bFGF mRNA Expression Research Articles

Basic Fibroblast Growth Factor Expression by Two Prolactin and Thyrotropin-Producing Pituitary Adenomas.

We investigated the expression of basic fibroblast growth factor (bFGF) in an aggressive type of PRL and TSH-producing pituitary adenoma. Immunocytochemistry and electron microscopy were used to characterize the tumors removed from two patients. lmmunoassays were used to measure hormone and bFGF levels in vitro and in vivo. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect bFGF mRNA expression by these tumors. Morphologically, these tumors were characterized by an unusual plurihormonal pattern with expression of PRL and TSH and the ultrastructural characteristics of the silent subtype 3 adenoma; in addition, both adenomas displayed marked interstitial fibrosis. bFGF was measurable in the circulation of these patients ranging from 7.5-20.5 pg/mL (normal < 1 pg/mL). bFGF concentrations were reduced following surgical adenomectomy. bFCF in culture media was present in concentrations of 197-387 pg/24h/10(5) cells. bFGF mRNA expression was identified in both adenomas examined. bFGF levels were unaltered in the culture media and in the serum of patients following GnRH and TRH treatment. In conclusion, the expression of bFGF by these plurihormonal pituitary adenomas suggests the possibility that it may play a role in the development of fibrosis and tumor cell proliferation of this unusual type of pituitary neoplasm.

Insulin‐like growth factor‐1 mRNA is increased in deafferented hippocampus: Spatiotemporal correspondence of a trophic event with axon sprouting

Deafferentation is known to induce axonal sprouting in adult brain, but the signals that direct this response are not understood. To evaluate the possible roles of insulin-like growth factor-1 (IGF-1) and basic fibroblast growth factor (bFGF) in central axonal sprouting, the present study used in situ hybridization to evaluate IGF-1 and bFGF mRNA expression in entorhinal deafferented rat hippocampus. Alternate tissue sections were processed for Fink-Heimer impregnation of axonal degeneration, Bandeiraea simplicifolia (BS-1) labeling of microglia, and glial fibrillary acidic protein immunocytochemistry. In control hippocampus, IGF-1 mRNA was localized to a few neurons, with no labeled cells in the dentate gyrus molecular layer; bFGF cRNA hybridization was diffuse in dendritic fields but was dense in CA2 stratum pyramidale. Both mRNA species were increased by deafferentation. The distribution of elevated IGF-1 mRNA corresponded precisely to fields of axonal degeneration and was greatest in the dentate gyrus outer molecular layer and stratum lacunosum moleculare. In these fields, IGF-1 mRNA was elevated by 2 days, reached maximal levels at 4 days, and declined by 10 days postlesion. Double labeling revealed that the majority of IGF-1 cRNA-labeled cells were microglia. In deafferented hippocampus, bFGF mRNA was broadly increased across fields both containing and lacking axonal degeneration. In the dentate, bFGF mRNA levels peaked at 5 days postlesion and remained elevated through 14 days. These results demonstrate that reactive microglia within deafferented hippocampal laminae express IGF-1 mRNA just prior to and during the period of reactive axonal growth and suggest that IGF-1 plays a role in directing the sprouting of spared afferents into these fields.

Expression of PCNA, Basic Fibroblast Growth Factor, FGF-receptor and Vascular Endothelial Growth Factor in Adenomas and Carcinomas of Human Colon.

This study was designed to clarify the role of growth factors and vascular proliferation in the growth of colon tumor. On immunohistochemical observation, the ratios of positive cells for PCNA, bFGF and VEGF in carcinomas and adenomas were higher than in non-neoplastic mucosa. On reverse transcriptasepolymerase chain reaction (RT-PCR) study, the expression of bFGF mRNA, FGF-receptor (FGFR) mRNA and VEGF mRNA was confirmed in all cases including non-neoplastic tissues, adenomas and carcinomas. On in situ hybridization, bFGF mRNA was expressed in carcinoma cells, vascular cells and fibroblastic cells, and the expression ratio of bFGF mRNA in carcinomas was higher than in non-carcinomatous mucosa. VEGF mRNA was expressed in carcinoma cells, medial smooth muscle cells and fibroblastic cells. These results suggest that bFGF and VEGF may contribute to tumor growth in association with neovascularization.

Increased expression of basic fibroblast growth factor in hyperoxic‐injured mouse lung

Basic fibroblast growth factor (bFGF) is a mitogenic polypeptide for a wide variety of cell types and has been immunolocalized in the rodent and human lung. We investigated the mRNA and protein expression of bFGF in hyperoxic-injured adult mouse lungs using northern blot analysis and immunohistochemistry. Mice (6-8 weeks) were continuously exposed to 80% oxygen up to 4 days. Levels of bFGF mRNA were increased from room air control on days 3 and 4 of hyperoxia. mRNA levels of acidic fibroblast growth factor (aFGF), fibronectin, and transin/stromelysin were also examined in this injury model. Similar to bFGF, the fibronectin and transin/stromelysin mRNA levels were increased after 3 days of hyperoxia. In contrast, the aFGF mRNA levels were gradually reduced on each day of hyperoxia. A rabbit polyclonal anti-bFGF antibody was used to determine the distribution and levels of expression in the hyperoxic-injured lungs. The room air control and day 1 hyperoxic-exposed lungs exhibited staining for bFGF in the basement membranes of the blood vessels, airways, and alveoli. Patchy but intense alveolar staining was prominent on day 4 of hyperoxia. The bFGF immunoreactivity of blood vessels and airways was unaffected by the hyperoxia exposure. These results suggest that bFGF may play a role in the alveolar response to hyperoxic-induced injury by virtue of the altered mRNA levels and protein distribution in this injury model.

Increased expression of basic fibroblast growth factor in squamous carcinogenesis of the head and neck is less prevalent following smoking cessation

Basic fibroblast growth factor (bFGF), a potent angiogenic peptide, is thought to provide a growth advantage to a number of tumors including squamous cancer of the head and neck. The purpose of this study was to demonstrate the in situ expression of bFGF in lesions of the upper aerodigestive tract (UADT) and to correlate that with clinical parameters and known risk factors for carcinoma. On surgical specimens from 52 patients, we used a colorimetric in situ hybridization assay to determine the expression of bFGF mRNA in normal and pathologic conditions commonly seen in squamous mucosa. The extent of reactivity for the bFGF transcript was recorded on a subjective scale from 1+ to 3+, based on the visual intensity of labeling. These findings were subsequently correlated with clinical data. Basic fibroblast growth factor mRNA was detected at low to moderate levels in all sections of normal mucosa, with no distinction between patients with or without squamous cancer. Inflamed mucosa had comparatively strong expression of bFGF mRNA. Among lesions implicated in the stepwise nature of squamous carcinogenesis, we found increases in bFGF expression that were most significant at the level of carcinoma in situ, persisting through the invasive and nodal metastatic stages of the disease (P < 0.005). Interestingly, those increases were significantly less frequent among former smokers (P = 0.02). We have established the expression of bFGF mRNA in normal, inflammatory, and neoplastic tissue within the UADT. Furthermore, we note for the first time that increased expression is associated with the acquisition of more aggressive biologic behavior in squamous carcinogenesis.

Interleukin-1β increases basic fibroblast growth factor mRNA expression in adult rat brain and organotypic hippocampal cultures

In situ hybridization was used to study the effect of IL-1β on acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) mRNA expression in rat brain. Intraventricular injection of recombinant human IL-1β did not affect hybridization to aFGF mRNA but did induce significant and widespread increases in hybridization to bFGF mRNA. IL-1β induced increases in bFGF mRNA were bilaterally distributed and appeared to correspond with the distribution of non-neuronal cells. Thus, hybridization was increased in regions of both gray and white matter (e.g., corpus callosum), the ependymal lining of the third ventricle, and the pia matter. In hippocampus of IL-1β injected rats, hybridization was markedly increased in the molecular layers but not significantly increased in the neuronal cell layers. Elevations in bFGF mRNA were transient, peaking at 8 h postinjection in most areas. To determine if IL-1β effects were independent of activation of the hypothalamo-pituitary-adrenal axis, and to compare the cellular localization of increases in bFGF mRNA expression induced by IL-1β and bFGF, the regulation of bFGF expression was also studied in organotypic hippocampal slice cultures. Treatment of cultures with either IL-1β or bFGF stimulated the same general distribution of increases in bFGF mRNA as seen after IL-1β treatment in vivo with an additional effect on immature neurons within the hilar side of stratum granulosum; hybridization of bFGF mRNA was not increased in association with the more mature neurons of stratum pyramidale or stratum granulosum. Colocalization of bFGF cRNA hybridization with immunostaining for glial fibrillary acidic protein demonstrated that increases in bFGF mRNA induced both by IL-1β in vivo and in vitro and by bFGF in vitro were largely associated with astroglial cells. These findings suggest that IL-1β inuction of bFGF contributes to the coactivation of these substances following various forms of insult to the CNS and initiates a cascade of trophic interactions that regulates processes of glial proliferation, neurotrophic factor expression, and neuroprotection.

Glucocorticoids and the expression of mRNAs for neurotrophins, their receptors and GAP-43 in the rat hippocampus

The genes encoding brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and basic fibroblast growth factor (bFGF) are all expressed in the adult rat hippocampus. The colocalization of the these factors with the receptors to which they bind, namely trkB, trkC and the bFGF receptor, respectively, suggests that in the hippocampus they may exert their putative protective and trophic effects through an autocrine mechanism. The morphology and survival of hippocampal neurons are also affected by glucocorticoids, which can act as transcriptional activators of gene expression. In this study we have used in situ hybridization to investigate the adrenal steroid regulation of the mRNAs encoding the neurotrophic factors BDNF, NT-3, and bFGF, their respective receptors, and the growth-associated protein GAP-43. After 7 days of adrenalectomy (ADX), there was an increase in the level of GAP-43 mRNA expression in the CA1 and CA3 pyramidal cell layers of the hippocampus, that was prevented by corticosterone replacement to the ADX animals. In the CA2 subregion, adrenalectomy resulted in a decrease in bFGF mRNA expression, that was reversed by steroid treatment. There was evidence for glucocorticoid modulation of the BDNF and NT-3 mRNAs in pyramidal cell layers and in the dentate gyrus, but not of the mRNAs encoding the trkB, trk C or bFGF receptors.

Differential regulation of acidic and basic fibroblast growth factor gene expression in fibroblast growth factor-treated rat aortic smooth muscle cells.

The acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) proteins are potent vascular smooth muscle cell (SMC) mitogens that are expressed by endothelial cells and SMCs in vivo. Overexpression of these proteins in transfected cell lines can result in autocrine transformation; therefore, the precise control of fibroblast growth factor gene expression in the vessel wall may be an important mechanism regulating vascular cell growth. In the present study, we demonstrate that bFGF can induce bFGF mRNA expression, but not aFGF mRNA expression, in serum-starved rat aortic SMCs. bFGF autoinduction is maximal at 4 hours, requires de novo RNA and protein synthesis, and is mediated predominantly by a protein kinase C-dependent signaling pathway. Furthermore, aFGF treatment of rat SMCs also increases bFGF mRNA and protein expression; however, aFGF mRNA levels are only slightly modulated. These results suggest that the local release of aFGF or bFGF within the vessel wall could promote a prolonged period of elevated bFGF synthesis. This, in turn, could be of importance in the SMC hyperplasia that occurs in response to vascular injury and during atherosclerotic plaque formation.

Transient global ischemia induces dynamic changes in the expression of bFGF and the FGF receptor

To study the roles of bFGF and its receptor in the process of neuronal cell death and the wound repair response, we induced 10 min of transient global cerebral ischemia in rats and measured changes in expression of both bFGF and the FGF receptor, flg. CA1 pyramidal cells are selectively vulnerable to ischemia and die one to 3 days after 10 min of ischemia. In these cells, bFGF mRNA was induced by 6 hours, reached a maximal level by 24 h after ischemia, and subsequently decreased. Message for the FGF receptor, flg, was present in the pyramidal cells layer, and vanished almost completely in parallel with neuronal death. In the granule cell layer of dentate gyrus, the expression of bFGF mRNA increased more rapidly. It was maximal by 6 h and returned to the basal level by 3 days. In the hilus of the dentate gyrus, bFGF expression was maximal at 24 h and returned to control levels by 3 days. Despite the rapid changes in expression of bFGF mRNA, there was no significant change of bFGF immunoreactivity in either the CA1 pyramidal cell layer or in the granule cell layer of dentate gyrus within 3 days after ischemia. The apparent failure of the message to be efficiently translated supports the idea that translation is impaired under conditions where ischemia leads to delayed neuronal cell death. Expression of bFGF mRNA, FGFR mRNA and bFGF immunoreactivity increased dramatically in a broad area of CA1 subfield from 7 days until 30 days after ischemia because of increased expression by reactive glial cells. We suggest that these rapid and complex changes in the expression of bFGF mRNA and bFGF protein may be part of a coordinated response to ischemic injury that is designed to minimize the severity of neuron death.

Expression and regulation of basic fibroblast growth factor mRNA levels in mouse osteoblastic MC3T3-E1 cells.

Basic fibroblast growth factor (bFGF) is a potent mitogen for bone cells and is a constituent of the bone matrix. We have found that osteoblastic MC3T3-E1 cells expressed bFGF mRNA transcript of 4.5 kilobases (kb). We examined factors that regulate the expression of bFGF mRNA and protein in MC3T3-E1 cells. Treatment of MC3T3-E1 cells with bFGF (10 nM) for 4-48 h induced another 7-kb bFGF transcript at 4 h. Treatment of MC3T3-E1 cells with TGF beta (10 ng/ml) also induced the 7-kb transcript of bFGF mRNA. In contrast, heparin, parathyroid hormone, and interleukin-1 had no effect on bFGF mRNA. Western blot analyses revealed that MC3T3-E1 cells produced a 24-kDa bFGF protein, which was increased by TGF beta. Immunofluorescence showed that bFGF protein was localized to the cytoplasm in serum-deprived MC3T3-E1 cells. Treatment of these cultures with medium containing fetal calf serum or TGF beta caused increased cytoplasmic staining for bFGF and marked shape change. Furthermore, in the cells treated with TGF beta there was both nuclear and cytoplasmic staining for the protein. These data demonstrate that bFGF mRNA and protein are expressed in osteoblastic cells and are regulated by treatment with TGF beta and bFGF. Production of bFGF may be important as an autocrine and paracrine mediator of bone cell replication, differentiation, and function.

Increased basic fibroblast growth factor mRNA following contusive spinal cord injury

Neurotrophic factors appear to be crucial for the survival and potential regeneration of injured neurons. Injury of the peripheral nervous system results in the induction of a number of neurotrophic molecules. Less is known about the response of central nervous tissue to injury. We have examined changes in levels of mRNA for three trophic factors, basic and acidic fibroblast growth factor (bFGF, aFGF), and nerve growth factor (NGF), after a standardized incomplete thoracic contusive spinal cord injury (SCI). RNase protection assays showed a rapid increase (3-fold) in the content of bFGF mRNA by 6 hours after SCI in tissue that included the injury site. No effect of injury was seen in segments of cervical or lumbar cord. bFGF mRNA at the injury site remained significantly increased at 1 and 7 days after SCI. Further, at 7 days, the increase was anatomically restricted to the rostral portion of the injury site suggesting the involvement of specific pathways in the maintenance of high levels of bFGF mRNA. No change in the levels of aFGF mRNA was seen after SCI. Similarly, no difference in the expression of the mRNA for NGF or its high affinity receptor ( trkA), were observed at 6 h, 1 or 7 days following SCI. Our observation of a specific effect of SCI on bFGF mRNA expression supports a speculative hypothesis that bFGF may play a role in the partial recovery of function seen following incomplete contusive spinal cord injury.

Seizures increase basic fibroblast growth factor mRNA in adult rat forebrain neurons and glia

The distribution of basic fibroblast growth factor (bFGF) mRNA in normal rat forebrain, and the influence of recurrent seizure activity on the expression of this mRNA, was evaluated using in situ hybridization and S1 nuclease protection techniques. In the untreated adult rat, hybridization of 35S-labeled bFGF cRNA densely labeled neurons in a few discrete areas including the tenia tecta, indusium gresium, and hippocampal stratum pyramidale of regions CA2 and rostromedial CA1. Neurons in the prosubiculum and rostromedial dentate gyrus stratum granulosum were lightly labeled. In addition, a diffuse distribution of autoradiographic labeling in areas such as the hippocampal molecular layers, olfactory cortical layer I, and the olfactory nerve layer was suggestive of localization in glial cells. Platinumwire hilar lesions, which did not induce seizures, increased cRNA hybridization in glial cells in primary and secondary areas of degeneration in the ipsilateral hemisphere only; hybridization was not noticeably increased in neurons in these lesion-control rats. Focal stainless-steelwire hilar lesions, which caused recurrent seizures 2–10 h postlesion, induced bilaterally distributed increases in cRNA hybridization in hippocampus, neocortex, olfactory cortex, amygdala, and septum. These seizure-dependent increases in hybridization were evident 6 h postlesion, were maximal from 12 to 24 h postlesion, and declined to near control levels by 4 days. In most regions the elevated hybridization appeared to be associated primarily with astroglia but in experimental seizure rats sacrificed 12 and 24 h postlesion hybridization was also markedly increased in the dentate gyrus granule cells and olfactory cortical neurons. These results demonstrate that recurrent seizures increase bFGF mRNA expression by both forebrain neurons and glia and implicate bFGF in the coordination of other changes in the biosynthetic activities of forebrain neurons that occur after seizures.

Studies on growth of brown adipose tissue by means of cell culture and angiogenesis in vitro techniques

To elucidate the mechanism of brown adipose tissue (BAT) enlargement, we investigated the effects of norepinephrine (NE) and insulin on the in vitro growth of rat brown adipose cells (RBAC) and the capillary growth in angiogenesis in vitro using co-culture of bovine capillary endothelial cells (BCEC) and rat smooth muscle cells. In the primary cell culture, NE significantly enhanced the growth of RBAC in the range of 10(-9)-10(-5)M, whereas it did not stimulate the growth of BCEC. Insulin showed the same trend. Moreover, both NE and insulin appeared to increase the expression of mRNA for basic fibroblast growth factor (bFGF), which is a potent angiogenic factor, in RBAC. At 4 h after NE stimulation, the bFGF mRNA expression was considerably increased but it decreased markedly after 16 h. These results suggest that the bFGF mRNA expression in RBAC is quickly simulated by NE, wih resulting bFGF production. Actually, bFGF stimulated the RBAC growth up to about 170% of the control level. However, neither NE nor insulin stimulated the expression of the bFGF gene in BCEC. On the other hand, NE notably increased the capillary growth in vitro compared with insulin. It is thus possible that NE and insulin contribute to the growth of RBAC and endothelial cells partly through bFGF production by an autocrine mechanism, suggesting that both agonists play an important role not only in the thermogenic function of BAT but also in BAT enlargement.

Expression of basic fibroblast growth factor in synovial tissues from patients with rheumatoid arthritis: detection by immunohistological staining and in situ hybridisation.

The distribution and production of basic fibroblast growth factor (bFGF) was examined on the synovium from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). The localisation of bFGF was determined by an immunohistochemical staining procedure using anti-bFGF monoclonal antibody. The expression of bFGF mRNA was detected by nonradioactive in situ hybridisation using bFGF antisense oligo DNA. The bFGF was found in the synovial lining cell, sublining stromal fibroblast-like cells, and vascular endothelial cells from patients with RA and OA. Little or no bFGF was found in non-inflamed synovium. Immunostaining of bFGF in the synovial cells was more extensive and intense in synovium of patients with RA than that of patients with OA. The nuclei of the synovial lining cell layer were also immunostained. These nuclear staining were more intense in the lining cell layer from RA patients with moderate or severe proliferation of synovial cells than in RA patients with mild proliferation. The bFGF mRNA was also detected in the synovial lining cell layer of the inflamed synovium. The synovial lining cells produced bFGF. The proliferation of synovial cells in the inflamed joints may be the results of stimulation by the bFGF in autocrine manner.

Localization of mRNA for basic fibroblast growth factor in human placenta.

The site of basic fibroblast growth factor (bFGF) gene expression in human placenta is not known. In situ hybridization using [35S]-labelled riboprobe was employed to localize the sites of expression of bFGF mRNA in placental sections from early and late gestation. Autoradiographic hybridization signal was present in all placental tissue examined, with no significant hybridization with sense control. Basic FGF expression was seen in the syncytiotrophoblast surrounding the placental villi and in or around cytotrophoblast cells in first trimester placenta. At term, the bFGF gene expression was detected in the syncytiotrophoblast and fetal membranes. Strong expression of bFGF mRNA was localized in the smooth muscle cells around the mid and large sized placental vessels. The detection of bFGF mRNA in the placenta during early pregnancy suggests a role for bFGF in angiogenesis, whereas, its expression at term suggests that bFGF may be associated with differentiated functions of the trophoblast.

Basic fibroblast growth factor messenger RNA is expressed strongly at the acute stage of cerebral contusion

Basic fibroblast growth factor (bFGF) has a neurotrophic effect both in vitro and in vivo, and is considered to play an important role in the maintenance of neuronal functions in the normal brain. Neural damage in brain contusion progresses after the primary injury of trauma because of cerebral hemodynamic and metabolic impairment including intracranial hemorrhage and/or brain swelling. Northern blot analysis of bFGF mRNA was performed in rats after cerebral contusion produced by our modified fluid percussion device. Expression of bFGF mRNA increased significantly on the second day after trauma. A possible role of bFGF is functioning to protect the critical neurons from secondary neural damage in cerebral contusion.

Expression of messenger ribonucleic acids encoding for basic fibroblast growth factor (FGF) and alternatively spliced FGF receptor in human fetal ovary and uterus.

Basic fibroblast growth factor (bFGF) is an angiogenic and mitogenic peptide that may have modulatory effects in the adult ovary and uterus. The FGF receptor is a tyrosine kinase and has similar affinity for both acidic FGF and bFGF. The ligand-binding portion of the receptor has three immunoglobulin-like domains. bFGF and the FGF receptor have been localized in the fetal rat ovary and Mullerian duct. bFGF is a proliferative agent recently shown to be vital for long term cultures of mouse fetal primordial germ cells. Expression of bFGF and FGF receptor mRNA have not heretofore been reported in human fetal ovary and uterus. We prepared RNA from whole human fetal ovaries and uteri at 10, 15, 19, and 22 weeks gestation. After reverse transcription of the RNA into cDNA, we used polymerase chain reaction (PCR) primers directed to specific portions of bFGF and the FGF receptor and performed PCR amplification using the fetal cDNA. We found mRNA expression of bFGF and two forms of FGF receptor in all fetal ovaries and uteri at these developmental stages. One of the PCR products for the FGF receptor was the sequence that contained three immunoglobulin-like domains, whereas a second PCR-amplified fragment was consistent with a FGF receptor mRNA that has a 267-basepair deletion in the first immunoglobulin-like loop. We conclude that bFGF and two forms of the FGF receptor mRNA are expressed in human fetal ovary and uterus. The finding that both bFGF and the FGF receptor are concurrently expressed suggests that bFGF may serve as an autocrine or paracrine modulator during early development of the human reproductive tract.

Photochemically induced focal cerebral ischemia in rat: time dependent and global increase in expression of basic fibroblast growth factor mRNA

Induction of basic fibroblast growth factor (bFGF) mRNA expression was studied in a Rose bengal induced focal cerebral ischemia during a time course of 2, 4, 24, 72 h and 7 days. Focal cerebral ischemia induced by Rose bengal resulted in a global upregulation in bFGF gene expression at the 24 h time-interval. This upregulation in bFGF gene expression was due to an upregulation in glial bFGF expression in most of the areas studied as seen by means of non-radioactive in situ hybridization in combination with immunocytochemistry for glial fibrillary acidic protein. However, in the piriform cortex a putative neuronal upregulation of bFGF could be detected by combination of non-radioactive in situ hybridization, immunohistochemistry for glial fibrillary acidic protein and nuclear staining with Neutral red. Semiquantitative data concerning bFGF mRNA expression were obtained by use of computer-assisted microdensitometry and revealed substantial increases in bFGF mRNA expression in the cingulate cortex, the neostriatum, a 1 mm marginal zone close to the external capsule and the olfactory tubercle at bregma levels 1 to 2 mm rostral to the lesion. No changes in bFGF gene expression were seen in field CA1 of Ammon's horn on the lesioned side and in dentate gyrus at bregma levels between −2.12 to −3.30 mm. We observed significant changes in bFGF upregulation in the caudate putamen, the piriform cortex and the amygdaloid region and the frontoparietal cortex at bregma levels −2.12 to −3.30 mm. These data indicate that photochemically induced focal cerebral ischemia leads to an early and global response in bFGF gene expression, which is due to an upregulation mainly in astrocytes. The observed widespread upregulation of the bFGF gene transcription rostral and caudal to the lesion is suggested to be due in part to neuronal glutaminergic connections between the areas investigated and in part due to increases in extracellular fluid signals (volume transmission).

Basic fibroblast growth factor-like immunoreactivity in the rat trigeminal sensory system and peri-oral skin with vibrissae

We have characterized an antiserum against basic fibroblast growth factor (bFGF) by immunoblot, investigated the location of bFGF-like immunoreactivity (bFGF-IR) in the trigeminal sensory system and perioral skin endowed with vibrissae, and demonstrated the site of bFGF mRNA expression in the vibrissae by in situ hybridization histochemistry. Light-microscopic immunohistochemistry has demonstrated that bFGF-IR is present not only in trigeminal ganglion neurons and their central and peripheral processes, but also in cells of the matrix, external root sheath and papillae of vibrissae and the stratum basale of the stratified squamous epithelium of the skin. Electron microscopy has revealed intense bFGF-IR mainly in cytoplasmic regions, other than the lumen of rough endoplasmic reticulum and the Golgi apparatus, in trigeminal ganglion neurons, in fibroblast-like cells in the papillae, and in capsules of vibrissae. In contrast, actively proliferating and/or differentiating cells in the matrix of vibrissae have intensely stained euchromatin and weakly labeled cytoplasm that, unlike that of the aforementioned cells, contain immunoreaction products in discrete spots less than 100 nm in diameter, implying the generation of different molecular forms of bFGF in cells of the matrix and papillae. Moreover, the accumulation of bFGF in the euchromatin appears to take place in cells at non-mitotic stages (possibly interphases), characterized by a conspicuous nucleolus and well-developed nuclear envelope. A digoxigenin-labeled cRNA probe for the demonstration of bFGF mRNA gives conspicuous hybridization signals mainly in the matrix of vibrissae. These findings suggest that bFGF is involved in the growth and differentiation of matrix cells during certain periods of the cell cycle and that it acts as a non-mitogenic mediator in the adult trigeminal sensory system.

Localization with a Digoxigenin-Labeled cRNA Probe of Basic Fibroblast Growth Factor mRNA in Dystrophic (mdx) Mouse Masseter Muscle and Rat Hair Follicles.

In situ hybridization histochemistry with the use of a digoxigenin-labeled ribonucleotide probe for basic fibroblast growth factor (bFGF) mRNA demonstrated bFGF transcripts in the masseter muscle of dystrophic (mdx) mouse and in vibrissae and small hair follicle of the rat peri-oral skin. A conspicuous hybridization signal was detected in the central part of the cytoplasm of the smallest myoblasts in the process of initial regeneration or differentiation. bFGF mRNA staining decreased in intensity as the myoblasts increased in size due to the production of myofilaments. Endomysial fibroblasts and extracellular matrix did not exhibit any detectable bFGF mRNA expression. In transverse sections of the hair follicles and vibrissae, a bFGF mRNA positive reaction was noted in the central portion of individual follicles, which were endowed with a non-hybridized core of variable diameter. The hybridization signal in longituidinal sections of hair follicles was localized mainly to keratinizing hair cortical cells; the matrix was scarcely labeled with the probe. The dermal papillae of hair follicles were devoid of bFGF mRNA staining. These findings suggest that early regenerating or differentiating myoblasts produce bFGF, rather than internalizing the growth factor originating in other tissues and that part of bFGF generated in the hair cortical cells is conveyed to the hair matrix and external root sheath which has been shown, by immunohistochemistry, to contain bFGF-like substances.