Kimura M, Ogihara M
Biochemical Pharmacology Group, Faculty of Pharmaceutical Sciences, Josai University, Sakado, Saitama, Japan.
Jpn J Pharmacol. 1998 Feb;76(2):165-74. doi: 10.1254/jjp.76.165.
We investigated whether or not proliferation of adult rat hepatocytes induced by platelet-derived growth factor (PDGF) is affected by alpha1-adrenoceptor agonists such as phenylephrine during the early and late phases of primary culture. Adult rat hepatocytes underwent significant DNA synthesis after culture with 10 ng/ml of PDGF for 2 hr at a low cell density (3.3 x 10(4) cells/cm2). Under these culture conditions, the number of nuclei increased significantly during the 3.5-hr culture period. Hepatocyte DNA synthesis and proliferation induced by 10 ng/ml of PDGF decreased slightly as a result of increasing the initial plating density. An alpha1-adrenoceptor agonist, phenylephrine (10(-6) and 10(-5) M), alone did not affect hepatocyte DNA synthesis and proliferation, but markedly potentiated PDGF-induced hepatocyte DNA synthesis and proliferation. The phenylephrine effect was mimicked by phorbol myristate acetate (10(-7) M), but not by ionomycin (10(-5) M). The mitogenic effects of PDGF were almost completely blocked by treating hepatocytes with genistein (5 x 10(-6) M), U-73122 (3 x 10(-6) M), sphingosine (10(-5) M), wortmannin (10(-7) M) and rapamycin (10 ng/ml). These results demonstrate that PDGF can induce the proliferation of adult rat hepatocytes rapidly in primary culture, regardless of the initial plating density. The present results also suggest that following stimulation with PDGF, activation of tyrosine kinase, phospholipase C, phosphatidylinositol 3-kinase, protein kinase C (PKC) and p70 ribosomal protein S6 kinase is essential for the proliferation of adult rat hepatocytes. The co-mitogenic effects of phenylephrine may involve PKC activation.
我们研究了在原代培养的早期和晚期，血小板衍生生长因子（PDGF）诱导的成年大鼠肝细胞增殖是否受苯肾上腺素等α1-肾上腺素能受体激动剂的影响。成年大鼠肝细胞在低细胞密度（3.3×10⁴个细胞/cm²）下用10 ng/ml的PDGF培养2小时后，DNA合成显著增加。在这些培养条件下，在3.5小时的培养期内核数量显著增加。由于初始接种密度的增加，10 ng/ml的PDGF诱导的肝细胞DNA合成和增殖略有下降。α1-肾上腺素能受体激动剂苯肾上腺素（10⁻⁶和10⁻⁵ M）单独不影响肝细胞DNA合成和增殖，但显著增强了PDGF诱导的肝细胞DNA合成和增殖。苯乙酸肉豆蔻酯（10⁻⁷ M）可模拟苯肾上腺素的作用，但离子霉素（10⁻⁵ M）不能。用染料木黄酮（5×10⁻⁶ M）、U-73122（3×10⁻⁶ M）、鞘氨醇（10⁻⁵ M）、渥曼青霉素（10⁻⁷ M）和雷帕霉素（10 ng/ml）处理肝细胞，几乎完全阻断了PDGF的促有丝分裂作用。这些结果表明，PDGF可在原代培养中迅速诱导成年大鼠肝细胞增殖，而与初始接种密度无关。目前的结果还表明，PDGF刺激后，酪氨酸激酶、磷脂酶C、磷脂酰肌醇3激酶、蛋白激酶C（PKC）和p70核糖体蛋白S6激酶的激活对于成年大鼠肝细胞的增殖至关重要。苯肾上腺素的协同促有丝分裂作用可能涉及PKC激活。
