Fukuda J, Aosaki T, Keino K, Yamaguchi T
Department of Physiology, Faculty of Medicine, University of Tokyo.
J Gerontol. 1991 Jan;46(1):B3-16. doi: 10.1093/geronj/46.1.b3.
Low density (20-50 cells/cm2), dissociated cultures of trigeminal ganglion (TRG) cells of the shrew, were made in a serum-free medium, and neurite growth was compared across ages of the animal and between NGF-free and NGF-rich conditions. TRG cells from newborn shrew (0-3 days old), which grew long neurites in an NGF-rich medium, failed to grow any neurites in an NGF-free medium. In contrast, TRG cells from aged shrew (16-19 months), which grew neurites without NGF, exhibited no further increment in neurite length when NGF (50-200 ng/ml) was added to the culture medium. TRG cells from adult shrew (4-5 months) were revealed to be a mixture of NGF-dependent and NGF-independent cells. The NGF-dependent cells (20% of the population) had large-sized somata of 24-32 microns diameter (L-type cells) and 2-7 long neurites enriched with arborizations. The remaining NGF-independent cells (80%) had small-sized somata (15-25 microns, S-type cells), and grew 1-3 neurites with a small number of arborizations. These findings suggest that the primary sensory neuron of the shrew has a cell-type specific critical period in the aging process with respect to the requirement of NGF for neurite promotion.
在无血清培养基中制备了低密度（20 - 50个细胞/cm²）的鼩鼱三叉神经节（TRG）细胞解离培养物，并比较了不同年龄动物以及无神经生长因子（NGF）和富含NGF条件下的神经突生长情况。新生鼩鼱（0 - 3天大）的TRG细胞在富含NGF的培养基中能长出长神经突，但在无NGF的培养基中则无法长出任何神经突。相反，老年鼩鼱（16 - 19个月）的TRG细胞在无NGF的情况下能长出神经突，当向培养基中添加NGF（50 - 200 ng/ml）时，神经突长度没有进一步增加。成年鼩鼱（4 - 5个月）的TRG细胞被发现是NGF依赖型和NGF非依赖型细胞的混合物。NGF依赖型细胞（占细胞总数的20%）具有直径为24 - 32微米的大型胞体（L型细胞），并有2 - 7条富含分支的长神经突。其余的NGF非依赖型细胞（80%）具有小型胞体（15 - 25微米，S型细胞），并长出1 - 3条分支较少的神经突。这些发现表明，鼩鼱的初级感觉神经元在衰老过程中，对于NGF促进神经突生长的需求存在细胞类型特异性的关键期。
