Gaston-Parry O, Heasman K, Nemorin J K, Robinson T J
Department of Animal Husbandry, University of Sydney, N.S.W.
Aust J Biol Sci. 1988;41(1):57-67.
Simultaneous concentrations of endogenous progesterone and exogenous FGA have been measured in ewes treated with FGA-impregnated intravaginal sponges at several times relative to the expected time of release of LH. First, a direct double antibody radioimmunoassay (RIA) for FGA, with good precision, sensitivity and reproducibility, was developed and validated. An oxime derivative was prepared and then conjugated to human serum albumen at the 3-position to produce the antigen. Antibodies raised in New Zealand White rabbits showed little cross-reactivity with related steroids. FGA was estimated in extracted and unextracted plasma; results were indistinguishable. Second, sponges impregnated with 40 mg FGA were inserted into 20 anoestrous crossbred ewes for 12 days; 500 i.u. pregnant mare serum gonadotrophin (PMSG) was injected at withdrawal. Similar sponges were reintroduced into four ewes at each of the intervals 1, 3, 5, and 7 days later; three ewes served as controls. Plasma concentrations of progesterone and FGA were estimated by RIA daily during treatment and at intervals of 2 h for 12 h and at 18 and 24 h after withdrawal. The plasma profiles of FGA during the two successive periods of insertion were remarkably similar. A concentration of 3.0 ng/ml (s.e.m. +/- 0.22) was attained on day 1, falling to 1.5 ng/ml (+/- 0.15) by day 4. Thereafter, the concentration was maintained at 1.1 ng/ml (+/- 0.08). Plasma progesterone concentrations were at basal levels of less than 0.2 ng/ml during the first (acyclic) period of sponge insertion. During the second (cyclic) period there was a marked difference related to the time of sponge insertion. Insertion on day 1 (before LH release) resulted in complete inhibition of luteal activity; insertion on day 3, 5 or 7 was followed by apparently normal luteal function. There was no evidence of any feedback mechanism of exogenous progestagen on endogenous progesterone and no interaction. It is concluded that a 12-day treatment is needed in cyclic ewes for full synchronization and that sponges impregnated with 40 mg FGA will maintain an effective plasma concentration of greater than 1 ng/ml to the end of this period.
在给母羊植入含氟孕酮（FGA）的阴道海绵栓后，于相对于促黄体生成素（LH）预期释放时间的几个时间点，同时测定了内源性孕酮和外源性FGA的浓度。首先，开发并验证了一种用于FGA的直接双抗体放射免疫测定法（RIA），该方法具有良好的精密度、灵敏度和重现性。制备了一种肟衍生物，然后将其在3位与人血清白蛋白偶联以产生抗原。在新西兰白兔中产生的抗体与相关类固醇的交叉反应很小。对提取和未提取的血浆中的FGA进行了测定；结果无差异。其次，将含40mg FGA的海绵栓插入20只乏情杂种母羊体内12天；撤栓时注射500国际单位孕马血清促性腺激素（PMSG）。在撤栓后1、3、5和7天的每个时间间隔，将类似的海绵栓重新植入4只母羊体内；3只母羊作为对照。在治疗期间每天通过RIA测定孕酮和FGA的血浆浓度，并在撤栓后12小时内每隔2小时以及在撤栓后18和24小时进行测定。在连续两个植入期内，FGA的血浆浓度曲线非常相似。第1天达到3.0ng/ml（标准误±0.22）的浓度，到第4天降至1.5ng/ml（±0.15）。此后，浓度维持在1.1ng/ml（±0.08）。在植入海绵栓的第一个（无周期）阶段，血浆孕酮浓度处于低于0.2ng/ml的基础水平。在第二个（有周期）阶段，与海绵栓植入时间存在明显差异。在第1天（LH释放前）植入导致黄体活动完全受抑制；在第3、5或7天植入后，黄体功能显然正常。没有证据表明外源性孕激素对内源性孕酮有任何反馈机制，也没有相互作用。得出的结论是，对于有周期的母羊，需要进行12天的治疗才能实现完全同步，并且含40mg FGA的海绵栓在这段时间结束时将维持大于1ng/ml的有效血浆浓度。
