Effects of Estrogen and Thyroxine in Vivo on the Biosynthesis and Release of Luteinizing Hormone by Rat Anterior Pituitary Glands in Vitro

體內之雌激素與甲狀腺素對大白鼠之腦下腺前葉在體外重新合成及釋放黃體生成素之影響

王錫崗(Paulus S. Wang) ； 劉孟粹珠(T. C. Liu) ； 賈克森(G. L. Jackson)

《The Chinese Journal of Physiology》 23卷2期 (1980/12) Pp. 39-50

摘要

本文研究甲狀腺素(T4)及雌素二醇酯(EB)對於同時切除卵巢及甲狀腺的大白鼠之黃體生成素(LH)之合成與分泌的影響。將大白鼠之卵巢及甲狀腺同時切除一個月後，連續九天皮下注射T4或生理塩水，及EB或玉米油。第十天取出各鼠的腦下腺前葉與含有性腺激素釋放素，放射性氨基丙酸及放射性葡萄糖胺的培養基在37C之下，一齊培養4小時。組織及培養基中，帶有放射性的LH係藉LH-β的抗體血清以免疫沈澱法測定；非放射性LH及放射性LH之總量則以放射免疫法測定。結果顯示EB和T4皆可降低鼠血中LH的濃度，而且腦下腺中LH的總量及由放射性前質合併成的LH可因EB的處理而減少。但是，EB却刺激儲於腦下腺中之LH（包含放射性及非放射性）以及重新合成帶有放射性葡萄糖胺之LH的釋放。注射T4會減少由放射性氨基丙酸合成的LH。然而，T4對其他，諸如腦下腺中LH的含量，培養基中LH的濃度，以及經由放射性葡萄糖胺合成的LH等，無明顯的影響。對於以上諸項有關LH的合成與分泌，EB與T4之間並無明顯的交感作用。由EB能減少LH的合成却能加速LH的釋放來看，雌激素對LH的合成與分泌的調節是彼此獨立的，同時，EB和T4對LH的分泌並未因彼此兩者的存在與否而受到影響。

並列摘要

The authors studied the effects of thyroxine(T4)and estradiol benzoate(EB) on the synthesis and release of luteinizing hormone(LH) in ovariectomized-thyroidectomized(Ovx-Tx) rats. Beginning 30 days after ovariectomy and thyroidectomy, rats were injected sc with either saline solution or T4 and either oil or EB for 9 days. The doses of hormones were 0.9 μg T4/100 g BW/day and 0.5 μg EB/day/rat in experiment 1 and 4 μg T4/100 g BW/day and 2 μg EB/day in experiment 2. Ten days after initiation of the injections,the anterior pituitary glands(APs)were removed and incubated in vitro with 3.6×10^(-8) M gonadotropin-releasing hormone(GnRH)and radioactive precursors, [(superscript 14)C]alanine and [(superscript 3)H]glucosamine, for 4 h at 37 C. Radiolabeled LH was measured by immunoprecipitation with specific anti-LH-β serum. Both EB and T4 reduced serum LH in Ovx-Tx rats. EB decreased the amount of immunoreactive LH(IR-LH) in the AP and decreased the incorporation of both[(superscript 14)C] alanine and[(superscript 3)H]glucosamine into LH in vitro. In contrast EB stimulated the release of stored IR-LH and of de novo synthesized [(superscript 3)H]glucosamine-LH in vitro. In one of two experiments T4 reduced incorporation of [(superscript 14)C]alanine into LH in vitro. However, T4 had no significant effect on the amount of IR-LH in the AP, the incorporation of [(superscript 3)H]glucosamine into LH in vitro, or the release of IR-LH, and radiolabeled LH. We observed no significant interactions between T4 and EB on any parameters of LH secretion. EB suppressed LH synthesis but accelerated LH release in response to GnRH thus, suggesting that estrogen modulates LH synthesis and release independently. Furthermore, the main effects of EB and T4 on LH secretion apparently are not significantly altered simply by the presence or absence of the other hormone.

並列關鍵字

LH biosynthesis ； estrogen ； thyroxine