Alcohol hangover effects on brain cortex non-synaptic mitochondria and synaptosomes bioenergetics.

Alcohol hangover (AH) has been associated with oxidative stress and mitochondrial dysfunction. We herein postulate that AH-induced mitochondrial alterations can be due to a different pattern of response in synaptosomes and non-synaptic (NS) mitochondria. Mice received i.p. injections of EtOH (3.8 g/kg) or saline and were sacrificed 6 hours after. Brain cortex NS mitochondria and synaptosomes were isolated by Ficoll gradient. 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 (ΔΨ) 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 ΔΨ 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 AH could be mainly due to changes in mitochondrial function at the level of synapses.