Ramsell K D, Cobbett P
Department of Pharmacology and Toxicology and The Neuroscience Program, Michigan State University, East Lansing, MI 48824-1317, USA.
J Neuroendocrinol. 2000 Oct;12(10):993-1000. doi: 10.1046/j.1365-2826.2000.00545.x.
Activation of adenylate cyclase induces cultured neurohypophysial astrocytes (pituicytes) to change from a protoplasmic, nonstellate form to a stellate form. Stellation is inhibited and reversed (destellation) by serum. The objective of the present studies was to examine the roles of Ca2+ and tyrosine phosphorylation in mediating these morphological changes. The effects of forskolin (to induce stellation) and serum (to inhibit and reverse stellation) were not affected by replacement of Ca2+ with Co2+ in the medium or by treatment of cultures with thapsigargin. However, genistein, a specific inhibitor of tyrosine kinase(s), significantly reduced the effect of serum on forskolin-induced stellation. Also, dephostatin, a specific inhibitor of tyrosine phosphatase, inhibited forskolin-induced stellation. In contrast, genistein did not have a dramatic effect on serum-induced destellation. The data demonstrate that morphological changes exhibited by cultured pituicytes are independent of Ca2+ but may be modulated by the activity of tyrosine kinase(s) and phosphatase(s).
腺苷酸环化酶的激活会诱导培养的神经垂体星形胶质细胞（垂体细胞）从原生质的、非星状形态转变为星状形态。血清会抑制并逆转（去星状化）这种星状化过程。本研究的目的是研究钙离子和酪氨酸磷酸化在介导这些形态变化中的作用。在培养基中用钴离子替代钙离子，或用毒胡萝卜素处理培养物，均不影响福斯高林（诱导星状化）和血清（抑制并逆转星状化）的作用。然而，酪氨酸激酶特异性抑制剂染料木黄酮显著降低了血清对福斯高林诱导的星状化的影响。此外，酪氨酸磷酸酶特异性抑制剂去磷酸化酶抑制了福斯高林诱导的星状化。相反，染料木黄酮对血清诱导的去星状化没有显著影响。数据表明，培养的垂体细胞所表现出的形态变化与钙离子无关，但可能受酪氨酸激酶和磷酸酶活性的调节。
