Kitahashi Takashi, Ogawa Satoshi, Soga Tomoko, Sakuma Yasuo, Parhar Ishwar
School of Medicine and Health Sciences, Monash University, 46150 Bandar Sunway, Selangor, Malaysia.
Endocrinology. 2007 Dec;148(12):5822-30. doi: 10.1210/en.2007-0311. Epub 2007 Sep 6.
The role of steroid/thyroid hormones in the regulation of endocrine cells at the level of the pituitary has remained unclear. Therefore, using single-cell quantitative real-time PCR, we examined absolute amounts of transcripts for nuclear receptors [estrogen receptors (ERs) alpha, beta, and gamma; androgen receptors (ARs) a and b; glucocorticoid receptors (GRs) 1, 2a, and 2b; and thyroid hormone receptors (TRs) alpha1, alpha2, and beta] in pituitary cells of immature (IM) and mature (M) male tilapia, Oreochromis niloticus. In the two reproductive stages, ACTH cells expressed only ERbeta, whereas all other pituitary cell types expressed ERalpha + beta, and a subpopulation coexpressed ARa, ARb, GR1, GR2b, and TRbeta but lacked ERgamma, GR2a, TRalpha1, and TRalpha2. IM males had high percentages of LH cells (IM 46.0% vs. M 10.0%), GH cells (IM 23.3% vs. M 7.9%), and prolactin cells (IM 68.8% vs. M 6.0%) with ERbeta, and TSH cells (IM 19.2% vs. M 0.0%) and MSH cells (IM 25.6% vs. M 0.0%) with ERalpha + TRbeta. A high percentage of FSH cells in IM males expressed ERbeta (IM 46.9% vs. M 18.8%), and FSH cells in M males showed significantly high GR1 transcripts (IM 76.0 +/- 5.0 vs. M 195.0 +/- 10.7 copies per cell; P < 0.05), suggesting that FSH cells are regulated differently in the two reproductive stages. Coexpression of ERalpha + beta in high percentages of cells of the GH family (GH, IM 43.8% vs. M 14.3%; prolactin, IM 8.3% vs. M 59.7%; somatolactin, IM 22.2% vs. M 42.2%) suggests that the expression of both ERs is important for functionality. Thus, differential coexpression of genes for nuclear receptors in subpopulations of pituitary cell types suggests multiple steroid/thyroid hormone regulatory pathways at the level of the pituitary during the two reproductive stages.
类固醇/甲状腺激素在垂体水平对内分泌细胞的调节作用仍不清楚。因此，我们采用单细胞定量实时PCR技术，检测了未成熟（IM）和成熟（M）雄性尼罗罗非鱼垂体细胞中核受体[雌激素受体（ERs）α、β和γ；雄激素受体（ARs）a和b；糖皮质激素受体（GRs）1、2a和2b；以及甲状腺激素受体（TRs）α1、α2和β]的转录本绝对量。在两个生殖阶段，促肾上腺皮质激素（ACTH）细胞仅表达ERβ，而所有其他垂体细胞类型均表达ERα+β，并且一个亚群共表达ARa、ARb、GR1、GR2b和TRβ，但缺乏ERγ、GR2a、TRα1和TRα2。未成熟雄性中，促黄体生成素（LH）细胞（IM为46.0%，M为10.0%）、生长激素（GH）细胞（IM为23.3%，M为7.9%）和催乳素细胞（IM为68.8%，M为6.0%）中表达ERβ的比例较高，促甲状腺激素（TSH）细胞（IM为19.2%，M为0.0%）和促黑素细胞（MSH）细胞（IM为25.6%，M为0.0%）中表达ERα+TRβ的比例较高。未成熟雄性中高比例的促卵泡激素（FSH）细胞表达ERβ（IM为46.9%，M为18.8%），而成熟雄性中的FSH细胞显示GR1转录本显著较高（IM为76.0±5.0，M为195.0±10.7拷贝/细胞；P<0.05），这表明FSH细胞在两个生殖阶段受到不同的调节。生长激素家族（GH，IM为43.8%，M为14.3%；催乳素，IM为8.3%，M为59.7%；生长抑素，IM为22.2%，M为42.2%）中高比例细胞共表达ERα+β，这表明两种ER的表达对功能很重要。因此，垂体细胞类型亚群中核受体基因的差异共表达表明在两个生殖阶段垂体水平存在多种类固醇/甲状腺激素调节途径。
