[Expression and activation of hypoxia inducible factor-1alpha and iNOS in the brain of rats with chronic intermittent hypoxia].
OBJECTIVE
To study the expression of iNOS and hypoxia inducible factor-1 (HIF-1)alpha in the brain of rats under chronic intermittent hypoxia, and therefore to explore the molecular mechanisms of hypoxia induced reactions in the nervous system according to the measure of HIF-1 transcription activity.


METHODS
Male Wistar rats were divided into 3 groups: a chronic hypoxia group (n = 8, breathing 10%O2 for 8 h per day), an intermittent hypoxia group (n = 8, breathing 10%O2 and air altered per 90 sec for 8 h per day) and a control group (n = 8, breathing air). Thirty days later, the expression of HIF-1alpha and iNOS was assessed by using immunohistochemical methods and Western blot, and HIF-1alpha and iNOS mRNA was assessed by RT-PCR. The detection of binding activity of HIF-1 to the iNOS promoter gene was assessed by electrophoretic mobility shift assay.


RESULTS
The productions of HIF-1alpha (508 +/- 77, 1118 +/- 106 and 1937 +/- 119) and iNOS (673 +/- 82, 1325 +/- 139 and 2088 +/- 130) were the highest in the intermittent hypoxia group. Only weaker binding activity between HIF-1 and iNOS promoter gene was detected in the control group, but the binding activity was increased significantly in the intermittent hypoxia group.


CONCLUSIONS
Hypoxia, especially intermittent hypoxia, can cause increased expression of iNOS and HIF-1alpha. HIF-1 may be a key factor in up-regulation of the transcription of iNOS under chronic intermittent hypoxia. HIF-1 promotes the transcription of iNOS though enhanced binding activity.
Wang
Zan-feng
ZF
Institute of Respiratory Diseases, First Affiliated Hospital, China Medical University, Shenyang, China. zanfengwang@163.com
Kang
Jian
J
Dai
Bing
B
D000818:Animals; D001921:Brain / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat