Lapierre H, Petitclerc D, Pelletier G, Delorme L, Dubreuil P, Morisset J, Gaudreau P, Couture Y, Brazeau P
Agriculture Canada Lennoxville Research Station, Quebec.
Domest Anim Endocrinol. 1990 Oct;7(4):485-95. doi: 10.1016/0739-7240(90)90006-l.
Two experiments were conducted to study the effects of growth hormone-releasing factor (GRF) and thyrotropin-releasing factor (TRF) administration on hormone concentrations in dairy cows. In the first trial, 12 cows were used on 5 consecutive days to determine the effect of four sc doses of GRF (0, 1.1, 3.3 and 10 micrograms.kg-1 BW) and three sc doses of TRF (0, 1.1 and 3.3 micrograms.kg-1 BW) combined in a factorial arrangement. GRF and TRF acted in synergy (P = .02) on serum growth hormone (GH) concentration even at the lowest dose tested and GH response to the two releasing factors was higher than the maximal response observed with each factor alone. TRF increased (P less than .01) prolactin (Prl), thyrotropin (TSH), triiodothyronine (T3) and thyroxine (T4) concentrations similarly at the 1.1 and 3.3 micrograms.kg-1 doses and GRF did not interact (P greater than .40) with TRF on the release of these hormones. In the second trial, the effect of GRF (3.3 micrograms.kg-1 BW, sc) and TRF (1.1 micrograms.kg-1 BW, sc) was tested at three stages (18, 72 and 210 days) of lactation on serum Prl and TSH concentrations. Eighteen cows (n = 6 per stage of lactation) were used in two replicates of a 3 X 3 latin square. The TRF and GRF-TRF treatments were equipotent (P greater than .05) in increasing Prl and TSH concentrations. Prl and TSH responses were similar (P greater than .40) throughout lactation. In summary, GRF at doses ranging from 1.1 to 10.0 micrograms.kg-1 and TRF at doses ranging from 1.1 to 3.3 micrograms.kg-1 act in synergy on GH release and do not interact on Prl, TSH, T3 and T4 concentrations in dairy cows. Furthermore, Prl and TSH response to TRF are not affected by stage of lactation.
进行了两项试验，以研究生长激素释放因子（GRF）和促甲状腺激素释放因子（TRF）给药对奶牛激素浓度的影响。在第一项试验中，连续5天使用12头奶牛，以析因设计的方式确定4种皮下注射剂量的GRF（0、1.1、3.3和10微克·千克-1体重）和3种皮下注射剂量的TRF（0、1.1和3.3微克·千克-1体重）的效果。即使在测试的最低剂量下，GRF和TRF对血清生长激素（GH）浓度也具有协同作用（P = 0.02），并且GH对这两种释放因子的反应高于单独使用每种因子时观察到的最大反应。TRF在1.1和3.3微克·千克-1剂量时，对催乳素（Prl）、促甲状腺激素（TSH）、三碘甲状腺原氨酸（T3）和甲状腺素（T4）浓度的升高作用相似（P < 0.01），并且GRF在这些激素的释放上与TRF没有相互作用（P > 0.40）。在第二项试验中，在泌乳的三个阶段（18、72和210天）测试了GRF（3.3微克·千克-1体重，皮下注射）和TRF（1.1微克·千克-1体重，皮下注射）对血清Prl和TSH浓度的影响。18头奶牛（每个泌乳阶段n = 6）用于3×3拉丁方设计的两个重复试验。TRF和GRF-TRF处理在提高Prl和TSH浓度方面等效（P > 0.05）。在整个泌乳期，Prl和TSH的反应相似（P > 0.40）。总之，剂量范围为1.1至10.0微克·千克-1的GRF和剂量范围为1.1至3.3微克·千克-1的TRF对奶牛的GH释放具有协同作用，并且对Prl、TSH、T3和T4浓度没有相互作用。此外，Prl和TSH对TRF的反应不受泌乳阶段的影响。
