Role of prolactin and growth hormone on thymus physiology.
Role of prolactin and growth hormone on thymus physiology.
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DOI：
10.1155/1998/89782
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发表时间：
1998-01-01
期刊：
影响因子：
--
通讯作者：
Dardenne, M
中科院分区：
文献类型：
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作者：
De Mello-Coelho, V;Savino, W;Dardenne, M
胸腺内T细胞的分化受胸腺微环境的控制，胸腺微环境通过膜和可溶性产物作用于成熟的胸腺细胞。越来越多的数据表明，这一过程可以被经典激素调节，例如催乳素(PRL)和生长激素(GH)，主要由脑下垂体分泌。催乳素和生长激素都能刺激胸腺上皮细胞产生的胸腺激素胸腺素的分泌。相反，低水平的循环胸腺激素平行于甲状腺功能低下状态。有趣的是，生长激素对胸腺液的增强作用似乎是由胰岛素样生长因子-1(IGF-1)介导的，因为它们可以被抗IGF-1或抗IGF-1受体抗体所消除。PRL和GH对胸腺上皮细胞的影响是多向性的：PRL在体内增强大分子细胞角蛋白的表达，并在体外刺激TEC增殖，GH和IGF-1也有这种作用。分化的T细胞也是PRL和GH胸腺内作用的靶点。将大鼠垂体细胞系体内接种到老年大鼠体内，可以恢复胸腺，包括将CD4-CD8-胸腺细胞分化为CD4+CD8+细胞。此外，在胸腺细胞分化的双阳性阶段，PRL可能调节胸腺细胞活性的维持。在衰老小鼠体内注射生长激素可增加胸腺细胞总数和携带CD3的细胞的百分比，以及胸腺细胞的刀豆蛋白-A有丝分裂反应和IL-6的产生。有趣的是，在用IGF-1治疗的动物身上也观察到了类似的发现。最后，GH治疗可以逆转侏儒鼠的胸腺发育不良。与前面总结的数据一致的是胸腺细胞和胸腺上皮细胞上PRL和GH受体的检测。重要的是，最近的研究表明，这两种细胞类型都可以在胸腺内产生催乳素和生长激素。同样，IGF-1的产生和相应受体的表达也已被证实。综上所述，这些数据有力地表明，胸腺在生理上受垂体激素PRL和GH的控制。除了经典的内分泌途径外，旁分泌和自分泌回路可能也参与了这种控制。
Intrathymic T-cell differentiation is under the control of the thymic microenvironment, which acts on maturing thymocytes via membrane as well as soluble products. Increasing data show that this process can be modulated by classical hormones, as exemplified herein by prolactin (PRL) and growth hormone (GH), largely secreted by the pituitary gland. Both PRL and GH stimulate the secretion of thymulin, a thymic hormone produced by thymic epithelial cells. Conversely, low levels of circulating thymulin parallel hypopituitary states. Interestingly, the enhancing effects of GH on thymulin seem to be mediated by insulinlike growth factor 1 (IGF-1) since they can be abrogated with anti-IGF-1 or anti-IGF-1-receptor antibodies. The influence of PRL and GH on the thymic epithelium is pleiotropic: PRL enhances in vivo the expression of high-molecular-weight cytokeratins and stimulates in vitro TEC proliferation, an effect that is shared by GH and IGF-1. Differentiating T cells are also targets for the intrathymic action of PRL and GH. In vivo inoculation of a rat pituitary cell line into old rats results in restoration of the thymus, including differentiation of CD4- CD8- thymocytes into CD4+ CD8+ cells. Furthermore, PRL may regulate the maintenance of thymocyte viability during the double-positive stage of thymocyte differentiation. Injections of GH into aging mice increase total thymocyte numbers and the percentage of CD3-bearing cells, as well as the Concanavalin-A mitogenic response and IL-6 production by thymocytes. Interestingly, similar findings are observed in animals treated with IGF-1. Lastly, the thymic hypoplasia observed in dwarf mice can be reversed with GH treatment. In keeping with the data summarized earlier is the detection of receptors for PRL and GH on both thymocytes and thymic epithelial cells. Importantly, recent studies indicate that both cell types can produce PRL and GH intrathymically. Similarly, production of IGF-1 and expression of a corresponding receptor has also been demonstrated. In conclusion, these data strongly indicate that the thymus is physiologically under control of pituitary hormones PRL and GH. In addition to the classical endocrine pathway, paracrine and autocrine circuits are probably implicated in such control.