Moreau C, Rasolojanahary R, Zamora A J, Enjalbert A, Kordon C, Llorens-Cortes C
ICNE, UMR 6544, CNRS-Université de la Méditerranée, Institut Jean-Roche, Faculté de Médecine, Marseille, France.
Neuroendocrinology. 1997 Dec;66(6):416-25. doi: 10.1159/000127267.
Differential evaluation of angiotensin II (Ang II) receptors (AT1A, AT1B and AT2) expression was performed in dispersed adenohypophyseal cells fractionated by unit gravity sedimentation. Binding of [125I-Sar1-Ile8]-Ang II and its displacement by specific nonpeptidic AT1 (DuP753) and AT2 (PD123319) antagonists was monitored throughout the gradient. Quantification of mRNA levels corresponding to both AT1 receptor subtypes (AT1A and AT1B) was achieved by reverse transcriptase polymerase chain reaction (RT-PCR) amplification in the presence of an AT1 receptor mutant cRNA as internal standard. Fractions were characterised by radioimmunoassay for the five major anterior pituitary hormones and by counting immunocytochemically labelled cells. Quantification of AT1 receptor subtype mRNA levels was also performed in four hypophyseal cell lines secreting prolactin, growth hormone, corticotropin and a gonadotropin subunit. As already described for the whole pituitary, AT1B receptor mRNA is predominantly expressed (80% of total AT1A + AT1B receptor mRNA content), whereas AT1A is expressed at lower level (20%) in dispersed pituitary cells. Most AT1 receptor mRNA and binding co-elute with fractions enriched in lactotropes and corticotropes. In contrast to AT1B, AT1A receptor mRNA is not present in heavier populations of lactotropes or in somatomammotropes. Low AT1B mRNA levels are detected in GH4C1 and in GC cells, two clones which secrete respectively prolactin and growth hormone. In contrast, no AT1 receptor mRNA expression was found in two other cell lines, AtT20 and alphaT3-1, which produce pro-opiomelanocortin and gonadotropin. It is concluded that expression of AT1 receptor subtypes is heterogeneous in different populations of lactotropes and corticotropes.
利用单位重力沉降法对腺垂体分散细胞进行分级分离，对血管紧张素II（Ang II）受体（AT1A、AT1B和AT2）的表达进行差异评估。在整个梯度过程中监测[125I- Sar1-Ile8]-Ang II的结合及其被特异性非肽类AT1（DuP753）和AT2（PD123319）拮抗剂的置换情况。在存在AT1受体突变体cRNA作为内标的情况下，通过逆转录聚合酶链反应（RT-PCR）扩增实现对应于两种AT1受体亚型（AT1A和AT1B）的mRNA水平的定量。通过放射免疫分析法对五种主要垂体前叶激素进行分级，并通过对免疫细胞化学标记细胞进行计数来对分级进行表征。还在四种分泌催乳素、生长激素、促肾上腺皮质激素和促性腺激素亚基的垂体细胞系中进行了AT1受体亚型mRNA水平的定量。如之前对整个垂体的描述，AT1B受体mRNA主要表达（占总AT1A + AT1B受体mRNA含量的80%），而AT1A在分散的垂体细胞中表达水平较低（20%）。大多数AT1受体mRNA和结合物与富含催乳素细胞和促肾上腺皮质激素细胞的分级一起洗脱。与AT1B相反，AT1A受体mRNA在较重的催乳素细胞群体或生长催乳素细胞中不存在。在GH4C1和GC细胞中检测到低水平的AT1B mRNA，这两个克隆分别分泌催乳素和生长激素。相反，在另外两种产生阿片-促黑素皮质素原和促性腺激素的细胞系AtT20和αT3-1中未发现AT1受体mRNA表达。得出的结论是，AT1受体亚型的表达在不同的催乳素细胞和促肾上腺皮质激素细胞群体中是异质性的。
