Sesca E, Chiara M, Binasco V, Premoselli F, Tessitore L
Dip. di Scienze Cliniche e Biologiche, Ospedale S. Luigi Gonzaga, Università degli Studi di Torino.
Boll Soc Ital Biol Sper. 1996 Nov-Dec;72(11-12):325-9.
The administration of an excess of choline for 3 weeks is able to delay the proliferative response to partial hepatectomy (PH) in female rats. Choline feeding can affect the phospholipid composition of cell membranes and, as a consequence, the transduction of the mitogenic signals. On these bases, we studied the turnover of phosphatidylinositol-4,5-biphosphate (PIP2) in the regenerating liver of female rats. The hydrolysis of PIP2 is catalysed by a specific phospholipase C (PL-C) and it generates the second messenger molecules, namely diacylglycerol and inositol-1,4,5-triphosphate (IP3). Our results showed that the administration of an excess of choline to females was able to reduce the PL-C activity and the membrane IP3 content in the quiescent liver. Both parameters remained lower than controls during liver regeneration, even if they were higher 1 and 2 h after PH in comparison with the quiescent liver, in choline-fed females. These data suggest that the delay in the liver regeneration by choline is due, at least in part, to the alteration in the pathway of PIP2 turnover for the transduction of mitogenic signals.
给雌性大鼠过量投喂胆碱3周能够延缓其对部分肝切除术（PH）的增殖反应。胆碱喂养会影响细胞膜的磷脂组成，进而影响有丝分裂信号的转导。基于这些原因，我们研究了雌性大鼠再生肝脏中磷脂酰肌醇-4,5-二磷酸（PIP2）的周转情况。PIP2的水解由特定的磷脂酶C（PL-C）催化，产生第二信使分子，即二酰基甘油和肌醇-1,4,5-三磷酸（IP3）。我们的结果表明，给雌性大鼠过量投喂胆碱能够降低静止肝脏中的PL-C活性和膜IP3含量。在肝脏再生过程中，这两个参数均低于对照组，即便在投喂胆碱的雌性大鼠中，与静止肝脏相比，它们在部分肝切除术后1小时和2小时时有所升高。这些数据表明，胆碱对肝脏再生的延迟作用至少部分归因于PIP2周转途径的改变，而该途径用于有丝分裂信号的转导。
