Changes in plasma and pituitary levels of prolactin in the toad, Bufo japonicus, throughout the year with special reference to the breeding migration

Susumu Ishii, Hiroko Yoneyama, Masami Inoue, Kazutoshi Yamamoto, Sakae Kikuyama

    研究成果: Article査読

    16 被引用数 (Scopus)

    抄録

    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 breading 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.

    本文言語English
    ページ(範囲)365-372
    ページ数8
    ジャーナルGeneral and Comparative Endocrinology
    74
    3
    DOI
    出版ステータスPublished - 1989

    ASJC Scopus subject areas

    • 内分泌学

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