Ishii S, Yoneyama H, Inoue M, Yamamoto K, Kikuyama S
Department of Biology, School of Education, Waseda University, Tokyo, Japan.
Gen Comp Endocrinol. 1989 Jun;74(3):365-72. doi: 10.1016/s0016-6480(89)80032-2.
Monthly surveys of the plasma prolactin level in Bufo japonicus at two localities, one in Tokyo and the other in Saitama Prefecture, revealed that the level was highest during the month of breeding in early spring with an additional peak recognized in autumn. The level was lowest during the winter torpid period before breeding and during the spring torpid period after breeding. The pituitary prolactin content observed in Tokyo also showed an annual cycle similar to the plasma prolactin, except that the content in winter was higher than that in summer. A further precise survey of the plasma prolactin level before and during the breeding period revealed that the level in male toads migrating toward the pond for breeding was as low as the level in torpid toads, and also that the level was elevated in only about 50% of migrating female toads. In the pond, almost all female and male toads showed high plasma prolactin levels. Soon after the females finished breeding and returned to land, the level declined to the baseline without exception. In contrast, many males retained high levels on land. The present results indicate that prolactin is not a water drive factor, at least in B. japonicus. Prolactin may, however, play a role in toad osmoregulation in water. There is a possibility that the high prolactin level in some of the migrating female toads is related to oviductal secretion, as some female toads ovulate during migration.
对东京和埼玉县两地的日本蟾蜍血浆催乳素水平进行的月度调查显示，在早春繁殖月份该水平最高，秋季还会出现一个额外的峰值。在繁殖前的冬季蛰伏期和繁殖后的春季蛰伏期，该水平最低。在东京观察到的垂体催乳素含量也呈现出与血浆催乳素相似的年度周期，只是冬季的含量高于夏季。对繁殖期前后血浆催乳素水平进行的进一步精确调查显示，向池塘迁移进行繁殖的雄性蟾蜍的水平与蛰伏蟾蜍的水平一样低，而且只有约50%的迁移雌性蟾蜍的水平会升高。在池塘中，几乎所有雌性和雄性蟾蜍的血浆催乳素水平都很高。雌性完成繁殖并回到陆地后不久，该水平无一例外地降至基线。相比之下，许多雄性在陆地上仍保持高水平。目前的结果表明，催乳素至少在日本蟾蜍中不是一种促使入水的因素。然而，催乳素可能在蟾蜍在水中的渗透调节中发挥作用。一些迁移的雌性蟾蜍催乳素水平较高，有可能与输卵管分泌有关，因为一些雌性蟾蜍在迁移过程中排卵。
