Minami S, Kamegai J, Hasegawa O, Sugihara H, Okada K, Wakabayashi I
Department of Medicine, Nippon Medical School, Tokyo, Japan.
J Neuroendocrinol. 1993 Dec;5(6):691-6. doi: 10.1111/j.1365-2826.1993.tb00541.x.
Growth hormone receptor (GHR) mRNA-expressing cells in the hypothalamus were observed using hybridization histochemistry in adult male rats. Digoxigenin-labeled cRNA corresponding to the extracellular part of rat GHR was used as a probe. Northern blotting analysis of hypothalamic total RNA from adult male rats revealed that the 4.5 kilobase (kb) transcript of the GHR gene corresponding to the GHR messenger RNA (mRNA) predominated over the 1.2 kb transcript corresponding to GH-binding protein mRNA. GHR mRNA-containing cells were observed in the arcuate nucleus (ARC), the periventricular nucleus (PeV), ventrolateral region of the ventromedial nucleus, the paraventricular nucleus and the supraoptic nucleus. To further understand the significance of the GHR gene expression in the hypothalamus, the effect of in vivo manipulation of GH on the somatostatin (SS) gene expression in the ARC and PeV, and the GRF gene expression in the ARC was observed among adult male rats using in situ hybridization histochemistry. Ten days after hypophysectomy, the SS mRNA level in the ARC as well as PeV was significantly lower than that in the respective nuclei of sham-operated control rats, while the GRF mRNA level in the ARC was significantly higher than that in the ARC of control animals. Subcutaneous injection of recombinant human GH (0.33 mg) to hypophysectomized rats every 12 h for 5 days restored the SS mRNA level in the ARC and PeV, and reduced the GRF mRNA level in the ARC to that of control animals. The data suggest that GH directly acts on the hypothalamic PeV and ARC, and alters the gene expression of SS and GRF.
采用杂交组织化学方法，在成年雄性大鼠中观察下丘脑内表达生长激素受体（GHR）mRNA的细胞。用地高辛标记的与大鼠GHR细胞外部分相对应的cRNA作为探针。对成年雄性大鼠下丘脑总RNA进行的Northern印迹分析显示，与GHR信使RNA（mRNA）相对应的GHR基因4.5千碱基（kb）转录本比与GH结合蛋白mRNA相对应的1.2 kb转录本占优势。在弓状核（ARC）、室周核（PeV）、腹内侧核腹外侧区、室旁核和视上核中观察到含有GHR mRNA的细胞。为了进一步了解下丘脑GHR基因表达的意义，采用原位杂交组织化学方法，在成年雄性大鼠中观察了体内操纵生长激素（GH）对ARC和PeV中生长抑素（SS）基因表达以及ARC中生长激素释放因子（GRF）基因表达的影响。垂体切除术后10天，ARC以及PeV中的SS mRNA水平显著低于假手术对照大鼠相应核团中的水平，而ARC中的GRF mRNA水平显著高于对照动物ARC中的水平。对垂体切除的大鼠每12小时皮下注射重组人生长激素（0.33 mg），持续5天，可使ARC和PeV中的SS mRNA水平恢复正常，并使ARC中的GRF mRNA水平降至对照动物的水平。这些数据表明，GH直接作用于下丘脑的PeV和ARC，并改变SS和GRF的基因表达。
