Hogg J, Hill D J, Han V K
Lawson Research Institute, St Joseph's Health Centre, London, Ontario, Canada.
J Mol Endocrinol. 1994 Aug;13(1):49-58. doi: 10.1677/jme.0.0130049.
Insulin is important for optimal fetal and neonatal growth and development. Its continued availability is due, in part, to ongoing islet cell growth within the pancreas. IGFs and IGF-binding proteins (IGFBPs) have been implicated as paracrine regulators of islet cell growth within the developing pancreas. The purpose of this study was to determine whether the intact rat pancreas expresses mRNAs for IGF-I, IGF-II and IGFBPs, and how these might change with development. Liver was studied as a control tissue. Pancreas and liver were taken from fetal rats at 20-22 days of gestation, from postnatal rats at 1-21 days and from adult animals, and mRNAs for IGFs-I and -II and IGFBPs-1 to -6 were detected by Northern blot hybridization. The amount of IGF-II mRNA was greatest in the liver and pancreas of the fetal rat, and declined in both tissues during the neonatal period. Conversely, IGF-I mRNA levels were low but detectable in fetal life, and rose to adult levels within 2 weeks of birth. Both IGFBP-1 and IGFBP-2 mRNAs were present in fetal rat liver, increasing in amount over the first week of life, and declining in the adult. However, within the pancreas, IGFBP-1 mRNA was undetectable and IGFBP-2 mRNA was very low in the fetus and neonate. Both IGFBP-1 and IGFBP-2 mRNAs transiently appeared in the pancreas between postnatal weeks 2 and 3 and declined in the adult. IGFBP-3 and IGFBP-4 mRNAs were detected in both the liver and pancreas throughout the developmental period studied. IGFBP-3 mRNA increased in amount immediately following birth, while the quantity of IGFBP-4 mRNA increased sharply in liver from postnatal day 21, but declined in the pancreas. mRNA for IGFBP-5 or -6 was undetectable in either tissue. The reslts show that both IGF-I and IGF-II are expressed by rat pancreas from at least 20 days of gestation, the latter being predominant in fetal life and the former during postnatal development. In addition, at least four IGFBP mRNAs (IGFBPs-1, -2, -3 and -4) were expressed within the pancreas with distinct developmental patterns. IGFBP-3 and -4 were predominant in the fetal and neonatal periods, while increased expression of IGFBPs-1 and -2 occurred 2-3 weeks after birth. The ontogeny of IGFBP mRNA expression in pancreas differed from that in liver.(ABSTRACT TRUNCATED AT 400 WORDS)
胰岛素对于胎儿和新生儿的最佳生长发育至关重要。其持续存在部分归因于胰腺内胰岛细胞的持续生长。胰岛素样生长因子（IGFs）和胰岛素样生长因子结合蛋白（IGFBPs）被认为是发育中胰腺内胰岛细胞生长的旁分泌调节因子。本研究的目的是确定完整的大鼠胰腺是否表达IGF-I、IGF-II和IGFBPs的mRNA，以及这些mRNA如何随发育而变化。肝脏作为对照组织进行研究。从妊娠20 - 22天的胎鼠、出生后1 - 21天的新生鼠以及成年动物获取胰腺和肝脏，通过Northern印迹杂交检测IGF-I、IGF-II以及IGFBPs - 1至 - 6的mRNA。IGF-II mRNA的量在胎鼠的肝脏和胰腺中最多，在新生儿期这两个组织中均下降。相反，IGF-I mRNA水平在胎儿期较低但可检测到，在出生后2周内升至成年水平。IGFBP-1和IGFBP-2 mRNA在胎鼠肝脏中均存在，在出生后的第一周内量增加，在成年期下降。然而，在胰腺中，IGFBP-1 mRNA在胎儿和新生儿中无法检测到，IGFBP-2 mRNA非常低。IGFBP-1和IGFBP-2 mRNA在出生后第2至3周期间在胰腺中短暂出现，在成年期下降。在整个研究的发育阶段，肝脏和胰腺中均检测到IGFBP-3和IGFBP-4 mRNA。出生后IGFBP-3 mRNA的量立即增加，而IGFBP-4 mRNA的量在出生后第21天起在肝脏中急剧增加，但在胰腺中下降。在这两种组织中均未检测到IGFBP-5或 - 6的mRNA。结果表明，至少从妊娠20天起大鼠胰腺就表达IGF-I和IGF-II，后者在胎儿期占主导，前者在出生后发育阶段占主导。此外，胰腺内至少有四种IGFBP mRNA（IGFBPs - 1、 - 2、 - 3和 - 4）以不同的发育模式表达。IGFBP-3和 - 4在胎儿期和新生儿期占主导，而IGFBPs - 1和 - 2的表达在出生后2 - 3周增加。胰腺中IGFBP mRNA表达的个体发生与肝脏中的不同。（摘要截短至400字）
