Licht P, Khorrami-Yaghoobi P, Porter D A
Gen Comp Endocrinol. 1985 Dec;60(3):441-9. doi: 10.1016/0016-6480(85)90079-6.
Gonadectomized (gonadex) turtles, Sternotherus odoratus, had significantly elevated plasma FSH, but LH was less consistently affected. Estradiol (E2)-implants suppressed plasma FSH in gonadex females but not in males: testosterone (T) partially suppressed FSH in males. In contrast, E2-treatment markedly suppressed pituitary LH content and in vitro LH secretion in gonadex and intact turtles (inhibitory effects of E2 were less in intact than ovariectomized females). These steroid effects were relatively specific for gonadotropin; pituitary TSH content was not altered. In vitro, pituitary LH secretion responded to doses of GnRH greater than or equal to 1 ng/ml and LH output remained elevated for at least 3 hr of continuous superfusion with gonadotropin-releasing hormone (GnRH). In general, gonadectomy elevated pituitary responsiveness to GnRH while E2 and T suppressed this responsiveness; the effects of E2 are greater in gonadectomized than intact turtles. Thus, negative gonadal feedback appears to be involved in the secretion of gonadotropins in turtles, and steroidal actions may be partly due to suppression of pituitary hormone content and responsiveness to GnRH.
性腺切除的（性腺切除的）麝香龟（Sternotherus odoratus）血浆促卵泡激素（FSH）显著升高，但促黄体生成素（LH）受影响的情况不太一致。雌二醇（E2）植入物可抑制性腺切除雌性龟的血浆FSH，但对雄性龟无效：睾酮（T）可部分抑制雄性龟的FSH。相比之下，E2处理显著抑制性腺切除和完整龟的垂体LH含量及体外LH分泌（E2对完整雌性龟的抑制作用小于卵巢切除的雌性龟）。这些类固醇作用对促性腺激素具有相对特异性；垂体促甲状腺激素（TSH）含量未改变。在体外，垂体LH分泌对剂量大于或等于1 ng/ml的促性腺激素释放激素（GnRH）有反应，并且在用GnRH连续超灌流至少3小时的情况下，LH产量仍保持升高。一般来说，性腺切除会提高垂体对GnRH的反应性，而E2和T会抑制这种反应性；E2对性腺切除龟的影响大于完整龟。因此，性腺的负反馈似乎参与了龟类促性腺激素的分泌，类固醇作用可能部分归因于垂体激素含量的抑制和对GnRH的反应性。
