ANALYSIS OF TROPHIC RESPONSES IN LESIONED BRAIN - FOCUS ON BASIC FIBROBLAST GROWTH-FACTOR MECHANISMS

The actions of fibroblast growth factors (FGFs), particularly the basi c form (bFGF), have been described in a large number of cells and incl ude mitogenicity, angiogenicity and wound repair. The present review d iscusses the presence of the bFGF protein and messenger RNA as well as the presence of the FGF receptor messenger RNA in the rodent brain by means of semiquantitative radioactive in situ hybridization in combin ation with immunohistochemistry. Chemical and mechanical injuries to t he brain trigger a reduction in neurotransmitter synthesis and neurona l death which are accompanied by astroglial reaction. The altered synt hesis of bFGF following brain lesions or stimulation was analyzed. Les ions of the central nervous system trigger bFGF gene expression by neu rons and/or activated astrocytes, depending on the type of lesion and time post-manipulation. The changes in bFGF messenger RNA are frequent ly accompanied by a subsequent increase of bFGF immunoreactivity in as trocytes in the lesioned pathway. The reactive astrocytes and injured neurons synthesize increased amount of bFGF, which may act as a paracr ine/autocrine factor, protecting neurons from death and also stimulati ng neuronal plasticity and tissue repair.