Cytoglobin, neuroglobin, and acetylcholinesterase activity in rat brain as adaptation responses to intermittent hypobaric hypoxia

Background: : Intermittent hypobaric hypoxia is suggested to possess a protective effect toward the hypoxic condition. The aim of this study is to analyze the expression of cytoglobin (Cygb), neuroglobin (Ngb) and the specific activity of acetylcholinesterase (AChE) in brain tissue as adaptive responses to intermittent hypobaric hypoxia. Methods: : Twenty-five adult Sprague-Dawley male rats were divided into 5 groups: 1) The control group (normoxia); 2) group exposed to acute hypobaric hypoxia (AHH); 3) group exposed to hypobaric hypoxia (HH) on day-1 and re-exposed on day-8 (intermittent hypobaric hypoxia once or IHH1x); 4) group that is exposed to HH on day-1, re-exposed to HH on day-8 and day-15 (intermittent hypobaric hypoxia two times or IHH2x); 5) group exposed to HH on day-1, re-exposed to HH on day-8, day-15 and day-22 (intermittent hypobaric hypoxia 3x or IHH3x). Homogenized brain tissue was then measured and analyzed for Cygb and Ngb protein expression, and also AChE specific activity. Results: : Cytoglobin and Ngb were decreased in the acute induction and increased significantly along with the increasing frequency of the IHH induction. There were significant differences in Cygb expression between IHH2x and IHH3x groups compared to normoxia group, and between IHH1x, IHH2x and IHH3x compared to AHH group. There were significant differences in Ngb expression between IHH2x and IHH3x groups compared to normoxia group and between IHH2x and IHH3x groups compared to AHH group. The specific activity of AChE was increased significantly since the first induction of AHH, but then decreased in IHH3x. There were significant differences in the specific activity of AChE between IHH2x and IHH3x groups compared to normoxia and between IHH2x and IHH3x groups compared to IHH1x groups. Conclusions: : We conclude that IHH, especially IHH3x, seems to induce the protective adaptive response in the rat brain tissue through the changes of these three parameters.