Department of Biology, Faculty of Science, Mahasarakham University, Khamriang Sub-district, Kantharawichai District, Mahasarakham Province 44150, Thailand.
Department of Endocrinology, Faculty of Medicine, University Medical Center Göttingen, Robert-Koch-Strasse 40, D-37075 Göttingen, Germany.
Life Sci. 2016 Nov 15;165:75-82. doi: 10.1016/j.lfs.2016.09.002. Epub 2016 Sep 8.
Previous research has revealed that puerarin, the major phytoestrogen in tuberous roots of Pueraria lobata and Pueraria mirifica, acts as a selective estrogen receptor modulator that displays predominantly estrogenic potential for health benefit. However, little is known about the estrogenic potency of puerarin in pituitary, especially in the rat model of postmenopausal females.
Plasma prolactin and growth hormone levels as well as mRNA expression levels of pituitary estrogen-regulated genes, such as estrogen receptor (ER) subtypes alpha (ERα) and beta (ERβ), truncated ER product-1 (TERP-1) and -2 (TERP-2) and gonadotropin alpha subunit, were examined using radioimmunoassay and TaqMan® real-time PCR, respectively. The effects were compared with the potent ER agonist, 17β-estradiol-3-benzoate (E2B), and both substances were supplemented at low and high doses, i.e., 0.6 or 3g puerarin and 0.0043 or 0.0173g E2B per kilogram of phytoestrogens-free rat chow, and applied to ovariectomized rats (five groups; 11-12 rats per group) for 12weeks.
Puerarin possessed weak E2B-like activities on pituitary function by acting as ERβ and TERP-1/-2 agonists, which resulted in the downregulation and upregulation of ERβ and TERP-1/-2 mRNA expressions, respectively, and elevation of growth hormone levels. There were trends of decreased levels of alpha subunit mRNA transcripts and increased levels of prolactin in puerarin-treated rats as observed in E2B-treated animals.
This is the first report in ovariectomized rats the effects of puerarin on somatotropes and pituitary estrogen-responsive mRNA expressions, which are very weakly estrogenic by acting through ERβ- and TERP-1/-2 mediated pathways.
先前的研究表明，葛根素是野葛和泰国野葛根块根中的主要植物雌激素，作为一种选择性雌激素受体调节剂，具有主要的雌激素潜力，有益于健康。然而，关于葛根素在垂体中的雌激素效力，特别是在绝经后雌性大鼠模型中，知之甚少。
使用放射免疫分析法和 TaqMan®实时 PCR 分别检测血浆催乳素和生长激素水平以及垂体雌激素调节基因的 mRNA 表达水平，如雌激素受体（ER）亚型 alpha（ERα）和 beta（ERβ）、截断的 ER 产物-1（TERP-1）和 -2（TERP-2）和促性腺激素 alpha 亚基。将这些影响与有效的 ER 激动剂 17β-雌二醇-3-苯甲酸酯（E2B）进行比较，并且两种物质均以低剂量和高剂量补充，即 0.6 或 3g 葛根素和 0.0043 或 0.0173g E2B 每公斤不含植物雌激素的大鼠饲料，并应用于去卵巢大鼠（五组；每组 11-12 只大鼠）12 周。
葛根素通过作为 ERβ 和 TERP-1/-2 激动剂发挥类似 E2B 的弱 E2B 样活性，导致 ERβ 和 TERP-1/-2 mRNA 表达分别下调和上调，并升高生长激素水平。在葛根素处理的大鼠中，观察到 alpha 亚基 mRNA 转录物水平降低和催乳素水平升高的趋势，这与 E2B 处理的动物相似。
这是首次在去卵巢大鼠中报告葛根素对生长激素细胞和垂体雌激素反应性 mRNA 表达的影响，通过 ERβ-和 TERP-1/-2 介导的途径，其雌激素活性非常弱。
