug
thyrotropin-releasing hormone (TRH). intravenously. Blood samples were
collected at - 10, 0, 30. 60. 90, 120. 180, 270 and 360 min after
challenge. Additionally, blood sampling was conducted three times per
week throughout the experimental period for the detection of peripheral
somatotropin, progesterone, T-3 and T-4 concentrations. Treatment with
rbST significantly increased somatotropin concentrations in treated
animals (21.2 +/- 1.3 ng/ml) as compared to controls (5.2 +/- 0.4
ng/ml). GnRH and TRH infusions resulted in similar LH, TSH, T3 and T4
responses in both groups. in terms of the area under the curve (AUC),
the peak value (PV) and the time to peak (PT). Plasma progesterone
concentrations during the treatment period did not differ between
groups. Treatment with rbST did not affect T4 levels during the
experimental period, but a highly significant effect of treatment was
observed for T3 levels, particularly after the second rbST
administration (1.47 +/- 0.06 ng/ml versus 2.01 +/- 0.1 ng/ml) for the
control and treated group. In conclusion, it has been shown that rbST
treatment did not affect pituitary responsiveness to GnRH or TRH
challenge, demonstrating that the pituitary control of ovarian and
thyroid function is not influenced by bST administration. (C) 2002
Elsevier Science B.V. All rights reserved.
ER -