Oxytocinによる培養ヒト子宮筋細胞の細胞内Ca^<2+>濃度変動ならびにPI responseに及ぼす各種ステロイドホルモンの影響  [in Japanese] Effects of Steroid Hormones on Change in [Ca^<2+>]_i and on PI Response Following Oxytocin Stimulation in Cultured Human Myometrial Cells  [in Japanese]

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Oxytocin (OT)による子宮筋収縮は, イノシトール燐酸回転 (PI response)の活性化に伴う筋小胞体よりのCa^<2+>放出が main cascadeであると考えられている. また, 妊娠末期に大量に産生され, 多彩な変動をみせる dehydroepiandrosterone-sulfate (DHAS), progesterone (P), cortisol (F)などのステロイドホルモンは, 分娩発来時期における子宮筋収縮に種々の関与をしていると思われる. 今回我々は, 培養ヒト子宮筋細胞を用い, 各種ステロイドホルモン存在下で48時間培養し, OTによる細胞内Ca^<2+>濃度 ([Ca^<2+>]_i)変動, およびPI responseに関して検討した. (1) ヒト子宮筋細胞をDHAS, P, Fを各々10^<-6>M含む培養液中で48時間培養した後, Ca^<2+>螢光指示薬 Fura2-AMを用い, [Ca^<2+>]_i変化を OLYMPUS OSP3にて測定した. OT 10^<-8>M刺激時の [Ca^<2+>]_i最大変化率を100%とした場合 (control), F負荷細胞では121.1±9.8%に増加し, P負荷細胞では89.4±4.0%に減少した. またDHAS負荷細胞では107.5±6.9%に増加したが, 有意差は認められなかった. (2) ヒト子宮筋細胞をDHAS, F 10^<-5>M,10^<-6>MおよびP 10^<-6>M, 10^<-7>Mとともに^3H myo-inositol 5μC_iを含む培養液中で48時間培養し, OT 10^<-8>Mによる細胞内IP_<1-3>の産生を測定した. その結果, F負荷細胞では controlに比しIP_<1-3>およびIP_<1-3>総産生(IP_n)は有意に増加し, 一方P負荷細胞では10^<-6>M ではIP_nは約40%減少した. また, DHASではIP_nは controlより軽度増加したが有意な差は認められなかった. 以上の成績は, ステロイドホルモンがOTによる子宮筋収縮に対して, OT receptorレベル又は PI responseを介して, 調節因子として作用していることを示唆するものである.

In oxytocin (OT)-induced myometrial contraction, it is considered that Ca^<2+> release associated with activation of PI response is the main cascade. Steroid hormones such as dehydroepiandrosterone-sulfate (DHAS), progesterone (P), and cortisol (F), which show diverse changes during pregnancy, are considered to be involved in myometrial contraction at the onset of delivery. In this study, we examined changes in the intracellular Ca^<2+> concentration ([Ca^<2+>]_i) and PI response under OT stimulation. (1) After cultured human myometrial cells were incubated for 48 hours in a medium containing 10^<-6>M of DHAS, P, or F, [Ca^<2+>]_i was measured with an OLYMPUS OSP3 by using the the fluorescent Ca^<2+> indicator Fura2-AM. When the maximum change in [Ca^<2+>]_i under stimulation with 10^<-8>M OT was regarded as 100% (control), it was increased significantly to 121.1±9.8% in the cells treated with F, but was reduced to 89.4±4% in those treated with P. It was increased to 107.5±6.9% in the cells treated with DHAS, but the difference was not significant. (2) After loading with 5μC_i ^3H myo-inositol and various steroid hormones for 24 hours in the cells, the intracellular IP_<1-3> production under stimulation with 10^<-8>M OT was examined. IP_<1-3> production and IP total production (IP_n) were significantly increased in the cells treated with F as compared with the control, but IP_n was reduced by about 40% in the cells treated with 10^<-6>M P. And in the cells treated with DHAS, IP_n was slightly increased. These results suggest that steroid hormones are regulating factors in OT-induced myometrial contraction acting at the OT receptor level or via PI response.


  • 日本産科婦人科學會雜誌

    日本産科婦人科學會雜誌 47(2), 94-100, 1995-02-01


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