The Effect Of Acute Hypoxic Exercise On Cerebral Oxygen In The Prefrontal Cortex And The Mechanism Related To TRPV4

PurposeAt the early stage of high altitude training,the decrease of motor ability caused by hypoxia makes it impossible for the training to be carried out normally.Since 90 s,researchers have focused more on the decrease of the cardiopulmonary function and muscle oxygen utilization capacity,but there are few studies on cerebral hemodynamic factors,and no related mechanism studies.This study will take this as a starting point,to study the acute hypoxic exercise and its biological mechanism for brain hemodynamic effects of prefrontal cortex,providing a new target in order to improve the athletes at the beginning of the plateau duration and decreased exercise capacity problems.Methods and resultsTo study the effect of acute hypoxic exercise on the hemodynamics of the frontal cortex of the human brain.Methods: In this work,we controlled for oxygen concentration by SPO2 when at rest as a measure of the adaptability of individuals to hypoxia.Twenty subjects were included in randomized controlled trials,including progressive load power bicycle movement during normoxia,95%SPO2 and 92%SPO2,monitoring the prefrontal cortex ?HbO2,?THb,heart rate,cardiac output,muscle tissue oxygen saturation during exercise.Results:(1)Normoxia exercise in ?HbO2 and ?THb inflection point appears in the fifth level,hypoxia exercise of ?HbO2 and ?THb inflection point appeared in the sixth grade.(2)In normoxic,95%SPO2 and 92%SPO2 environment,there was significant correlation between VO2 max and ?HbO2max.(3)In the 95% and 92% oxygen saturation quiet environment,VO2 max were significantly reduced.To study the effect of acute hypoxia exercise on the oxygen concentration in the prefrontal cortex of the rat.Methods: three groups of Wistar rats under normoxia,hypoxia simulated 2500 meters altitude(H-1 group)and hypoxia simulated 4500 meters altitude(H-2 group)completed the incremental exercise,mornitering the changes in oxygen concentration of the prefrontal cortex by using the method of the platinum microelectrode.Results:(1)When the quiet state,there was a significant difference between the prefrontal cortex oxygen concentration in the H-1 group and that in the normoxia group,and there was a very significant difference between the prefrontal cortex oxygen concentration in the H-2 group and that in the normoxia group.(2)When in normoxia environment,the rising inflection point appeared in the ninth level,but when in hypoxia environment,in advance to the eighth level.(3)Comparing the three environment the same level groups found that,when fifth and eighth level,there were very significant differences between the groups in each environment.To study the effect of acute hypoxia exercise on the TRPV4 channel in the frontal cortex of the rat brain.Methods: 120 male Wistar rats were randomly divided into 12 groups: normoxia control group(N-C),normoxia fifth level group(N-5),normoxia eighth level group(N-8),normoxia exhaustive group(N-E),hypoxia simulated 2500 meters altitude control group(H1-C),hypoxia simulated 2500 meters altitude fifth level group(H1-5),hypoxia simulated 2500 meters altitude eighth level group(H1-8),hypoxia simulated 2500 meters altitude exhaustive group(H1-E),hypoxia simulated 4500 meters altitude control group(H2-C),hypoxia simulated 4500 meters altitude fifth level group(H2-5),hypoxia simulated 4500 meters altitude eighth level group(H2-8),hypoxia simulated 4500 meters altitude exhaustive group(H2-E).After 5 days of adaptation training,every groups performed incremental load exercise in the corresponding oxygen concentration environment.After completing the corresponding exercise level of each group,we immediately anesthetized and took the prefrontal cortex tissue of brain.HE staining was used to observe morphologic index,5,6-EET concentration in enzyme-linked immunosorbent assay,TRPV4 expression in immunohistochemistry,RT-qPCR was used to detect mRNA expression in TRPV4 and IP3 R,Fluo-4/AM fluorescence staining and Fura-2/AM fluorescence staining were used to determine intracellular calcium concentration.Results:(1)In H2-5 group,venous congestion was obvious,which was similar to the symptoms of N-8 group.H2-8 groups,such as meningeal loose edema and submeningeal venous congestion,were similar to those seen in the N-E group and the H-E group.(2)No matter the normal oxygen environment or the hypoxic environment,the 5,6-EET of each exercise load group had significant or very significant differences compared with those in the same environment control group.Compared the two hypoxic environment with the normal oxygen environment,the level of 5,6-EET was significantly higher.(3)With the increase of exercise load,the expression of TRPV4 in the prefrontal cortex of rats increased significantly,and the expression of TRPV4 in the hypoxia environment,each level of the exercise group was significantly higher than that of the normal oxygen group.(4)Whatever in normoxia or hypoxia,25m/min exercise can increase the rat prefrontal cortex IP3 R mRNA expression,hypoxia significantly increased the expression of IP3 R in prefrontal cortex of mRNA,and the changes are similar as TRPV4 channels,but significantly no better than the TRPV4 channel,especially in the H1 environment.(5)The results of calcium ion concentration showed that in the three environment,the eighth level group was significantly higher,and the exhaustion group was significantly lower than the eighth group,and the H2-8 was significantly higher than the N-8.ConclusionThe early onset of HbO2 and THb in the prefrontal cortex may be an important factor in the decrease of exercise ability in the acute hypoxia exercise.TRPV4 channels play an important role in the regulation of intracellular calcium concentration in the acute prefrontal cortex of acute hypoxic exercise,and thus provide a new improvement target for athletes on the plateau.