Expression of Basic Fibroblast Growth Factor and Its Receptor in the Rat Subfornical Organ

Abstract

Basic fibroblast growth factor (FGF), its mRNA and the mRNA that encodes for its receptor have all been localized in the rat subfornical organ (SFO). Basic FGF is widely distributed throughout the SFO; it is present in neurons, in the vascular basement membrane of lateral blood vessels (but not those within the SFO) and in ependymal cells surrounding the SFO. Results of in situ hybridization show that the expression of basic FGF mRNA is detected throughout the organ. Similarly, the expression of flg, the gene for the putative basic FGF receptor, can also be detected in the SFO. The results all support the possibility that this growth factor may modulate the known physiological functions of the SFO.

Structure of the subfornical organ: A review

“…These findings supplement and support previous observations of increased glucose metabolism in response to intravenous angiotensin II in the same region of the SFO (Kadekaro et al, 1989;Shaver et al, 1990a-c). Neurons throughout the SFO react positively for basic fibroblast growth factor (bFGF) and its receptor, a finding whose functional significance remains unknown (Frautschy et al, 1991). Other neurotransmitters and neurohormones that have been detected biochemically in the SFO (for citations, see Palkovits, 1987;Summy-Long, 1987) include acetylcholine, gamma-aminobutyric acid (GABA), noradrenaline, dopamine, histamine, serotonin, luteinizing hormone releasing hormone (LHRH), thyrotropin releasing hormone (TRH), somatostatin (SST), vasopressin (AVP), oxytocin, enkephalin, dynorphin, substance P, and motilin, but have so far escaped histochemical or immunohistochemical detection in neuronal perikarya.…”

Co-localization and regulation of basic fibroblast growth factor and arginine vasopressin in neuroendocrine cells of the rat and human brain

“…A co-localization of immunoreactive FGF2, AVP and their cognate receptors in the hypothalamus and choroid plexus epithelium [17-19] supports an hypothesized role [21] for integrating ion transport, membrane permeability and fluid balance in CNS. In peripheral tissues, the peptide trio of AVP, angiotensin II (AII) and atrial natriuretic peptide (ANP) maintain plasma volume and osmolality while FGF2 has significant hypotensive activity.…”

“…In 1991, Frautschy et al first hypothesized that FGF2 could be associated with water balance [21]. Since then, numerous studies have intimated an FGF2 involvement with hypophyseal-integrated water homeostasis [19,23,24].…”

“…But while stimuli that activate magnocellular neurons in the paraventricular (PVN) and supraoptic nucleus (SON) enhance secretion of AVP into blood and CSF [20], FGF2 function in the hypothalamo-hypophyseal system is less understood. Still, the prominent distribution of FGF2 and its receptors within SON, PVN, median eminence and neurohypophysis, as well as choroid plexus, implies a role for FGF2 in ion/water homeostasis [14,18,19,21-23]. To this end, the more recent observations intimating a functional link between FGF2 secretion and the ion-transporting Na + -K + ATPase [24,25] strongly supports involvement of FGF2 in water homeostasis.…”

SPATIAL DISTRIBUTION OF FIBROBLAST GROWTH FACTOR RECEPTOR 2 IN NORMAL AND LESIONED CENTRAL NERVOUS SYSTEM OF <I>PLEURODELES WALTLII</I>

“…However, relatively little is known about FGFR 2 distribution in the CNS. Previous studies provide conflicting evidence (Pettmann et al, 1986;Finklestein et al, 1988;Grothe et al, 1991;Yamamoto et al, 1991;Gomez-Pinilla et al, 1992;Matsuda et al, 1992;Matsuyama et al, 1992;Woodward et al, 1992;Eckenstein et al, 1994) or are limited to specific areas of the brain Frautschy et al, 1991;Matsuda et al, 1992;1993;Stock et al, 1992;Tooyama et al, 1992;Tooyama et al, 1993a;1993b;Gonzalez et al, 1994;Saarimaki-Vire et al, 2007).…”