Förander P, Krieglstein K, Söderström S, Strömberg I
Department of Neuroscience, Karolinska Institutet, Stockholm, S-171 77, Sweden.
Exp Neurol. 2000 Aug;164(2):303-13. doi: 10.1006/exnr.2000.7443.
Chromaffin cells have been recognized for their ability to transform into sympathetic ganglion-like cells in response to nerve growth factor (NGF) or to stimulation of other neurotrophic factors. Transforming growth factor beta (TGFbeta) family members have been shown to potentiate the effect of different trophic factors. The aim of this study was to investigate if TGFbeta may influence NGF-induced neuronal transformation and regulation of NGF, TGFbeta1, and their receptors in the adult rat chromaffin tissue after grafting. Intraocular transplantation of adult chromaffin tissue was employed and grafts were treated with TGFbeta1 and/or NGF. Graft survival time was 18 days after which the grafts were processed for TGFbeta luciferase detection assay, NGF enzyme immunoassay, or in situ hybridization. In grafts stimulated with NGF, increased levels of TGFbeta1 and TGFbeta1 mRNA were detected. When grafts instead were treated with TGFbeta1, enhanced levels of NGF protein were found. Furthermore, a positive mRNA signal corresponding to the transforming growth factor II receptor (TbetaRII) was found in the chromaffin cells of the normal adrenal medulla as well as after grafting. No increase of TbetaRII mRNA levels was detected after transplantation or after TGFbeta1 treatment. Instead a reduction of TbetaRII mRNA expression was noted after NGF treatment. NGF stimulation of grafts increased the message for NGF receptors p75 and trkA in the chromaffin transplants. Grafts processed for evaluations of neurite outgrowth were allowed to survive for 28 days and were injected weekly with NGF and/or TGFbeta1. NGF treatment resulted in a robust innervation of the host irides. TGFbeta1 had no additive effect on nerve fiber formation when combined with NGF. Combined treatment of NGF and anti-TGFbeta1 resulted in a significantly larger area of reinnervation. In conclusion, it was found that NGF and TGFbeta1 may regulate the expression of each other's protein in adult chromaffin grafts. Furthermore, TbetaRII mRNA was present in the adult rat chromaffin cells and became downregulated as a result of NGF stimulation. Although no synergistic effects of TGFbeta1 were found on NGF-induced neurite outgrowth, it was found that TGFbeta1 and NGF signaling are closely linked in the chromaffin cells of the adrenal medulla.
嗜铬细胞因其能够响应神经生长因子（NGF）或其他神经营养因子的刺激而转化为交感神经节样细胞的能力而被认识。转化生长因子β（TGFβ）家族成员已被证明能增强不同营养因子的作用。本研究的目的是调查TGFβ是否可能影响成年大鼠嗜铬组织移植后NGF诱导的神经元转化以及NGF、TGFβ1及其受体的调节。采用成年嗜铬组织的眼内移植，并对移植物用TGFβ1和/或NGF进行处理。移植物存活时间为18天，之后对移植物进行TGFβ荧光素酶检测分析、NGF酶免疫分析或原位杂交。在用NGF刺激的移植物中，检测到TGFβ1和TGFβ1 mRNA水平升高。当移植物改用TGFβ1处理时，发现NGF蛋白水平升高。此外，在正常肾上腺髓质的嗜铬细胞以及移植后均发现了与转化生长因子II型受体（TβRII）相对应的阳性mRNA信号。移植后或TGFβ1处理后未检测到TβRII mRNA水平升高。相反，在NGF处理后，TβRII mRNA表达降低。对移植物进行神经突生长评估时，使其存活28天，并每周注射NGF和/或TGFβ1。NGF处理导致宿主虹膜有强大的神经支配。TGFβ1与NGF联合使用时对神经纤维形成无相加作用。NGF和抗TGFβ1联合处理导致再支配面积显著增大。总之，发现NGF和TGFβ1可能在成年嗜铬移植物中调节彼此蛋白的表达。此外，TβRII mRNA存在于成年大鼠嗜铬细胞中，并因NGF刺激而下调。虽然未发现TGFβ1对NGF诱导的神经突生长有协同作用，但发现TGFβ1和NGF信号在肾上腺髓质的嗜铬细胞中紧密相连。
