Friedman W J, Ernfors P, Persson H
Department of Medical Chemistry, Karolinska Institute, Stockholm, Sweden.
J Neurosci. 1991 Jun;11(6):1577-84. doi: 10.1523/JNEUROSCI.11-06-01577.1991.
Neurotrophin-3 (NT-3) is closely related to two known neurotrophic agents, NGF and brain-derived neurotrophic factor (BDNF), and acts upon overlapping, yet distinct, populations of peripheral ganglia. NT-3 mRNA expression in the adult rat brain is largely confined to the hippocampus. In this study, we have used in situ hybridization to examine expression of this novel neurotrophic factor during postnatal development. The striking observation was made that NT-3 mRNA was transiently expressed at high levels in the cingulate cortex during the first 2 weeks of age. In the hippocampus, the adult pattern of expression, in the CA2, medial CA1, and granule layer of the dentate gyrus, was detected at all ages examined. However, there were two major differences in NT-3 mRNA expression in the developing hippocampus: Labeled cells were detected in the hilar region of the dentate gyrus at postnatal day 1 (P1) and 1 week that were absent by 2 weeks of age. Further, the caudal hippocampus, which has a lower intensity of labeling than the rostral region in the adult, was devoid of NT-3-expressing cells in the P1 and 1-week-old rat brain. These data indicate a substantial plasticity in NT-3 mRNA expression and suggest that the spectrum of neurons supported by NT-3 during development is partially different from that in the mature rat brain.
神经营养因子-3（NT-3）与两种已知的神经营养因子，即神经生长因子（NGF）和脑源性神经营养因子（BDNF）密切相关，并作用于外周神经节中部分重叠但又不同的细胞群。成年大鼠脑中NT-3 mRNA的表达主要局限于海马体。在本研究中，我们利用原位杂交技术来检测这种新型神经营养因子在出生后发育过程中的表达情况。我们有一个惊人的发现，即在出生后的前两周，扣带回皮质中NT-3 mRNA会短暂地高水平表达。在海马体中，在所检测的各个年龄段均能检测到成年期的表达模式，即在齿状回的CA2、内侧CA1和颗粒层中表达。然而，发育中的海马体中NT-3 mRNA的表达存在两个主要差异：在出生后第1天（P1）和1周时，在齿状回的门区检测到有标记的细胞，但在2周龄时这些细胞消失了。此外，在成年期尾侧海马体的标记强度低于头侧区域，而在P1和1周龄大鼠脑中，尾侧海马体没有表达NT-3的细胞。这些数据表明NT-3 mRNA的表达具有显著的可塑性，并表明在发育过程中由NT-3支持的神经元谱系与成熟大鼠脑中的部分不同。
