Frödin M, Gammeltoft S
Department of Clinical Chemistry, Bispebjerg Hospital, Copenhagen NV, Denmark.
Proc Natl Acad Sci U S A. 1994 Mar 1;91(5):1771-5. doi: 10.1073/pnas.91.5.1771.
We have investigated the effects of insulin-like growth factors (IGFs), basic fibroblast growth factor (bFGF), and nerve growth factor (NGF) on DNA synthesis in cultured chromaffin cells from fetal, neonatal, and adult rats by using 5-bromo-2'-deoxyuridine (BrdUrd) pulse labeling for 24 or 48 h and immunocytochemical staining of cell nuclei. After 6 days in culture in the absence of growth factors, nuclear BrdUrd incorporation was detected in 30% of fetal chromaffin cells, 1.5% of neonatal cells, and 0.1% of adult cells. Addition of 10 nM IGF-I or IGF-II increased the fraction of BrdUrd-labeled nuclei to 50% of fetal, 20% of neonatal, and 2% of adult chromaffin cells. The ED50 value of IGF-I- and IGF-II-stimulated BrdUrd labeling in neonatal chromaffin cells was 0.3 nM and 0.8 nM, respectively. In neonatal and adult chromaffin cells, addition of 1 nM bFGF or 2 nM NGF stimulated nuclear BrdUrd incorporation to approximately the same level as 10 nM IGF-I or IGF-II. However, the response to bFGF or NGF in combination with either IGF-I or IGF-II was more than additive, indicating that the combined effect of the IGFs and bFGF or NGF is synergistic. The degree of synergism was 2- to 4-fold in neonatal chromaffin cells and 10- to 20-fold in adult chromaffin cells compared with the effect of each growth factor alone. In contrast, the action of bFGF and NGF added together in the absence of IGFs was not synergistic or additive. IGF-II acted also as a survival factor on neonatal chromaffin cells and the cell survival was further improved when bFGF or NGF was added together with IGF-II. In conclusion, we propose that IGF-I and IGF-II act in synergy with bFGF and NGF to stimulate proliferation and survival of chromaffin cells during neonatal growth and adult maintenance of the adrenal medulla. Our findings may have implications for improving the survival of chromaffin cell implants in diseased human brain.
我们通过使用5-溴-2'-脱氧尿苷（BrdUrd）脉冲标记24或48小时以及细胞核免疫细胞化学染色，研究了胰岛素样生长因子（IGF）、碱性成纤维细胞生长因子（bFGF）和神经生长因子（NGF）对来自胎儿、新生和成年大鼠的培养嗜铬细胞中DNA合成的影响。在无生长因子的情况下培养6天后，在30%的胎儿嗜铬细胞、1.5%的新生细胞和0.1%的成年细胞中检测到细胞核BrdUrd掺入。添加10 nM的IGF-I或IGF-II可使BrdUrd标记细胞核的比例增加到胎儿嗜铬细胞的50%、新生细胞的20%和成年嗜铬细胞的2%。IGF-I和IGF-II刺激新生嗜铬细胞BrdUrd标记的ED50值分别为0.3 nM和0.8 nM。在新生和成年嗜铬细胞中，添加1 nM的bFGF或2 nM的NGF刺激细胞核BrdUrd掺入的水平与10 nM的IGF-I或IGF-II大致相同。然而，bFGF或NGF与IGF-I或IGF-II联合使用时的反应大于相加效应，表明IGF与bFGF或NGF的联合作用是协同的。与单独使用每种生长因子的效果相比，协同程度在新生嗜铬细胞中为2至4倍，在成年嗜铬细胞中为10至20倍。相反，在无IGF的情况下一起添加bFGF和NGF的作用既不是协同的也不是相加的。IGF-II对新生嗜铬细胞也起存活因子的作用，当bFGF或NGF与IGF-II一起添加时，细胞存活率进一步提高。总之，我们提出IGF-I和IGF-II与bFGF和NGF协同作用，以刺激嗜铬细胞在新生期生长和成年期肾上腺髓质维持过程中的增殖和存活。我们的发现可能对提高患病人类大脑中嗜铬细胞植入物的存活率有影响。
