To study the distribution and expression of Semaphorins-3A protein in brain of postnatal rats.

Semaphorins-3A positive cells were observed by immunohistochemistry in the cerebral cortex, hippocampus, dentate gyrus and entorhinal cortex in postnatal 0d, 7d, 14d, 21d and 28d of Sprague Dawley rats.

Semaphorins-3A positive cells widely distributed in the granule cell layer (Ⅱ), external pyramidal cell layer (Ⅲ), internal granular cell layer (Ⅳ), pyramidal cell layer (Ⅴ) and layer of polymorphous cells (Ⅵ), in addition to the molecular layer (Ⅰ) of the parietal, occipital, frontal, temporal, insular, cingulate cortex, piriform cortex and entorhinal cortex with postnatal 0d, 7d, 14d, 21d and 28d rats.The amount of semaphorins-3A positive cells(IOD) in the entorhinal cortex was 84916.23±3266.34 in P0d, 77711.41±2634.26 in P7d, 74124.25±3989.09 in P14d, 65887.63±3406.57 in P21d and 57705.96±3136.35 in P28d, meanwhile the region of semaphorins-3A positive cells narrowed in the part level with Ⅱ-Ⅵ levels of cortex.Similarly semaphorins-3A positive cells distributed mainly in granule cell layer of dentate gyrus, CA1, CA3 region and only a few of semaphorins-3A positive cells scattered in the multi-line layer in hippocampus.The expression level of semaphorins-3A was significant difference among postnatal 0d, 7d, 14d, 21d and 28d rats (P<0.01).

Semaphorins-3A positive cells widely distribute in the various cortex and hippocampus in developing rat brain, and the region of semaphorins-3A is reduced with age growth of rats.

Semaphorins-3A; Developing rats; Cerebral cortex; Hippocampus; Entorhinal cortex