The Effect Of PI3K-Akt Signal Transduction Molecules On Erythroblasts Apoptosis In Rats With Chronic Mountain Sickness

Objective In this study, we established rat models of CMS and researched theimpact of chronic hypoxia on apoptosis and expressions of Akt, Bcl-xl andcaspase-9proteins of erythroblasts. At the same time, the intervention function ofcelecoxib, which is Akt inhibitor, was observed in rats in vivo.Methods91healthy male Wistar rats from Lanzhou to Xining were involved inthis study. The80rats were randomly classified into four groups: normoxic group,hypoxia group, low dose of intervention group, high dose of intervention group,each group of20animals. The rats of Normoxic group were fed in Xining naturalconditions, the rats of other three groups were fed in a hypobaric chamber. After30days, the arterial blood was taken for gas analysis and blood cell analysis. Theplasma was separated and the levels of EPO and VEGF were detected by ELISA.The bone marrow mononuclear cells (BMMNCs) were isolated from bone marrowsolution which was collected from rats’ femurs. The apoptotic rate of BMMNCswas measured by FCM. After labeling of monoclonal antibodies, the apoptotic rateand expressions of Akt, Bcl-xl, and caspase-9in CD71+CD45-erythroblasts wereexamined by FCM. In addition, the pulmonary artery pressure was detected in6rats of normoxic group and5rats of hypoxia group in the last.Results The levels of HCT, HGB and RBC were significantly higher in hypoxiagroup, low dose of intervention group and high dose of intervention group thanthose in the normoxia group, respectively(all P <0.05). RBC count of the high doseof intervention group was less than those of hypoxia group and low dose ofintervention group (all P <0.05). The PLT of hypoxia group, low dose ofintervention group and high dose of intervention group were, respectively, lowerthan normoxia group (all P <0.05). WBC count in low dose of intervention groupwas significantly higher than those in normoxia group, hypoxia group and, highdose of intervention group (all P <0.05). The mean pulmonary arterial pressure inhypoxia group was significantly increased, compared with normoxia group. Theplasma EPO level in low dose of intervention group was lower than those innormoxic group, hypoxia group and highe dose of intervention group (all P <0.05). But there was no difference among normoxic group, hypoxia group and high doseof intervention group (P>0.05). The plasma VEGF level in the high dose ofintervention group was significantly increased, compared with that in the hypoxiagroup (P <0.05). The apoptosis rates of erythroblasts in hypoxia group, low dose ofintervention group and high dose of intervention group were significantly reduced,which compared with in normoxia group (all P <0.05). The Bcl-xl expression oferythroblasts was no difference among four groups. The Akt protein in normoxiagroup was significantly lower than that in hypoxia group (P<0.05). The caspase-9protein levels in normoxic group, hypoxia group and high dose of interventiongroup were markedly reduced, which compared with in low dose of interventiongroup (all P <0.05).Conclusions It is confirmed by the results of peripheral blood cytology index andpulmonary artery pressure determination that CMS animal model could be madesuccessfully by the method used in this study. The apoptosis of erythroblasts inCMS rat reduced, which might play certain role in erythrocytes excessivelyaccumulation in CMS. The expression of Akt, one of the major signalingmolecules in PI3K-Akt signaling pathway, was increased in erythroblasts of CMSrat, which may play a role in the mechanisms of reduced apoptosis. However, noobvious effect of celecoxib on apoptosis of erythroblasts was observed in CMS ratin this study.