Cochlear ablation alters acoustically induced c-fos mRNA expression in the adult rat auditory brainstem

Expression of c-fos mRNA was studied in the adult rat brain following cochlear ablations by using in situ hybridization. In normal animals, expression was produced by acoustic stimulation and was found to be tonotopically distributed in many auditory nuclei. Following unilateral cochlear ablation, acoustically driven expression was eliminated or decreased in areas normally activated by the ablated ear, e.g., the ipsilateral dorsal and ventral cochlear nuclei, dorsal periolivary nuclei, and lateral nucleus of the trapezoid body and the contralateral medial and ventral nuclei of the trapezoid body, lateral lemniscal nuclei, and inferior colliculus. These deficits did not recover, even after long survivals up to 6 months. Results also indicated that neurons in the dorsal cochlear nucleus could be activated by contralateral stimulation in the absence of ipsilateral cochlear input and that the influence of the contralateral ear was tonotopically organized. Results also indicated that c-fos expression rose rapidly and persisted for up to 6 months in neurons in the rostral part of the contralateral medial nucleus of the trapezoid body following a cochlear ablation, even in the absence of acoustic stimulation. This response may reflect a release of constitutive excitatory inputs normally suppressed by missing afferent input or changes in homeostatic gene expression related to sensory deprivation. Instances of transient, surgery-dependent increases in c-fos mRNA expression in the absence of acoustic stimulation were observed in the superficial dorsal cochlear nucleus and the cochlear nerve root on the ablated side.     

A comparison of delta 9-THC and anandamide induced c-fos expression in the rat forebrain

Early studies have shown mitochondrially-mediated oxidative phosphorylation is diminished in cancer cells, with glycolysis being the main source of energy production. More recent provocative reports have indicated that the mitochondria may be involved in a host of different aspects of tumorigenesis, including mutagenesis, maintenance of the malignant phenotype, and control of apoptosis. These studies have broadened the possible roles mitochondria may play in malignancy. Further studies to define the importance of mitochondria should revolve around the functional assessment of these changes in vitro and in vivo, and will be interesting for determining their significance in human cancer.     

c-fos expression in hypothalamic neurosecretory and brainstem catecholamine cells following noxious somatic stimuli

Noxious somatic stimuli elicit vasopressin secretion, an effect thought to result from activation of a facilitatory input from A1 catecholamine cells of the medulla oblongata. To better characterize the A1 cell response and effects on other neuroendocrine A1 projection targets, particularly within the paraventricular nucleus, we have now mapped c-fos expression in neurochemically identified catecholamine and neurosecretory cells following a noxious somatic stimulus. Unilateral hind paw pinch significantly increased c-fos expression in contralateral A1 cells whereas other brainstem catecholamine cell groups were unaffected. Expression of c-fos was also increased in the supraoptic nucleus, this effect being more pronounced for vasopressin than oxytocin neurosecretory cells and, as with A1 cells, primarily on the side contralateral to the stimulated paw. In contrast, the increase in the paraventricular nucleus was greater in oxytocin rather than in vasopressin cells. Additionally there was a significant rise in c-fos expression in medial parvocellular paraventricular nucleus cells of noxiously stimulated animals. Notably, the majority of tuberoinfundibular corticotropin-releasing factor cells are located in this medial parvocellular zone. These results are consistent with and expand on those previously reported from electrophysiological and anatomical studies. The finding of differing neurosecretory cell responses between supraoptic and paraventricular nuclei has interesting implications with regard to the afferent control of neurosecretory cell activity. For example, the substantially greater activation of supraoptic versus paraventricular nucleus vasopressin cells, despite being innervated by the same medullary noradrenergic cell group, raises the possibility of a differential input or differences in responsiveness. Furthermore, the activation of paraventricular nucleus parvocellular cells is consistent with suggestions that the A1 cell group provides an excitatory input to this population.     

Cocaine-induced expression of striatal c-fos in the rat is inhibited by NMDA receptor antagonists

To assess the possible involvement of NMDA receptors in mediating the expression of striatal c-fos by cocaine injection, we investigated the effects of the noncompetitive NMDA receptor antagonists, ketamine and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801), as well as the competitive NMDA receptor antagonist, 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), in the perikarya of cocaine-treated rat brains. As previously shown by our group, administration of 20 mg/kg cocaine (IP) resulted in the immunocytochemical expression of the protooncogene in numerous cells of the caudate putamen (dorsal/sensorimotor striatum). A ketamine mixture anesthetic (2 mg/kg), however, administered 30 min prior to cocaine exposure completely blocked such genomic expression. Pretreatment with MK-801 (1 mg/kg) or CPP (5 mg/kg) also interfered, albeit to a lesser extent, with the expression of c-fos by cocaine in awake animals. These results indicate that cocaine induction of cellular c-fos in the caudate putamen is mediated at least in part by NMDA-sensitive receptors.     

Systemic interleukin-1 induces early and late patterns of c-fos mRNA expression in brain

This study was designed to examine the mechanisms by which systemic interleukin-1 affects neuroendocrine systems in the brain. Intraperitoneal injections of interleukin-1 beta (1.25 micrograms/rat) were administered to rats. One or three hours after injection, the expression levels of the immediate-early gene c-fos and of genes for several neuropeptides, receptors, and enzymes were examined by in situ hybridization histochemistry. In the brainstem at 1 hr, c-fos mRNA was elevated in the area postrema and nucleus of the solitary tract, but not in the locus coeruleus. At 3 hr, the c-fos mRNA levels had increased further in the nucleus of the solitary tract. Rostrally, elevations in c-fos mRNA levels were found in the hypothalamic and thalamic paraventricular nuclei, central nucleus of amygdala, bed nucleus of the stria terminalis, and medial preoptic area, peaking at 1 hr and diminishing at 3 hr. In addition, at 3 hr a new pattern of c-fos activity emerged--the arcuate nucleus and cells at the external margins throughout the brain now expressed c-fos mRNA. Corticotropin-releasing hormone mRNA levels were doubled in the paraventricular nucleus at 1 and 3 hr, concomitant with elevations in plasma adrenocorticotrophic hormone (ACTH) and corticosterone. Tyrosine hydroxylase mRNA levels in the brainstem did not change. The c-fos mRNA induction patterns reveal a temporally dynamic response to interleukin-1 administration. We propose that the early set of structures responding to interleukin-1 initiates the neuroendocrine response to cytokines. Coactivation of the area postrema and nucleus of the solitary tract may reflect entry into the brain and neural transduction of the peripheral signal. The late set--including the nucleus of the solitary tract, arcuate nucleus, and the brain's edge--may reflect cellular activation along the diffusion routes traveled by interleukin-1 or a bioactive transduction product, because the pattern of edge labeling is similar to the autoradiographic pattern of flow lf radiolabeled tracer substances in the cerebrospinal fluid. The late c-fos mRNA response to interleukin-1, therefore, may represent a demonstration of information transfer in the parasynaptic mode, also known as volume transmission.     

Cholecystokinin- and dexfenfluramine-induced anorexia compared using devazepide and c-fos expression in the rat brain

It has been proposed that there might be a link between the anorectic actions of cholecystokinin (CCK) and serotonin (5HT). The present study compared the patterns of c-fos protein-like immunoreactivity (FLI) induced in rat brain by CCK and the indirect 5HT agonist dexfenfluramine (DFEN), as well as the ability for devazepide, a CCK-A receptor antagonist, to antagonize both anorexia and FLI induced by these agents. Devazepide reversed the anorectic effect of CCK but not that of DFEN in food deprived rats. The FLI induced by CCK and DFEN occurred in similar brain regions, but in different subdivisions. Such regions included the bed nucleus of the stria terminalis (BST), the lateral central nucleus of the amygdala (CeL), and the lateral parabrachial nucleus (LPB). Devazepide abolished the FLI induced by CCK in most of these brain regions, but had no effect on FLI induced by DFEN. These results suggest that the LPB-CeL/BST pathway might be responsible for the anorectic effects of both CCK and DFEN, but different parts or neuronal populations in these structures might be differentially engaged by CCK and DFEN. The putative interaction between CCK and 5HT might happen along this pathway, rather than in the periphery.     

The effect of adrenalectomy on stress-induced c-fos mRNA expression in the rat brain

Hydrophilic-interaction liquid chromatography (HILIC) has recently been introduced as a highly efficient chromatographic technique for the separation of a wide range of solutes. The present work was performed with the aim of evaluating the potential utility of HILIC for the separation of postranslationally acetylated histones. The protein fractionations were generally achieved by using a weak cation-exchange column and an increasing sodium perchlorate gradient system in the presence of acetonitrile (70%, v/v) at pH 3.0. In combination with reversed-phase high-performance liquid chromatography (RP-HPLC) we have successfully separated various H2A variants and posttranslationally acetylated forms of H2A variants and H4 proteins in very pure form. An unambiguous assignment of the histone fractions obtained was performed using high-performance capillary and acid-urea-Triton gel electrophoresis. Our results demonstrate that for the analysis and isolation of modified core histone variants HILIC provides a new and important alternative to traditional separation techniques and will be useful in studying the biological function of histone acetylation.     

Oral-motor patterns of rhythmic trigeminal activity generated in fetal rat brainstem in vitro

Development of neural circuits generating fetal oral-motor activity was characterized in an in vitro isolated brainstem block preparation. Rhythmical trigeminal activity (RTA) at E20-E21 resembled either the pattern or rhythm of neonatal RTA. Conversely, at E18-E19, RTA displayed a different pattern of discharge from neonatal RTA, and output was not regular but intermittent with another slow rhythm.     

Norepinephrine induces expression of c-fos mRNA through the alpha-adrenoceptor in rat aortic rings

We examined whether norepinephrine at pharmacologically relevant doses induces increased expression of c-fos mRNA in rat aortic rings. c-fos mRNA was expressed at norepinephrine concentrations known to cause minimum and maximum contraction of rat aorta in vitro. At the concentration known to cause maximum contraction, norepinephrine produced a marked and sustained increase of c-fos mRNA expression. Induction of c-fos was blocked completely by the alpha 1-adrenergic antagonist prazosin, partially by the alpha 2-adrenergic antagonist yohimbine, and not at all by the beta-adrenergic antagonist propranolol. A prazosin inhibition curve showed that 1 nmol/L prazosin inhibited 10 micromol/L norepinephrine induced c-fos expression by 40%. At the pharmacologic dose known to cause maximum contraction, norepinephrine induces c-fos mRNA expression through the alpha-adrenoceptor in rat aortic rings.     

Control of expression of differentiated functions in neuroblastoma cell hybrids

Cell hybrids have been extensively utilized for gene mapping; more than 50 enzymes and nonenzyme proteins have been assigned to individual human chromosomes. Hybrids have also been used in the study of differentiation; fusions involving mouse or human neuroblastoma cells and various nonneuronal lines resulted in hybrid cells that continued to express neuronspecific functions. The expression of the differentiated state is, however, not an all-or-none phenomenon: One neuronal trait may be evident in such hybrids, in the absence of others. The potential usefulness of the human neuroblastoma hybrids for the assignment of genes involved in the expression of differentiated functions to specific chromosomes is discussed.     

Psychomotor stimulant- and opiate-induced c-fos mRNA expression patterns in the rat forebrain: comparisons between acute drug treatment and a drug challenge in sensitized animals

Amphetamine-, cocaine-, and morphine-induced c-fos expression patterns were examined following an injection protocol that has previously been shown to produce behavioral sensitization and enhanced dopamine release in the striatal complex. Drug-specific c-fos patterns were observed in both acute and sensitization injection paradigms. A sensitization pretreatment schedule did, however, alter the c-fos expression patterns induced by all the drugs in the caudate putamen, nucleus accumbens, and the cerebral cortex. In some striatal and cortical regions, there was an increase or recruitment of cells expressing c-fos whereas in others there was an apparent decrease or inhibition. The somatosensory cortex was one area where pretreatment with all three drugs increased c-fos expression. The results suggest that the neuronal networks that are modulated by systemic drug injections in the sensitized animal differ from those affected by the initial drug exposure; areas of overlap may indicate common "sensitization' circuits.     

Clonal patterns of cell proliferation, migration, and dispersal in the brainstem of the chicken embryo

Retroviral-mediated gene transfer was used to study clonal patterns of proliferation, migration, and dispersal in the brainstem of the chicken embryo. Clones were generated at stages 13-17 (Hamburger and Hamilton, 1951), a period of neurogenesis in the brainstem neural tube subsequent to the formation of rhombomeres. Clones were examined in separate experiments at stages 24-27, when many neurons migrate and differentiate; at stages 28-29, when brainstem nuclei begin to form; and at stages 34-35, when brainstem nuclei are fully formed. Stages 24-29 are characterized by a general variability in proliferative kinetics and migratory behavior. Clone sizes range from 1 to 29 cells, and migration patterns range from strictly radial (i.e., normal to the ventricular surface) to combined radial and tangential (i.e., perpendicular to the radial component). There is, however, an underlying systematic variation: (1) clones exhibiting tangential migration contain on average more cells than clones exhibiting only radial migration, and (2) the proportion of tangentially migrating clones increases from medial to lateral. By stages 34-35 some individual clones have apparently dispersed to disparate neuronal groups. The regional diversity observed among clones suggests that position along the mediolateral axis may determine the proliferative potential of progenitors and the migratory behavior and subsequent dispersal of their descendants.     

Increased intraluminal pressure induces DNA synthesis and c-fos expression in perfused rat aorta

The metabolic syndrome is a well-known risk for the development of cardiovascular disease. In the present study the possible importance of an altered visceral adipocyte beta-adrenoceptor function in this syndrome was investigated. In 65 subjects of both sexes undergoing elective surgery for non-malignant disorders, the metabolic syndrome phenotype and the lipolytic sensitivity for various beta-adrenoceptor subtype agonists in omental adipocytes were determined. The study group represented a wide range of abdominal adipose tissue distribution (waist-to-hip ratios 0.76-1.13), but was otherwise apparently healthy. The subjects were divided into three subgroups according to their waist-to-hip (WHR) ratios: 1) WHR < 0.92; 2) WHR 0.92-1.04; 3) WHR > 1.04. The subgroups demonstrated significant differences regarding body mass index, sagittal diameter, systolic and diastolic blood pressures, plasma concentrations of glucose, insulin, triglycerides and HDL-cholesterol (p = 0.005-0.0001). Furthermore, in omental adipocytes beta 3-adrenoceptor sensitivity, but not beta 1-and beta 2-adrenoceptor sensitivities, differed significantly between the WHR subgroups (p = 0.0001). beta 3-adrenoceptor sensitivity was also related to the other components of the metabolic syndrome, although a strong covariation between WHR and beta 3-adrenoceptor sensitivity vs blood pressure and the metabolic parameters was found. The present data provide evidence of a relationship between upperbody obesity and its associated metabolic complications and also, an increased visceral fat beta 3-adrenoceptor sensitivity. We suggest that the latter finding results in an augmented release of non-esterified fatty acids from the visceral fat depot to the portal venous system. This may in turn contribute to the development of the metabolic syndrome.     

Temporal expression of c-fos mRNA following balloon injury in the rat common carotid artery

OBJECTIVE: Restenosis is a common problem which limits the effectiveness of percutaneous transluminal coronary angioplasty (PTCA). The cellular mechanisms of restenosis appear to involve smooth muscle cell (SMC) migration to the neointima in response to mitogens and growth factors, resulting in proliferation and deposition of cells in the lumen of the vessel. An antibody directed against PDGF attenuates this response in the rat. Thus, signaling cascades induced by growth factors including PDGF may be important targets for therapeutic intervention. METHODS: Since a number of growth factors activate c-fos via the p21-ras signaling pathway, we examined c-fos expression in a time course experiment involving restenotic lesions in rat carotid arteries. Sections of arteries collected at 1, 3, 7, 14 and 28 days following balloon injury were hybridized using a fluorescein-labeled RNA probe to c-fos. Immunohistochemistry was performed with antibodies to proliferating cell nuclear antigen (PCNA) and alpha-smc actin to characterize cellular constituents of the neointima, and detect any correlation between fos expression and PCNA localization. RESULTS: Expression of c-fos was low at day 1. By day 3, the media and adventitia were positively stained. At days 7 and 14, most cells in the neointima were labeled. By day 28, c-fos was expressed mainly in scattered cells along the luminal surface. Control sections revealed little labeling and confirmed specific staining by the antisense strand, PCNA localization and c-fos expression were similar at days 1, 3, 7 and 28, but at day 14 c-fos was expressed throughout the lesion, with PCNA localized mainly along the luminal edge. The majority of the cells making up the neointima stained rather intensely for alpha-smc actin, identifying them as SMCs. CONCLUSIONS: Results of these experiments indicate that, while c-fos expression correlates with lesion formation, it may be associated with a cellular process distinct from proliferation in this model.     

cAMP-mediated c-fos expression in pressure-overloaded acceleration of protein synthesis in adult rat heart

This study was carried out to investigate the amplification of HER-2/neu oncogene in 66 patients with primary breast cancer and 90 samples from benign breast disease (BBD). The amplification of HER-2/neu oncogene in the DNA of paraffin-embedded specimens was determined by differential PCR. Nineteen out of 66 (28.8%) breast cancer patients showed amplification of the gene. No gene amplification was found in benign breast disease. There was no significant correlation of HER-2/neu amplification with, age, menopausal status, the number of positive nodes, tumor size, estrogen receptor, however, amplification of HER-2/neu gene was strongly correlated with nodal status (p = 0.0049). In node positive patients, the incidence of HER-2/neu amplification was high (43%). These findings indicate that the amplification of HER-2/neu gene may be of pathogenetic significance in breast cancer and may have a poor prognosis in node positive breast cancer patients while no gene amplification in benign breast disease suggests that HER-2/neu amplification is a late molecular alteration event in the pathogenesis of breast cancer.     

Effects of MK801 on Fos expression in the rat brainstem after unilateral labyrinthectomy

Unilateral labyrinthectomy (UL) causes ocular and postural asymmetries, which disappear over time in the processes of equilibrium recovery known as vestibular compensation. It has been reported that N-methyl-D-aspartate (NMDA) receptors are involved in vestibular compensation. In the present study, in order to elucidate the NMDA receptor-mediated neural circuit responsible for the development of vestibular compensation, we used Fos expression as a marker of neural activation and examined the effects of MK801, a specific antagonist of NMDA receptors, on UL-induced Fos expression in the rat brainstem. After UL, Fos-like immunoreactive (-LIR) neurons were observed in the ipsilateral medial vestibular nucleus (ipsi-MVe), the contralateral prepositus hypoglossal nucleus (contra-PrH) and the contralateral inferior olive beta subnucleus (contra-IOb). Fos-LIR neurons gradually disappeared in the processes of vestibular compensation. It is suggested that the activation of the ipsi-MVe, the contra-PrH and the contra-IOb neurons after UL are the initial event of vestibular compensation. Intraperitoneal injection of MK801 in the processes of vestibular compensation caused reappearance of UL-induced behavioral deficits. During the decompensation induced by MK801, Fos-LIR neurons appeared in the contra-MVe, the ipsi-PrH and the bilateral-IOB. It is suggested that the contra-MVe, the ipsi-PrH and the bilateral-IOb neurons are inhibited by glutamatergic synapses driving inhibitory neurons via NMDA receptors in the processes of vestibular compensation and that disinhibition of these nuclei induced by MK801 causes decompensation. However, MK801 caused neither Fos expression nor behavioral decompensation after vestibular compensation is accomplished. All these findings that the NMDA receptor-mediated inhibitory modulation in the central vestibular system plays an important role for the initial processes of the development of vestibular compensation.