Wang R N, Rehfeld J F, Nielsen F C, Klöppel G
Department of Pathology, University of Kiel, Germany.
Diabetologia. 1997 Aug;40(8):887-93. doi: 10.1007/s001250050764.
In adult rats islet cell neogenesis can be stimulated by partial duct ligation. Duct to islet cell differentiation is thought to be regulated by growth factors such as gastrin and transforming growth factor-alpha (TGF alpha). To test this hypothesis, we examined the expression of gastrin and TGF alpha at the mRNA and protein level in pancreatic tissue following partial duct ligation. Pancreatic specimens were investigated on days 3, 5, 7 and 14 after duct ligation by means of non-isotopic in situ hybridization, immunocytochemistry and Western blotting. Gastrin mRNA was strongly expressed in newly developed duct-like cell structures in the ligated tail portion of the pancreas before the period of pronounced islet cell neogenesis (days 5 and 7), and immunostaining for gastrin peptides was positive at days 5-7. In the non-ligated head portion and in control pancreases, gastrin was not expressed. Expression of TGF alpha was found to be increased in the ligated tail portion of the pancreas on day 3 and particularly on day 5, while there was no enhanced signal in the non-ligated part. Western blotting revealed two different TGF alpha isoforms (18 kDa and 42 kDa) in the ligated tail part and three isoforms (18 kDa, 24 kDa and 42 kDa) in the non-ligated head part and in untreated pancreases. The induction of gastrin and TGF alpha expression preceded the peak in the bromodeoxyuridine pulse labelling index of beta cells, known from a previous study to occur on day 7. We conclude that pancreas duct ligation induces the overexpression of gastrin and TGF alpha in the first days following ligation. Since ductal cells are known to give rise to endocrine cells after duct ligation, gastrin and TGF alpha may play a role as growth factors in islet neogenesis.
在成年大鼠中，部分胆管结扎可刺激胰岛细胞新生。胆管向胰岛细胞的分化被认为受胃泌素和转化生长因子-α（TGFα）等生长因子调控。为验证这一假说，我们检测了部分胆管结扎后胰腺组织中胃泌素和TGFα在mRNA和蛋白水平的表达。通过非同位素原位杂交、免疫细胞化学和蛋白质印迹法，对胆管结扎后第3、5、7和14天的胰腺标本进行研究。在明显的胰岛细胞新生期（第5和7天）之前，胃泌素mRNA在胰腺结扎尾部新形成的导管样细胞结构中强烈表达，胃泌素肽的免疫染色在第5 - 7天呈阳性。在未结扎的头部和对照胰腺中，胃泌素未表达。发现TGFα的表达在结扎后第3天，尤其是第5天，在胰腺结扎尾部增加，而在未结扎部分没有增强信号。蛋白质印迹显示，结扎尾部有两种不同的TGFα异构体（18 kDa和42 kDa），未结扎头部和未处理的胰腺中有三种异构体（18 kDa、24 kDa和42 kDa）。胃泌素和TGFα表达的诱导先于β细胞溴脱氧尿苷脉冲标记指数的峰值，此前一项研究表明该峰值出现在第7天。我们得出结论，胰腺胆管结扎在结扎后的头几天诱导胃泌素和TGFα的过表达。由于已知胆管结扎后导管细胞可产生内分泌细胞，胃泌素和TGFα可能在胰岛新生中作为生长因子发挥作用。
