[Effects of estrogen on activity and subunits expression of cytochrome C oxidase in mitochondria from genioglossus of rats subjected to chronic intermittent hypoxia].
OBJECTIVE
To investigate the effects of estrogen on the activity and subunits expression of cytochrome c oxidase (COX) in mitochondria from genioglossus of chronic intermittent hypoxia (CIH) rat.


METHODS
Forty-eight male Sprague-Dawley (SD) rats were randomly divided into three groups: the normal control group (NC), the chronic intermittent hypoxia group (CIH) and estrogen plus hypoxia group (E + CIH). Rats in the latter two groups were used to build CIH models (8 h/d, 5 w). In the mean time, rats in NC group and CIH group were injected with sterile olive oil (0.2 ml each time, twice a week), and rats in E + CIH group were injected with estrogen (0.2 mg/kg, twice a week), respectively. At the end of the treatment, the genioglossus of the rat was removed and the mitochondria were isolated by centrifugation program. COX activity was measured with a spectrophotometer. The protein content of COX subunit I and IV was detected by Western blotting analysis, and mRNA expression levels of COXI and COXIV were determined by real-time polymerase chain action.


RESULTS
COX activity in CIH group [(0.143 +/- 0.029) microkat/mg] was lower significantly than that in NC group [(0.273 +/- 0.058) microkat/mg, P < 0.01]; In E + CIH group [(0.203 +/- 0.073) microkat/mg], COX activity was higher than that in CIH group (P < 0.05), but still lower than that in NC group (P < 0.05). Compared with NC group (47.325 +/- 7.502), decreased COXI expression was observed in CIH group (10.789 +/- 8.144, P < 0.01) and E + CIH group (25.593 +/- 11.108, P < 0.01). While in the mean time, the protein content of COXI in E + CIH group was higher than that in CIH group (P < 0.05). There was no significant difference in protein content of COXIV among the three groups (P > 0.05). COXI and COXIV mRNA levels had no significant change among the three groups (P > 0.05).


CONCLUSIONS
CIH exposure could decrease mitochondrial COX protein expression and activity in the genioglossus of the rat, while estrogen administration might be beneficial to the recovery of those.
Liu
Yue-hua
YH
Department of Orthodontics, School of Stomatology, Tongji University, Shanghai 200072, China. joshua66@126.com
Qi
Juan
J
Jia
Shan-shan
SS
D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D000860:Hypoxia; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014059:Tongue / Q000378:metabolism
D004967:Estrogens; D003576:Electron Transport Complex IV