Studies from Carleton University, Institute of Biochemistry Add New Findings in the Area of Metalloporphyrins – Obesity, Fitness & Wellness Week
Publication: Obesity, Fitness & Wellness Week
Date: Saturday February 5th, 2011
Page: 2193
Summary
Researchers detail in ‘Heme oxygenase expression and Nrf2 signaling during hibernation in ground squirrels,’ new data in Metalloporphyrins. According to recent research from Ottawa, Canada, “Mammalian hibernation is composed of long periods of deep torpor interspersed with brief periods of arousal in which the animals, fueled by high rates of oxygen-based thermogenesis in brown adipose tissue and skeletal muscle, power themselves back to euthermic (~37 degrees C) body temperatures. Strong antioxidant defences are important both for long-term cytoprotection during torpor and for coping with high rates of reactive oxygen species generated during arousal.”
“The present study shows that the antioxidant enzyme heme oxygenase 1 (HO1) is strongly upregulated in selected organs of thirteen-lined ground squirrels (Spermophilus tridecemlineatus) during hibernation. Compared with euthermic controls, HO1 mRNA transcript levels were 1.4-to 3.8-fold higher in 5 organs of hibernating squirrels, whereas levels of the constitutive isozyme HO2 were unchanged. Similarly, HO1 protein levels increased by 1.5-to 2.0-fold in liver, kidney, heart, and brain during torpor. Strong increases in the levels of the Nrf2 transcription factor and its heterodimeric partner protein, MafG, in several tissues indicated the mechanism of activation of hibernation-responsive HO1 gene expression. Furthermore, subcellular distribution studies with liver showed increased nuclear translocation of both Nrf2 and MafG in torpid animals,” wrote Z. Ni and colleagues, Carleton University, Institute of Biochemistry (see also ).
The researchers concluded: “The data are consistent with the suggestion that Nrf2-mediated upregulation of HO1 expression provides enhanced antioxidant defence to counter oxidative stress in hibernating squirrels during torpor and (or) arousal.”
Ni and colleagues published their study in Canadian Journal of Physiology and Pharmacology (Heme oxygenase expression and Nrf2 signaling during hibernation in ground squirrels. Canadian Journal of Physiology and Pharmacology, 2010;88(3):379-87).
For additional information, contact Z. Ni, Institute of Biochemistry, Dept. of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
Publisher contact information for the Canadian Journal of Physiology and Pharmacology is: National Research Council of Canada, NRC Communications & Corporate Relations, 1200 Montreal Road, Bldg. M-58, Ottawa, Ontario, Canada K1A 0R6.
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