Abbot S D, Docherty K, Clayton R N
Department of Medicine, University of Birmingham, Edgbaston.
J Mol Endocrinol. 1988 Jul;1(1):49-60. doi: 10.1677/jme.0.0010049.
To determine the physiological role of the ovaries in regulation of LH subunit gene expression, levels of cytoplasmic mRNA were measured in a cDNA-RNA dot-blot hybridization assay. An increase (twofold) in alpha mRNA was first detected 8 days after ovariectomy and then remained stable for 4 weeks. In contrast, LH-beta mRNA increased by 60-79% within 12 h of removing the ovaries and then rose progressively to six times the intact values at 3 and 4 weeks. Increases in LH-beta mRNA were always greater than those of alpha mRNA. Oestradiol, and oestradiol plus progesterone, but not progesterone alone, prevented the rise in alpha and LH-beta mRNA 10 days after ovariectomy. Three days after ovariectomy, alpha mRNA, but not LH-beta mRNA, was suppressed to below intact control values by oestradiol and oestradiol plus progesterone, indicating greater sensitivity of alpha mRNA to oestradiol inhibition at this stage. A single injection of oestradiol (1 microgram s.c.) to rats ovariectomized 14 days previously transiently suppressed alpha and LH-beta mRNA levels and serum LH concentrations in parallel for 1-8 h, after which high preinjection values were restored. However, pituitary LH content remained suppressed after LH mRNA levels had returned to the control values of ovariectomized rats. In most instances there was a qualitative positive correlation between changes in alpha and LH-beta mRNA, pituitary LH content and serum LH concentrations. LH content reflected LH-beta mRNA changes more closely than those of alpha mRNA. However, in oestradiol-treated rats ovariectomized 10 days previously, LH content remained increased despite normalization of the LH-beta and alpha mRNA levels, suggesting differential sensitivity to oestradiol of the gene expression and translational processes. Thus divergence of pre- and post-translational regulation of LH biosynthesis was demonstrated. These results imply an important physiological role for female sex hormones in the control of LH gene expression and LH biosynthesis. Prolactin mRNA fell by 30-50% for the first 2 weeks after ovariectomy, but by 3 and 4 weeks values were similar to those of intact controls. Serum and pituitary prolactin levels were reduced by 50% or more at all time-points, despite normalization of mRNA. Treatment of ovariectomized rats for 10 days with oestradiol and progesterone, either alone or combined, reversed the fall in prolactin mRNA and serum and pituitary prolactin levels. These changes in prolactin gene expression and synthesis were opposite to those of LH subunits in response to the same in-vivo hormone manipulations.(ABSTRACT TRUNCATED AT 400 WORDS)
为确定卵巢在促黄体生成素（LH）亚基基因表达调控中的生理作用，采用cDNA-RNA斑点杂交分析法检测细胞质mRNA水平。切除卵巢8天后首次检测到α mRNA增加（两倍），随后4周保持稳定。相比之下，切除卵巢12小时内LH-β mRNA增加60 - 79%，然后在3周和4周时逐渐升至完整值的6倍。LH-β mRNA的增加总是大于α mRNA。雌二醇以及雌二醇加孕酮可阻止切除卵巢10天后α和LH-β mRNA的升高，但单独孕酮则无此作用。切除卵巢3天后，雌二醇和雌二醇加孕酮可将α mRNA而非LH-β mRNA抑制至低于完整对照值，表明此阶段α mRNA对雌二醇抑制更为敏感。对14天前切除卵巢的大鼠单次皮下注射1微克雌二醇，可使α和LH-β mRNA水平以及血清LH浓度在1 - 8小时内同时短暂降低，之后恢复至注射前的高水平。然而，在LH mRNA水平恢复至切除卵巢大鼠的对照值后，垂体LH含量仍受抑制。在大多数情况下，α和LH-β mRNA、垂体LH含量及血清LH浓度的变化之间存在定性正相关。LH含量比α mRNA变化更紧密地反映LH-β mRNA的变化。然而，在10天前切除卵巢并用雌二醇处理的大鼠中，尽管LH-β和α mRNA水平恢复正常，但LH含量仍升高，提示基因表达和翻译过程对雌二醇的敏感性不同。因此，证明了LH生物合成在翻译前和翻译后的调控存在差异。这些结果表明雌性性激素在LH基因表达和LH生物合成的控制中具有重要生理作用。切除卵巢后的前2周，催乳素mRNA下降30 - 50%，但在3周和4周时其值与完整对照相似。尽管mRNA恢复正常，但在所有时间点血清和垂体催乳素水平均降低50%或更多。用雌二醇和孕酮单独或联合处理切除卵巢的大鼠10天，可逆转催乳素mRNA以及血清和垂体催乳素水平的下降。催乳素基因表达和合成的这些变化与相同体内激素处理下LH亚基的变化相反。（摘要截短于400字）
