Prominent expression of acidic fibroblast growth factor in motor and sensory neurons

Co-localization of basic fibroblast growth factor-like immunoreactivity and its receptor mRNA in the rat spinal cord and the dorsal root ganglion

In the present study, we examined the localizations of basic fibroblast growth factor-like immunoreactivity (bFGF-LI) and its receptor mRNA in the spinal cord and the dorsal root ganglion of the rat. Anti-bFGF peptide antibody and cRNA probe were employed to visualize the localizations of bFGF-LI and FGF receptor (FGF-R) mRNA, respectively. In the spinal cord, we observed that a number of neurons including the motor neurons and interneurons were positive for both substances. In the dorsal root ganglion (DRG), the large neurons preferentially showed co-localization of bFGF-LI and FGF-R mRNA, while the small neurons were not always positive for both. Given the fact that FGF-R is a membrane-spanning protein, these findings suggest the following two possibilities: (1) bFGF acts on the neurons of the spinal cord and the DRG in an autocrine and/or paracrine manner; (2) FGF-R mRNA-positive neurons take up bFGF from innervating neurons and/or surrounding glias in a receptor-mediated fashion.

Diverse receptors for fibroblast growth factors

The development and maintenance of multicellular organisms requires a complex interplay between cells in different tissues. Many of the factors mediating cell-cell communication are polypeptides, which were originally identified because of their ability to stimulate cell growth. In addition to growth signalling several of these factors have been observed to modulate cell survival, chemotaxis and differentiation both in vitro and in vivo. Fibroblast growth factors are a good example of polypeptide mitogens eliciting a wide variety of responses depending on the target cell type. Our knowledge of the cell surface receptors mediating the effects of FGFs has recently expanded remarkably. Perhaps not surprisingly, the complexity of the FGF family and FGF induced responses is reflected as diversity and redundancy of the FGF receptors.

Expression of acidic and basic fibroblast growth factors in the substantia nigra of rat, monkey, and human

The distribution of acidic (aFGF) and basic (bFGF) fibroblast growth factor mRNA and protein were examined in mesencephalon by immunohistochemistry, immunoblot analysis, in situ hybridization histochemistry, and RNA analysis. Coexistence of aFGF or bFGF with tyrosine hydroxylase protein in nigral cells was observed with immunohistochemistry. Both aFGF and bFGF mRNAs were found in the substantia nigra. Unilateral 6-hydroxydopamine lesions of nigrostriatal neurons resulted in a loss of aFGF and tyrosine hydroxylase [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] mRNA-positive neurons on the lesioned side. The distribution of aFGF mRNA in monkey brain was similar to that seen in the rat. RNA and immunoblot analysis confirmed the presence of both aFGF and bFGF mRNAs and proteins in the substantia nigra of rat, monkey, and human.