RESUMO
When a social sound category initially gains behavioral significance to an animal, plasticity events presumably enhance the ability to recognize that sound category in the future. In the context of learning natural social stimuli, neuromodulators such as norepinephrine and estrogen have been associated with experience-dependent plasticity and processing of newly salient social cues, yet continued plasticity once stimuli are familiar could disrupt the stability of sensorineural representations. Here we employed a maternal mouse model of natural sensory cortical plasticity for infant vocalizations to ask whether the engagement of the noradrenergic locus coeruleus (LC) by the playback of pup-calls is affected by either prior experience with the sounds or estrogen availability, using a well-studied cellular activity and plasticity marker, the immediate early gene c-Fos. We counted call-induced c-Fos immunoreactive (c-Fos-IR) cells in both LC and physiologically validated fields within the auditory cortex (AC) of estradiol or blank-implanted virgin female mice with either 0 or 5-days prior experience caring for vocalizing pups. Estradiol and pup experience interacted both in the induction of c-Fos-IR in the LC, as well as in behavioral measures of locomotion during playback, consistent with the neuromodulatory center's activity being an online reflection of both hormonal and experience-dependent influences on arousal. Throughout core AC, as well as in a high frequency sub-region of AC and in secondary AC, a main effect of pup experience was to reduce call-induced c-Fos-IR, irrespective of estradiol availability. This is consistent with the hypothesis that sound familiarity leads to less c-Fos-mediated plasticity, and less disrupted sensory representations of a meaningful call category. Taken together, our data support the view that any coupling between these sensory and neuromodulatory areas is situationally dependent, and their engagement depends differentially on both internal state factors like hormones and external state factors like prior experience.
Assuntos
Córtex Auditivo/fisiologia , Estradiol/fisiologia , Locus Cerúleo/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Estimulação Acústica , Animais , Córtex Auditivo/anatomia & histologia , Comportamento Animal/fisiologia , Feminino , Imuno-Histoquímica , Aprendizagem/fisiologia , Locus Cerúleo/anatomia & histologia , Camundongos , Camundongos Endogâmicos CBA , Plasticidade Neuronal/fisiologia , Norepinefrina/fisiologia , Reconhecimento Psicológico/fisiologia , Comportamento Social , Vocalização Animal/fisiologiaRESUMO
Osteoporosis results from imbalance between new bone formation and bone resorption leading to bone loss and is especially troublesome for postmenopausal women who suffer from estrogen deficiency. The ability of new therapeutic agents to treat this bone disease with minimal side effects has been extensively reported on and is continuously being sought out by researchers in this field. Thus, the purpose of this study was to investigate a natural herb that was already being used as a new treatment for osteoporosis. Here we found that water extract of Glycyrrhizae radix (GR) inhibits receptor activator of nuclear factor-[Formula: see text]B ligand (RANKL)-induced osteoclast differentiation in a dose-dependent manner without causing cytotoxicity. The mRNA expression of c-Fos, nuclear factor of activated T cells cytoplasmic 1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), and osteoclast-associated receptor (OSCAR) was considerably inhibited by GR treatment. GR inhibited RANKL-mediated c-Fos and NFATc1 expression in a dose-dependent manner. GR inhibited the degradation of I-[Formula: see text]B in RANKL-stimulated BMMs. However, GR-mediated inhibition of osteoclast differentiation and osteoclast-specific gene expression, including NFATc1, was reversed by ectopic expression of c-Fos. Also, GR significantly inhibited osteoclast formation in mouse calvariae in the presence of IL-1 and prostaglandin E2 (PGE2). Taken together, these results suggest that GR inhibited osteoclast differentiation, raising the possibility that GR may serve as a useful drug for osteoporosis.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Glycyrrhiza , Fatores de Transcrição NFATC/genética , Osteoclastos/citologia , Extratos Vegetais/farmacologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Acorus , Animais , Células da Medula Óssea , Células Cultivadas , Depressão Química , Relação Dose-Resposta a Droga , Masculino , Camundongos Endogâmicos ICR , Terapia de Alvo Molecular , Fatores de Transcrição NFATC/metabolismo , Osteoporose/tratamento farmacológico , Extratos Vegetais/uso terapêuticoRESUMO
The Fos- and Jun family proteins are immediate-early gene products, and the Fos/Jun heterodimer, activator protein-1 (AP-1), may be involved in the regulation of corticotropin-releasing factor (CRF) gene expression. FosB is a member of the Fos family proteins that is expressed in the paraventricular nucleus of the hypothalamus upon stress exposure, but it has not been clear whether FosB participates in the regulation of CRF gene expression. This study aimed to explore the effect of the FosB and cJun proteins on CRF gene expression in rat hypothalamic 4B cells. The levels of FosB mRNA and cJun mRNA increased following treatment with forskolin, phorbol-12-myristate-13-acetate (PMA), or A23187 in the hypothalamic cells. Overexpression of FosB or cJun potently increased CRF mRNA levels. Furthermore, downregulation of FosB or cJun suppressed the CRF gene expression induced by forskolin, PMA, or A23187. In addition, the basal CRF mRNA levels were partially reduced by cJun downregulation. These findings suggest that FosB, together with cJun, may mediate CRF gene expression in the hypothalamic cells.
Assuntos
Hormônio Liberador da Corticotropina/genética , Hipotálamo/citologia , Células Neuroendócrinas/metabolismo , Proteínas Proto-Oncogênicas c-fos/fisiologia , Ativação Transcricional , Adenilil Ciclases/metabolismo , Animais , Calcimicina/farmacologia , Células Cultivadas , Colforsina/farmacologia , Hormônio Liberador da Corticotropina/metabolismo , Ativadores de Enzimas/farmacologia , Expressão Gênica , Células Neuroendócrinas/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-jun/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Sistemas do Segundo Mensageiro , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
ΔFosB protein accumulates in the striatum in response to chronic administration of drugs of abuse, L-DOPA, or stress, triggering long lasting neural and behavioral changes that underlie aspects of drug addiction, abnormal involuntary movements (dyskinesia), and depression. ΔFosB binds AP-1 DNA consensus sequences found in promoters of many genes and can both repress or activate gene transcription. In the striatum, ΔFosB is thought to dimerize with JunD to form a functional transcription factor, though strikingly JunD does not accumulate in parallel. One explanation is that ΔFosB can recruit different partners, including itself, depending on the neuron type in which it is induced and the chronic stimulus, generating protein complexes with different effects on gene transcription. To develop chemical probes to study ΔFosB, a high-throughput screen was carried out to identify small molecules that modulate ΔFosB function. Two compounds with low micromolar activity, termed C2 and C6, disrupt the binding of ΔFosB to DNA via different mechanisms, and in in vitro assays stimulate ΔFosB-mediated transcription. In cocaine-treated mice, C2 significantly elevates mRNA levels of the AMPA glutamate receptor GluR2 subunit with specificity, a known target gene of ΔFosB that plays a role in drug addiction and endogenous resilience mechanisms. C2 and C6 show different activities against ΔFosB homodimers compared to ΔFosB/JunD heterodimers, suggesting that these compounds can be used as probes to study the contribution of different ΔFosB-containing complexes on the regulation of gene transcription in biological systems and to assess the utility of ΔFosB as a therapeutic target.
Assuntos
Preparações Farmacêuticas/química , Proteínas Proto-Oncogênicas c-fos/metabolismo , Fatores de Transcrição/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/fisiologia , Avaliação Pré-Clínica de Medicamentos/métodos , Insetos , Camundongos , Preparações Farmacêuticas/metabolismo , Ligação Proteica/fisiologia , Proteínas Proto-Oncogênicas c-fos/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-fos/fisiologia , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/fisiologiaRESUMO
Many temperate-zone animals use changes in photoperiod to time breeding. Shorter term cues, like food availability, are integrated with photoperiod to adjust reproductive timing under unexpected conditions. Many mice of the genus Peromyscus breed in the summer. California mice (Peromyscus californicus), however, can breed year round, but tend to begin breeding in the winter. Glial cells may be involved in transduction of environmental signals that regulate gonadotrophin releasing hormone I (GnRH) activity. We examined the effects of diet and photoperiod on reproduction in female California mice. Mice placed on either short days (8L:16D) or long days (16L:8D) were food restricted (80% of normal intake) or fed ad libitum. Short day-food restricted mice showed significant regression of the reproductive system. GnRH-immunoreactivity was increased in the tuberal hypothalamus of long day-food restricted mice. This may be associated with the sparing effect long days have when mice are food restricted. The number of GFAP-immunoreactive fibers in proximity to GnRH nerve terminals correlated negatively with uterine size in ad libitum but not food restricted mice, suggesting diet may alter glial regulation of the reproductive axis. There was a trend towards food restriction increasing uterine expression of c-fos mRNA, an estrogen dependent gene. Similar to other seasonally breeding rodents, short days render the reproductive system of female California mice more susceptible to effects of food restriction. This may be vestigial, or it may have evolved to mitigate consequences of unexpectedly poor winter food supplies.
Assuntos
Privação de Alimentos/fisiologia , Hormônio Liberador de Gonadotropina/fisiologia , Hipotálamo/fisiologia , Peromyscus/fisiologia , Reprodução/fisiologia , Animais , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/fisiologia , Feminino , Proteína Glial Fibrilar Ácida , Hipotálamo/citologia , Imuno-Histoquímica/veterinária , Camundongos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/fisiologia , Neuroglia/fisiologia , Fotoperíodo , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/fisiologia , RNA Mensageiro/química , RNA Mensageiro/genética , Distribuição Aleatória , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Estatísticas não Paramétricas , Útero/fisiologiaRESUMO
Contingency learning is essential for establishing predictive or causal judgements. Retrospective revaluation captures essential aspects of the updating of this knowledge, according to new experience. In the present study, retrospective revaluation and its neural substrate was investigated in a rat conditioned magazine approach. One element of a previously food-reinforced Tone-Light compound stimulus was either further reinforced (inflation) or extinguished (extinction). These treatments affected the predictive value of the alternate stimulus (target), but only when the target was a weakly salient stimulus such as a Light, and the inflation/extinction procedure concerned the more salient element, that is the Tone. As the predictive value of the Light was decreased in comparison with a relevant control group, this revaluation was interpreted as backward blocking, and not unovershadowing. This observation challenges retrospective revaluation models focused on acquisition and prediction error detection, and is better accounted for by retrieval-based associative theories such as the comparator model (Miller and Matzel) [5]. Immunohistochemical detection of the Fos protein after the test phase revealed activation of the orbitofrontal and infralimbic cortices as well as nucleus accumbens core and shell, in rats that exhibited retrospective revaluation. Our results suggest that rats integrate successive experiences at the retrieval stage of retrospective revaluation, and that prefronto-accumbal interactions are involved in this function.
Assuntos
Rede Nervosa/fisiologia , Estimulação Acústica , Animais , Aprendizagem por Associação/fisiologia , Encéfalo/fisiologia , Química Encefálica/fisiologia , Condicionamento Operante/fisiologia , Sinais (Psicologia) , Interpretação Estatística de Dados , Imuno-Histoquímica , Julgamento/fisiologia , Aprendizagem/fisiologia , Imageamento por Ressonância Magnética , Masculino , Proteínas Proto-Oncogênicas c-fos/biossíntese , Proteínas Proto-Oncogênicas c-fos/fisiologia , Ratos , Ratos Long-EvansRESUMO
OBJECTIVE: An impaired ability to sense and appropriately respond to insulin-induced hypoglycemia is a common and serious complication faced by insulin-treated diabetic patients. This study tests the hypothesis that insulin acts directly in the brain to regulate critical glucose-sensing neurons in the hypothalamus to mediate the counterregulatory response to hypoglycemia. RESEARCH DESIGN AND METHODS: To delineate insulin actions in the brain, neuron-specific insulin receptor knockout (NIRKO) mice and littermate controls were subjected to graded hypoglycemic (100, 70, 50, and 30 mg/dl) hyperinsulinemic (20 mU/kg/min) clamps and nonhypoglycemic stressors (e.g., restraint, heat). Subsequently, counterregulatory responses, hypothalamic neuronal activation (with transcriptional marker c-fos), and regional brain glucose uptake (via (14)C-2deoxyglucose autoradiography) were measured. Additionally, electrophysiological activity of individual glucose-inhibited neurons and hypothalamic glucose sensing protein expression (GLUTs, glucokinase) were measured. RESULTS: NIRKO mice revealed a glycemia-dependent impairment in the sympathoadrenal response to hypoglycemia and demonstrated markedly reduced (3-fold) hypothalamic c-fos activation in response to hypoglycemia but not other stressors. Glucose-inhibited neurons in the ventromedial hypothalamus of NIRKO mice displayed significantly blunted glucose responsiveness (membrane potential and input resistance responses were blunted 66 and 80%, respectively). Further, hypothalamic expression of the insulin-responsive GLUT 4, but not glucokinase, was reduced by 30% in NIRKO mice while regional brain glucose uptake remained unaltered. CONCLUSIONS: Chronically, insulin acts in the brain to regulate the counterregulatory response to hypoglycemia by directly altering glucose sensing in hypothalamic neurons and shifting the glycemic levels necessary to elicit a normal sympathoadrenal response.
Assuntos
Glicemia/metabolismo , Encéfalo/fisiologia , Hipoglicemia/metabolismo , Hipotálamo/fisiologia , Insulina/fisiologia , Receptor de Insulina/deficiência , Animais , Cruzamentos Genéticos , Regulação da Expressão Gênica , Glucoquinase/genética , Homozigoto , Temperatura Alta , Hipoglicemia/genética , Hipoglicemia/fisiopatologia , Integrases/genética , Proteínas de Filamentos Intermediários/genética , Masculino , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Nestina , Neurônios/fisiologia , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/fisiologia , Ratos , Receptor de Insulina/genética , Restrição Física , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estresse Psicológico/sangueRESUMO
CONTEXT: According to the traditional two-cell two-gonadotropin model of follicular steroidogenesis, androgen production arises exclusively from theca cells. The granulosa cells, in turn, utilize androstenedione and testosterone, which are aromatized into estrone and estradiol, respectively. Differential expression of the activator protein-1 (AP-1) transcription factor, c-fos, has been postulated to result in distinct patterns of steroidogenesis in the theca and granulosa cell compartments. We hypothesize that c-fos functions to inhibit the production of 17alpha-hydroxylase 17,20 lyase (CYP17) in granulosa cells, thereby suppressing androgen synthesis. OBJECTIVE: Our objective was to define the role of c-fos in the regulation of CYP17 production in granulosa cells. DESIGN AND METHODS: Human luteinized granulosa (HGL5) cells were utilized for all experiments. The following techniques were used: mRNA extraction, steroid quantification, small interfering RNA silencing, microarray analysis, and immunohistochemistry. RESULTS: Immunohistochemistry studies demonstrated significant staining of c-fos in the granulosa cell layer, but absent staining for CYP17. Conversely, the theca cell layer did not stain for c-fos, but staining was evident for CYP17. Treatment of HGL5 cells with the MAPK kinase inhibitor PD98059 resulted in an 11-fold increase in CYP17 mRNA levels. In c-fos gene silenced cells, CYP17 mRNA levels increased 8-fold. Androstenedione production was increased 13-fold after treatment with PD98059. CONCLUSIONS: These results suggest that the AP-1 transcription factor, c-fos, may be one of the factors responsible for CYP17 repression and hence suppression of androstenedione production in granulosa cells. This may provide an explanation for the lack of CYP17 in granulosa cells.
Assuntos
Androstenodiona/biossíntese , Células da Granulosa/metabolismo , Esteroide 17-alfa-Hidroxilase/biossíntese , Adulto , Androstenodiona/genética , Células Cultivadas , DNA Complementar/biossíntese , DNA Complementar/genética , Inibidores Enzimáticos/farmacologia , Repressão Enzimática , Feminino , Flavonoides/farmacologia , Regulação Enzimológica da Expressão Gênica/genética , Regulação Enzimológica da Expressão Gênica/fisiologia , Células da Granulosa/enzimologia , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Ovário/metabolismo , Proteínas Proto-Oncogênicas c-fos/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-fos/fisiologia , RNA/biossíntese , RNA/isolamento & purificação , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Esteroide 17-alfa-Hidroxilase/genética , Esteroides/metabolismoRESUMO
The ability to assess the activity of gonadotropin-releasing hormone (GnRH) neurons has been greatly enhanced by transgenic animal models with targeted expression of green fluorescent protein (GFP). However, it has yet to be demonstrated that the GnRH system continues to exhibit a full range of normal physiological functions in the presence of such genetic manipulation. Accordingly, we have used repetitive blood sampling via indwelling venous catheters to define LH secretory patterns in normal and transgenic mice. Transgenic females proved to be reproductively competent as defined by fecundity, appropriate cyclic changes in vaginal cytology in intact adult females, and spontaneous LH surges as well as surges in response to steroid or mating stimuli. The expression of c-fos following such steroid treatment and mating in ovariectomized transgenics was similar to the expression previously reported in nontransgenic mice. Likewise, the percentage of retrogradely labeled GnRH neurons was similar to that reported in nontransgenic mice. However, episodic LH secretion, an index of GnRH pulse generator activity, was dramatically compromised in ovariectomized female transgenics compared with C57BL6 controls of both sexes and castrated transgenic males. Taken together, these findings suggest that the GnRH pulse generator is selectively impaired in ovariectomized females in which GnRH neurons express GFP.
Assuntos
Hormônio Liberador de Gonadotropina/fisiologia , Hipotálamo/fisiologia , Hormônio Luteinizante/metabolismo , Neurônios/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Animais , Feminino , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/genética , Hormônio Luteinizante/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia de Fluorescência , Orquiectomia , OvariectomiaRESUMO
Using a fear conditioning preparation, [Carnicella, S., Pain, L., Oberling, P., 2005a. Cholinergic effects on fear conditioning I: The degraded contingency effect is disrupted by atropine but reinstated by physostigmine. Psychopharmacology 178, 524-532] showed that the muscarinic receptor antagonist atropine disrupted the degraded contingency effect (DCE) in the rat, that is, the processes by which contextual memory competes with cued memory for the control over conditioned responding. Here, we investigated neural substrates involved in the expression of normal and atropine-disrupted DCE, using the protein Fos as a marker of neuronal activity. Compared to contingent conditioning, the DCE was associated with a decrease of the amount of Fos immunoreactive neurons within the auditory system and the amygdala and an increase within the medial prefrontal cortex (mPFC). Compared to the normal DCE, atropine-induced disruption of the DCE was associated with an increase of the amount of Fos immunoreactive neurons within the central nucleus of the amygdala. When atropine-induced suppression of the DCE, Fos pattern was modified in the mPFC with a change in Fos immunoreactivity, but no longer associated with the DCE. However, the mPFC was the unique structure studied in which the amount of Fos immunoreactive neurons was differentially affected according to both the conditioning procedure and the pharmacological treatment. These results are discussed in the framework of the cholinergic modulation of context processing in the rat and are put in parallel with an emerging set of studies in humans regarding the role of the PFC in such processing.
Assuntos
Atropina/farmacologia , Química Encefálica/efeitos dos fármacos , Química Encefálica/fisiologia , Condicionamento Clássico/efeitos dos fármacos , Condicionamento Clássico/fisiologia , Antagonistas Muscarínicos/farmacologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Estimulação Acústica , Tonsila do Cerebelo/fisiologia , Animais , Córtex Auditivo/efeitos dos fármacos , Córtex Auditivo/metabolismo , Córtex Auditivo/fisiologia , Interpretação Estatística de Dados , Medo/efeitos dos fármacos , Medo/fisiologia , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/fisiologia , Imuno-Histoquímica , Masculino , Memória/efeitos dos fármacos , Sistema Nervoso Parassimpático/efeitos dos fármacos , Sistema Nervoso Parassimpático/metabolismo , Sistema Nervoso Parassimpático/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
The obese Zucker rat, whose genotype is transmitted in an autosomal recessive fashion, is an animal model widely used in the field of obesity. The expression of the nuclear transcription factors c-Fos and c-Jun in the paraventricular nucleus (PVN) and arcuate nucleus (ARC) of the hypothalamus of obese Zucker rats was studied using immunohistochemical methods. PVN and ARC in the hypothalamus are known as centers for the control of food intake. It was observed that the numbers of c-Fos-positive and c-Jun-positive neurons in these regions decreased in obese rats compared to lean rats, and that difference was more evident in the ARC than in the PVN which has to do with the regulation of body weight. The reduction in expression in the ARC of obese rats was greater for c-Jun than for c-Fos. These results suggest a possible difference in Fos immunoreactivity in hypothalamic resistance to circulating satiety factors in genetically obese Zucker rats.
Assuntos
Hipotálamo/química , Obesidade/metabolismo , Proteínas Proto-Oncogênicas c-fos/análise , Proteínas Proto-Oncogênicas c-jun/análise , Animais , Peso Corporal , Imuno-Histoquímica , Masculino , Proteínas Proto-Oncogênicas c-fos/fisiologia , Proteínas Proto-Oncogênicas c-jun/fisiologia , Ratos , Ratos Zucker , Saciação , Distribuição TecidualRESUMO
Interoceptive stimuli modulate stress responses and emotional state, in part, via ascending viscerosensory inputs to the hypothalamus and limbic forebrain. It is unclear whether similar viscerosensory pathways are recruited by emotionally salient exteroceptive stimuli, such as odors. To address this question, we investigated conditioned avoidance and central c-Fos activation patterns in rats exposed to synthetic trimethylthiazoline (TMT), an odiferous natural component of fox feces. Experiment 1 demonstrated that rats avoid consuming novel flavors that previously were paired with TMT exposure, evidence that TMT supports conditioned flavor avoidance. Experiment 2 examined central neural systems activated by TMT. Odor-naive rats were acutely exposed to low or high levels of TMT or a novel nonaversive control odor and were perfused with fixative 60-90 min later. A subset of rats received retrograde neural tracer injections into the central nucleus of the amygdala (CeA) 7-10 days before odor exposure and perfusion. Brain sections were processed for dual-immunocytochemical detection of c-Fos and other markers to identify noradrenergic (NA) neurons, corticotropin-releasing hormone (CRH) neurons, and retrogradely labeled neurons projecting to the CeA. Significantly greater proportions of medullary and pontine NA neurons, hypothalamic CRH neurons, and CeA-projecting neurons were activated in rats exposed to TMT compared with activation in rats exposed to the nonaversive control odor. Thus the ability of TMT to support conditioned avoidance behavior is correlated with significant odor-induced recruitment of hypothalamic CRH neurons and brain stem viscerosensory inputs to the CeA.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Hipotálamo/efeitos dos fármacos , Sistema Límbico/efeitos dos fármacos , Rede Nervosa/efeitos dos fármacos , Sensação/efeitos dos fármacos , Paladar/efeitos dos fármacos , Tiazóis/farmacologia , Tonsila do Cerebelo/citologia , Tonsila do Cerebelo/fisiologia , Animais , Axônios/fisiologia , Tronco Encefálico/fisiologia , Hormônio Liberador da Corticotropina/metabolismo , Hipotálamo/citologia , Imuno-Histoquímica , Sistema Límbico/citologia , Masculino , Rede Nervosa/citologia , Neurônios/fisiologia , Norepinefrina/fisiologia , Odorantes , Ponte/citologia , Ponte/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
Brain sexual differentiation is mediated through testosterone, which acts during the perinatal period in the form of both 5alpha-dihydrotestosterone and estradiol. In order to gain insight into the molecular mechanisms involved, we studied induction of c-fos, an index of functional neuronal activation, in the 2-day-old female rat brain after injection of a masculinizing dose of testosterone. Administration of testosterone resulted in induction of c-fos gene expression in the hypothalamus, as determined by Northern analysis. Following immunocytochemistry, we demonstrated an increase in the number of Fos-positive nuclei in the median and medial preoptic nucleus, the medial preoptic area extending to the lateral preoptic area, and the peri- and paraventricular area. In an effort to see whether testosterone acted as 5alpha-dihydrotestosterone or as estradiol, we injected either steroid and looked at fos induction. Estradiol mimicked the effect of testosterone, while 5alpha-dihydrotestosterone was without effect. Furthermore, injection of an estrogen receptor blocker, clomiphene, together with testosterone, abolished the testosterone-induced increase in Fos-positive nuclei, thus confirming the finding that testosterone induces c-fos by acting through estrogen receptors. Electrophoretic mobility shift assays showed that nuclear extracts from 2-day-old female hypothalamus contain a protein, most probably the estrogen receptor, which binds specifically to oligodeoxynucleotides with the sequence of either vitERE, the consensus estrogen-responsive element (ERE) found in the vittelogenin gene, or fosERE, the ERE found in the 3'-untranslated region of the mouse c-fos gene. This suggests that the effect of testosterone-derived estradiol on c-fos expression is a direct one, mediated by binding of estrogen receptors to an ERE in the c-fos gene-regulatory regions.
Assuntos
Encéfalo/crescimento & desenvolvimento , Proteínas Proto-Oncogênicas c-fos/fisiologia , Caracteres Sexuais , Animais , Animais Recém-Nascidos , Northern Blotting , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Clomifeno/farmacologia , Di-Hidrotestosterona/farmacologia , Estradiol/farmacologia , Feminino , Expressão Gênica/efeitos dos fármacos , Hipotálamo/química , Hipotálamo/metabolismo , Imuno-Histoquímica , Proteínas Proto-Oncogênicas c-fos/análise , Proteínas Proto-Oncogênicas c-fos/genética , Ratos , Ratos Wistar , Receptores de Estrogênio/antagonistas & inibidores , Testosterona/administração & dosagem , Testosterona/farmacologiaRESUMO
Chemical (mainly oxidative) and mechanical (anterior capsule injury) stresses have been reported to up-regulate the expression of the protooncogenes c-fos and c-jun in the lens. Another potentially stressful, yet largely unexplored condition, inherent to all experiments requiring the in vitro culturing of isolated lenses, is vitreous removal. Based on the results of an extensive RNA gel blot analysis conducted on epithelial/capsule preparations isolated from calf lenses dissected and cultured under different conditions, we show, here, that lens isolation and short-term culture (1-2.5 hr, without any significant GSH depletion) result in a strong and time-dependent up-regulation of the c-jun and c-fos mRNAs. This response, which relies on transcriptional protooncogene activation and is more intense for c-fos than for c-jun, is in part prevented by the preservation of the lens-vitreous contact, but not by the culture of vitreous-stripped lenses on a vitreous bed. Supplementation of the culture medium with the antioxidant N -acetyl-cysteine slightly reduced the c-jun, but not the c-fos response. Protooncogene up-regulation thus appears to be mainly determined by the disruption of critical lens-vitreous interactions. Since this response takes place in the epithelial cells, these data also point to the existence of a communication mechanism whereby a posteriorly applied mechanical stress is transmitted to, and perceived by, the anterior lens surface.
Assuntos
Cristalino/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Proteínas Proto-Oncogênicas c-jun/fisiologia , Ativação Transcricional/fisiologia , Corpo Vítreo/fisiologia , Acetilcisteína/farmacologia , Animais , Bovinos , Sondas de DNA , Dissecação , Hibridização In Situ , Cristalino/anatomia & histologia , Técnicas de Cultura de Órgãos , Corpo Vítreo/anatomia & histologiaRESUMO
Several lines of evidence substantiate the important role of the central nervous system melanocortin 3- and 4-receptor (MC3/4-R) system in the control of food intake and energy balance. Agouti-related peptide (AgRP), an endogenous antagonist of these receptors, produces a robust and unique pattern of increased food intake that lasts up to 7 days after a single injection. Little is known about brain regions that may mediate this powerful effect of AgRP on food intake. To this end we compared c-Fos-like immunoreactivity (c-FLI) in several brain sites of rats injected intracerebroventricularly with 1 nmol AgRP-(83--132) 2 and 24 h before death and compared c-FLI patterns to those induced by another potent orexigenic peptide, neuropeptide Y (NPY). Although both NPY and AgRP induced c-FLI in hypothalamic areas, AgRP also produced increased c-FLI in the accumbens shell and lateral septum. Although NPY elicited no changes in c-FLI 24 h after administration, AgRP induced c-FLI in the accumbens shell, nucleus of the solitary tract, central amygdala, and lateral hypothalamus. These results indicate that an NPY-like hypothalamic circuit mediates the short-term effects of AgRP, but that the unique sustained effect of AgRP on food intake involves a complex circuit of key extrahypothalamic reward and feeding regulatory nuclei.
Assuntos
Encéfalo/metabolismo , Fragmentos de Peptídeos/farmacologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Proteína Relacionada com Agouti , Animais , Hipotálamo/metabolismo , Imuno-Histoquímica , Injeções Intraventriculares , Masculino , Neuropeptídeo Y/farmacologia , Ratos , Ratos Long-Evans , Fatores de Tempo , Distribuição Tecidual/efeitos dos fármacosRESUMO
Intraspecific confrontation has been used to study effect of depleting central serotonin on the adaptation of male rats to repeated social stress (social defeat). Four groups of adult male rats were used (serotonin depletion/sham: stressed; serotonin depletion/sham: non-stressed). Central serotonin was reduced (by 59-97%) by a single infusion of the neurotoxin 5,7-dihydroxtryptamine (150 microg) into the cerebral ventricles; levels of dopamine and noradrenaline were unaltered (rats received appropriate uptake blockers prior to neurotoxic infusions). Sham-operated animals received solute only. Rats were then either exposed daily for 10 days to a second larger aggressive male in the latter's home cage, or simply transferred to an empty cage (control procedure). Rats with reduced serotonin failed to show the increased freezing behaviour during the pre-defeat phase of the social interaction test characteristic of sham animals. There was no change in the residents' behaviour. Core temperature increased during aggressive interaction in sham rats, and this did not adapt with repeated stress. By contrast, stress-induced hyperthermia was accentuated in serotonin-reduced rats as the number of defeat sessions increased. Basal core temperature was unaffected by serotonin depletion. Heart rate increased during social defeat, but this did not adapt with repeated stress; serotonin depletion had no effect on this cardiovascular response. Basal corticosterone was increased in serotonin-depleted rats, but the progressive reduction in stress response over days was not altered. C-fos expression in the brain was not altered in control (non-stressed) rats by serotonin reduction in the areas examined, but there was increased expression after repeated social stress in the medial amygdala of 5-HT depleted rats. These experiments show that reduction of serotonin alters responses to repeated social stress in male rats, and suggests a role for serotonin in the adaptive process.
Assuntos
Agressão/fisiologia , Atividade Motora/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Serotonina/fisiologia , Estresse Fisiológico/fisiopatologia , 5,7-Di-Hidroxitriptamina , Adaptação Psicológica , Tonsila do Cerebelo/química , Animais , Regulação da Temperatura Corporal , Tronco Encefálico/química , Corticosterona/sangue , Feminino , Frequência Cardíaca/fisiologia , Ácido Hidroxi-Indolacético/análise , Hipotálamo/química , Masculino , Ratos , Ratos Sprague-Dawley , Serotonina/metabolismo , Serotoninérgicos , Predomínio SocialRESUMO
Extract of Tripterygium wilfordii Hook. f (TWHf) has immunosuppressive activity and has been used as anti-inflammatory agent in traditional Chinese medicine for centuries. Recent studies have demonstrated that triptolide is the major active component in the extract that inhibits antigen or mitogen-induced T cell proliferation. In attempting to investigate its effect on activation of T lymphocytes, we found triptolide induces apoptotic death of T cell hybridomas and peripheral T cells but not that of thymocytes. The triptolide-induced apoptosis is accompanied by increase of DEVD-cleavable caspases activity and degradation of caspase substrate poly (ADP-ribose) polymerase (PARP). A specific inhibitor of caspases, zVAD-FMK, prevents triptolide-induced PARP degradation and DNA fragmentation but not growth arrest. Furthermore, enforced expression of Bcl-2 inhibited triptolide-induced degradation of PARP and apoptosis. These results indicate that triptolide induces T cell apoptosis through activating caspases, and suggest the growth arrest and apoptotic effect of triptolide may contribute to the immunosuppressive activity of TWHf extract.
Assuntos
Apoptose/efeitos dos fármacos , Diterpenos/farmacologia , Imunossupressores/farmacologia , Fenantrenos , Linfócitos T/efeitos dos fármacos , Animais , Caspases/metabolismo , Divisão Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Compostos de Epóxi , Humanos , Interleucina-2/biossíntese , Ativação Linfocitária/efeitos dos fármacos , Camundongos , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Linfócitos T/citologia , Linfócitos T/imunologiaRESUMO
Scheduled arousal by handling and sub-cutaneous saline injection entrains the free-running clock of the adult Syrian hamster and outbred (ID(ICR)) but not inbred (C57B16) mice. Syrian hamsters bearing lesions of the intergeniculate leaflet of the thalamus remain able to entrain and phase-shift to light, but the lesions block completely entrainment by serial arousal, even though lesioned animals continue to respond acutely to the arousing cue. This suggests that the innervation from the IGL to the SCN is a necessary component of the pathways which signal an aroused state to the clock. Siberian hamsters do not entrain to serial arousal but they do entrain to serial injections of melatonin, whereas in adult Syrian hamster, systemic treatment with melatonin has no effect above that of arousal. In contrast to the adult, the foetal and neonatal Syrian hamster can be entrained by melatonin. These variations in sensitivity correlate with inter-specific and developmental differences in the pattern and level of expression of melatonin receptors in the SCN. The perinatal hamster can also be entrained by dopaminergic agonists. SCN tissue from neonatal Syrian hamsters was used to characterise the biochemical actions of dopamine and melatonin. In primary culture and tissue explants, forskolin, dopamine and glutamatergic agonists all stimulated the phosphorylation of the transcription factor CREB. This probably occurred via convergent actions through Ca2+ (glutamate) and cyclic AMP-dependent (forskolin, dopamine) signalling pathways. Dopamine induced phospho-CREB-ir exclusively in GABA-ir neurons and melatonin reversed this effect of dopamine, indicative of an inhibitory Gi protein linking via the Mel1a receptor to adenylyl cyclase. The regulation of phospho-CREB by multiple entraining cues in the SCN highlights its position as a point of convergence for regulators of the clock, and indicates a possible role in entrainment.
Assuntos
Nível de Alerta/fisiologia , Ritmo Circadiano/fisiologia , Roedores/fisiologia , Transdução de Sinais/fisiologia , Núcleo Supraquiasmático/fisiologia , Vias Aferentes/fisiologia , Fatores Etários , Animais , Animais Recém-Nascidos , Cálcio/fisiologia , Ritmo Circadiano/efeitos dos fármacos , Colforsina/farmacologia , Cricetinae , AMP Cíclico/fisiologia , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/fisiologia , Manobra Psicológica , Injeções Subcutâneas , Melatonina/farmacologia , Mesocricetus , Camundongos , Camundongos Endogâmicos C57BL , Neurotransmissores/fisiologia , Phodopus , Fosforilação , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas c-fos/fisiologia , Núcleos da Rafe/fisiologia , Roedores/embriologia , Roedores/crescimento & desenvolvimento , Transdução de Sinais/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Especificidade da Espécie , Tálamo/fisiologiaRESUMO
A polyclonal antibody raised against a conserved region of a mammalian FOS sequence was tested for its use as an activity marker in the rainbow trout. The FOS-like expression in the trout is entirely cytoplasmic and appears in a Nissl-like pattern. The reaction is specifically induced by both orthodromic and antidromic electrical stimuli and during motor responses evoked by natural stimulation, although some positive neurons are found at locations that are not obviously related to the presented stimuli. Following spinal nerve stimulation, antidromically activated motoneurons were found to be positive in the ipsilateral spinal cord. Orthodromic driving of spinal moto- and interneurons by stimulation of the medial longitudinal fasciculus (MLF) in the hindbrain evoked FOS-like immunoreactivity throughout the motor column in the spinal cord, but not in regions lying caudal to a lesion of the MLF-axons. Evoking about 25 startle responses by natural auditory stimulation gives FOS-like immunoreactivity in the Mauthner cell, which initiates the response, whereas positive Mauthner cells were never observed in control fish. The stimulation protocols that were used strongly activated the stimulated cells and so the observed FOS-like immunoreactivity might be related to an increase protein synthesis needed to restore their depleted transmitter levels.
Assuntos
Anticorpos , Citoplasma/fisiologia , Neurônios/fisiologia , Oncorhynchus mykiss/fisiologia , Proteínas Proto-Oncogênicas c-fos/fisiologia , Estimulação Acústica , Animais , Axônios/fisiologia , Biomarcadores , Estimulação Elétrica , Imuno-Histoquímica , Neurônios Motores/fisiologia , Proteínas Proto-Oncogênicas c-fos/imunologia , Reflexo de Sobressalto/fisiologia , Rombencéfalo/citologia , Rombencéfalo/fisiologia , Medula Espinal/citologia , Medula Espinal/fisiologiaRESUMO
Intracerebroventricular (i.c.v.) infusions of neuropeptide Y (NPY) (2500 pmol) induced c-fos protein in the paraventricular nucleus (PVN) of intact male rats 60 min later. The greatest expression was observed in the dorsal (parvicellular) region of the PVN; there were intermediate levels in the lateral (magnocellular) and lowest ones in the medial (parvicellular) regions. Allowing rats to eat during the post-infusion interval did not modify this pattern of c-fos expression. Depriving rats of food for either 24 or 48 h did not induce recognisable expression of c-fos in the PVN, and allowing 24 h-deprived rats to eat also had no effect on PVN c-fos. Plasma insulin was increased by i.c.v. NPY, and raised still further in rats that were allowed to eat following NPY infusions. However, plasma glucose was not altered by either treatment. Food-deprived rats had low levels of insulin, but unaltered blood glucose, compared to controls. These results show that NPY can induce c-fos expression in both parvicellular and magnocellular areas of the PVN. The pattern of expression within the PVN seems to differ from that induced by other peptides, such as angiotensin II, vasopressin and corticotropin-releasing factor, suggesting that distinct populations of neurons are activated by different peptides within the complex structure of the PVN. Food deprivation does not induce c-fos expression within the PVN, though other studies have shown that NPY levels and release are both increased, so there is no simple relation between current energy state, blood levels of either glucose or insulin and c-fos expression within the PVN.