Abstract
The comprehension of the mechanisms at the basis of astrocytic dysfunction in ALS is crucial to limit neuronal injury. Most of the toxic astrocytic effects highlight the role of intracellular calcium. S100B is a Ca2+-binding protein particularly present in astrocytes, behaving as a neuroinflammatory mediator as it is secreted by astrocytes under pathological conditions and can display paracrine toxicity by binding to RAGE. During ALS progression S100B increases in patient astrocytes and, in a rat model of the disease, S100B is augmented in “aberrant astrocytes”, characterized by their neurotoxic potential. The induction of S100B in astrocytes, its release and its interaction with RAGE in motoneurons could represent a hazardous mechanism that takes place during ALS. Main objectives of this work were to investigate 1) if the expression of S100B protein and RAGE change during the course of the disease in rodent models of ALS, 2) if the expression of mutant SOD1 protein per se is sufficient to modify S100B levels in astrocytic cultures. We observed that S100B levels and localization are modulated in the spinal cord and in the brain cortex of rat and mouse models of ALS. We also demonstrated a differential expression of RAGE subunits in SOD1-G93A-derived CNS tissues. Moreover, we showed that the overexpression of mutant SOD1 in astrocytic cell line is sufficient to increase the intracellular levels and release of S100B, while it is not enough to induce a differential expression of RAGE. Thus, the expression of mutant SOD1 interferes with the physiological expression of S100B and RAGE and reveals that in astrocytes S100B modulation is an early event related to the mere expression of mutant SOD1, while the dysregulation of RAGE might be a phenomenon possibly requiring a more complex interplay between different cell types and pathways. Overall, these data suggest that S100B might be a toxic mediator released by astrocytes in the ALS-linked neuroinflammatory process.
Highlights
Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by progressive dementia
The results of the present study indicate that development of the neuronal hypoxic tolerance induced by the three-trial, in contrast to one-trial, mild hypoxic preconditioning is apparently largely associated with the activation of CREB, as well as brain-derived neurotrophic factor (BDNF) and Bcl-2 overexpression
No significant differences in serum level of Solubile form of RAGE (sRAGE) where found between rapidly progressing and slow progressing subgroup of multiple sclerosis (MS) patients.Our results suggest for the role of sRAGE in MS ethiopathogenesis, but we did not find any association of sRAGE in serum with the rate of MS disability progression
Summary
Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by progressive dementia. The aim of the study was to characterize the effects of streptozocin (STZ)-indced diabetes on learning and memory of 5XFAD and wild-type (WT) mice in Morris water maze (MWM) at ages 2 and 6 months and on brain amyloid load. Existing evidence suggests GABAergic system is involved in pathophysiology of Alzheimer’s disease (AD) via inhibitory interneuron deficits (Verret et al, 2012) and decrease in functional GABAA receptors (Limon et al, 2012). Our concept: low doses of muscimol may prevent learning/memory deficits in intracerebroventricular (icv) streptozocin (STZ)-induced AD nontransgenic rat model. The Sigma-1 receptor is a chaperone protein that modulates intracellular calcium signalling of the endoplasmatic reticulum and is involved in learning and memory processes.The aim of the present study was to compare in vitro Ca2+ concentration modulating activity and in vivo behavioural effects of enantiomers of methylphenylpiracetam, a novel positive allosteric modulator of Sigma-1 receptors
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