Fibroblast growth factor in the hypothalamic-pituitary axis: differential expression of fibroblast growth factor-2 and a high affinity receptor.
In situ hybridization and immunohistochemistry were used to map gene expression and protein distribution of basic fibroblast growth factor (FGF-2) in the hypothalamic-pituitary system. Although the expression of FGF-2 mRNA in the pituitary is low, the protein is widely distributed in both its neural and anterior lobes. In the anterior lobe, immunoreactive (ir-) FGF-2 localizes to basement membranes and select endocrine cells. In the neural lobe, ir-FGF-2 is detected in basement membranes, pituicytes, and Herring bodies. Analyses of FGF high affinity receptor (FGFR) immunoreactivity in the anterior pituitary establishes a distribution of FGFR similar to that of FGF-2. In the neural lobe, ir-FGFR is associated with nerve fibers, pituicytes, and Herring bodies. Unlike FGF-2, the distribution of FGFR1 mRNA correlates well with the presence of the immunoreactive receptor. In the hypothalamus, magnocellular neurons of paraventricular and supraoptic nuclei contain ir-FGF-2 and ir-FGFR. In the median eminence, ir-FGF-2 and ir-FGFR is associated with fibers, glial, and endothelial cells. Ependymal and subependymal cells lining the third ventricle also show high levels of ir-FGF-2 and ir-FGFR and mRNAs. Overall, there is a specific and selective distribution of FGF-2 and its high affinity receptor(s) in the hypothalamo-pituitary axis. This localization lead us to postulate a role in neurohypophyseal functions, possibly water balance.
Gonzalez
A M
AM
Department of Molecular and Cellular Growth Biology, Whittier Institute for Diabetes and Endocrinology, La Jolla, California 92037.
Logan
A
A
Ying
W
W
Lappi
D A
DA
Berry
M
M
Baird
A
A
D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D016222:Fibroblast Growth Factor 2 / Q000032:analysis / Q000235:genetics*; D015870:Gene Expression; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D010902:Pituitary Gland / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D010903:Pituitary Gland, Anterior / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017468:Receptors, Fibroblast Growth Factor / Q000032:analysis / Q000235:genetics*; D014018:Tissue Distribution
D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D016222:Fibroblast Growth Factor 2