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Alzheimer’s Disease (AD) is a slow-developing neurodegenerative disorder in which the main pathogenic
role has been assigned to β-amyloid protein (Aβ) that accumulates in extracellular plaques. The mechanism
of action of Aβ has been deeply analyzed and several membrane structures have been identified as potential mediators
of its effect. The ability of Aβ to modify neuronal activity, receptor expression, signaling pathways, mitochondrial
function, and involvement of glial cells have been analyzed. In addition, extensive literature deals with
the involvement of oxidative stress in Aβ effects. Herein we focus more specifically on the reciprocal regulation
of Aβ, that causes oxidative stress, that favors Aβ aggregation and toxicity and negatively affects the peptide
clearance. Analysis of this strict interaction may offer novel opportunities for therapeutic intervention. Both
common and new molecules endowed with antioxidant properties deserve attention in this regard.
Carnosine (β-alanyl-L-histidine) is a naturally occurring endogenous peptide widely distributed in excitable tissues such as the brain. This dipeptide possesses well-demonstrated antioxidant, anti-inflammatory, and anti-aggregation properties, and it may be useful for treatment of pathologies characterized by oxidative stress and energy unbalance such as depression and Alzheimer’s disease (AD). Microglia, the brain-resident macrophages, are involved in different physiological brain activities such synaptic plasticity and neurogenesis, but their dysregulation has been linked to the pathogenesis of numerous diseases. In AD brain, the activation of microglia towards a pro-oxidant and pro-inflammatory phenotype has found in an early phase of cognitive decline, reason why new pharmacological targets related to microglia activation are of great importance to develop innovative therapeutic strategies. In particular, microglia represent a common model of lipopolysaccharides (LPS)-induced activation to identify novel pharmacological targets for depression and AD and numerous studies have linked the impairment of energy metabolism, including ATP dyshomeostasis, to the onset of depressive episodes. In the present study, we first investigated the toxic potential of LPS + ATP in the absence or presence of carnosine. Our studies were carried out on human microglia (HMC3 cell line) in which LPS + ATP combination has shown the ability to promote cell death, oxidative stress, and inflammation. Additionally, to shed more light on the molecular mechanisms underlying the protective effect of carnosine, its ability to modulate reactive oxygen species production and the variation of parameters representative of cellular energy metabolism was evaluated by microchip electrophoresis coupled to laser-induced fluorescence and high performance liquid chromatography, respectively. In our experimental conditions, carnosine prevented LPS + ATP-induced cell death and oxidative stress, also completely restoring basal energy metabolism in human HMC3 microglia. Our results suggest a therapeutic potential of carnosine as a new pharmacological tool in the context of multifactorial disorders characterize by neuroinflammatory phenomena including depression and AD.
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