RESUMEN
It has been shown recently that Bay X 3702 ((-)-(R)-2-[4-[[(3,4-dihydro-2H-1-benzopyran-2-yl)methyl]amino]butyl]-1, 2,-benzisothiazol-3(2H)-one 1,1-dioxide monohydrochloride), a highly potent and selective 5-HT1A receptor agonist, has a neuroprotective potency associated with its ability to inhibit ischemia-induced excessive release of glutamate. 5-HT1A receptors are highly expressed in brain areas, such as the hippocampus and the cerebral cortex, sensitive to neuronal damage induced by ischemic stroke or brain trauma. Therefore, we investigated whether Bay X 3702 can rescue cultured hippocampal neurons subjected to excitotoxic damage. The hippocampal neurons exposed to 0.5 mM L-glutamate for 1 h had pronounced damage characteristic of neuronal necrosis as evaluated 18 h later by trypan blue staining and morphological criteria. However, treatment with Bay X 3702 (0.001 to 1 microM) reduced the number of damaged neurons, and preserved cell morphology and integrity of the neuronal network. Bay X 3702 was added immediately after the end of exposure to glutamate and was present until the evaluation of neuronal damage. Furthermore, the neuroprotective activity of Bay X 3702 (0.1 microM) was abolished by WAY 100635 (N-[2-[4-(methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl cyclo-hexanecarboxamide) (1 microM), a selective 5-HT1A receptor antagonist, indicating that the neurorescuing activity of Bay X 3702 was mediated via stimulation of 5-HT1A receptors. Additionally, we attempted to find whether the drug could protect rat brain tissue from ischemic insult due to permanent occlusion of the middle cerebral artery in rats. Bay X 3702 (12 and 40 microg/kg), infused within a period of 4 h, immediately after induction of ischemia greatly reduced cortical infarct volume (57 and 55% of controls, respectively) suggesting that this drug might be useful for the treatment of acute cerebral infarction.
Asunto(s)
Benzopiranos/farmacología , Encéfalo/efectos de los fármacos , Agonistas de Receptores de Serotonina/farmacología , Tiazoles/farmacología , Animales , Benzopiranos/uso terapéutico , Encéfalo/metabolismo , Encéfalo/patología , Isquemia Encefálica/metabolismo , Isquemia Encefálica/prevención & control , Muerte Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Infarto Cerebral/tratamiento farmacológico , Infarto Cerebral/patología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Ácido Glutámico/efectos adversos , Hipocampo/citología , Hipocampo/efectos de los fármacos , Masculino , Neuronas/citología , Neuronas/efectos de los fármacos , Ratas , Ratas Endogámicas F344 , Ratas Long-Evans , Agonistas de Receptores de Serotonina/uso terapéutico , Tiazoles/uso terapéuticoRESUMEN
There is increasing evidence that microglia serve as antigen presenters in the human CNS. Although the occurrence of MHC class II immunoreactive cells has been reported in astrocytic gliomas, the relative contribution of microglia to this cell population has not been studied in detail. Using computer-assisted image analysis, we have investigated the expression of MHC class II molecules and of the microglia/macrophage markers Ki-MIP, RCA-1, KP1 and iba1, in 97 astrocytic gliomas comprising all WHO grades to answer the question whether there is a correlation between tumour grade and the number of MHC class II positive microglia/macrophage profiles. Microglia expressing MHC class II were common in astrocytomas and anaplastic astrocytomas but rare in pilocytic tumours although there was significant variation within each group. MHC class II immunoreactivity was reduced in highly cellular areas of glioblastomas where large numbers of cells expressing macrophage markers were still present. Thus, there was no simple relationship between tumour grade and microglial/macrophage MHC class II expression. In addition, up to 55% of astrocytic gliomas contained MHC class II immunoreactive tumour cells. Microglia but not tumour cells were found to express the BB1/B7 costimulator. We conclude that microglia in astrocytic gliomas are well equipped to function as antigen presenting cells. Yet, neoplastic astroglia appear to acquire the capacity to downregulate microglial MHC class II expression and, at the same time, may induce T-cell clonal anergy through aberrant expression of MHC class II molecules.
Asunto(s)
Astrocitos/fisiología , Regulación Neoplásica de la Expresión Génica/inmunología , Glioblastoma/inmunología , Antígenos de Histocompatibilidad Clase II/genética , Presentación de Antígeno/inmunología , Biopsia , Glioblastoma/patología , Glioblastoma/terapia , Humanos , Inmunoterapia , Macrófagos/inmunología , Adhesión en Parafina , Linfocitos T/inmunologíaRESUMEN
Previously reported effects of lubeluzole, such as inhibition of glutamate release, inhibition of nitric oxide (NO) synthesis and blockage of voltage-gated Na+- and Ca2+-ion channels, suggest a neuroprotective action of this drug. Here we report about the effects of lubeluzole and its R-isomer on glutamate-induced neuronal cell death in mixed hippocampal cultures. In addition, we studied the effect of lubeluzole in focal cerebral ischemia models in mice and rats. In hippocampal cultures exposed to 500 nM glutamate for 1 h, lubeluzole (0.1-100 nM), but not the R-isomer (1-100 nM), reduced the percentage of damaged neurons from 42 +/- 8% to 18 +/- 7% (P < 0.01). In mice and rats, lubeluzole reduced ischemic brain damage, when administered immediately after middle cerebral artery occlusion. Interestingly, the protective effect (reduction of the infarct volume in rats to 77% of control; P < 0.01) was also found when the lubeluzole treatment (2.5 mg/kg) was started 3 h after ischemia. Especially this latter effect suggests that lubeluzole will be a useful drug for stroke therapy.
Asunto(s)
Isquemia Encefálica/tratamiento farmacológico , Aminoácidos Excitadores/antagonistas & inhibidores , Hipocampo/efectos de los fármacos , Neuronas/efectos de los fármacos , Fármacos Neuroprotectores/uso terapéutico , Piperidinas/uso terapéutico , Tiazoles/uso terapéutico , Animales , Animales Recién Nacidos , Astrocitos/efectos de los fármacos , Isquemia Encefálica/patología , Células Cultivadas , Aminoácidos Excitadores/toxicidad , Ácido Glutámico/toxicidad , Hipocampo/citología , Masculino , Ratones , Ratas , Ratas Endogámicas F344 , EstereoisomerismoRESUMEN
It has been previously demonstrated that selegiline, an irreversible monoamine oxidase B (MAO-B) inhibitor, potentiates glial reaction to injury and possesses some 'trophic-like' activities which do not depend on the inhibition of MAO-B and which are probably associated with the induction of astrocyte-derived neurotrophic substances. Based on these findings, we tried to find out whether selegiline is able to modify the expression of nerve growth factor (NGF) and to protect central nervous system (CNS) neurons from excitotoxic and ischemic damage. Selegiline (10 pM-1 nM) induced NGF messenger RNA (mRNA) expression in cultured rat cortical astrocytes as determined by reverse transcription-polymerase chain reaction (RT-PCR) followed by a corresponding increase in NGF protein content measured by two-site NGF-enzyme-linked immunosorbent assay (ELISA) in astrocyte-conditioned medium. Additionally, exposure of hippocampal cultures containing neuronal and glial cells to this drug at the same concentrations enhanced significantly the content of NGF measured in the culture medium after 6 h of incubation. We hypothesize that selegiline could rescue hippocampal neurons from injury by induction of astrocyte-derived NGF in this cell culture system. To test this hypothesis, an excitotoxic damage was induced in the same type of cells by exposure to 0.5 mM L-glutamate for 1 h. Selegiline (10 pM-1 nM) present in the growth medium 6 h before until 18 h after induction of injury (the point of glutamate-toxicity measurement) protected hippocampal neurons from excitotoxic death. Furthermore, administered intraperitoneally (i.p.) (8 x 15 mg/kg per day) this drug enhanced the expression of NGF message in intact rat cerebral cortex and protected rat cortical tissue from ischemic insult due to permanent occlusion of the middle cerebral artery (MCA). The neuroprotective activity of selegiline (5 x 10 mg/kg per day i.p.) was also demonstrated in a mouse model of focal cerebral ischemia. The present data show that selegiline induced NGF expression in cultured rat cortical astrocytes. In mixed primary cultures of hippocampal neuronal and glial cells, selegiline increased NGF protein content and protected hippocampal neurons from excitotoxic degeneration. In vivo, this drug induced NGF gene expression in cerebral cortex from intact rats and protected rat and mouse cortical tissue from ischemic insult after occlusion of the MCA. Our results indicate that the induction of astrocyte-derived NGF could contribute to the neuroprotective activity of selegiline demonstrated both in vivo and in vitro and can explain, in part, the 'trophic-like' properties of this compound which has been observed by others.
Asunto(s)
Astrocitos/efectos de los fármacos , Corteza Cerebral/efectos de los fármacos , Factores de Crecimiento Nervioso/biosíntesis , Neuronas/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Selegilina/farmacología , Animales , Animales Recién Nacidos , Astrocitos/química , Astrocitos/metabolismo , Isquemia Encefálica/prevención & control , Células Cultivadas , Corteza Cerebral/química , Corteza Cerebral/metabolismo , Ácido Glutámico , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Inmunohistoquímica , Masculino , Ratones , ARN Mensajero/análisis , Ratas , Ratas Endogámicas F344RESUMEN
The purpose of this study was to investigate whether alpha-lipoic acid (LA), the oxidized form of the radical scavenger dihydrolipoic acid (DLA), protected brain tissue against ischemic damage and whether there were differences in the neuroprotective potencies between its enantiomers. We used the models of focal cerebral ischemia in mice and rats. The infarct area on the mouse brain surface and the infarct volume of the rat brain were determined by means of an image analyzing system. The LA was capable of reducing the infarct area only when it was administered subcutaneously, but not when it was administered intraperitoneally or into the cisterna magna. Both the R- and the S-enantiomer of LA protected brain tissue against ischemic damage, but their protective activities seemed to be related to the time period of pretreatment. In mice, both enantiomers revealed a similar neuroprotective potency when they were administered subcutaneously 1 or 2 hr before occlusion of the middle cerebral artery (MCA), whereas a longer time period of pretreatment (4 or 6 hr) failed to exert neuroprotection. In rats, subcutaneous pretreatment with R- or S-LA for 2 hr before ischemia significantly diminished the infarct volume. We assume that LA has to be reduced to DLA which finally causes neuroprotection.