Effects Of Intermittent Hypoxia Training On Activation Of Caspase3and Free Radical Metabolism In Brains Of Rats

Objective: As a substitute method of altitude training, Intermittent hypoxiatraining has been used for enhancing the physical performance of endurance athletes. Incontrast to the traditional high altitude training, however, there is substantially lessresearch dedicated to the responses and adaptations to intermittent hypoxia. From theexisting literature, it is clear that there are some fundamental differences, in terms of thehuman physiological response, to intermittent hypoxia training in comparison to acutehypoxia exposure. And in recent years, some studies show that this training method maycause cell apoptosis in animal’s brain cells. Also, there always has been a controversyamong the “dose” of hypoxia necessary to achieve the desired effect-how severe is thehypoxic stimulus, how long should each exposure be(how many minutes or hour perday),how often should the stimulus persist(how many weeks)? In addition, there arevery few studies comparing one strategy against the others. On one hand, if the oxygenconcentration is too low,the hypoxia time is too long, it may harmful to body health,such as cerebrovascular, cardiopulmonary disease, and sleep apnoea, cause the braindamage, memory deficits. On the other hand, if the oxygen concentration is too high,the hypoxia time too short, it may not has achieved the effect of training expected, orthere is no obviously change in the athlete work capacity. Upon this situation, accordingto the different strategies of previous intermittent hypoxia training showed the adaptiveresponse，using the experimental Kun Ming mice as the object of study,taking thelow-pressure chamber to create the artificial intermittent hypoxia environment. Toobserve the effects of intermittent hypoxia training on activation of caspse3and freeradical metabolism in brains of rats with different hypoxic strategies. The goal of thestudy were to providing a theory basis for intermittent hypoxia training, for better usingin the athletes’ training programs.Methods: A total of40male Kun Ming rats at the beginning of the experiment were randomly divided into4groups, control group(n=10),5minutes intermittent hypoxia training group(n=10),(5INH).10minutesintermittent hypoxia training group(n=10),(10INH).1hour acute hypoxia exposuregroup(n=10).(AHE)In all these hypoxic groups using11%of the oxygenconcentration(simulated altitude of5000M).5INH:six cycles of5min on, and5min off,one hour a day, total hypoxic time is half an hour.10INH:six cycles of10min on,and,5min off, one and a half hour a day, total hypoxic time is one hour. AHE:given thepersistent hypoxia explorsure for one hour, and then putting the mice under thenormoxic to rest. All the experiment lasted for5weeks, in the end of experiment kill allthe mice after fasting12hours. Test the following indexes: MDA contents, SODactivity,and caspase3activity.Results:1Caspase3activity: The caspase3activity of the brain in the AHE(49887±1053.33U/mgprot) is significantly higher than the other three groups.(P<0.01).However,there are no significant differences between the two INH groups(11835±765.69U/mgprot;12756±874.62U/mgprot)and the control group(13267±978.86U/mgprot).(P>0.05)2SOD activity: The SOD activity of the brain in the AHE(148.28±11.22U/mgprot)is lower than the other three groups.(P<0.05).And the two IHNgroups(424.54±69.89U/mgprot,517.34±74.62U/mgprot)is significant higher than thecontrol group(295.29±89.37U/mgprot)and the AHE group.3MDA content:The MDA content of the brain in the AHE(623±13.5nmol/mgprot) is significantly higher than the other three groups.(P<0.01).And the two IHNgroups(326±15.9nmol/mgprot,367±33.6nmol/mgprot)is lower than the controlgroup(453±28.3nmol/mgprot)and the AHE group(P<0.01).Conclusions:1Cause the two IHT group has no differences with the control groupin the caspase3activity, it could proved that these IHT strategies are safety method.However, there are significantly higher of caspase3activity in AHE groups than theother three groups. It can be proved in these oxygen concentrations if the hypoxic timeis too long, it can cause damage in the animal’s brain-brain cells apoptosis.2Our two IHE strategies can significantly reduce damages cause by the lipidperoxidation, improve the capacity of anti-oxidation system, enhance the adaptabilityof hypoxic stress.3Contrast to the10IHE group and AHE group, as the same total hypoxic times,only in AHE group there is a higher caspase3activity. It can be prove that the rest normal oxygen could make body to adapted to the hypoxia,and achieved the long-termantioxidant adaptation.