Diversities in hepatic HIF-1, IGF-I/IGFBP-1, LDH/ICD, and their mRNA expressions induced by CoCl(2) in Qinghai-Tibetan plateau mammals and sea level mice.
Ochotona curzoniae and Microtus oeconomus are the native mammals living on the Qinghai-Tibetan-Plateau of China. The molecular mechanisms of their acclimatization to the Plateau-hypoxia remain unclear. Expressions of hepatic hypoxia-inducible factor (HIF)-1alpha, insulin-like growth factor-I (IGF-I)/IGF binding protein (BP)-1(IGFBP-1; including genes), and key metabolic enzymatic genes [lactate dehydrogenase (LDH)-A/isocitrate dehydrogenase (ICD)] are compared in Qinghai-Tibetan-Plateau mammals and sea-level mice after injection of CoCl(2) (20, 40, or 60 mg/kg) and normobaric hypoxia (16.0% O(2), 10.8% O(2), and 8.0% O(2)) for 6 h, tested by histochemistry, Western blot analysis, ELISA, and RT-PCR. Major results are CoCl(2) markedly increased 1) HIF-1alpha only in mice, 2) hepatic and circulatory IGF-I in M. oeconomus, 3) hepatic IGFBP-1 in mice and O. curzoniae, and 4) LDH-A but reduced ICD mRNA in mice (CoCl(2) 20 mg/kg) but were unchanged in the Tibetan mammals. Normobaric hypoxia markedly 1) increased HIF-1alpha and LDH-A mRNA in mice and M. oeconomus (8.0% O(2)) not in O. curzoniae, and 2) reduced ICD mRNA in mice and M. oeconomus (8.0% O(2)) not in O. curzoniae. Results suggest that 1) HIF-1alpha responsiveness to hypoxia is distinct in lowland mice and plateau mammals, reflecting a diverse tolerance of the three species to hypoxia; 2) CoCl(2) induces diversities in HIF-1, IGF-I/IGFBP-1 protein or genes in mice, M. oeconomus, and O. curzoniae. In contrast, HIF-1 mediates IGFBP-1 transcription only in mice and in M. oeconomus (subjected to severe hypoxia); 3) differences in IGF-I/IGFBP-1 expressions induced by CoCl(2) reflect significant diversities in hormone regulation and cell protection from damage; and 4) activation of anaerobic glycolysis and reduction of Krebs cycle represents strategies of lowland-animals vs. the stable metabolic homeostasis of plateau-acclimatized mammals.
Chen
Xue-Qun
XQ
Division of Neurobiology and Physiology, College of Life Sciences, Zhejiang University, Yuquan Campus, Hangzhou 310027, China. chewyg@zju.edu.cn
Wang
Shi-Jun
SJ
Du
Ji-Zeng
JZ
Chen
Xiao-Cheng
XC
D000199:Actins / Q000096:biosynthesis; D000531:Altitude; D000818:Animals; D003411:Arvicolinae / Q000378:metabolism*; D015153:Blotting, Western; D003035:Cobalt / Q000494:pharmacology*; D051793:Hypoxia-Inducible Factor 1 / Q000096:biosynthesis / Q000378:metabolism*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000096:biosynthesis / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000378:metabolism*; D007521:Isocitrate Dehydrogenase / Q000096:biosynthesis / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis / Q000378:metabolism*; D007793:Lagomorpha / Q000378:metabolism*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013385:Succinate Dehydrogenase / Q000096:biosynthesis / Q000378:metabolism; D018609:Tibet
D000199:Actins; D051793:Hypoxia-Inducible Factor 1; D018970:Insulin-Like Growth Factor Binding Protein 1; D012333:RNA, Messenger; D003035:Cobalt; D007334:Insulin-Like Growth Factor I; D007770:L-Lactate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D013385:Succinate Dehydrogenase; C018021:cobaltous chloride