McGraw J, Gaudet A D, Oschipok L W, Kadoya T, Horie H, Steeves J D, Tetzlaff W, Ramer M S
ICORD (International Collaboration On Repair Discoveries), Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, Canada V6T 1Z4.
Exp Neurol. 2005 Sep;195(1):103-14. doi: 10.1016/j.expneurol.2005.04.004.
Galectin-1 (Gal1) is an endogenously-expressed protein important for the embryonic development of the full complement of primary sensory neurons and their synaptic connections in the spinal cord. Gal1 also promotes axonal regeneration following peripheral nerve injury, but the regulation of Gal1 by axotomy in primary afferent neurons has not yet been examined. Here, we show by immunohistochemistry and in situ hybridization that Gal1 expression is differentially regulated by peripheral nerve injury and by dorsal rhizotomy. Following peripheral nerve injury, the proportion of Gal1-positive DRG neurons was increased. An increase in the proportion of large-diameter DRG neurons immunopositive for Gal1 was paralleled by an increase in the depth of immunoreactivity in the dorsal horn, where Gal1-positive terminals are normally restricted to laminae I and II. Dorsal rhizotomy did not affect the proportions of neurons containing Gal1 mRNA or protein, but did deplete the ipsilateral dorsal horn of Gal1 immunoreactivity, indicating that it is transported centrally by dorsal root axons. Dorsal rhizotomy also resulted in an increase in Gal1 mRNA the nerve peripheral to the PNS-CNS interface (likely within Schwann cells and/or macrophages), and to a lesser extent within deafferented spinal cord regions undergoing Wallerian degeneration. This latter increase was notable in the dorsal columns and along the prior trajectories of myelinated afferents into the deeper dorsal horn. These results show that neuronal and glial expressions of Gal1 are tightly correlated with regenerative success. Thus, the differential expression pattern of Gal1 following peripheral axotomy and dorsal rhizotomy suggests that endogenous Gal1 may be a factor important to the regenerative response of injured axons.
半乳糖凝集素-1（Gal1）是一种内源性表达的蛋白质，对初级感觉神经元的完整胚胎发育及其在脊髓中的突触连接至关重要。Gal1还能促进周围神经损伤后的轴突再生，但初级传入神经元中轴突切断对Gal1的调节作用尚未得到研究。在此，我们通过免疫组织化学和原位杂交表明，Gal1的表达受周围神经损伤和背根切断术的差异调节。周围神经损伤后，Gal1阳性背根神经节（DRG）神经元的比例增加。Gal1免疫阳性的大直径DRG神经元比例增加的同时，背角免疫反应性深度也增加，而Gal1阳性终末通常局限于I层和II层。背根切断术不影响含有Gal1 mRNA或蛋白质的神经元比例，但确实使同侧背角的Gal1免疫反应性耗尽，表明它是由背根轴突向中枢运输的。背根切断术还导致在PNS-CNS界面外周神经（可能在施万细胞和/或巨噬细胞内）以及在较小程度上在经历瓦勒变性的去传入脊髓区域内Gal1 mRNA增加。后者的增加在背柱以及有髓传入纤维进入更深背角的先前轨迹上很明显。这些结果表明，Gal1的神经元和胶质细胞表达与再生成功密切相关。因此，外周轴突切断术和背根切断术后Gal1的差异表达模式表明，内源性Gal1可能是损伤轴突再生反应的一个重要因素。
