NEURONAL AND GLIAL EXPRESSION OF HEPARIN-BINDING EGF-LIKE GROWTH-FACTOR IN CENTRAL-NERVOUS-SYSTEM OF PRENATAL AND EARLY POSTNATAL RAT

We investigated heparin-binding epidermal growth factor-like growth fa ctor (HB-EGF) gene and protein expression in the central nervous syste m of prenatal and early postnatal rats. Assay by northern blot analysi s showed that the HB-EGF mRNA was markedly expressed in the brain. In situ hybridization and immunohistochemical techniques showed that conc ordant expression of HB-EGF mRNA and protein was widely observed in th e neurons and interfascicular oligodendrocytes, especially in the cere bellum, the hippocampus, the cerebral cortex, the subventricular area, and the brain stem nuclei. The intense expression of the HB-EGF mRNA was related anatomically and temporally to the proliferating neuroblas ts in the external granular layer of the cerebellum and the subventric ular layer of the cerebrum. These findings suggest that HB-EGF acts as a mitogen for the neuroblasts. Moreover, HB-EGF expression was observ ed in the post-mitogenic cells, such as in the cells of the molecular layer, the white matter, the IGL, or the Purkinje cells of the cerebel lum. Since EGF receptors ate abundantly expressed in the post-mitogeni c period, the HB-EGF mRNA expression observed in the post-mitogenic pe riod in our study suggests that HB-EGF also has a non-mitogenic functi on. These results suggest that HB-EGF significantly contributes to the development of the brain. (C) 1998 Elsevier Science B.V. All rights r eserved.