The Effect of 7-Day Cold Water Acclimation on Autophagic and Apoptotic Responses in Young Males.

While cold acclimation can enhance thermoregulation in humans, the potential to improve cellular cold tolerance remains unknown. Thus, this work aims to evaluate the effect of a 7-day cold-water acclimation on the cytoprotective mechanism of autophagy in young males. Further, this work assesses changes in cellular cold tolerance by employing hypothermic ex vivo (whole blood) cooling prior to and following acclimation. Peripheral blood mononuclear cells are isolated before and after cold exposures on days 1, 4, and 7 of acclimation and following ex vivo cooling. Proteins associated with autophagy, apoptosis, the heat shock response, and inflammation are analyzed via Western blotting. Indicators of autophagic dysfunction paired with increased apoptotic signaling are prevalent at the beginning of acclimation. At the end of acclimation, autophagic activity increased while apoptotic and inflammatory signaling decreased. Although an elevated heat shock response is observed following cold exposure, this does not change throughout the acclimation. Further, improvements of autophagic activity are observed during ex vivo cooling along with a reduction of apoptotic signaling, albeit still elevated compared to basal levels. This work shows that 7-day cold acclimation elicits improvements in cellular cold tolerance in young males through enhanced autophagic responses concomitant with reductions in apoptotic signaling.