Ding S L, Elberger A J
Institute of Neuroscience, Guangzhou Medical College, Guangzhou, PR China.
Brain Res Dev Brain Res. 2000 Nov 30;124(1-2):59-65. doi: 10.1016/s0165-3806(00)00109-7.
Corpus callosum (CC) projections in adult mammals were generally thought to be excitatory and to use excitatory amino acids as their transmitters. Little information has been available about the electrical properties and neurochemical status of developing CC connections. The present study investigated the chemical status of rat CC axons during postnatal development by using antibodies to neuropeptide Y (NPY) and to somatostatin (SOM). Both NPY-immunoreactive (ir) and SOM-ir axons were found in the CC of the rat from newborn through adult; however, the number of SOM-ir CC axons is less than that of NPY-ir CC axons at corresponding ages. The density of both NPY-ir and SOM-ir CC axons initially increased, then peaked, and finally decreased to the mature level. In the adult, only a few NPY-ir and SOM-ir CC axons were found in the CC. These results indicate that many NPY-ir and SOM-ir CC axons are transitory during early postnatal development. The results also suggest that the functions of CC connections in adult mammals may be different from that of developing ones. The present results as well as the previous results demonstrate that both developing and mature CC connections are chemically heterogeneous.
成年哺乳动物的胼胝体（CC）投射通常被认为是兴奋性的，并使用兴奋性氨基酸作为其递质。关于发育中的CC连接的电特性和神经化学状态，目前可用的信息很少。本研究通过使用抗神经肽Y（NPY）和抗生长抑素（SOM）的抗体，研究了大鼠出生后发育过程中CC轴突的化学状态。从新生大鼠到成年大鼠的CC中均发现了NPY免疫反应性（ir）和SOM-ir轴突；然而，在相应年龄时，SOM-ir CC轴突的数量少于NPY-ir CC轴突。NPY-ir和SOM-ir CC轴突的密度最初增加，然后达到峰值，最后降至成熟水平。在成年大鼠中，在CC中仅发现少数NPY-ir和SOM-ir CC轴突。这些结果表明，许多NPY-ir和SOM-ir CC轴突在出生后早期发育过程中是短暂的。结果还表明，成年哺乳动物中CC连接的功能可能与发育中的功能不同。目前的结果以及先前的结果表明，发育中和成熟的CC连接在化学上都是异质的。
