Changes in active oxygen species production in brain cortex synaptosomes during aging

ANALIA G. KARADAYIAN; JUANITA BUSTAMANTE; SILVIA LORES ARNAIZ; PAULINA LOMBARDI

Buenos Aires

Congreso; IV International Congress In Translational Medicine; 2018

Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires

Aging is characterized by a progressive deterioration in physiological and metabolic processes.It has been extensively reported that reactive oxygen species can play a major role in neural damage associated with aging and aging-related neurodegenerative diseases.Previous results from our laboratory have shown alterations in reactive oxygen species in brain cortex synaptosomes and non-synaptic mitochondria from animals of 14, 17 and 20 months of age. With the purpose of analyzingthe effect of aging on oxidative stress in nerve terminals, male Swiss mice of 3 and 24 months old were used. Brain cortex synaptosomes were isolated by Ficoll gradient procedures.Reactive oxygen species superoxide anionand hydrogen peroxide (H2O2)were measured. Superoxide anion level was assayed by flow cytometry after synaptosome loading withthe fluorescent mitochondrial probe Mitosox and H2O2 production was determined by a fluorometric method with scopoletin and HRP.Also,the activity of enzymatic complexes I-III of the mitochondrial respiratory chainwere determined.Finally, acetylcholinesterase activitywas assayed as an indicator of synaptic neuronal function.Results show that levels of superoxide anion wereincreased by 22% in 24 months old animals as comparedwith3 months oldmice.An increase of 33% in basal H2O2production was observed in old animals as compared with young mice.When measurements were performed in the presence of malate and glutamate, H2O2production rates were increased by 45% in synaptosomes from young mice, while in old animals the increase was only of 16%. Therefore, this result suggests that the observed increase in hydrogen peroxide production in old animals wouldnot be a consequence of mitochondrial respiratory chain activity. As a matter of fact, complex I-III activity declined by 20% in synaptosomes from 24 months old animals. Furthermore, the activity of acetylcholinesterase was diminished by 29% in old mice.From these results we can conclude that the decline of enzymatic activities would be probably connected with the accumulation of protein damage during aging.Oxidative damage induced by reactive oxygen speciescould contribute to decrease mitochondrial bioenergetic function and impairneurotransmission in brain cortex with age.