Protection Of Ketogenic Diet On Cognitive Dysfunction In Mice Exposure High Altitude Hypobaric Hypoxia

Objective: To explore the protection of ketogenic diet on cognitive dysfunction and brain damage in mice induced by hypobaric hypoxia environment at high altitude,and explored possible related mechanisms.Methods: C57BL/6 mice randomly allocated into four groups: a normal oxygen control(NC)group,a normal oxygen with ketogenic diet(NK)group,a hypoxia control(HC)group,a hypoxia with ketogenic diet(HK)group.The hypobaric oxygen chamber was used to simulate high altitude(6000 m)hypobaric hypoxia environment,operating time 24h/d,the control ratio of 12h:12h.HC group and HK group were given standard diet and ketogenic diet respectively for 3 weeks,and then were exposed to high altitude hypoxia circumstances for 6 days.NC group and NK group were raised outside the chamber after 3-week standard diet and ketogenic diet respectively.The pathological morphology of hippocampus was examined by pathological staining.Cognitive function in mice was examined by Morris Water Maze.Expression of mitochondrial fusion/fission proteins was assayed by Western blot.Change of mitochondrial oxygen consumption rate(OCR)in brain was detected by Seahorse energy metabolism analyzer.Results: 1 Effect of ketogenic diet on cognitive dysfunction in mice exposure high altitude hypobaric hypoxia1.1 Effect of ketogenic diet and hypobaric hypoxia treatment on basic characteristics in miceCompared with standard diet,ketogenic diet could reduce the weight,increase blood ketone body,blood triglyceride and blood cholesterol levels of mice significantly(P<0.01 or P<0.05).Compared with normoxic environment,hypoxic environment could increase the expression of HIF-1?(hypoxia inducible protein-1?)in hippocampus significantly(P<0.05).1.2 Effect of ketogenic diet and hypobaric hypoxia treatment on cognitive function in miceMorris Water Maze experiment found that,compared with NC group,HC group showed that the cross times of platform was reduced significantly(P<0.01),the percentage of time in the quadrant where the platform was located was reduced significantly(28.81±10.49 vs.17.96±7.08,P<0.05),and the percentage of distance in the quadrant where the platform was located was reduced significantly(30.21±8.91 vs.20.75±5.16,P<0.05).While compared with HC group,HK group showed that the cross times of platform was increased significantly(P < 0.05),the percentage of time in the quadrant where the platform was located was increased significantly(17.96±7.08 vs.26.36±8.40,P<0.05),and the percentage of distance in the quadrant where the platform was located was increased significantly(20.75±5.16 vs.27.47±6.34,P<0.05).1.3 Effect of ketogenic diet and hypobaric hypoxia treatment on pathological morphology of hippocampus in miceHE staining and Nissl staining pathological experiments found that,compared with NC group,HC group showed the pathological damage such as decreased of hippocampal neurons,widening of intercellular spaces and nuclear pyknosis.Compared with HC group,HK group showed an increase of hippocampal neurons,a gradual alignment of cells,and a decrease of nuclear pyknosis.2 Effect of ketogenic diet on mitochondrial function of hippocampus in mice exposure high altitude hypobaric hypoxia2.1 Effect of ketogenic diet and hypobaric hypoxia treatment on mitochondrial fusion/fission proteins of hippocampus in miceWestern blot experiment showed that,compared with NC group,the expression of MFN1(mitochondrial fusion protein 1)was decreased significantly(P<0.05),and the expression of FIS1(mitochondrial fission protein 1)was increased significantly in the hippocampus of mice in HC group(P<0.05).Compared with HC group,the expression of MFN1 increased significantly(P<0.05),while the expression of FIS1 decreased significantly in the hippocampus of mice in HK group(P<0.05).2.2 Effect of ketogenic diet and hypobaric hypoxia treatment on mitochondrial oxidative respiration of brain in miceThe Seahorse experiment found that,compared with NC group,the mitochondrial oxygen consumption rate(OCR)in brain of HC group caused by ADP was decreased significantly(P < 0.01),and which caused by FCCP stimulation was decreased significantly(P<0.05).Compared with HC group,the OCR in brain of HK group caused by ADP was increased significantly(P<0.05),and which caused by FCCP stimulation was increased without significance.Conclusion: High altitude hypobaric hypoxia could result in brain damage and cognitive dysfunction in mice.In addition,ketogenic diet could effectively prevent the brain damage and cognitive dysfunction in mice caused by hypobaric hypoxia,which mechanisms might be about the improvement of mitochondrial fission/fusion balance and mitochondrial oxidative respiration.In a word,ketogenic diet could improve the damage of hippocampus and cognitive dysfunction in mice exposure high altitude hypobaric hypoxia.