Sepsis induces brain mitochondrial dysfunction.
OBJECTIVE
Mitochondrial dysfunctions have been associated with the pathogenesis of sepsis. A systematic survey of mitochondrial function in brain tissues during sepsis is lacking. In the present work, we investigate brain mitochondrial function in a septic mouse model.


METHODS
Prospective animal study.


METHODS
University research laboratory.


METHODS
Male Swiss mice, aged 6-8 wks.


METHODS
Mice were subjected to cecal ligation and perforation (sepsis group) with saline resuscitation or to sham operation (control group).


RESULTS
Oxygen consumption was measured polarographically in an oximeter. Brain homogenates from septic animals presented higher oxygen consumption in the absence of adenosine 5'-diphosphate (state 4) compared with control animals. The increase in state 4 respiration in animals in the cecal ligation and perforation group resulted in a drastic decrease in both respiratory control and adenosine 5'-diphosphate/oxygen ratios, indicating a reduction in the oxidative phosphorylation efficiency. Septic animals presented a significant increase in the recovery time of mitochondrial membrane potential on adenosine 5'-diphosphate addition compared with control animals, suggesting a proton leak through the inner mitochondrial membrane. The septic group presented a general reduction in the content of cytochromes. Moreover, the activity of cytochrome c oxidase was specifically and significantly decreased in the brain during sepsis. Hydrogen peroxide generation by brain mitochondria from septic mice did not respond to substrates of electron transport chain or to adenosine 5'-diphosphate, showing that mitochondrial function may be compromised in a critical level in the brain during sepsis.


CONCLUSIONS
The mitochondrial dysfunctions demonstrated here indicate that uncoupling of oxidative phosphorylation takes place in the brain of septic mice, compromising tissue bioenergetic efficiency.
d'Avila
Joana da Costa P
JC
Laboratório de Bioquímica Redox, Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, Brazil.
Santiago
Ana Paula S A
AP
Amâncio
Rodrigo T
RT
Galina
Antonio
A
Oliveira
Marcus F
MF
Bozza
Fernando A
FA
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000503:physiopathology*; D004195:Disease Models, Animal; D004579:Electron Transport / Q000502:physiology; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000502:physiology; D028361:Mitochondrial Diseases / Q000503:physiopathology*; D051336:Mitochondrial Membranes / Q000502:physiology; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000502:physiology; D018805:Sepsis / Q000503:physiopathology*
D000244:Adenosine Diphosphate; D006861:Hydrogen Peroxide; D003576:Electron Transport Complex IV