The role of leucine in the modulation of beta amyloid peptide activity in SH-SY5Y cells

Author(s)

Fabio Medici Lorenzeti

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola de Educação Física e Esportes (EEFE/BT)
• Defense date: 2014-12-04

Examining board members

Antonio Herbert Lancha Junior; Waldecir Paula Lima

• Advisor: Antonio Herbert Lancha Junior

Abstract

Studies demonstrate that induction of oxidative stress by beta amyloid peptide (A?) plays an important role in triggering neuronal excitotoxicity which can result in the development of neurodegenerative diseases. The formation of A? peptide are due to changes in the amyloid precursor protein (APP) which is cleaved to form the peptide A?. On the other hand, the mechanisms of action of A? in the C.N.S. occur through signaling of the NMDA (N-methyl-D-aspartate) receptor that when activated by glutamate plays an important physiological role in the C.N.S., as has inotropic activity that allows the influx of Na+ and Ca2+ into the neuronal cells, assisting in procedures of memory formation and learning. However, despite its physiological role, the excessive activation of the NMDA receptor is strongly correlated with C.N.S. lesions due to excess permeability of Ca2+ ions into the cytosol of neuronal cells. Thus the concentrations of glutamate in the synaptic cleft are strictly controlled so that there is excessive activation of receptors with glutamatergic activity, as the NMDA receptor. Studies indicate that the transport of glutamine/glutamate across the blood brain barrier is lower than that of other amino acids, of which about 25% to 30% of the amino acid transport blood vessels to the brain through the blood brain barrier is occupied by leucine this being one largely responsible for the synthesis of glutamate/glutamine in the C.N.S. Thus, studies have shown that diets enriched in branched chain amino acids, including leucine, are responsible for altering the metabolism of glutamate and excitotoxic increase susceptibility to neural cells. To test this hypothesis we used a cell culture model of human neuroblastoma and carry out the treatment with different concentrations of leucine associated with the processing of amyloid-beta peptide. We performed analysis of cytotoxicity (LDH), cell viability (MTT assay) and apoptosis using flow cytometry (Annexin V staining with PE and 7-AAD). Our results indicate that there were differences only between the control compared to the other treatment groups (AU)

• FAPESP's process: 12/02060-8 - The role of leucine in the formation of beta amyloid peptide in cell culture SH-SY5Y of human neuroblastoma
• Grantee: Fábio Medici Lorenzeti
• Support Opportunities: Scholarships in Brazil - Master