Bockmann J, Kreutz M R, Wittkowski W, Böckers T M
AG Molecular Neuroendocrinology, Institute of Anatomy, University of Münster, Germany.
Acta Anat (Basel). 1997;160(3):189-94. doi: 10.1159/000148010.
Several experiments in photoperiod-dependent species suggest that the hypophyseal pars tuberalis (PT) plays a key role in transducing light/dark information to the endocrine system. In rat and hamster it has been shown that both TSH subunits (TSH-alpha and -beta) are expressed in PT-specific cells, a morphologically distinct cell type which does not resemble thyrotropes of the pars distalis (PD). In order to investigate whether TSH expression is a characteristic and common feature of PT-specific cells we studied cellular morphology and TSH subunit expression in mouse pars tuberalis by electron microscopy, immunocytochemistry and in situ hybridization. In contrast to all other species investigated so far the number and size of secretory granules in mouse PT-specific cells is enlarged. As in rat and hamster, however, TSH subunit expression (mRNA and protein) was found in thyrotropes of the PD and throughout the whole extent of the PT cell layer. We conclude that although mouse PT-specific cells display an ultrastructural morphology that is different from other species, they are nevertheless characterized by TSH subunit expression. Further studies are needed to determine the physiological role of 'PT-specific cell TSH' and to elucidate whether TSH is the only PT-specific cell secretory product.
在光周期依赖性物种中进行的多项实验表明，垂体结节部（PT）在将光/暗信息传递给内分泌系统方面发挥着关键作用。在大鼠和仓鼠中，已证明促甲状腺激素的两个亚基（TSH-α和-β）在PT特异性细胞中表达，这是一种形态上独特的细胞类型，与远侧部（PD）的促甲状腺细胞不同。为了研究TSH表达是否是PT特异性细胞的一个特征性和共同特征，我们通过电子显微镜、免疫细胞化学和原位杂交技术研究了小鼠垂体结节部的细胞形态和TSH亚基表达。与迄今为止研究的所有其他物种不同，小鼠PT特异性细胞中分泌颗粒的数量和大小有所增加。然而，与大鼠和仓鼠一样，在PD的促甲状腺细胞以及整个PT细胞层中都发现了TSH亚基表达（mRNA和蛋白质）。我们得出结论，尽管小鼠PT特异性细胞表现出与其他物种不同的超微结构形态，但它们仍然以TSH亚基表达为特征。需要进一步的研究来确定“PT特异性细胞TSH”的生理作用，并阐明TSH是否是唯一的PT特异性细胞分泌产物。
