Allen W R, Mathias S S, Wooding F B P, Skidmore J A, van Aarde R J
Department of Clinical Veterinary Medicine Equine Fertility Unit, University of Cambridge, Newmarket, UK.
Reprod Suppl. 2002;60:105-16.
Placental and fetal tissues were recovered from the uteri of 59 pregnant elephant that ranged in estimated age from day 18 to month 21 of gestation. Incubation of placenta and fetal gonad, alone or in combination, with tritium-labelled cholesterol, pregnenolone and androstenedione failed to yield any labelled progestagens or oestrogens from placenta, but did produce small amounts of labelled progesterone and 5alpha-dihydroprogesterone from fetal gonad. Immunochemical staining of tissues with four antisera specific for enzymes involved in the steroidogenic pathway revealed no staining in sections of placenta but positive labelling for P450 side chain cleavage enzyme (SCC450) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) of the interstitial cells that comprise the bulk of the enlarged fetal gonads during the second half of gestation. Saline extracts of placental tissue showed no activity in three different gonadotrophin assays. In view of this endocrinological inactivity in the zonary elephant placenta and the probable reliance on maternal luteal sources of progestagens for maintenance of the pregnant state, the argument is advanced that uncomplicated abortion would probably follow a single administration of a PGF analogue given at any stage of pregnancy. If so, the treatment might constitute an efficacious method for controlling population increases in elephants maintained in enclosed game parks in Africa.
从59头怀孕大象的子宫中获取了胎盘和胎儿组织，这些大象的估计孕期从妊娠第18天到21个月不等。将胎盘和胎儿性腺单独或联合用氚标记的胆固醇、孕烯醇酮和雄烯二酮进行孵育，未能从胎盘中产生任何标记的孕激素或雌激素，但确实从胎儿性腺中产生了少量标记的孕酮和5α-二氢孕酮。用四种针对类固醇生成途径中相关酶的抗血清对组织进行免疫化学染色，结果显示胎盘切片无染色，但在妊娠后半期构成大部分增大的胎儿性腺的间质细胞中，P450侧链裂解酶（SCC450）和3β-羟基类固醇脱氢酶（3β-HSD）呈阳性标记。胎盘组织的盐水提取物在三种不同的促性腺激素测定中均无活性。鉴于带状大象胎盘的这种内分泌无活性以及维持妊娠状态可能依赖母体黄体来源的孕激素，有人提出，在妊娠的任何阶段单次给予PGF类似物可能会导致单纯性流产。如果是这样，这种治疗方法可能构成一种有效的方法，用于控制非洲封闭狩猎公园中大象种群的增长。
