Thyroid hormones inhibit frog corticotropin-releasing factor-induced thyrotropin release from the bullfrog pituitary in vitro

Miyoko Kaneko, Hitomi Fujisawa, Reiko Okada, Kazutoshi Yamamoto, Masahisa Nakamura, Sakae Kikuyama*

*この研究の対応する著者

    研究成果: Article査読

    19 被引用数 (Scopus)

    抄録

    Due to the lack of a radioimmunoassay (RIA) system for amphibian thyrotropin (TSH), no direct evidence that thyroid hormone suppresses the release of TSH from the amphibian pituitary has been obtained. However, we recently developed an RIA for bullfrog (Rana catesbeiana) TSH and thus were able to study the effect of thyroid hormone on the release of TSH from the bullfrog pituitary. Enzymatically dispersed pituitary cells of larval, juvenile, and adult bullfrogs were cultured in the absence or presence of 100 nM corticotropin-releasing factor of bullfrog origin (fCRF), which is known to be a potent stimulator of the release of TSH. The amount of spontaneously released TSH was higher in late prometamorphic and climactic tadpoles than in early prometamorphic larvae and juvenile and adult frogs. Pituitary cells from tadpoles at metamorphic climax responded to fCRF to release much more TSH than those from early and late prometamorphic tadpoles and juvenile and adult frogs. In all cases, the fCRF (100 nM)-induced, but not the basal, release of TSH was significantly suppressed by 1 nM triiodothyronine (T3) and 1000 nM thyroxine (T4), when examined using adult pituitary cells. The suppressive effect of thyroid hormones was revealed to be dependent on their concentrations.

    本文言語English
    ページ(範囲)122-127
    ページ数6
    ジャーナルGeneral and Comparative Endocrinology
    144
    2
    DOI
    出版ステータスPublished - 2005 11

    ASJC Scopus subject areas

    • 内分泌学

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