Brecht S, Martin-Villalba A, Zuschratter W, Bravo R, Herdegen T
II. Institute of Physiology, University of Heidelberg, Germany.
Exp Neurol. 1995 Jul;134(1):112-25. doi: 10.1006/exnr.1995.1042.
The fimbria-fornix (FF) fiber tract was unilaterally transected in adult rats by a stereotaxic knife cut. In the axotomized neurons of the medial septal nucleus (MS) and ventral diagonal band of Broca (VDB), the expression of Jun, Fos, Krox, CREB transcription factors, choline acetyltransferase (ChAT) and nitric oxide synthase (NOS) were studied by immunocytochemistry. In addition, NADPH-diaphorase (NDP) and acetylcholine esterase (AChE) were visualized by activity assays. For retrograde tracing of axotomized neurons, either HRP-coupled gold was injected in the entorhinal cortex prior to axotomy, or Fast Blue was injected into the transection site subsequently to FF transection. Following FF transection c-Jun and in a less extend JunD were expressed in axotomized MS and VDB neurons. Expression levels rose at 24 h, but not at 18 h, postaxotomy, reached their maximal levels between 5 and 7 days, and then gradually declined. Up to 100 days, c-Jun was still present in a substantial number of septal neurons. JunB, Krox-20, Krox-24, c-Fos, and pan-Fos immunoreactivities (IR) were not detectable in axotomized septal neurons and CREB-IR did not change compared to the intact contralateral side. ChAT-IR dramatically declined over 36 h, and furthermore AChE reactivity had substantially fallen after 5 days. The number and intensity of cytoplasmic neuronal NOS-IR and NDP which generated congruent temporospatial patterns gradually fell between 3 and 5 days postaxotomy. The surviving neurons labeled by NOS and NDP showed a high coexpression of c-Jun, whereas c-Jun was almost completely absent in neurons stained for ChAT and AChE. Finally, ChAT-IR and NDP reaction labeled different subpopulations. Our findings demonstrate a lasting expression of the c-Jun transcription factor in axotomized MS and VDB neurons that might indicate the regenerative propensity of damaged neurons. The decrease of NOS and NDP in MS and VDB neurons demonstrates that neuronal populations respond to axotomy with an individual regulation of NOS expression.
采用立体定位刀切割法，在成年大鼠中单侧横断穹窿-海马伞（FF）纤维束。运用免疫细胞化学方法，研究内侧隔核（MS）和布罗卡腹侧斜角带（VDB）轴突切断神经元中Jun、Fos、Krox、CREB转录因子、胆碱乙酰转移酶（ChAT）和一氧化氮合酶（NOS）的表达。此外，通过活性检测观察烟酰胺腺嘌呤二核苷酸磷酸黄递酶（NDP）和乙酰胆碱酯酶（AChE）。为逆行追踪轴突切断神经元，在轴突切断前将辣根过氧化物酶偶联金注入内嗅皮质，或者在FF切断后将快蓝注入切断部位。FF切断后，c-Jun以及在较小程度上的JunD在轴突切断的MS和VDB神经元中表达。表达水平在轴突切断后24小时上升，但18小时未上升，在5至7天达到最高水平，然后逐渐下降。直至100天，c-Jun仍存在于大量隔区神经元中。在轴突切断的隔区神经元中未检测到JunB、Krox-20、Krox-24、c-Fos和泛Fos免疫反应性（IR），与完整的对侧相比，CREB-IR没有变化。ChAT-IR在36小时内显著下降，此外，AChE反应性在5天后大幅下降。轴突切断后3至5天，产生一致时空模式的细胞质神经元NOS-IR和NDP的数量和强度逐渐下降。被NOS和NDP标记的存活神经元显示c-Jun高共表达，而在ChAT和AChE染色的神经元中几乎完全没有c-Jun。最后，ChAT-IR和NDP反应标记不同的亚群。我们的研究结果表明，c-Jun转录因子在轴突切断的MS和VDB神经元中持续表达，这可能表明受损神经元的再生倾向。MS和VDB神经元中NOS和NDP的减少表明，神经元群体对轴突切断的反应是对NOS表达的个体调节。
