RESUMO
CHF5074 is a non-steroidal anti-inflammatory derivative holding disease-modifying potential for the treatment of Alzheimer's disease. The aim of the present study was to characterize the electrophysiological and metabolic profile of CHF5074 in the hippocampus. Electrophysiological recordings show that CHF5074 inhibits in a dose-dependent manner the current-evoked repetitive firing discharge in CA1 pyramidal neurons. This result is paralleled by a dose-dependent reduction of field excitatory post-synaptic potentials with no effect on the paired-pulse ratio. The effects of CHF5074 were not mediated by AMPA or NMDA receptors, since the inward currents induced by local applications of AMPA and NMDA remained constant in the presence of this compound. We also suggest a possible activity of CHF5074 on ASIC1a receptor since ASIC1a-mediated current, evoked by application of a pH 5.5 solution, is reduced by pretreatment with this compound. Moreover, we demonstrate that CHF5074 treatment is able to counteract in hippocampal slices the OGD-induced increase in alanine, lactate and acetate levels. Finally, CHF5074 significantly reduced the apoptosis in hippocampal neurons exposed to OGD, as revealed by cleaved-caspase-3 immunoreactivity and TUNEL staining. Overall, the present work identifies novel mechanisms for CHF5074 in reducing metabolic acidosis, rendering this compound potentially useful also in conditions of brain ischemia.
Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Ciclopropanos/farmacologia , Flurbiprofeno/análogos & derivados , Hipocampo/efeitos dos fármacos , Isquemia/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Acetatos/metabolismo , Alanina/metabolismo , Animais , Ácido Aspártico/análogos & derivados , Ácido Aspártico/metabolismo , Células Cultivadas , Fenômenos Eletrofisiológicos , Flurbiprofeno/farmacologia , Hipocampo/irrigação sanguínea , Hipocampo/fisiologia , Técnicas In Vitro , Isquemia/fisiopatologia , Ácido Láctico/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ratos WistarRESUMO
AIM: The aim of this paper was to determine the prevalence of isolated left ventricular noncomapction (ILVNC) in a sample of 150 athletes send by sports doctors to the Valmontone Hospital's Cardiology Division in a span of about three years, with particular interest in non-compacted segments evaluation. The prevention of cardiovascular complications occurring during sporting activity requires detection of pathologies most often clinically latent but whose first presentation can be sudden cardiac death. In Italy, the pre-participation screening program comprises family history and personal cardiac history, clinical examination and electrocardiography. Subjects with abnormalities are further investigated by stress test, echocardiography and laboratory investigations, and those with significant abnormalities are disqualified from sports training and competition. ILVNC results in multiple trabeculations in the left ventricular myocardium and it is postulated to be caused by intrauterine arrest of compaction of the myocardial fibres and meshwork, an important process in myocardial development. This cardiomyopathy should be considered one of the structural cardiac abnormalities responsible for sudden cardiac death. METHODS: There were 150 athletes seen in the Cardiology Division from 2007 to 2010 for an echocardiographic evaluation in order to clarify the nature of physical examination and/or electrocardiogram abnormalities. Echocardiographic diagnosis of ILVNC was based on criteria published by Jenni et al., and by Stölberger et al. RESULTS: Twenty-four of the 150 tested resulted positive for ILVNC (16.0%). This high prevalence is justified because it was a population originally selected because of electrocardiographic abnormalities. CONCLUSION: We believe that in case of unspecific ECG findings, it would be useful to perform echocardiographic examination in order to highlight structural defects. We also believe that it is very important to contemplate ILVNC between the causes of sudden death in young competitive athletes.
Assuntos
Atletas , Miocárdio Ventricular não Compactado Isolado/diagnóstico , Adolescente , Adulto , Criança , Pré-Escolar , Morte Súbita Cardíaca/prevenção & controle , Ecocardiografia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Parkinson's disease (PD) is a neurodegenerative disorder mainly characterized by a loss of dopaminergic (DA) neurons in the substantia nigra pars compacta. In recent years, several new genes and environmental factors have been implicated in PD, and their impact on DA neuronal cell death is slowly emerging. However, PD etiology remains unknown, whereas its pathogenesis begins to be clarified as a multifactorial cascade of deleterious factors. Recent epidemiological studies have linked exposure to environmental agents, including pesticides, with an increased risk of developing the disease. As a result, over the last two decades the "environmental hypothesis" of PD has gained considerable interest. This speculates that agricultural chemicals in the environment, by producing selective dopaminergic cell death, can contribute to the development of the disease. However, a causal role for pesticides in the etiology of PD has yet to be definitively established. Importantly, most insights into PD pathogenesis came from investigations performed in experimental models of PD, especially those produced by neurotoxins. This review presents data obtained in our laboratories along with current views on the neurotoxic actions induced by the two most popular parkinsonian pesticide neurotoxins, namely paraquat and rotenone. Although confined to these two chemicals, mechanistic studies underlying dopaminergic cell death are of the utmost importance to identify new drug targets for the treatment of PD.
Assuntos
Degeneração Neural/induzido quimicamente , Vias Neurais/efeitos dos fármacos , Paraquat , Transtornos Parkinsonianos/induzido quimicamente , Praguicidas , Rotenona , Animais , Morte Celular/efeitos dos fármacos , Modelos Animais de Doenças , Dopamina/metabolismo , Humanos , Degeneração Neural/metabolismo , Degeneração Neural/fisiopatologia , Vias Neurais/metabolismo , Vias Neurais/fisiopatologia , Estresse Oxidativo/efeitos dos fármacos , Transtornos Parkinsonianos/metabolismo , Transtornos Parkinsonianos/fisiopatologiaRESUMO
The present experiments were aimed to characterize in immortalized human HaCat keratinocytes the gene expression induced by paraquat and capsaicin, two agents known to induce cell death or to affect inflammatory and pain pathways, respectively. In particular, the following set of genes were analysed by qRealtime PCR: CXCL10,CXCL11, IL-10 (inflammatory and immune responses), TP73, BCL2, (apoptotic and anti-apoptotic genes), MMP9 (proteolysis), SOD-1, BAK-1 and CAT (peroxysomal and microsomal oxidation pathways). In this way, we were able to differentiate the two toxins since they had a different profile of gene expression. In fact, paraquata was found to activate set of genes involved in inflammatory (CXL10,CXL11 and IL-10), and cell death (BCL2, BAK-1, MMP9) pathways. Another specific site of action of paraquat was represented by an activation of the gene involved in SOD-1 transcription. On the contrary, capsaicin was found to produce only an up-regulation of BCL2, an anti-apoptotic gene and MMP9, whereas no significant changes were reported in genes involved in inflammatory and immune responses. Finally, in comparison to previous experiments carried out with TNF-alpha and IL-1beta, we have shown that paraquat produced a similar pattern of activation of set of genes involved both in inflammation and apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Capsaicina/farmacologia , Inflamação/genética , Queratinócitos/efeitos dos fármacos , Paraquat/farmacologia , Apoptose/genética , Catalase/genética , Linhagem Celular , Quimiocina CXCL10/genética , Quimiocina CXCL11/genética , Proteínas de Ligação a DNA/genética , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Inflamação/enzimologia , Inflamação/imunologia , Interleucina-10/genética , Queratinócitos/enzimologia , Queratinócitos/imunologia , Queratinócitos/patologia , Metaloproteinase 9 da Matriz/genética , Proteínas Nucleares/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Reação em Cadeia da Polimerase em Tempo Real , Superóxido Dismutase/genética , Superóxido Dismutase-1 , Proteína Tumoral p73 , Proteínas Supressoras de Tumor/genética , Proteína Killer-Antagonista Homóloga a bcl-2/genéticaRESUMO
The present experiments were designed to characterize by microarray analysis the transcriptional responses of human keratinocytes (HaCat) to TNF-α and IL-1 ß, given alone or in combination, in order to better understand the mechanisms underlying inflammatory, immune responses and cell death in which both cytokines play a pathophysiological role. Significant differences in the percentage and quality of genes dysregulated by TNF-α and IL-1 ß were shown. Both cytokines activated a series of genes involved in inflammatory, immune response as well as in cell death. In our experimental conditions, TNF-α, in contrast to IL-1 ß, did not induce a significant level of apoptosis in keratinocytes. However, given together both cytokines produced a significant decrease in apoptotic cells and synergistic transcriptional response which was due to the activation of several specific genes occurring after application of each cytokine. TNF-α and IL-1 ß evoked apoptotic effect and transcriptional responses were linked to the stimulation of their specific receptors since a pre-treatment with monoclonal antibodies vs TNF-α and/or IL-1 ß receptors was able to significantly reduce them.
Assuntos
Apoptose/efeitos dos fármacos , Perfilação da Expressão Gênica , Interleucina-1beta/farmacologia , Queratinócitos/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Quimiocinas/biossíntese , Humanos , Queratinócitos/imunologia , Queratinócitos/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Fator de Necrose Tumoral alfa/antagonistas & inibidoresRESUMO
BACKGROUND AND PURPOSE: Reactive oxygen species (ROS) have been postulated to play a crucial role in the pathogenesis of ischaemia-reperfusion injury. Among these, hydrogen peroxide (H(2)O(2)) is known to be a toxic compound responsible for free-radical-dependent neuronal damage. In recent years, however, the 'bad reputation' of H(2)O(2) and other ROS molecules has changed. The aim of this study was to assess the protective role of H(2)O(2) and modification in its endogenous production on the electrophysiological and morphological changes induced by oxygen/glucose deprivation (OGD) on CA1 hippocampal neurons. EXPERIMENTAL APPROACH: Neuroprotective effects of exogenous and endogenous H(2)O(2) were determined using extracellular electrophysiological recordings of field excitatory post synaptic potentials (fEPSPs) and morphological studies in a hippocampal slice preparation. In vitro OGD was delivered by switching to an artificial cerebrospinal fluid solution with no glucose and with oxygen replaced by nitrogen. KEY RESULTS: Neuroprotection against in vitro OGD was observed in slices treated with H(2)O(2) (3 mM). The rescuing action of H(2)O(2) was mediated by catalase as pre-treatment with the catalase inhibitor 3-amino-1,2,4-triazole blocked this effect. More interestingly, we showed that an increase of the endogenous levels of H(2)O(2), due to a combination of an inhibitor of the glutathione peroxidase enzyme and addition of Cu,Zn-superoxide dismutase in the tissue bath, prevented the OGD-induced irreversible depression of fEPSPs. CONCLUSIONS AND IMPLICATIONS: Taken together, our results suggest new possible strategies to lessen the damage produced by a transient brain ischaemia by increasing the endogenous tissue level of H(2)O(2).
Assuntos
Isquemia Encefálica/tratamento farmacológico , Peróxido de Hidrogênio/farmacologia , Fármacos Neuroprotetores/farmacologia , Animais , Isquemia Encefálica/fisiopatologia , Catalase/efeitos dos fármacos , Catalase/metabolismo , Modelos Animais de Doenças , Eletrofisiologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Peróxido de Hidrogênio/metabolismo , Técnicas In Vitro , Masculino , Fármacos Neuroprotetores/metabolismo , Células Piramidais/efeitos dos fármacos , Células Piramidais/patologia , Ratos , Ratos WistarRESUMO
The human immunodeficiency virus type 1 (HIV-1) coat glycoprotein gp120 represents a likely contributor to the development of HIV-1 associated dementia (HAD), a neurological syndrome often observed in AIDS patients and characterised by significant neuronal loss in the neocortex. Since recent studies have highlighted that female sex hormones represent potential neuroprotective agents against damage produced by acute and chronic injuries in the adult brain, we have investigated whether estrogens exert protection in a rat model of gp120 neurotoxicity. Our results demonstrate that systemic administration of 17beta-estradiol (E2, 0.02-0.2 mg/kg) significantly reduces apoptotic cell death observed in the neocortex of rat following subchronic i.c.v. administration of gp120 (100 ng/rat/day). Furthermore, both tamoxifen and ICI182,780, two selective antagonists of estrogen receptors (ER) in the brain, reverted the neuroprotective effect of E2. The molecular mechanism of estrogenic neuroprotection does not appear to involve modulation of the antiapoptotic Bcl-2 or the proapoptotic Bax since we failed to observe changes in the levels of the two proteins in the neocortical tissue after gp120 and/or E2 treatment. However, we detected increased levels of IL-1beta in the neocortex of rats injected with gp120, as early as 6h after drug administration, and this effect was potentiated following pretreatment with E2. Taken together, our results demonstrate that E2 exerts neuroprotection against gp120 neurotoxicity in vivo through a mechanism involving ER activation and, possibly, via modulation of neocortical levels of IL-1beta.
Assuntos
Apoptose/efeitos dos fármacos , Estradiol/farmacologia , Proteína gp120 do Envelope de HIV/toxicidade , Neocórtex/citologia , Neurônios/efeitos dos fármacos , Animais , Western Blotting , Química Encefálica/efeitos dos fármacos , Ensaio de Imunoadsorção Enzimática , Humanos , Marcação In Situ das Extremidades Cortadas , Interleucina-1/metabolismo , Masculino , Neocórtex/efeitos dos fármacos , Neurônios/patologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína X Associada a bcl-2/metabolismoRESUMO
Cocaine, often abused by human immunodeficiency virus (HIV) infected patients, has been suggested to worsen the HIV associated dementia via unknown mechanisms. Here we report that subchronic treatment with a dose of cocaine (30 mg/kg i.p.), unable per se to cause neuronal death, increases the number of apoptotic cells typically observed in the neocortex of rats treated with HIV-1 gp120 (100 ng given i.c.v.). A pre-treatment with MK801 (0.3 mg/kg i.p.), a NMDA receptor antagonist, L-NAME (10 mg/kg i.p.) and 7-nitroindazole (50 mg/kg i.p.), two specific inhibitors of NOS, or with 1400 W (1 mg/kg s.c.), a selective inhibitor of inducible NOS (iNOS), minimized neurotoxicity by combined administration of cocaine and gp120 thus implicating iNOS. This conclusion is supported by the evidence that cocaine increases brain neocortical citrulline, the co-product of NO synthesis.
Assuntos
Apoptose , Cocaína/farmacologia , Proteína gp120 do Envelope de HIV/toxicidade , Neocórtex/patologia , Neurônios/efeitos dos fármacos , Óxido Nítrico Sintase/fisiologia , Anestésicos Locais/farmacologia , Animais , Maleato de Dizocilpina/farmacologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Inibidores Enzimáticos/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Masculino , Neocórtex/efeitos dos fármacos , Neocórtex/fisiopatologia , Neurônios/patologia , Óxido Nítrico Sintase Tipo II , Ratos , Ratos WistarRESUMO
Visual experience during early postnatal life is essential for normal development of synaptic connections in the visual system. In fact, altered visual experiences such as monocular deprivation (MD) or abnormal visual stimulation (e.g. strabismus, anisometropia) during this period disrupt the physiologic organization of the visual pathway, leading to loss of visual responses in cortical neurons and reduction in visual acuity of the affected eye, so that it becomes amblyopic. The authors review the main functional and morphologic changes induced by altered visual experiences in the developing visual system and focus on the recent discovery that MD induces apoptotic cell death in the lateral geniculate nucleus of newborn rats. Particular attention is given to the authors' studies documenting that, during development, MD leads retinal terminals to release excessive glutamate in the lateral geniculate nucleus where it elevates nitric oxide and causes DNA fragmentation. The latter event is known to activate poly-(ADP-ribose) polymerase, which in turn may trigger apoptosis. Better understanding of the mechanisms underlying the morphologic changes induced by altered visual experiences during development may open new venues for studying novel neuroprotective strategies for amblyopia and, more generally, for the treatment of ophthalmic diseases associated with neuronal apoptosis.
Assuntos
Apoptose , Olho/crescimento & desenvolvimento , Plasticidade Neuronal/fisiologia , Vias Visuais/fisiologia , Ambliopia/patologia , Animais , Corpos Geniculados/patologia , Humanos , Privação Sensorial , Visão MonocularRESUMO
The lateral geniculate nucleus (LGN) is the thalamic relay of retinal inputs to the visual cortex. It contains a rich array of brain terminals, which modulate the visual signals to the cortex. Several data have documented that beside cholinergic, GABA-nergic, istaminergic, serotoninergic, and glutamatergic signals, the LGN contains also fibers and interneurons expressing the enzyme that produces nitric oxide (NO). Here, we review the documented physiological roles of NO in the transmission of visual inputs to the cortex and in the processes of activity-dependent refinement of LGN connections. Moreover we focus on the recently suggested role of NO in processes of neurotoxicity in the LGN. Particular relevance is given to studies documenting that, through an excitotoxic cascade, NO triggers apoptosis in the LGN of new-born rats deprived of vision in one eye. Data are also discussed on a possible role of NO in the mechanisms of LGN neuronal loss induced by glaucoma. We believe that a better understanding of the role of NO in the LGN may contribute to discover new experimental strategies for the treatment of degenerative ophthalmic diseases.
Assuntos
Apoptose , Corpos Geniculados/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Óxido Nítrico/metabolismo , Transdução de Sinais , Percepção Visual , Animais , Corpos Geniculados/citologia , Corpos Geniculados/enzimologia , Glaucoma/metabolismo , Glaucoma/patologia , Neurônios/citologia , Óxido Nítrico Sintase/metabolismoRESUMO
The HIV-1 coat protein, gp120 (100 ng given intracerebroventricularly (i.c.v.) daily for seven consecutive days) causes DNA fragmentation in the brain neocortex of rat. In neocortical cells bearing ultrastructural features typical of apoptosis, electron microscopy revealed specific immunopositivity for neurofilament cytoskeletal proteins, suggesting the neuronal nature of dying cells. Neuronal apoptosis by gp120 implicates CXCR4 chemokine receptors; in fact, in rats receiving a single daily, non-neurotoxic, dose of SDF-1alpha (0.25 pmoles given i.c.v. for 7 days before gp120), the natural ligand of CXCR4 receptor, apoptosis was significantly hindered. The mechanism of SDF-1alpha protection involves inhibition of gp120-enhanced expression of IL-1beta, a cytokine implicated in the mechanisms of apoptosis induced by the viral protein in the neocortex of rat.
Assuntos
Complexo AIDS Demência/metabolismo , Apoptose/efeitos dos fármacos , Proteína gp120 do Envelope de HIV/farmacologia , Neocórtex/efeitos dos fármacos , Degeneração Neural/induzido quimicamente , Receptores CXCR4/efeitos dos fármacos , Complexo AIDS Demência/patologia , Complexo AIDS Demência/fisiopatologia , Animais , Apoptose/imunologia , Quimiocina CXCL12 , Quimiocinas CXC/imunologia , Quimiocinas CXC/farmacologia , Relação Dose-Resposta a Droga , Proteína Glial Fibrilar Ácida/metabolismo , Proteína gp120 do Envelope de HIV/imunologia , HIV-1/imunologia , HIV-1/patogenicidade , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Interleucina-1/imunologia , Interleucina-1/metabolismo , Masculino , Microglia/citologia , Microglia/imunologia , Microglia/metabolismo , Microscopia Eletrônica , Neocórtex/patologia , Neocórtex/ultraestrutura , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Proteínas de Neurofilamentos/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/ultraestrutura , Neurotoxinas/imunologia , Neurotoxinas/farmacologia , Ratos , Ratos Wistar , Receptores CXCR4/imunologia , Receptores CXCR4/metabolismoRESUMO
Copper plays a key role in brain development, function and survival. Alteration of its homeostasis is suggested to be an aetiological factor in several neurodegenerative diseases. However, the molecular mechanisms relating copper to neurodegeneration are still unknown. In the present report, using morphological analyses of brain sections of mottled/brindled mutant (Mo(br/y)) mice, the animal model of the human genetic copper deficiency associated with neurodegeneration (Menkes' disease), we demonstrated that a high degree of apoptotic cells is present in the neocortex and in the hippocampus. Biochemical characterisation revealed decreased levels of copper content and of the activity of the mitochondrial copper-dependent enzyme cytochrome c oxidase. Copper, zinc-superoxide dismutase activity also shows a slight decrease, while no change was observed for glutathione content. Lower levels of ATP were also found, indicative of a copper-dependent impairment of energy metabolism. Changes appear to be specific for the brain, since no alterations in the activity of liver enzymes were found, although the level of copper was strongly decreased. We also tested biochemical factors involved in cell commitment to apoptosis. The expression of the anti-apoptotic protein Bcl-2, which plays a fundamental role in brain development and morphogenesis, was dramatically decreased and the levels of cytochrome c released from mitochondria into the cytosol were significantly increased. On the basis of these findings, we propose that down-regulation of Bcl-2 can cause neurodegeneration triggered by mitochondrial damage due to copper depletion during brain development in Mo(br/y) mice.
Assuntos
Apoptose , Encéfalo/patologia , Síndrome dos Cabelos Torcidos/patologia , Degeneração Neural/patologia , Proteínas Proto-Oncogênicas c-bcl-2 , Trifosfato de Adenosina/metabolismo , Animais , Western Blotting , Encéfalo/metabolismo , Cobre/metabolismo , Modelos Animais de Doenças , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Glutationa/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Marcação In Situ das Extremidades Cortadas , Masculino , Síndrome dos Cabelos Torcidos/metabolismo , Camundongos , Camundongos Mutantes , Neocórtex/metabolismo , Neocórtex/patologia , Degeneração Neural/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Superóxido Dismutase/metabolismoRESUMO
In mammals, visual experience during early postnatal life is critical for normal development of the visual system. Here we report that monocular deprivation for 2, 7, and 14 consecutive days causes p53 accumulation, cell death, and progressive loss of neurones in the dorsal lateral geniculate nucleus (dLGN) of newborn rats and these are prevented by NMDA and non-NMDA glutamate receptor antagonists, and by L-NAME, an inhibitor of nitric oxide synthesis. Monocular deprivation also increases dLGN levels of citrulline, the coproduct of nitric oxide synthesis, and this, as well as cell death and neuronal loss, is abolished by antagonists of glutamate receptors and by L-NAME. Finally, poly-(ADP-ribose) polymerase (PARP) knock-out mice appear to be protected from monocular deprivation-induced cell death. In conclusion, during early postnatal development of the rat visual system monocular deprivation causes excitotoxic, nitric oxide-mediated, cell death in the dLGN that appears to be apoptotic and also requires activation of PARP.
Assuntos
Apoptose , Corpos Geniculados/citologia , Ácido Glutâmico/metabolismo , Óxido Nítrico/biossíntese , Poli(ADP-Ribose) Polimerases/metabolismo , Transdução de Sinais , Animais , Animais Recém-Nascidos , Ativação Enzimática , Corpos Geniculados/metabolismo , Imuno-Histoquímica , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Long-Evans , Receptores de Glutamato/metabolismoRESUMO
The effects of a single dose of the HIV-1 coat protein gp120 given into one lateral cerebral ventricle (i.c.v.) on the expression of cyclooxygenase type 2 (COX-2) and PGE(2) levels have been studied using Western blotting and ELISA techniques applied to brain tissue extracts obtained from the neocortex of individual rats, one of the regions of the central nervous system where the viral protein causes apoptosis. The results demonstrate that COX-2 expression is almost doubled 6 h after a single dose (100 ng) of gp120 and this is paralleled by a statistically significant elevation of PGE(2). Enhanced COX-2 expression is implicated in the mechanisms of apoptosis evoked by gp120 because the latter is prevented by NS398 (10 mg/kg i.p.), a selective inhibitor of COX-2 activity. Protection is also afforded by NMDA receptor antagonists, such as MK801 (0.3 mg/kg i.p.) and CGP040116 (10 mg/kg i.p.), and by the free radical scavenger, U-74389G (10 mg/kg i.p.), supporting a glutamate-mediated, excitotoxic, mechanism of apoptotic death induced by gp120. These data together with the observation that MK801 failed to prevent gp120-enhanced COX-2 expression indicate that products of the arachidonic cascade may be responsible for elevation of synaptic glutamate leading neocortical cells to oxidative stress and excitotoxic apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Proteína gp120 do Envelope de HIV/farmacologia , Isoenzimas/biossíntese , Neocórtex/metabolismo , Neocórtex/patologia , Fármacos Neuroprotetores/farmacologia , Pregnatrienos/farmacologia , Prostaglandina-Endoperóxido Sintases/biossíntese , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Animais , Ciclo-Oxigenase 2 , Inibidores de Ciclo-Oxigenase 2 , Inibidores de Ciclo-Oxigenase/farmacologia , Maleato de Dizocilpina/farmacologia , Antagonismo de Drogas , Masculino , Nitrobenzenos/farmacologia , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Sulfonamidas/farmacologiaRESUMO
Injection of paraquat, a redox-cycling compound, into the rat hippocampus produces limbic seizures and hippocampal damage. Here we report that a proportion of the neuronal cell death caused by the herbicide occurs via an apoptotic mechanism which appears to be mediated by oxygen free radicals. Adult male Wistar rats (n=12) received a single dose of paraquat (25 nmol/0.5 microl; 0.5 microl/min rate) and were sacrificed 24 h later. Paraquat caused DNA fragmentation, nuclear chromatin marginalization and compaction in all hippocampal subsectors, 24 h after its injection, as revealed by both the TUNEL procedure and hematoxylin eosin staining of coronal brain tissue sections. Pre-treatment with the free radical scavenger lazaroid U74389G (30 mg/kg given i.p. 30 min beforehand) significantly reduced paraquat-induced apoptosis, but did not protect against non apoptotic neuronal cell loss caused by the herbicide.
Assuntos
Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Herbicidas/administração & dosagem , Hipocampo/efeitos dos fármacos , Paraquat/administração & dosagem , Pregnatrienos/farmacologia , Animais , Fragmentação do DNA , Sequestradores de Radicais Livres , Herbicidas/farmacologia , Injeções , Masculino , Paraquat/farmacologia , Ratos , Ratos WistarRESUMO
Administration of tacrine (5 mg/kg i.p.), an anticholinesterase agent, in rats pretreated (24 h beforehand) with lithium chloride (LiCl; 12 mEq/kg i.p.) enhances the expression of neuronal nitric oxide (NO) synthase (NOS), increases NO, and causes seizures and hippocampal damage. Here we report immunohistochemistry evidence showing that in rat LiCl and tacrine enhance the expression of cyclooxygenase type 2 (COX-2) enzyme protein in the dorsal hippocampus and elevate brain PGE2 content during the preconvulsive period. The latter effect, but not enhanced COX-2 expression, is inhibited by previous (30 min before tacrine) administration of N omega-nitro-L-arginine-methyl ester (L-NAME; 10 mg/kg i.p.), an inhibitor of NO synthesis, thus implicating NO in the mechanism of stimulation of COX activity leading to elevation of brain PGE2 content. Indomethacin (10 mg/kg given i.p. 30 min before tacrine), an inhibitor of COX activity, prevented brain PGE2 elevation and abolished the expression of seizures and hippocampal damage thus supporting a role for this metabolite of the arachidonic acid cascade in the mechanisms of LiCl and tacrine-evoked neurotoxicity in rat.
Assuntos
Dinoprostona/metabolismo , Hipocampo/efeitos dos fármacos , Indometacina/farmacologia , Cloreto de Lítio/toxicidade , NG-Nitroarginina Metil Éster/farmacologia , Neurônios/fisiologia , Óxido Nítrico Sintase/biossíntese , Convulsões/prevenção & controle , Tacrina/toxicidade , Animais , Inibidores da Colinesterase/toxicidade , Ciclo-Oxigenase 2 , Indução Enzimática/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Isoenzimas/metabolismo , Cinética , Masculino , Neurônios/efeitos dos fármacos , Neurônios/patologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , Convulsões/metabolismoRESUMO
The epileptogenic and neurodegenerative effects of dendrotoxin K (DTx-K), from Dendroaspis polylepsis, a specific blocker of a noninactivating, voltage-sensitive K+ channel, were studied after focal injection into one dorsal hippocampus in rats pretreated with the 21-aminosteriod U-74389G, a scavenger of free oxygen radicals. Administration of 35 pmol DTx-K elicited in all of the treated animals (n = 6) motor seizures and bilateral electrocortical (ECoG) discharges after a latent period of approximately 5 min. At 24 h, histological examination of brain (n = 6) coronal sections (10 microns; n = 6 per brain) detected bilateral damage to the hippocampal formation. Quantitation of damage revealed significant bilateral neuronal cell loss in the CA1 and CA4 pyramidal cell layer and dentate gyrus granule cell layer relative to the corresponding brain regions of rats (n = 6) injected with bovine serum albumin (300 ng), which per se was ineffective in all respects. DTx-K (35 pmol) also caused a significant loss of CA3 pyramidal neurons ipsilateral to the site of toxin injection. Systemic (i.p.) administration of U-74389G (5 mg/kg given 30 min beforehand) delayed the onset of motor and ECoG seizures and reduced the number of epileptogenic discharges typically observed in rats receiving an injection of DTx-K (35 pmol) alone. Similarly, this treatment prevented the damage inflicted to the hippocampus by the toxin and in no instance was significant neuronal loss observed. At variance with these results, pretreatment with U-74389G (up to 10 mg/kg i.p.) failed to prevent seizures and CA1 hippocampal damage evoked by intra-hippocampal injection of alpha-DTx (35 pmol), a DTx-K homologue which preferentially inhibits a slowly inactivating, voltage-dependent K+ conductance in nerve cells. In conclusion, the present data support a role for free oxygen radicals in mediating hippocampal damage induced by DTx-K, but not alpha-DTx, and confirm the original deduction that these DTx homologues are complementary neurobiological tools to study mechanisms of seizures and neuronal death.
Assuntos
Antioxidantes/farmacologia , Hipocampo/efeitos dos fármacos , Peptídeos/farmacologia , Pregnatrienos/farmacologia , Convulsões/induzido quimicamente , Convulsões/prevenção & controle , Animais , Córtex Cerebral/fisiopatologia , Eletroencefalografia , Hipocampo/patologia , Masculino , Ratos , Ratos Wistar , Convulsões/fisiopatologiaRESUMO
Mono or binocular deprivation, during early postnatal development, produces dramatic effects on the anatomy and physiology of the visual system. Here we report that dark exposure induces apoptotic cell death in the lateral geniculate nucleus (LGN) of adult rabbit and this may be related to activation of N-methyl-D-aspartate (NMDA) and non-NMDA subtypes of glutamate receptors. In situ DNA fragmentation (TUNEL) was observed in the LGN of rabbits exposed to dark for 48 h. Morphological changes were confirmed on hematoxylin-eosin stained brain tissue coronal sections. Systemic treatment with CGP 040116 or MK 801, two NMDA receptor antagonists, and with GYKI 52466, a non-NMDA receptor antagonist, prevented in situ DNA fragmentation and nuclear chromatin marginalization and condensation. In no instance was apoptosis seen in rabbits kept under a normal light-dark cycle. Our findings indicate that glutamate, acting on NMDA and non-NMDA receptors, may be involved in the mechanisms of apoptotic cell death induced in the LGN of adult rabbits exposed to darkness.
Assuntos
Ansiolíticos , Apoptose/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Corpos Geniculados/citologia , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Animais , Benzodiazepinas/farmacologia , Biotina , Fragmentação do DNA , Escuridão , Nucleotídeos de Desoxiuracil , Maleato de Dizocilpina/farmacologia , Corpos Geniculados/crescimento & desenvolvimento , Masculino , Coelhos , Coloração e Rotulagem , Visão Monocular/fisiologiaRESUMO
Exposure of adult rabbits to darkness for 48 h produces bilateral DNA fragmentation in the lateral geniculate nucleus as revealed in brain sections by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) technique, suggesting an apoptotic type of cell death. In agreement with the latter deduction, light microscopy assessment of the morphological characteristics showed marginalization and condensation of nuclear chromatin, typical features of apoptosis. These effects were abolished by systemic administration of N omega-nitro-L-arginine methyl ester, an inhibitor of nitric oxide (NO) synthesis, whereas the D isomer was ineffective. In conclusion, the present data demonstrate that light deprivation for 48 h produces apoptosis in the lateral geniculate nucleus of rabbit and suggest that NO might be involved.