Comparative localization of fibroblast growth factor receptor-1, -2, and -3 mRNAs in the rat brain: In situ hybridization analysis

Abstract

The present study provides a detailed comparative description in the adult rat brain of areas that express mRNAs coding for the fibroblast growth factor subtype receptors 1-3 (FGFR1-3). One observation in this analysis was a widespread expression in the brain of all three FGFR mRNAs, according to the following rank order: FGFR1, diencephalon < telencephalon < mesencephalon and metencephalon < myelencephalon; FGFR2 and FGFR3, telencephalon < diencephalon < mesencephalon and metencephalon < myelencephalon. Another observation was an apparent cellular specificity in their basal expression. Thus, the FGFR1 mRNA was expressed mainly in large and weakly stained cells, whereas FGFR2 transcripts were expressed primarily in small and strongly stained cells and in cells of brain regions devoid of neuronal cells, such as the white matter. FGFR3 mRNA was always detected in small and strongly stained cells with scattered distribution and was not expressed in the white matter. However, FGFR2 mRNA was weakly expressed also in large cells localized in some nuclei of the lower brainstem, in the diagonal band, and in the septum. Furthermore, in the medial habenula and in the nuclei of the pons, there exists a high density of cells expressing both FGFR1 and FGFR2 (60-100%). With neurotoxic lesions involving 6-hydroxydopamine microinjections in the substantia nigra, reactive glial cells in the lesioned area and surrounding the cannula tract showed an increase in the expression of both FGFR1 and FGFR2 mRNAs, whereas no increased expression was found for FGFR3 mRNA. Taken together, these findings showed that these three FGF receptors exist in all subtypes of cells of each brain region. Their apparent cellular specificity suggests that these receptor subtypes can have a differential trophic role in the brain, reflecting the various biological activities shown by the ligands of the FGF family.

Fibroblast growth factor-9 modulates the expression of myelin related proteins and multiple fibroblast growth factor receptors in developing oligodendrocytes

“…These findings were consistent with reports of FGFR-2 mRNA expression in vivo (Asai et al, 1993;Miyake et al, 1996;Belluardo et al, 1997). In these studies, however, double staining procedures were not carried out to confirm expression in oligodendrocytes.…”

“…Our findings that cultured OLs expressed FGFR-1, -3, and -4 suggest that after injury or in the absence of neurons, OLs may express a wide variety of FGFRs. Several studies demonstrated that FGFR expression changed after brain or spinal cord injury (Koshinaga et al, 1993;Reilly and Kumari, 1996;Belluardo et al, 1997). These investigations, however, did not document the expression patterns of each receptor subtype in oligodendroglia.…”

Evidence for the existence of FGFR1–5-HT1A heteroreceptor complexes in the midbrain raphe 5-HT system

“…PLA technique as previously postulated [4]. These 5-HT neurons are known from previous work to express FGFR1 and to contain high amounts of 5-HT1A immunoreactivity and a high density of 5-HT1A binding sites [14][15][16]. The PLA positive clusters have a location in the cytoplasm and are also associated with the plasma membrane.…”

“…Further specificity is given from the very low density of PLA positive clusters in negative controls (only one primary antibody used) from the raphe nuclei and the selective location of the PLA positive clusters in the midbrain raphe nuclei. Also co-location of FGFR1 and 5-HT1A immunoreactivities was demonstrated in the majority of the 5-HT nerve cells within the dorsal and median raphe nuclei in line with the presence of FGFR1 mRNA levels in the midbrain 5-HT nerve cells [14].…”

Basic Fibroblast Growth Factor Enhances Transduction, Distribution, and Axonal Transport of Adeno-Associated Virus Type 2 Vector in Rat Brain

“…Coinjection of vector with heparin also significantly increased the extent of transgene expression, although to a lesser extent (2-fold). Belluardo et al provided an extensive and detailed comparative description of FGFR type 1, 2, and 3 mRNAs in the rat brain (Belluardo et al, 1997). According to this in situ hybridization analysis, however, the striatum showed no labeling for FGFR-1.…”