Lopez-Picon F R, Uusi-Oukari M, Holopainen I E
Department of Pharmacology and Clinical Pharmacology, University of Turku, Turku, Finland.
Hippocampus. 2003;13(7):767-79. doi: 10.1002/hipo.10122.
Neurofilament (NF) proteins are expressed in most mature neurons in the central nervous system. Although they play a crucial role in neuronal growth, organization, shape, and plasticity, their expression pattern and cellular distribution in the developing hippocampus remain unknown. In the present study, we have used Western blotting and immunocytochemistry to study the low- (NF-L), medium- (NF-M), and high- (NF-H) molecular-weight NF proteins; phosphorylated epitopes of NF-M and NF-H; and a nonphosphorylated epitope of NF-H in the early postnatal (through P1-P21) development of the rat hippocampus. During the first postnatal week, NF-M was the most abundantly expressed NF, followed by NF-L, whereas the expression of NF-H was very low. Through P7-P14, the expression of NF-H increased dramatically and later began to plateau, as also occurred in the expression of NF-M and NF-L. At P1, no NF-M immunopositive cell bodies were detected, but cell processes in the CA1-CA3 fields were faintly immunopositive for NF-M and for the phosphorylated epitopes of NF-M and NF-H. At P7, CA3 pyramidal neurons were strongly immunopositive for NF-L and NF-H, but not for NF-M. The axons of granule cells, the mossy fibers (MFs), were NF-L and NF-M positive through P7-P21 but were NF-H immunonegative at all ages. Although they stained strongly for the phosphorylated NF-M and NF-H at P7, the staining intensity sharply decreased at P14 and remained so at P21. The cell bodies of CA1 pyramidal neurons and granule cells remained immunonegative against all five antibodies in all age groups. Our results show a different time course in the expression and differential cell type and cellular localization of the NF proteins in the developing hippocampus. These developmental changes could be of importance in determining the reactivity of hippocampal neurons in pathological conditions in the immature hippocampus.
神经丝（NF）蛋白在中枢神经系统的大多数成熟神经元中表达。尽管它们在神经元生长、组织、形态和可塑性中发挥着关键作用，但其在发育中的海马体中的表达模式和细胞分布仍不清楚。在本研究中，我们使用蛋白质免疫印迹法和免疫细胞化学方法，研究了出生后早期（P1 - P21）大鼠海马体中低分子量（NF-L）、中分子量（NF-M）和高分子量（NF-H）的NF蛋白；NF-M和NF-H的磷酸化表位；以及NF-H的非磷酸化表位。在出生后的第一周，NF-M是表达最丰富的NF，其次是NF-L，而NF-H的表达非常低。在P7 - P14期间，NF-H的表达急剧增加，随后开始趋于平稳，NF-M和NF-L的表达也出现了同样的情况。在P1时，未检测到NF-M免疫阳性细胞体，但CA1 - CA3区域的细胞突起对NF-M以及NF-M和NF-H的磷酸化表位呈微弱免疫阳性。在P7时，CA3锥体神经元对NF-L和NF-H呈强免疫阳性，但对NF-M呈阴性。颗粒细胞的轴突，即苔藓纤维（MFs），在P7 - P21期间对NF-L和NF-M呈阳性，但在所有年龄段对NF-H均呈免疫阴性。尽管它们在P7时对磷酸化的NF-M和NF-H染色强烈，但在P14时染色强度急剧下降，并在P21时保持如此。在所有年龄组中，CA1锥体神经元和颗粒细胞的细胞体对所有五种抗体均呈免疫阴性。我们的结果显示了发育中的海马体中NF蛋白表达、细胞类型差异和细胞定位的不同时间进程。这些发育变化可能对确定未成熟海马体在病理条件下海马神经元的反应性具有重要意义。
