ACh对人垂体腺瘤细胞内蛋白激酶C、胞内游离钙及cAMP/cGMP的影响

Influence of ACh on the level of protein kinase C, intracellular free Ca^(2+) and cyclic AMP/cyclic GMP of cultured human pituitary adenoma cells

我们曾发现ACh可明显地抑制垂体腺瘤细胞的增殖代谢 ,为深入探讨ACh抑制垂体腺瘤细胞增殖作用的机制 ,观察了ACh作用后垂体腺瘤细胞内蛋白激酶C (PKC)、[Ca2 +]i及cAMP/cGMP的变化。结果发现 :( 1)与空白处理组相比 ,使用PKC的激动剂PMA处理培养的人垂体腺瘤细胞时可使胞浆、胞膜和细胞总PKC活性浓度均升高 ,但ACh ( 10 μmol/L)作用 15min后 ,胞浆、胞膜和细胞总PKC活性均下降 ,且此作用可被阿托品阻断 ;( 2 )ACh ( 10 μmol/L)作用于单个人垂体腺瘤细胞后 ,立即使垂体腺瘤细胞 [Ca2 +]i 相对水平降低 ,但此作用可被阿托品阻断 ;( 3 )ACh作用于人垂体腺瘤细胞 15min后 ,胞内cAMP水平均明显升高 ,而cGMP没有改变。该结果为探讨ACh抑制垂体腺瘤细胞增殖的分子机制提供了重要线索 ,同时提示 。

We found previously that ACh can significantly inhibit the proliferation of cultured human pituitary adenoma cells. In order to make a further investigation of the mechanism of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, we observed the levels of protein kinase C (PKC), i and cAMP/cGMP in cultured pituitary adenoma cells after treatment with ACh. The results demonstrate that (1) compared with control, PMA, a PKC activator, increased the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells. However, after a 15-min treatment with ACh (10 μmol/L), a significant reduction of the activity of cytoplasm, membrane and total PKC in human pituitary adenoma cells was observed, and the reduction effect could be blocked by atropine. (2) The level of i of single adenoma cells was found to decrease immediately on the addition of ACh (10 μmol/L), which could also be blocked by atropine. (3) ACh increased the amount of cAMP in the cytoplasm of human pituitary adenoma cells, but had no effect on that of cGMP. These data provide an important clue to explore the molecular mechanisms of the inhibitory effect of ACh on the proliferation of pituitary adenoma cells, and suggest that the modulating effect of ACh on the proliferation of pituitary adenoma cells results from the interactions of several cellular signaling pathways.