Establishment of model cell lines for analyzing relation of angiotensin II-caused diseases with long term potentiation

1.建立了稳定表达重组人血管紧张素II受体1型(AT1)的AtT20细胞系，为分析血管紧张素Ⅱ引起的疾病与长时程增强的关系提供了模型。AtT20细胞来源于分泌促肾上腺皮质激素(ACTH)的小鼠垂体前叶细胞。结果表明：(1)在这些细胞中，Ang II通过AT1受体诱导磷脂酶C和电压依赖性钙通道的激活，并抑制腺苷环化酶的活性。其中，前两条途径与Ang II诱导的ACTH分泌有关。(2)该细胞系是研究Ang II和促肾上腺皮质激素释放因子(CRF)信号通路之间相互作用的良好模型，因为Ang II与CRF对ACTH分泌有协同作用，其作用由cAMP介导。2.我们试图建立一个微灌流系统来研究Ang II是否在这些内分泌细胞中诱导与神经细胞中观察到的长期增强相对应的现象。不幸的是，在这个系统中没有得到可靠的结果，因为高水平的基础ACTH分泌阻止了我们选择性地检测Ang II诱导的ACTH分泌量。我们现在正在寻找最佳条件，在这种条件下，使用培养在培养皿中的细胞观察到长时程增强，而不是使用微灌流系统中填充的微吸管。

1.We have established an AtT20 cell line stably expressing the recombinant human angiotensin II (Ang II) receptor type 1 (AT1) to provide a model for analyzing the relation of Ang II-caused diseases with long term potentiation. AtT20 cells are derived from mouse anterior pituitary cells secreting adrenocorticotropin (ACTH). Following finding were obtained concerning characteristics of this cell line, which are essential for the purpose of this study.(1) In these transfected cells, Ang II induced activation of phospholipase C and voltage-dependent calcium channel, and inhibition of adenylate cyclase activity through the AT1 receptor. Among these the former two pathways were found to relate with Ang II-induced ACTH secretion.(2) This cell line was found to be a good model for elucidating the cross-talk between Ang II and corticotropin releasing factor (CRF) signalling pathways, because Ang II had a synergistic effect with CRF,whose functions are mediated by cAMP,on ACTH secretion.2.We tried to develop a microperfusion system to investigate whether Ang II induces a phenomenon in these endocrine cells corresponding to long term potentiation observed in neural cells. Unfortunately, reliable results were not obtained in this system since high levels of basal ACTH secretion prevented us from selectively detecting the amount of Ang II-induced ACTH secretion. We are now looking for optimal conditions in which the long term potentiation is observed using the cells cultured in dishes but not those filled in micropipette in the microperfusion system.