Wise T, Day M L, Vakharia D D
U.S. Department of Agriculture, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska 68933-0166.
J Reprod Immunol. 1990 Oct;18(3):225-35. doi: 10.1016/0165-0378(90)90045-8.
To monitor the relationships of luteinizing hormone (LH) and thymosin-alpha 1 and -beta 4 in conjunction with possible gonadal feedback mechanisms that could alter thymic function (thymosin secretion), circulating thymosin-alpha 1 and -beta 4 and LH concentrations of control heifers (n = 6), ovariectomized heifers (n = 5) and ovariectomized heifers implanted with estradiol (n = 5) were determined during the prepubertal period (initiated at 266 days of age). Sequential blood samples were collected at 12-min intervals for 8 h before ovariectomy on day 0 and on days 8, 36, 50, 64, 78, 92, 106, 120 and 134 of the experiment. Thymosin-beta 4 concentrations were not different between treatments. Thymosin-beta 4 concentrations gradually decreased until day 92 of the study, then increased two-fold by day 134 of experimental sampling (400 days of age) when all control animals had attained puberty. Concentrations of thymosin-alpha 1 changed little as animals matured, but peak amplitude did increase over time (0.287 ng/ml at day 0 to 0.403 ng/ml at day 120; P less than 0.05). Mean concentration, number of episodic peaks and peak amplitude of thymosin-alpha 1 was increased in ovariectomized heifers in comparison to ovariectomized plus estradiol implants (P less than 0.05). Prior to cyclic ovarian function (prepuberty), changes in circulating thymosin-beta 4 concentrations seem to be independent of effects of gonadal steroids but thymosin-alpha 1 was responsive to estradiol.
为监测促黄体生成素（LH）与胸腺素α1和β4之间的关系，以及可能改变胸腺功能（胸腺素分泌）的性腺反馈机制，在青春期前阶段（始于266日龄）测定了对照小母牛（n = 6）、去卵巢小母牛（n = 5）和植入雌二醇的去卵巢小母牛（n = 5）的循环胸腺素α1和β4以及LH浓度。在实验的第0天去卵巢前8小时以及实验的第8、36、50、64、78、92、106、120和134天，每隔12分钟采集一次连续血样。各处理组之间胸腺素β4浓度无差异。胸腺素β4浓度在研究第92天之前逐渐降低，然后在实验取样第134天（400日龄）时增加了两倍，此时所有对照动物均已进入青春期。随着动物成熟，胸腺素α1浓度变化不大，但峰值幅度随时间增加（第0天为0.287 ng/ml，第120天为0.403 ng/ml；P<0.05）。与去卵巢加植入雌二醇的小母牛相比，去卵巢小母牛的胸腺素α1平均浓度、脉冲峰值数量和峰值幅度均增加（P<0.05）。在周期性卵巢功能之前（青春期前），循环胸腺素β4浓度的变化似乎与性腺类固醇的作用无关，但胸腺素α1对雌二醇有反应。
