Dobson H, Alam M G, Kanchev L N
J Reprod Fertil. 1987 May;80(1):25-30. doi: 10.1530/jrf.0.0800025.
Betamethasone (a synthetic glucocorticoid, 15 mg) was administered i.m. twice daily for 10 days to 4 regularly cycling dairy cows, beginning on Day 10 of the oestrous cycle. Luteal function, monitored by plasma progesterone, was extended by 7, 9, 19 and 20 days, respectively. Luteal function in the next cycle was normal. Endogenous cortisol values were suppressed for 14, 13, 34 and 27 days, respectively. Pituitary responsiveness to 20 micrograms GnRH was assessed by LH measurement on Days -1, +3 and +7 relative to the start of betamethasone treatment. There was a progressive decrease in peak LH concentrations after each GnRH challenge compared to control cows. Hourly measurements of PGF-2 alpha metabolite during the expected period of luteolysis failed to reveal normal increases. It is suggested that betamethasone caused prolonged luteal function, either by directly inhibiting PGF-2 alpha release, or by suppressing pituitary stimulation of follicular growth and hence lowering oestradiol concentrations, since it is known that PGF-2 alpha and oestradiol act synergistically to cause luteolysis.
从发情周期的第10天开始，对4头正常发情的奶牛每天两次肌肉注射倍他米松（一种合成糖皮质激素，15毫克），持续10天。通过血浆孕酮监测黄体功能，分别延长了7、9、19和20天。下一个周期的黄体功能正常。内源性皮质醇值分别被抑制了14、13、34和27天。在相对于倍他米松治疗开始的第-1、+3和+7天，通过测量促黄体生成素（LH）来评估垂体对20微克促性腺激素释放激素（GnRH）的反应性。与对照奶牛相比，每次GnRH刺激后促黄体生成素峰值浓度逐渐降低。在预期的黄体溶解期每小时测量前列腺素F2α代谢物，未发现正常升高。有人认为，倍他米松导致黄体功能延长，要么是通过直接抑制前列腺素F2α的释放，要么是通过抑制垂体对卵泡生长的刺激从而降低雌二醇浓度，因为已知前列腺素F2α和雌二醇协同作用导致黄体溶解。
