Effects of Interval and Continuous Exercise Regimens on CD4 lymphocyte Apoptotic and Autophagic Responses to Hypoxic Stress

Abstract

This study investigates how interval and continuous exercise regimens affect CD4 lymphocyte apoptotic and autophagic responses to hypoxic stress. Twenty sedentary males were randomly divided into moderate continuous exercise training group (MCT; 60% VO2max, n=10) and aerobic interval exercise training group (AIT; 3-minute intervals at 80% and 40% of VO2max, n=10) for 30 minutes per day, 5 days per week for 5 weeks. The results demonstrated that acute 12%O2 exercise enhanced apoptosis (phosphotidyl serine exposure) by promoting phosphorylation of Bcl-2 and activations of caspase-9 and -3, as well as, suppressed autophagy (acridin orange staining) by down-regulating expressions of m-TOR, Atg-1, Atg-12, and LAMP-2 in CD4 lymphocytes. However, 5 weeks of MCT and AIT decreased levels of phosphorylated Bcl-2 and active-form caspase-9 and -3 in CD4 lymphocytes, consequently suppressing the cell apoptosis induced by the 12%O2 exercise. Simultaneously, the two regimens promoted autophagy of CD4 lymphocytes at rest or following the 12%O2 exercise, which responses were accompanied by increased cellular Beclin, Atg-1, Atg-12, LC3B, or LAMP-2 level. Therefore, we conclude that both MCT and AIT regimens alleviate apoptosis and promote autophagy of CD4 lymphocytes during hypoxic exercise, which may, in turn, reduce the risk of immune suppression evoked by hypoxic stress.