Effect of mild hypothermia on mitochondrial function in the brain tissues of rats with acute phase of spontaneous subarachnoid hemorrhage / 中华神经医学杂志

ABSTRACT

Objective To observe the effect of mild hypothermia on mitochondrial reactive oxygen species (ROS) generation and energy metabolism in acute phase of spontaneous subarachnoid hemorrhage (SAH) in rats,and to explore the relative signaling pathway in this process.Methods SD rats were randomly divided into three groups:sham-operated group,normothermic SAH group (SAH-N),and hypothermic SAH group (SAH-H).The SAH models were induced by injection of autologous arterial blood into the prechiasmatic cistem.After the injection,rats in SAH-H group were subjected to mild hypothermia intervention (32.5-33.5 ℃).All animals were sacrificed by decapitation two hours after SAH.Ultrastructures of CA1 section of the hippocampus were observed under transmission electron microscopy.The enzyme activities of mitochondrial manganese superoxide dismutase (MnSOD),glutathione peroxidase (GPx) and catalase (CAT),and the malonaldehyde (MDA) level were measured with colorimetry method.Mitochondrial respiratory function was measured with polarography method.Mitochondrial ROS generation was determined using dichlorofluorescein (DCF) method.Membrane potent was determined using JC-1 fluorescence labeling.Adenodine triphospate (ATP) synthesis capacity was determined using bioluminescence technique.The Sirtuin-3 (SIRT3) mRNA expression in the brain tissues was detected by real-time quantitative PCR.The mitochondrial SIRT3 protein expression was detected by Western blotting.Results As compared with those in the SAH-N group,mitochondrial SIRT3 mRNA and protein expressions,ATP synthetase activity,membrane potent,state 3 respiratory rate,respiratory control ratio,ratio of ADP to oxygen,and activities of MnSOD,GPx and CAT significantly increased in the SAH-H group (P＜0.05); and state 4 respiratory rate,mitochondrial ROS generation and MDA level significantly decreased in SAH-H group (P＜0.05).Conclusion Mild hypothermia could efficiently promote mitochondrial energy metabolism and ROS scavenging capacity,and in turn improve SAH tolerance in brain mitochondria.