title: Effect of temperature on oxidative stress, antioxidant levels and uncoupling protein expression in striped hamsters.
abstract: According to the rate of living-free radical hypothesis, higher metabolic rates should increase reactive oxygen species (ROS) production. However, the "uncoupling to survive" hypothesis postulates that uncoupling proteins (UCPs) can decrease ROS production by lowering the potential of the inner mitochondrial membrane, in which case the correlation between metabolic rate and ROS levels would be a negative rather than positive. In this study, we examined energy intake, oxidative stress levels, antioxidant activity and the expression of UCPs in brown adipose tissue (BAT), and in the liver, heart, skeletal muscle and brain, of striped hamsters (Cricetulus barabensis) acclimated to either 5 °C or 32.5 °C. The energy intake of hamsters acclimated to 5 °C increased by 70.7%, whereas the energy intake of hamsters acclimated to 32.5 °C decreased by 31.3%, relative to hamsters kept at room temperature (21 °C) (P<0.05). Malonadialdehyde (MDA) levels, total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX) activity in BAT significantly decreased in 5 °C group, but increased in 32.5 °C group, relative to the 21 °C group. Neither ROS levels (i.e. H2O2 levels), nor antioxidants in skeletal muscle, liver, heart or brain tissue, were affected by temperature. UCP1 expression in BAT was significantly up-regulated in 5 °C group, but down-regulated in 32.5 °C group, relative to the 21 °C group. UCP3 expression of skeletal muscle was also up-regulated significantly in hamsters acclimated to 5 °C. These results suggest that the relationship between ROS levels and metabolic rate was negative, rather than positive. UCP1 expression in BAT may have played a role in lowering ROS levels.
authors.affiliation: College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
authors.forename: Si-Si
authors.initials: SS
authors.lastname: Zhou
authors.affiliation: College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Cao
authors.affiliation: College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Xu
authors.affiliation: College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Cao
authors.affiliation: College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China. Electronic address: zhao73@foxmail.com.
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Zhao
mesh_terms: D000064:Acclimatization / Q000502:physiology; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D015870:Gene Expression; D005979:Glutathione Peroxidase / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics*; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D000071256:Uncoupling Protein 1
chemical_list: D000975:Antioxidants; D007473:Ion Channels; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D000071256:Uncoupling Protein 1; D008315:Malondialdehyde; D005979:Glutathione Peroxidase
keywords: Antioxidants; Brown adipose tissue (BAT); Oxidative stress; Striped hamster; Temperature; Uncoupling proteins