title: Impact of high altitude on the hepatic fatty acid oxidation and synthesis in rats.
abstract: High altitude (HA) affects energy metabolism. The impact of acute and chronic HA acclimatization on the major metabolic pathways is still controversial. In this study, we aimed to unveil the impact of HA on the key enzymes involved in the fatty acid (FA) metabolism in liver. Rats were exposed to an altitude of 4300 m for 30 days and the expressions of two key proteins involved in FA β-oxidation (carnitine palmitoyl transferase I, CPT-I; and peroxisome proliferator-activated receptor alpha, PPARα), two proteins involved in FA synthesis (acetyl CoA carboxylase-1, ACC-1; and AMP-activated protein kinase, AMPK), as well as the total ketone body in the liver and the plasma FFAs were examined. Rats without HA exposure were used as controls. We observed that the acute exposure of rats to HA (3 days) led to a significant increase in the expressions of CPT-I and PPARα and in the total hepatic ketone body. Longer exposure (15 days) caused a marked decrease in the expression of CPT-I and PPARα. By 30 days after HA exposure, the expression levels of CPT-I and PPARα returned to the control level. The hepatic ACC-1 level showed a significant increase in rats exposed to HA for 1 and 3 days. In contrast, the hepatic level of AMPK showed a significant reduction throughout the experimental period. Plasma FFA concentrations did not show any significant changes following HA exposure. Thus, increased hepatic FA oxidation and synthesis in the early phase of HA exposure may be among the important mechanisms for the rats to respond to the hypoxic stress in order to acclimatize themselves to the stressful environments.
authors.affiliation: Department of General Surgery, Hepatic-biliary-pancreatic Institute, Lanzhou University Second Hospital, Lanzhou, China; Department of Pediatrics, Lanzhou University Second Hospital, Lanzhou, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Department of General Surgery, Hepatic-biliary-pancreatic Institute, Lanzhou University Second Hospital, Lanzhou, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Shao
authors.affiliation: Department of General Surgery, Hepatic-biliary-pancreatic Institute, Lanzhou University Second Hospital, Lanzhou, China.
authors.forename: Ying Zhen
authors.initials: YZ
authors.lastname: Wang
authors.affiliation: Institute of Anatomy, School of Basic Medicine, Lanzhou University, Lanzhou, China.
authors.forename: Yu Hong
authors.initials: YH
authors.lastname: Jing
authors.affiliation: Department of General Surgery, Hepatic-biliary-pancreatic Institute, Lanzhou University Second Hospital, Lanzhou, China. Electronic address: zhangychmd@126.com.
authors.forename: You Cheng
authors.initials: YC
authors.lastname: Zhang
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000531:Altitude; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology; D005227:Fatty Acids / Q000096:biosynthesis / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D047495:PPAR gamma / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005227:Fatty Acids; D047495:PPAR gamma; D002334:Carnitine O-Palmitoyltransferase
keywords: AMP-activated protein kinase; Acetyl CoA carboxylase; Carnitine palmitoyl transferase-I; High altitude; Liver; Peroxisome proliferator-activated receptor alpha