Castrén E, Zafra F, Thoenen H, Lindholm D
Department of Neurochemistry, Max Planck Institute for Psychiatry, Planegg-Martinsried, Federal Republic of Germany.
Proc Natl Acad Sci U S A. 1992 Oct 15;89(20):9444-8. doi: 10.1073/pnas.89.20.9444.
Specific sensory input has profound transient and long-lasting effects on the function of corresponding sensory cortical areas both during development and in adulthood. To study whether neurotrophic factors might play a role in such processes, we investigated the effects of light on the nerve growth factor and brain-derived neurotrophic factor (BDNF) mRNA levels in rat visual cortex. Keeping adult rats in the dark or preventing normal activity of retinal ganglion cells by intraocular injection of tetrodotoxin significantly decreased the levels of BDNF mRNA in the visual cortex but not in other cortical areas. Exposure to light after a period in darkness rapidly restored the mRNA to control levels. These alterations in visual input had no effect on nerve growth factor mRNA. The mRNA of trkB, the putative signal-transducing receptor unit for BDNF, was also decreased in darkness, although less than BDNF mRNA. BDNF mRNA levels increased in the visual cortex of newborn rats after eye-opening. This increase is retarded, although not completely abolished, by rearing the pups in darkness. Thus, the levels of BDNF mRNA are rapidly regulated by sensory input during development and in adulthood. BDNF may therefore play an important role in formation and in activity-dependent modulation of specific connections in the visual cortex.
特定的感觉输入在发育过程中和成年期对相应感觉皮层区域的功能具有深刻的短暂和长期影响。为了研究神经营养因子是否可能在此类过程中发挥作用，我们研究了光照对大鼠视觉皮层中神经生长因子和脑源性神经营养因子（BDNF）mRNA水平的影响。将成年大鼠置于黑暗中或通过眼内注射河豚毒素阻止视网膜神经节细胞的正常活动，可显著降低视觉皮层中BDNF mRNA的水平，但对其他皮层区域无此影响。在黑暗中一段时间后暴露于光照下可迅速将mRNA恢复至对照水平。这些视觉输入的改变对神经生长因子mRNA无影响。BDNF假定的信号转导受体单位trkB的mRNA在黑暗中也减少，尽管比BDNF mRNA减少得少。睁眼后新生大鼠视觉皮层中的BDNF mRNA水平升高。通过在黑暗中饲养幼崽，这种升高受到抑制，尽管没有完全消除。因此，BDNF mRNA水平在发育过程中和成年期受到感觉输入的快速调节。因此，BDNF可能在视觉皮层中特定连接的形成和依赖活动的调节中发挥重要作用。
