Kwun J K, Emmens C W
Aust J Biol Sci. 1975 Jun;28(3):291-9. doi: 10.1071/bi9750291.
While the necessity for progesterone administration throughout pregnancy in the ovariectomized rabbit is not questioned, the roles of 20alpha-dihydroprogesterone and oestradiol are still in doubt. 20alpha-dihydroprogesterone was shown to be a weak inducer of implantation with less than one-tenth the potency of progesterone. The significance of its high level of production on the day after mating remains obscure. In combination with the earlier results of Kwun and Emmens (1974), further work with oestradiol suggests that at no stage is it clearly needed for successful maintenance of pregnancy. However, in low doses (0.125-0.2 mug/day prior to implantation, 0.2 rising to 1.6 mug, or remaining at 0.2 mug/day thereafter) it produced slight but sometimes significant improvements in implantation and foetal development percentages. Birth processes were abnormal if progesterone injections were continued beyond day 29. Foetuses were most frequently retained in utero or born dead after a somewhat prolonged pregnancy. The cessation of injections on day 29, whether or not a low dosage of 0.2 mug of oestradiol per day were continued, resulted in 94-98% normal parturition, but the percentage of live births was still significantly below that of controls unless oestradiol was given.
虽然在切除卵巢的兔子整个孕期给予孕酮的必要性毋庸置疑，但20α-二氢孕酮和雌二醇的作用仍存在疑问。已证明20α-二氢孕酮是一种较弱的着床诱导剂，其效力不到孕酮的十分之一。交配后一天其高水平产生的意义仍不清楚。结合Kwun和Emmens（1974年）早期的结果，对雌二醇的进一步研究表明，在成功维持妊娠的任何阶段都显然不需要它。然而，低剂量（植入前每天0.125 - 0.2微克，植入后从0.2微克升至1.6微克，或此后保持在每天0.2微克）会使着床和胎儿发育百分比略有但有时显著提高。如果在第29天后继续注射孕酮，分娩过程会异常。胎儿最常滞留于子宫内或在稍长时间的妊娠后死产。在第29天停止注射，无论是否继续每天给予0.2微克的低剂量雌二醇，都会有94 - 98%的正常分娩，但除非给予雌二醇，活产百分比仍显著低于对照组。
