M.E. Flores-Soto

Proinflammatory cytokines and apoptosis following glutamate-induced excitotoxicity mediated by p38 MAPK in the hippocampus of neonatal rats

The proinflammatory cytokines TNF-alpha, IL-1beta, and IL-6 rise during neuronal damage and activate the apoptotic mitogen-activated protein kinase p38. We studied apoptosis, the levels of TNF-alpha, IL-1beta, and IL-6, and the cell type producing TNF-alpha in rats at 8, 10, and 14 days of age after neonatal exposure to glutamate, which induces neuronal damage. TNF-alpha production was significantly increased by glutamate, but inhibited by SB203580 (a p38 inhibitor). TNF-alpha, IL-1beta, and IL-6 mRNA levels increased, but SB203580 did not modify their expression. Thus, the p38 signaling pathway influences the expression of inflammatory genes and its inhibition may offer anti-inflammatory therapy.

Expression of HIF-1α, VEGF and EPO in peripheral blood from patients with two cardiac abnormalities associated with hypoxia

OBJECTIVES HIF-1 alpha (hypoxia-inducible factor-1 alpha) mediates the responses of mammalian cells to hypoxia/ischemia by inducing the expression of adaptive gene products (e.g., vascular endothelial growth factor (VEGF) and erythropoietin (EPO)). Persistent pulmonary hypertension of the newborn (PPHN) and cyanotic congenital heart disease (CCHD) are common neonatal diseases considered as paradigms of hypoxemia. Since the expression HIF-1 alpha, VEGF and EPO in newborns diagnosed with these diseases has yet to be studied, we set out to define the expression of these genes in peripheral blood from newborn infants diagnosed with PPHN and CCHD. DESIGN AND METHODS The mRNA transcripts encoding HIF-1 alpha, VEGF and EPO were measured by RT-PCR in healthy newborn infants and infants diagnosed with PPHN and CCHD. RESULTS An important increase in HIF-1 alpha expression was observed in both pathological conditions, accompanied by significant increases in VEGF and EPO expression when compared to healthy infants. CONCLUSIONS HIF-1 alpha mRNA expression increases in newborn infants with PPHN or CCHD, as does the expression of its target genes VEGF and EPO.

Role of p38 MAPK and pro-inflammatory cytokines expression in glutamate-induced neuronal death of neonatal rats.

Pro‐inflammatory cytokines TNF‐α, IL‐1β and IL‐6 rises significantly during neuronal damage and activate the signaling p38 MAPK pathway, which is involved in the apoptotic (AP) neuronal death. Systemic administration of glutamate as monosodium salt (MSG) to newborn animals induces neuronal death, however whether neurons die by AP or necrosis through MAPK p38 pathway activation it is unknown. In this study, TNF‐α, IL‐1β and IL‐6 expression levels, AP neuronal death and cellular type that produces TNF‐α was also identified in the cerebral cortex (CC) and striatum (St) of rats at 8, 10, and 14 days of age after neonatal exposure to MSG. TNF‐α production and AP neuronal death was significantly increased in the CC at PD8–10, and in the St in all ages studied by excitotoxicity effect induced with MSG. This effect was completely inhibited by SB203580 (p38 inhibitor) in both regions studied. TNF‐α, IL‐1β and IL‐6 RNAm increased after MSG administration, whereas SB203580 did not modify their expression. These data indicates that neuronal death induced by excitotoxicity appears to be mediated through p38 signaling pathway activated by TNF‐α and their inhibition may have an important neuroprotective role as part of anti‐inflammatory therapeutic strategy.

Estructura y función de las subunidades del receptor a glutamato tipo NMDA

INTRODUCTION To review the physiology of the glutamate receptor subunits such as N-methyl-D-aspartate (NMDA). DEVELOPMENT Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system which interacts with two types classified into two types: metabotropic and ionotropic. Ionotropic receptors are classified according to the affinity of their specific agonists: N-methyl-D-aspartate (NMDA), α-amino acid-3-hydroxy-5-methyl-4-isoxazole (AMPA) and kainic acid (KA). NMDA receptors are macromolecular structures that are formed by different combinations of subunits, NMDAR1 (NR1), NMDAR2 (NR2) and NMDAR3 (NR3) CONCLUSIONS The study of this receptor has been of great interest due to its role in synaptic plasticity, but mainly due to the permeability it has to Ca(++) ion. This review examines the molecular composition of NMDA receptor and the variants of NR1 subunit edition in association with NR2 subunit dimer, the main form of this receptor. The composition, structure and function and their distinct expression patterns in both time and space, has shown the versatility and diversity of functionally different isoforms of the NR1 subunit and various pharmacological properties of the NR2 subunit.

Plastic changes in dendritic spines of hippocampal CA1 pyramidal neurons from ovariectomized rats after estradiol treatment

Cognitive impairment or its recovery has been associated with the absence or reestablishment of estrogenic actions in the central nervous system of female experimental animals or women. It has been proposed that these cognitive phenomena are related to estrogen-mediated modulatory activity of synaptic transmission in brain structures involved in cognitive functions. In the present work a morphological study was conducted in adult female ovariectomized rats to evaluate estradiol-dependent dendritic spine sprouting in hippocampal pyramidal neurons, and changes in the presynaptic marker synaptophysin. Three or ten days after estradiol treatment (10 μg/day, twice) in the ovariectomized rats, a significant increase of synaptophysin was observed, which was coincident with a significant higher numerical density of thin (22%), stubby (36%), mushroom (47%) and double spines (125%), at day 3, without significant changes of spine density at day 10, after treatment. These results may be interpreted as evidence of pre- and postsynaptic plastic events that may be involved in the modulation of cognitive-related behavioral performance after estrogen replacement therapy.

HIF-1α expression in the hippocampus and peripheral macrophages after glutamate-induced excitotoxicity.

Hypoxia-inducible factor-1 alpha (HIF-1α) is a master transcription factor that regulates the response to hypoxia and ischemia and induces the expression of various genes, including vascular endothelial growth factor (VEGF) and erythropoietin (EPO). This study shows the systemic response of increased HIF-1α, EPO, and VEGF mRNA and protein. In addition, VEGF expression was increased in neurons and over-expressed in glial cells in a model of neuroexcitotoxicity in the hippocampus, in which rats were neonatally exposed to high glutamate concentrations. Simultaneous increases in HIF-1α, EPO and VEGF mRNA in peritoneal macrophages were also observed. Our study is consistent with the hypothesis that these genes exert a protective effect in response to neurotoxicity.

Neural restrictive silencer factor and choline acetyltransferase expression in cerebral tissue of Alzheimer's Disease patients: a pilot study

Decreased Choline Acetyltransferase (ChAT) brain level is one of the main biochemical disorders in Alzheimer’s Disease (AD). In rodents, recent data show that the CHAT gene can be regulated by a neural restrictive silencer factor (NRSF). The aim of the present work was to evaluate the gene and protein expression of CHAT and NRSF in frontal, temporal, entorhinal and parietal cortices of AD patient brains. Four brains from patients with AD and four brains from subjects without dementia were studied. Cerebral tissues were obtained and processed by the guanidine isothiocyanate method for RNA extraction. CHAT and NRSF gene and protein expression were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. CHAT gene expression levels were 39% lower in AD patients as compared to the control group (p < 0.05, U test). ChAT protein levels were reduced by 17% (p = 0.02, U test). NRSF gene expression levels were 86% higher in the AD group (p = 0.001, U test) as compared to the control group. In the AD subjects, the NRSF protein levels were 57% higher (p > 0.05, U test) than in the control subjects. These findings suggest for the first time that in the brain of AD patients high NRSF protein levels are related to low CHAT gene expression levels.

Natural polymorphisms and unusual mutations in HIV-1 protease with potential antiretroviral resistance: a bioinformatic analysis

BackgroundThe correlations of genotypic and phenotypic tests with treatment, clinical history and the significance of mutations in viruses of HIV-infected patients are used to establish resistance mutations to protease inhibitors (PIs). Emerging mutations in human immunodeficiency virus type 1 (HIV-1) protease confer resistance to PIs by inducing structural changes at the ligand interaction site. The aim of this study was to establish an in silico structural relationship between natural HIV-1 polymorphisms and unusual HIV-1 mutations that confer resistance to PIs.ResultsProtease sequences isolated from 151 Mexican HIV-1 patients that were naïve to, or subjected to antiretroviral therapy, were examined. We identified 41 unrelated resistance mutations with a prevalence greater than 1%. Among these mutations, nine exhibited positive selection, three were natural polymorphisms (L63S/V/H) in a codon associated with drug resistance, and six were unusual mutations (L5F, D29V, L63R/G, P79L and T91V). The D29V mutation, with a prevalence of 1.32% in the studied population, was only found in patients treated with antiretroviral drugs. Using in silico modelling, we observed that D29V formed unstable protease complexes when were docked with lopinavir, saquinavir, darunavir, tipranavir, indinavir and atazanavir.ConclusionsThe structural correlation of natural polymorphisms and unusual mutations with drug resistance is useful for the identification of HIV-1 variants with potential resistance to PIs. The D29V mutation likely confers a selection advantage in viruses; however, in silico, presence of this mutation results in unstable enzyme/PI complexes, that possibly induce resistance to PIs.

Proinflammatory Cytokines, Enolase and S-100 as Early Biochemical Indicators of Hypoxic-Ischemic Encephalopathy Following Perinatal Asphyxia in Newborns

BACKGROUND Estimation of the neurological prognosis of infants suffering from perinatal asphyxia and signs of hypoxic-ischemic encephalopathy is of great clinical importance; however, it remains difficult to satisfactorily assess these signs with current standard medical practices. Prognoses are typically based on data obtained from clinical examinations and neurological tests, such as electroencephalography (EEG) and neuroimaging, but their sensitivities and specificities are far from optimal, and they do not always reliably predict future neurological sequelae. In an attempt to improve prognostic estimates, neurological research envisaged various biochemical markers detectable in the umbilical cord blood of newborns (NB). Few studies examining these biochemical factors in the whole blood of newborns exist. Thus, the aim of this study was to determine the expression and concentrations of proinflammatory cytokines (TNF-α, IL-1β and IL-6) and specific CNS enzymes (S-100 and enolase) in infants with perinatal asphyxia. These data were compared between the affected infants and controls and were related to the degree of HIE to determine their utilities as biochemical markers for early diagnosis and prognosis. METHODS The levels of the proinflammatory cytokines and enzymes were measured by enzyme-linked immunosorbent assay (ELISA) and Reverse Transcription polymerase chain reaction (RT-PCR). RESULTS The expression and serum levels of the proinflammatory cytokines, enolase and S-100 were significantly increased in the children with asphyxia compared with the controls. CONCLUSION The role of cytokines after hypoxic-ischemic insult has been determined in studies of transgenic mice that support the use of these molecules as candidate biomarkers. Similarly, S-100 and enolase are considered promising candidates because these markers have been correlated with tissue damage in different experimental models.

Prophylactic Role of Oral Melatonin Administration on Neurogenesis in Adult Balb/C Mice during REM Sleep Deprivation

Purpose. The aim of this study was to assess the effect of melatonin in the proliferation of neural progenitors, melatonin concentration, and antiapoptotic proteins in the hippocampus of adult mice exposed to 96 h REM sleep deprivation (REMSD) prophylactic administration of melatonin for 14 days. Material and Methods. Five groups of Balb/C mice were used: (1) control, (2) REMSD, (3) melatonin (10 mg/kg) plus REMSD, (4) melatonin and intraperitoneal luzindole (once a day at 5 mg/kg) plus REMSD, and (5) luzindole plus REMSD. To measure melatonin content in hippocampal tissue we used HPLC. Bcl-2 and Bcl-xL proteins were measured by Western Blot and neurogenesis was determined by injecting 5-bromo-2-deoxyuridine (BrdU) and BrdU/nestin expressing cells in the subgranular zone of the dentate gyrus were quantified by epifluorescence. Results. The melatonin-treated REMSD group showed an increased neural precursor in 44% with respect to the REMSD group and in 28% when contrasted with the control group (P < 0.021). The melatonin-treated REMSD group also showed the highest expression of Bcl-2 and Bcl-xL as compared to the rest of the groups. Conclusion. The exogenous administration of melatonin restores the tissue levels of sleep-deprived group and appears to be an efficient neuroprotective agent against the deleterious effects of REMSD.