Role of SIRT1 in mitochondrial dysfunction in mice with lipopolysaccharide-induced brain injury / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of silent information regulator sirtuin 1 (SIRT1) in mitochondrial dysfunction in mice with lipopolysaccharide (LPS)-induced brain injury.Methods:Eighty clean-grade male C57BL/6 mice, aged 6-8 weeks, were divided into 4 groups ( n=20 each) by the random number table method: control group (group C), LPS-induced brain injury group (LPS group), LPS-induced brain injury plus SIRT1 inhibitor EX527 group (LPS+ E group), and LPS-induced brain injury plus SIRT1 agonist SRT1720 group (LPS+ S group). Brain injury was induced by intravenous injection of LPS 10 mg/kg. EX527 10 mg/kg was intraperitoneally injected at 72 h before LPS injection in group LPS+ E, and the equal volume of dimethyl sulfoxide was intraperitoneally injected instead in the other three groups. SRT1720 100 mg/kg was intraperitoneally injected at 30 min before LPS injection in group LPS+ S, and the equal volume of dimethyl sulfoxide was intraperitoneally injected instead in the other three groups. The novel object recognition test was performed at 24 h after LPS injection, then the mice were sacrificed, and hippocampal tissues were harvested for determination of the number of the normal neurons in the hippocampal CA1 area, ATP content and activities of mitochondrial respiratory chain complexes Ⅰ, Ⅱ, Ⅲ and Ⅳ (by spectrophotometry), and mitochondrial membrane potential (MMP) (by Jc-1 staining) and for microscopic examination of pathological changes (by Nissl staining) and ultrastructure of neuronal mitochondria (with a transmission electron microscope). Results:Compared with group C, the preference index in novel object recognition, normal neuron count, activities of mitochondrial respiratory chain complexes Ⅰ, Ⅱ, Ⅲ and Ⅳ, MMP and ATP content were significantly decreased ( P<0.05), damage to hippocampal neurons was found, mitochondrial swelling was observed and cristae structure ruptured in LPS, LPS+ S and LPS+ E groups. Compared with group LPS, the preference index in novel object recognition, activities of mitochondrial respiratory chain complexes, MMP and ATP content were significantly decreased ( P<0.05), neuronal damage was aggravated, the mitochondrial swelling and fracture of crista structure were accentuated in group LPS+ E; the preference index in novel object recognition, activities of mitochondrial respiratory chain complexes, MMP and ATP content were significantly increased ( P<0.05), neuronal damage was alleviated, and the mitochondrial swelling and fracture of crista structure were ameliorated in group LPS+ S. Conclusions:Activation of SIRT1 can improve mitochondrial dysfunction and alleviate LPS-induced brain injury in mice.