Postnatal Development of Transforming-growth factor-alpha Immunoreactivity in the Cerebral Cortex of the Rat

Chung, Yoon Young; Kim, Hong Soon; Kim, Jong Joong; Moon, Jeong Seok

Abstract

Transforming growth factor-alpha (TGF-alpha) induces the proliferation and differentiation of central nervous system (CNS) as well as the survival and differentiation of postmitotic CNS neurons. Previous studies have mainly focused on the TGF-alpha expression throughout brain regions. The purpose of this study was to examine TGF-alpha immunoreactivity in the neocortex of the rat during postnatal development in detail. TGF-alpha immunoreactivity in the neocortex of the rat followed very different patterns according to postnatal ages and cortical areas. In the newborn rat, TGF-alpha-immunore-active neurons were found in all cortical areas except the gustatory area. Especially, In the parietal cortex, weakly-labelled TGF-alpha-immunoreactive neurons appeared in layers II and III from P0 to P5. Areal difference between primary and secondary somatosensory area was observed in the rostral parietal zone at P10, but TGF-alpha-immunore-active neurons distributed in layers from II to VI in the caudal parietal zone. From P15 to P90, heavily-labelled neurons appeared in layers from II to VI throughout the parietal cortex. In the granular retrosplenial area, TGF-alpha-immunore-active neurons first appeared at P15. The intensity and number of the immunoreactivity of TGF-alpha-containing neurons increased during the first 20 day of postnatal life but dramatically decreased at P30. Mature patterns of TGF-alpha-immunoreactive neurons were achieved at P20. These results indicate that TGF-alpha immunoreactivity in the neocortex may be related to the early appearance of TGF-alpha immunoreactivity in many other brain regions, and suggest that TGF-alpha is widely distributed in the brain of rat and TGF-alpha may play a role during postnatal development of the cerebral cortex.