Croissandeau G, Schussler N, Grouselle D, Pagesy P, Rauch C, Bayet M C, Peillon F, Le Dafniet M
Unité INSERM 223, Faculté de Médecine Pitié-Salpĕtrière, Paris, France.
J Endocrinol. 1996 Oct;151(1):87-96. doi: 10.1677/joe.0.1510087.
TRH gene expression in the anterior pituitary has previously been reported in the human in vivo and in the rat in vitro. Until now, modulation of this synthesis with glucocorticoids and thyroid hormones has been observed in rats. The present study demonstrates for the first time that the TRH gene is also expressed, in vivo, in the rat anterior pituitary and that anterior pituitary TRH-like immunoreactivity (TRH-LI) and elongated forms of the immediate TRH progenitor sequence (TRH-elongated peptide) contents are also modulated by estrogens (E2). To investigate the presence of proTRH mRNA in the rat anterior pituitary, total RNA was reverse transcribed (RT) and the RT products were then amplified by PCR. Treatments with E2 were performed on intact and ovariectomized (OVX) rats for 2 months. TRH-LI was measured by RIA with an antibody which did not recognize the TRH-like peptide. pGlu-Glu-Pro-NH2 (< EEP-NH2) (cross-reactivity < 0.1%) and was characterized further as TRH-LI by HPLC. TRH-elongated peptides were measured by EIA and characterized by Sephadex G-50 chromatography and immunoblotting (molecular mass 25-35 kDa). The plasma prolactin levels and the pituitary sizes were increased by E2 treatment in both intact and OVX rats. Anterior pituitary TRH-LI increased in intact E2-treated rats compared with intact rats (82.7 +/- 19.0 versus 39.6 +/- 3.6 fmol/mg protein; means +/- S.E.M.; P < 0.001). This increase was greater when E2 was administered to OVX rats (599.0 +/- 98.4 after E2 treatment versus 58.6 +/- 3.6 fmol/mg protein: P < 0.001). In intact rats, anterior pituitary TRH-elongated peptide contents were not modified by E2 treatment while they were significantly decreased in OVX E2-treated rats (144.6 +/- 8.8 versus 223.7 +/- 9.5 fmol/mg protein; P < 0.001). These results demonstrate TRH gene expression in the rat anterior pituitary in vivo and suggest that E2 treatment is responsible for an increase in anterior pituitary TRH-LI, together with a decrease in TRH-elongated peptide contents.
此前已有报道称，促甲状腺激素释放激素（TRH）基因在人体内和大鼠体外的垂体前叶中表达。到目前为止，在大鼠中已观察到糖皮质激素和甲状腺激素对这种合成的调节作用。本研究首次证明，TRH基因在大鼠垂体前叶中也有体内表达，并且垂体前叶中TRH样免疫反应性（TRH-LI）以及TRH前体序列的延长形式（TRH延长肽）的含量也受到雌激素（E2）的调节。为了研究大鼠垂体前叶中促TRH mRNA的存在情况，提取了总RNA并进行逆转录（RT），然后通过PCR扩增RT产物。对完整大鼠和去卵巢（OVX）大鼠进行了为期2个月的E2处理。使用一种不识别TRH样肽的抗体，通过放射免疫分析（RIA）测量TRH-LI。pGlu-Glu-Pro-NH2（<EEP-NH2）（交叉反应性<0.1%），并通过高效液相色谱（HPLC）进一步鉴定为TRH-LI。通过酶免疫分析（EIA）测量TRH延长肽，并通过葡聚糖凝胶G-50色谱和免疫印迹法（分子量25-35 kDa）进行鉴定。E2处理使完整大鼠和OVX大鼠的血浆催乳素水平和垂体大小均增加。与完整大鼠相比，完整E2处理大鼠的垂体前叶TRH-LI增加（82.7±19.0对39.6±3.6 fmol/mg蛋白；平均值±标准误；P<0.001）。当对OVX大鼠给予E2时，这种增加更为明显（E2处理后为599.0±98.4对58.6±3.6 fmol/mg蛋白：P<0.001）。在完整大鼠中，E2处理未改变垂体前叶TRH延长肽的含量，而在OVX E2处理大鼠中，其含量显著降低（144.6±8.8对223.7±9.5 fmol/mg蛋白；P<0.001）。这些结果证明了TRH基因在大鼠垂体前叶中的体内表达，并表明E2处理导致垂体前叶TRH-LI增加，同时TRH延长肽含量减少。
