RESUMO
Previous studies in our laboratory showed an interaction between the GABAergic and opioid systems involved in the analgesic effect of baclofen (BAC). Furthermore, it is known that sex differences exist regarding various pharmacological responses of morphine (MOR) and they are related to an increased sensitivity to MOR effects in males. The aims of the present study were to evaluate the possible involvement of the GABAB receptors in the antinociceptive responses induced by MOR (1, 3 and 9â¯mg/kg, s.c.) administration using both pharmacological (BAC 2â¯mg/kg, i.p.; and 2-OH-saclofen, SAC 0.3â¯mg/kg, intra cisterna magna) and genetic approaches (GABAB1 knockout mice; GABAB1 KO) in mice of both sexes. In addition, we explored the alterations in c-Fos expression of different brain areas involved in the antinociceptive effect of MOR using both approaches. The pharmacological approach showed a higher dose-dependent antinociceptive effect of MOR in male mice compared to female mice. BAC and SAC pretreatment potentiated and attenuated the antinociceptive effect of MOR, respectively, in both sexes. The genetic approach revealed a dose-dependent antinociceptive effect of MOR in the wild type mice, but not in the GABAB1 KO mice and no sex differences were observed. Additionally, BAC and SAC pretreatment and the lack of GABAB1 subunit of the GABAB receptor prevented the changes observed in c-Fos expression in the cingulate cortex and nucleus accumbens of male mice. Our results suggest that the GABAB receptors are involved in the MOR antinociceptive effect of both male and female mice.
Assuntos
Analgésicos/farmacologia , Morfina/farmacologia , Receptores de GABA-B/genética , Receptores de GABA-B/metabolismo , Analgésicos/administração & dosagem , Animais , Baclofeno/administração & dosagem , Baclofeno/análogos & derivados , Baclofeno/farmacologia , Comportamento Animal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Agonistas dos Receptores de GABA-B/administração & dosagem , Agonistas dos Receptores de GABA-B/farmacologia , Técnicas de Inativação de Genes , Genes fos/genética , Genótipo , Giro do Cíngulo/efeitos dos fármacos , Giro do Cíngulo/metabolismo , Locomoção/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Morfina/administração & dosagem , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Proteínas Proto-Oncogênicas c-fos/imunologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Fatores Sexuais , Transdução de Sinais/efeitos dos fármacosRESUMO
Undernutrition promotes morphofunctional adaptations in neuroanatomical circuits, leading to behavioural changes. Adolescence is a period of vulnerability for these adaptations, such as the control of food intake and the serotonergic system. The serotonergic system is capable of promoting satiety. However, its role in hedonic control has not been fully elucidated. The involvement of the 5-HT6 receptor in motivational feeding behaviours was recently observed. Therefore, we aimed to evaluate the effect of a 5-HT6 receptor agonist on food intake and neuronal activation in areas of the reward system in adolescent rats subjected to perinatal protein undernutrition. Wistar rats were divided into two groups according to nutritional manipulation during gestation and lactation. It has been observed that undernourished animals present greater neuronal activation in response to the 5HT-6 receptor agonist in areas of the food reward system.
Assuntos
Genes fos/fisiologia , Indóis/farmacologia , Desnutrição , Fenômenos Fisiológicos da Nutrição Materna , Piridinas/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Ingestão de Alimentos , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Lactação , Masculino , Gravidez , Ratos , Ratos Wistar , Receptores de Serotonina , Maturidade SexualRESUMO
Abstract Introduction: Salicylate at high doses induces tinnitus in humans and experimental animals. However, the mechanisms and loci of action of salicylate in inducing tinnitus are still not well known. The expression of Immediate Early Genes (IEG) is traditionally associated with long-term neuronal modifications but it is still not clear how and where IEGs are activated in animal models of tinnitus. Objectives: Here we investigated the expression of c-fos and Egr-1, two IEGs, in the Dorsal Cochlear Nucleus (DCN), the Inferior Colliculus (IC), and the Posterior Ventral Cochlear Nucleus (pVCN) of rats. Methods: Rats were treated with doses known to induce tinnitus in rats (300 mg/kg i.p. daily, for 3 days), and c-fos and Egr-1 protein expressions were analyzed using western blot and immunocytochemistry. Results: After administration of salicylate, c-fos protein expression increased significantly in the DCN, pVCN and IC when assayed by western blot. Immunohistochemistry staining showed a more intense labeling of c-fos in the DCN, pVCN and IC and a significant increase in c-fos positive nuclei in the pVCN and IC. We did not detect increased Egr-1 expression in any of these areas. Conclusion: Our data show that a high dose of salicylate activates neurons in the DCN, pVCN and IC. The expression of these genes by high doses of salicylate strongly suggests that plastic changes in these areas are involved in the genesis of tinnitus.
Resumo Introdução: Salicilato em doses elevadas induz zumbido nos seres humanos e em animais experimentais. No entanto, os mecanismos e loci de ação do salicilato na indução de zumbido ainda não são bem conhecidos. A expressão dos genes precoces imediatos (GPIs) está tradicionalmente associada a alterações neuronais em longo prazo, mas ainda não está claro como e onde os GPIs são ativados em modelos animais de zumbido. Objetivos: No presente estudo investigamos a expressão de c-fos e Egr-1, dois GPIs, no núcleo coclear dorsal (NCD), colículo inferior (CI) e núcleo coclear ventral posterior (NCVp) de ratos. Métodos: Os ratos foram tratados com doses que, conhecidamente, induzem zumbido em ratos (300 mg/kg IP/dia, por três dias) e as expressões das proteínas c-fos e Egr-1 foram analisadas por meio de Western blot e imunoistoquímica. Resultados: Após a administração de salicilato, a expressão da proteína c-fos aumentou significativamente no NCD, NCVp e CI, quando analisados por Western blot. A coloração imunoistoquímica mostrou uma marcação mais intensa de c-fos no NCD, NCVp e CI e um aumento significativo de núcleos positivos de c-fos no NCVp e CI. Não detectamos aumento da expressão de Egr-1 em qualquer dessas áreas. Conclusão: Nossos dados mostram que uma dose alta de salicilato ativa neurônios no NCD, NCVp e CI. A expressão desses genes por doses altas de salicilato sugere que as alterações plásticas nessas áreas estão envolvidas na gênese do zumbido.
Assuntos
Animais , Masculino , Ratos , Colículos Inferiores/efeitos dos fármacos , Salicilatos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Genes Precoces/efeitos dos fármacos , Núcleo Coclear/efeitos dos fármacos , Salicilatos/administração & dosagem , Western Blotting , Genes fos/efeitos dos fármacos , Ratos Wistar , Relação Dose-Resposta a Droga , Proteína 1 de Resposta de Crescimento Precoce/efeitos dos fármacosRESUMO
INTRODUCTION: Salicylate at high doses induces tinnitus in humans and experimental animals. However, the mechanisms and loci of action of salicylate in inducing tinnitus are still not well known. The expression of Immediate Early Genes (IEG) is traditionally associated with long-term neuronal modifications but it is still not clear how and where IEGs are activated in animal models of tinnitus. OBJECTIVES: Here we investigated the expression of c-fos and Egr-1, two IEGs, in the Dorsal Cochlear Nucleus (DCN), the Inferior Colliculus (IC), and the Posterior Ventral Cochlear Nucleus (pVCN) of rats. METHODS: Rats were treated with doses known to induce tinnitus in rats (300mg/kg i.p. daily, for 3 days), and c-fos and Egr-1 protein expressions were analyzed using western blot and immunocytochemistry. RESULTS: After administration of salicylate, c-fos protein expression increased significantly in the DCN, pVCN and IC when assayed by western blot. Immunohistochemistry staining showed a more intense labeling of c-fos in the DCN, pVCN and IC and a significant increase in c-fos positive nuclei in the pVCN and IC. We did not detect increased Egr-1 expression in any of these areas. CONCLUSION: Our data show that a high dose of salicylate activates neurons in the DCN, pVCN and IC. The expression of these genes by high doses of salicylate strongly suggests that plastic changes in these areas are involved in the genesis of tinnitus.
Assuntos
Núcleo Coclear/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Genes Precoces/efeitos dos fármacos , Colículos Inferiores/efeitos dos fármacos , Salicilatos/farmacologia , Animais , Western Blotting , Relação Dose-Resposta a Droga , Proteína 1 de Resposta de Crescimento Precoce/efeitos dos fármacos , Genes fos/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Salicilatos/administração & dosagemRESUMO
Amphibians are central to discussions of vertebrate evolution because they represent the transition from aquatic to terrestrial life, a transition with profound consequences for the selective pressures shaping brain evolution. Spatial navigation is one class of behavior that has attracted the interest of comparative neurobiologists because of the relevance of the medial pallium/hippocampus, yet, surprisingly, in this regard amphibians have been sparsely investigated. In the current study, we trained toads to locate a water goal relying on the boundary geometry of a test environment (Geometry-Only) or boundary geometry coupled with a prominent, visual feature cue (Geometry-Feature). Once learning had been achieved, the animals were given one last training session and their telencephali were processed for c-Fos activation. Compared to control toads exposed to the test environment for the first time, geometry-only toads were found to have increased neuronal labeling in the medial pallium, the presumptive hippocampal homologue, while geometry-feature toads were found to have increased neuronal labeling in the medial, dorsal, and lateral pallia. The data indicate medial pallial participation in guiding navigation by environmental geometry and lateral, and to a lesser extent dorsal, pallial participation in guiding navigation by a prominent visual feature. As such, participation of the medial pallium/hippocampus in spatial cognition appears to be a conserved feature of terrestrial vertebrates even if their life history is still tied to water, a brain-behavior feature seemingly at least as ancient as the evolutionary transition to life on land.
Assuntos
Bufonidae/fisiologia , Neurônios/fisiologia , Aprendizagem Espacial/fisiologia , Memória Espacial/fisiologia , Navegação Espacial/fisiologia , Telencéfalo/fisiologia , Animais , Argentina , Genes fos , Imuno-Histoquímica , Telencéfalo/citologiaRESUMO
Predominantly emotional stressors activate a wide range of brain areas, as revealed by the expression of immediate early genes, such as c-fos. Chlorella vulgaris (CV) is considered a biological response modifier, as demonstrated by its protective activities against infections, tumors and stress. We evaluated the effect of acute pretreatment with CV on the peripheral and central responses to forced swimming stress in adult male rats. Pretreatment with CV produced a significant reduction of stress-related hypothalamic-pituitary-adrenal activation, demonstrated by decreased corticotrophin releasing factor gene expression in the hypothalamic paraventricular nucleus (PVN) and lower ACTH response. Hyperglycemia induced by the stressor was similarly reduced. This attenuated neuroendocrine response to stress occurred in parallel with a diminished c-fos expression in most evaluated areas, including the PVN. The data presented in this study reinforce the usefulness of CV to diminish the impact of stressors, by reducing the HPA response. Although our results suggest a central effect of CV, further studies are necessary to understand the precise mechanisms underpinning this effect.
Assuntos
Encéfalo/fisiologia , Chlorella vulgaris , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipófise-Suprarrenal/fisiologia , Proteínas Proto-Oncogênicas c-fos/biossíntese , Estresse Fisiológico/fisiologia , Hormônio Adrenocorticotrópico/efeitos dos fármacos , Hormônio Adrenocorticotrópico/metabolismo , Animais , Encéfalo/metabolismo , Corticosterona/metabolismo , Hormônio Liberador da Corticotropina/efeitos dos fármacos , Hormônio Liberador da Corticotropina/metabolismo , Genes fos , Sistema Hipotálamo-Hipofisário/metabolismo , Hipotálamo/metabolismo , Hibridização In Situ , Masculino , Núcleo Hipotalâmico Paraventricular/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo , RNA Mensageiro/metabolismo , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Estresse Psicológico/genética , Estresse Psicológico/metabolismo , NataçãoRESUMO
A growing body of evidence suggests that learned fear may be related to the function of the interoceptive insular cortex. Using an auditory fear conditioning paradigm in rats, we show that the inactivation of the posterior insular cortex (pIC), the target of the interoceptive thalamus, prior to training produced a marked reduction in fear expression tested 24h later. Accordingly, post-training anisomycin infused immediately, but not 6h after, also reduced fear expression tested the following day, supporting a role for the pIC in consolidation of fear memory. The long-term (ca. a week) and reversible inactivation of the pIC with the sodium channel blocker neosaxitoxin, immediately after fear memory reactivation induced a progressive decrease in the behavioral expression of conditioned fear. In turn, we observed that fear memory reactivation is accompanied by an enhanced expression of Fos and Zif268, early genes involved in neural activity and plasticity. Taken together these data indicate that the pIC is involved in the regulation of fear memories.
Assuntos
Comportamento Animal/fisiologia , Córtex Cerebral/fisiologia , Condicionamento Psicológico/fisiologia , Medo/fisiologia , Interocepção/fisiologia , Memória/fisiologia , Animais , Anisomicina/farmacologia , Comportamento Animal/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Condicionamento Psicológico/efeitos dos fármacos , Proteína 1 de Resposta de Crescimento Precoce/fisiologia , Inibidores Enzimáticos/farmacologia , Medo/efeitos dos fármacos , Genes fos/fisiologia , Interocepção/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Saxitoxina/análogos & derivados , Saxitoxina/farmacologia , Bloqueadores dos Canais de Sódio/farmacologia , TálamoRESUMO
c-Fos is a proto-oncogene involved in diverse cellular functions. Its deregulation has been associated to abnormal development and oncogenic progression. c-fos-/- mice are viable but present a reduction in their body weight and brain size. We examined the importance of c-Fos during neocortex development at 13.5, 14.5 and 16.5 days of gestation. At E14.5, neocortex thickness, apoptosis, mitosis and expression of markers along the different stages of Neural Stem Progenitor Cells (NSPCs) differentiation in c-fos-/- and wild-type mice were analyzed. A ~15% reduction in the neocortex thickness of c-fos-/- embryos was observed which correlates with a decrease in the number of differentiated cells and an increase in apoptosis at the ventricular zone. No difference in mitosis rate was observed, although the mitotic angle was predominantly vertical in c-fos-/- embryos, suggesting a reduced trend of NSPCs to differentiate. At E13.5, changes in differentiation markers start to be apparent and are still clearly observed at E16.5. A tendency of more AP-1/DNA complexes present in nuclear extracts of cerebral cortex from c-fos-/- embryos with no differences in the lipid synthesis activity was found. These results suggest that c-Fos is involved in the normal development of NSPCs by means of its AP-1 activity.
Assuntos
Diferenciação Celular/genética , Genes fos/genética , Neocórtex/embriologia , Células-Tronco Neurais/citologia , Neurogênese/genética , Animais , Ensaio de Desvio de Mobilidade Eletroforética , Embrião de Mamíferos , Imunofluorescência , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
OBJECTIVE: Intestinal ischemia-reperfusion injury occurs in several clinical conditions and after intestinal transplantation. The aim of the present study was to investigate the phenomena of apoptosis and cell proliferation in a previously described intestinal ischemia-reperfusion injury autograft model using immunohistochemical markers. The molecular mechanisms involved in ischemia-reperfusion injury repair were also investigated by measuring the expression of the early activation genes c-fos and c-jun, which induce apoptosis and cell proliferation. MATERIALS AND METHODS: Thirty adult male Wistar rats were subjected to surgery for a previously described ischemia-reperfusion model that preserved the small intestine, the cecum and the ascending colon. Following reperfusion, the cecum was harvested at different time points as a representative segment of the intestine. The rats were allocated to the following four subgroups according to the reperfusion time: subgroup 1: 5 min; subgroup 2: 15 min; subgroup 3: 30 min; and subgroup 4: 60 min. A control group of cecum samples was also collected. The expression of c-fos, c-jun and immunohistochemical markers of cell proliferation and apoptosis (Ki67 and TUNEL, respectively) was studied. RESULTS: The expression of both c-fos and c-jun in the cecum was increased beginning at 5 min after ischemia-reperfusion compared with the control. The expression of c-fos began to increase at 5 min, peaked at 30 min, and exhibited a declining tendency at 60 min after reperfusion. A progressive increase in c-jun expression was observed. Immunohistochemical analyses confirmed these observations. CONCLUSION: The early activation of the c-fos and c-jun genes occurred after intestinal ischemia-reperfusion injury, and these genes can act together to trigger cell proliferation and apoptosis.