Olsén K H, Sawisky G R, Stacey N E
School of Life Sciences, Södertörn University College, SE-141 89 Huddinge, Sweden.
Gen Comp Endocrinol. 2006 Dec;149(3):294-302. doi: 10.1016/j.ygcen.2006.06.011. Epub 2006 Aug 24.
Laboratory studies in domesticated goldfish (Carassius auratus) show that, during the preovulatory luteinizing hormone (LH) surge, females release a complex steroidal pheromone that induces in males a rapid increase of plasma LH, which in turn increases strippable milt (sperm and seminal fluid) prior to ovulation and spawning. The objective of this study was to determine if the same phenomenon occurs in a wild congener, the crucian carp (Carassius carassius), under field conditions where fish are held in natural waters under ambient temperature and photoperiod. During the spawning season in June 2003, crucian carp were trapped in a small pond near Uppsala, Sweden, and held separately by sex in floating net pens. Addition of untreated females to male pens did not change male LH concentrations or milt volume during the 17 h sampling period. In contrast, addition of females injected with Ovaprim (to induce an LH surge and ovulation) increased male LH concentrations at all sample times (5, 9, 13, and 17h) following female addition and increased milt volumes at all but the first (5h) sample time. Similar increases in male LH and milt that also occurred when untreated females ovulated spontaneously after addition to male pens suggest it is female ovulatory condition, rather than injection of ovaprim per se, that induced male LH and milt responses. Males also increased LH and milt 9h after addition of females injected with the goldfish pheromonal steroid 4-pregnen-17,20beta-diol-3-one (17,20betaP), suggesting that similar responses to ovaprim-injected females were due, at least in part, to release of preovulatory pheromonal steroid(s). The clear and consistent effects of ovulatory females on male LH and milt, and the fact that crucian carp adapted well to confinement, ovulated spontaneously, and exhibited apparently normal spawning behavior, all suggest that this species can serve as a useful cyprinid model to study reproductive processes in natural conditions.
对养殖金鱼（Carassius auratus）的实验室研究表明，在排卵前促黄体生成素（LH）激增期间，雌性会释放一种复杂的甾体信息素，这种信息素会使雄性血浆LH迅速增加，进而在排卵和产卵前增加可采精液量（精子和精液）。本研究的目的是确定在野外条件下，即在自然水温与光照周期下的天然水域中，其同属野生鱼类鲫鱼（Carassius carassius）是否会出现相同现象。在2003年6月的产卵季节，鲫鱼被困在瑞典乌普萨拉附近的一个小池塘中，并按性别分别饲养在浮动网箱中。在17小时的采样期内，将未处理的雌鱼放入雄鱼网箱中，并不会改变雄鱼的LH浓度或精液量。相比之下，放入注射了促排卵素（诱导LH激增和排卵）的雌鱼后，在放入雌鱼后的所有采样时间点（5、9、13和17小时），雄鱼的LH浓度均有所增加，除第一个采样时间点（5小时）外，其他采样时间点的精液量也有所增加。当未处理的雌鱼放入雄鱼网箱后自然排卵时，雄鱼的LH和精液量也出现了类似的增加，这表明是雌性的排卵状态，而非注射促排卵素本身，引发了雄鱼的LH和精液量反应。在放入注射了金鱼信息素甾体4 - 孕烯 - 17,20β - 二醇 - 3 - 酮（17,20βP）的雌鱼9小时后，雄鱼的LH和精液量也增加了，这表明对注射促排卵素的雌鱼产生的类似反应至少部分是由于排卵前甾体信息素的释放。排卵雌鱼对雄鱼LH和精液量有明显且一致的影响，而且鲫鱼能很好地适应圈养环境，自然排卵，并表现出明显正常的产卵行为，所有这些都表明该物种可作为研究自然条件下繁殖过程的有用鲤科鱼类模型。
