Developmental expression of the basic fibroblast growth factor gene in rat brain.

Basic fibroblast growth factor (bFGF) is a trophic factor for a variety of neuronal/glial cell populations. The RNase protection assay, with a cRNA complementary to the coding region of bFGF mRNA, was used to investigate the brain distribution and developmental regulation of bFGF mRNA expression. In adult rats bFGF mRNA is distributed throughout the brain, the highest levels being observed in cerebral cortex, hippocampus and spinal cord. The levels of bFGF mRNA in all the brain structures are low in newborn rats, increase thereafter to reach a peak of expression around postnatal day 21. bFGF mRNA levels are significantly different between various brain structures during the first and second postnatal week. Adult and aged rats (Fisher 344) express the same levels of bFGF mRNA in the various brain regions. The onset of bFGF mRNA expression suggests that this growth factor is important for the maturation as well as for the maintenance of different cell populations of the central nervous system.