Reduced sympathetic outflow and adrenal secretory activity during a 40-day stay in the Antarctic

Autonomic Nervous Function During Whole-Body Cold Exposure Before and After Cold Acclimation

“…This change from the cold-induced elevation in low frequency power on Day 1 to the elevation in high frequency power on Day 10 suggests that at the sinus node level the sympathetic activation due to cold exposure is blunted during cold acclimation, and replaced to some extent by increased parasympathetic infl uence. This shift in autonomic nervous system activity resembles the results obtained from studies of over-wintering personnel in Antarctica ( 4,11 ). The increase in parasympathetic effects at the sinus node level may be due to a true increase in parasympathetic activity.…”

“…Changes in autonomic nervous system activity assessing HRV and hormonal secretion among over-wintering personnel in Antarctica have been followed previously. Those studies detected decreased sympathetic and increased parasympathetic activity during the residence, followed by a reduction in anterior pituitary and adrenal hormonal secretion ( 4,11 ). However, the presence of several concurrent stressors in these isolated environments makes it diffi cult to distinguish the effects of cold exposure.…”

Circadian Rhythm of Autonomic Cardiovascular Control During Mars500 Simulated Mission to Mars

“…A signifi cant reduction of the adrenal hormonal levels of the pituitary-adrenal hormonal axis and reduced sympathetic activity during the day was reported during a 40-d stay in the Italian Antarctic Station of Terra Nova Bay ( 7 ). Similarly, in the context of the Mars500 pilot study (Mars105), we observed that a 105-d period of confi nement was associated with an increase in parasympathetic activity during wakefulness.…”

Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

“…Besides, we observed a greater percentage decrease in NE and E at Zhongshan Station than Great Wall Station, which indicates a reduction of the sympathetic activity. Farrace et al (2003) had described a similar significant reduction of sympathetic outflow and adrenal secretory activity at the Italian Antarctic Station of Terra Nova Bay (74°42′ S), and they regarded this pattern as a trophotropic neurovegetative adaptive process. The negative correlation was found between catecholamines and negative mood in our subjects, consistent with other studies (Ressler and Nemeroff 2000;Fava 2003).…”