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Adaptability to hypobaric hypoxia is facilitated through mitochondrial bioenergetics: an in vivo study
Author(s) -
Chitra Loganathan,
Boopathy Rathanam
Publication year - 2013
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.12179
Subject(s) - mitochondrial biogenesis , mfn2 , fis1 , mitochondrial fission , mitochondrial dna , tfam , biology , mitochondrion , dnm1l , mitochondrial fusion , microbiology and biotechnology , oxidative phosphorylation , gene , genetics , biochemistry
Background and Purpose H igh‐altitude pulmonary oedema ( HAPE ) experienced under high‐altitude conditions is attributed to mitochondrial redox distress. Hence, hypobaric hypoxia ( HH )‐induced alteration in expression of mitochondrial biogenesis and dynamics genes was determined in rat lung. Further, such alteration was correlated with expression of mitochondrial DNA ( mtDNA )‐encoded oxidative phosphorylation ( mtOXPHOS ) genes. The prophylactic effect of dexamethasone ( DEX ) in counteracting the HH ‐induced mitochondrial distress was used as control to understand adaptation to high‐altitude exposure. Experimental Approach Rats pretreated with DEX were exposed to normobaric normoxia ( NN ) or HH . HH ‐induced injury was assessed as an increase in lung water content, tissue damage and oxidant generation. Mitochondrial number, mtDNA content and mtOXPHOS activities were measured to determine mitochondrial function. The expression of mitochondrial biogenesis, dynamics and mtOXPHOS genes was studied. Key Results HH ‐induced lung injury was associated with decreased mitochondrial number, mtDNA content and mtOXPHOS activities. HH exposure decreased the nuclear gene oestrogen‐related receptor‐α ( ERR α ), which interacts with PPAR‐γ coactivator‐1 α (PGC ‐1α ) in controlling mitochondrial metabolism. Consequently, mtOXPHOS transcripts are repressed under HH . Further, HH modulated mitochondrial dynamics by decreasing mitofusin 2 ( Mfn2) and augmenting fission 1 ( Fis1) and dynamin‐related protein 1 ( Drp1) expression. Nevertheless, DEX treatment under NN (i.e. adaptation to HH ) did not affect mitochondrial biogenesis and dynamics, but increased mtOXPHOS transcripts. Further, mtOXPHOS activities increased together with reduced oxidant generation. Also, DEX pretreatment normalized ERR α along with mitochondrial dynamics genes and increased mtOXPHOS transcripts to elicit the mitochondrial function under HH . Conclusions and Implications HH stress ( HAPE )‐mediated mitochondrial dysfunction is due to repressed ERR α and mtOXPHOS transcripts. Thus, ERR α ‐mediated protection of mitochondrial bioenergetics might be the likely candidate required for lung adaptation to HH .