Matsukawa M, Nakadate K, Ishihara I, Okado N
Department of Anatomy, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba, Ibaraki 305-8577, Japan.
Neuroscience. 2003;122(3):627-35. doi: 10.1016/j.neuroscience.2003.08.047.
Biogenic amines have a trophic-like role for the formation and the maintenance of synapses in the CNS. We examined the changes in the number of synaptic profiles in the developing and adult rat visual cortex following selective depletion of noradrenaline and/or serotonin. By the drug-induced decreases in levels of noradrenaline or serotonin between 1 and 2 weeks after birth, the number of synaptic profiles was decreased by 29-55% compared with that of control animals. The magnitude of reduction in the number of synaptic profiles was virtually the same following simultaneous depletion of both noradrenaline and serotonin compared with the depletion of noradrenaline or serotonin alone. Later in the developmental period, the function of noradrenaline and serotonin in facilitating synapse formation and maintenance became less prominent than that in younger animals. In the control animals, the number of axosomatic synapses was the highest at around 2 weeks after birth, and decreased with development. The number of axodendritic synapses was the highest between 2 and 7 weeks after birth, and decreased to 50% at 11 weeks after birth. These data demonstrate that synapses in the rat visual cortex are overproduced during the early developmental period. We suggest that both serotonin and noradrenaline are necessary for synapse formation during the early stages of development of the rat visual cortex.
生物胺在中枢神经系统中对突触的形成和维持具有类似营养的作用。我们研究了去甲肾上腺素和/或5-羟色胺选择性耗竭后，发育中和成年大鼠视皮层中突触轮廓数量的变化。通过药物诱导出生后1至2周内去甲肾上腺素或5-羟色胺水平降低，与对照动物相比，突触轮廓数量减少了29 - 55%。与单独耗竭去甲肾上腺素或5-羟色胺相比，同时耗竭去甲肾上腺素和5-羟色胺后突触轮廓数量的减少幅度几乎相同。在发育后期，去甲肾上腺素和5-羟色胺在促进突触形成和维持方面的功能不如年幼动物明显。在对照动物中，轴体突触数量在出生后约2周时最高，并随发育而减少。轴树突触数量在出生后2至7周时最高，在出生后11周时降至50%。这些数据表明，大鼠视皮层中的突触在发育早期过度产生。我们认为，5-羟色胺和去甲肾上腺素在大鼠视皮层发育早期对突触形成都是必需的。
