Ghrelin increases intracellular Ca2+ concentration in the various hormone-producing cell types of the rat pituitary gland
Ghrelin increases intracellular Ca2+ concentration in the various hormone-producing cell types of the rat pituitary gland
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DOI：
10.1016/j.neulet.2012.07.063
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发表时间：
2012-09
影响因子：
2.5
通讯作者：
Mami Yamazaki;S. Aizawa;Toru Tanaka;T. Sakai;I. Sakata
中科院分区：
文献类型：
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作者：
Mami Yamazaki;S. Aizawa;Toru Tanaka;T. Sakai;I. Sakata
Ghrelin是从胃中分离的生长激素促分泌素受体（GHS-R）的内源性配体，在体内和体外都具有强的生长激素释放能力。虽然GHS-R在脑垂体中大量表达，但没有直接证据表明脑垂体中产生神经元的细胞与功能性GHS-R之间存在关系。本研究的目的是确定哪些垂体前叶细胞对ghrelin刺激有反应。我们使用分离的垂体细胞进行Fura-2 Ca 2+成像分析，并进行免疫细胞化学以鉴定垂体分泌细胞的类型。在Fura-2 Ca 2+成像分析中，ghrelin给药增加了约50%的总分离的垂体前叶细胞中的细胞内Ca 2+浓度，并且这些细胞中的20%强烈响应ghrelin。免疫细胞化学分析显示，82.9±1.3%的细胞响应于生长激素释放肽刺激是GH免疫阳性。另一方面，PRL、LH和ACTH免疫阳性细胞分别占Ghrelin反应细胞的2.0± 0.3%、12.6± 0.3%和2.5±0.8%。促甲状腺激素免疫阳性细胞没有回应ghrelin治疗。这些结果表明，生长激素释放肽不仅直接作用于生长激素细胞，但也对乳房细胞，促性腺激素细胞，促肾上腺皮质激素细胞在大鼠脑垂体。
Ghrelin, isolated from the stomach as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), has potent growth hormone release ability in vivo and in vitro. Although GHS-R is abundantly expressed in the pituitary gland, there is no direct evidence of a relationship between hormone-producing cells and functional GHS-R in the pituitary gland. The aim of this study was to determine which anterior pituitary cells respond to ghrelin stimulation in male rats. We performed Fura-2 Ca2+imaging analysis using isolated pituitary cells, and performed immunocytochemistry to identify the type of pituitary hormone-producing cells. In Fura-2 Ca2+imaging analysis, ghrelin administration increased the intracellular Ca2+concentration in approximately 50% of total isolated anterior pituitary cells, and 20% of these cells strongly responded to ghrelin. Immunocytochemical analysis revealed that 82.9±1.3% of cells that responded to ghrelin stimulation were GH-immunopositive. On the other hand, PRL-, LH-, and ACTH-immunopositive cells constituted 2.0±0.3%, 12.6±0.3%, and 2.5±0.8% of ghrelin-responding pituitary cells, respectively. TSH-immunopositive cells did not respond to ghrelin treatment. These results suggest that ghrelin directly acts not only on somatotrophs, but also on mammotrophs, gonadotrophs, and corticotrophs in the rat pituitary gland.