Alcohol hangover: Oxidative stress and bioenergetics in central nervous system

ANALIA G. KARADAYIAN

Buenos Aires

Workshop; Workshop: Redox Mechanisms in pathophysiology; 2018

Cátedra de Química General e Inorgánica. Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires

Alcohol hangover (AH) is a pathophysiological state after a binge-like drinking. We have previously demonstrated that AH induced bioenergetics impairments in a total fresh mitochondrial fraction in brain cortex and cerebellum. We herein postulate that the alterations induced by hangover can be due to a different pattern of response in synaptosomes and non-synaptic (NS) mitochondria. Therefore, our aim was to determine free radical production and antioxidant systems in brain cortex NS-mitochondria and synaptosomes in control and hangover animals. Male Swiss mice received i.p. injections of EtOH (3.8 g/kg) or saline and were sacrificed 6 hours after when blood alcohol concentration was zero and it corresponds with AH onset. Brain cortex NS mitochondria and synaptosomes from brain cortex were isolated by Ficoll gradient.Results indicated that superoxide production was not modified in NS-mitochondria while a 17.5% increase was observed in synaptosomes. A similar response was observed for cardiolipin content as no changes were evidenced in NS-mitochondria while a 55% decrease in cardiolipin content was found in synaptosomes. Hydrogen peroxide production was 3-fold increased in NS-mitochondria and 4-fold increased in synaptosomes. Particularly, in the presence of deprenyl, synaptosomal H2O2 production was 67% decreased in the AH condition. Hydrogen peroxide generation was not affected by deprenyl addition in NS-synaptic mitochondria from AH mice indicating a possible contribution of monoamine oxidase (MAO) in the generation of H2O2. In line with this, MAO activity resulted to be 57% increased in NS-synaptic mitochondria and 3-fold increased in synaptosomes. Catalase activity was 40% and 50% decreased in non-synaptic mitochondria and synaptosomes, respectively. Superoxide dismutase was 60% decreased in non-synaptic mitochondria and 80% increased in synaptosomal fractions. On the other hand, GSH (glutathione) content was 43% and 17% decreased in synaptosomes and cytosol. GSH-related enzymes were mostly affected in synaptosomes fractions by AH condition. Acetylcholinesterase activity in synaptosomes was 11% increased due to AH. As a whole the results reveal that AH provokes an imbalance in the cellular redox homeostasis. Together with this, mitochondrial function was studied in both subcellular fractions. In this context, oxygen consumption rates were measured in NS mitochondria and synaptosomes by high-resolution respirometry. Results showed that NS-synaptic mitochondria from AH animals presented a 26% decrease in malate-glutamate state 3 respiration, a 64% reduction in ATP content, 28-37% decrements in ATP production rates (malate-glutamate or succinate-dependent respectively) and 44% inhibition in complex IV activity. No changes were observed in mitochondrial transmembrane potential (∆Ψ) or in UCP-2 expression in NS-mitochondria. Synaptosomes respiration driving proton leak (in the presence of oligomycin), and spare respiratory capacity (percentage ratio between maximum and basal respiration) were 30% and 15% increased in hangover condition respectively. Synaptosomal ATP content was 26% decreased and ATP production rates were 40-55% decreased (malate-glutamate or succinate-dependent respectively) in AH mice. In addition, a 24% decrease in ∆Ψ and a 21% increase in UCP-2 protein expression were observed in synaptosomes from AH mice. Moreover, mitochondrial respiratory complexes I-III, II-III and IV activities measured in synaptosomes from AH mice were decreased by 18%, 34% and 50% respectively. Results of this study reveal that alterations in bioenergetics status during alcohol hangover could be mainly due to changes in mitochondrial function at the level of synapses.