The Correlation between Serum Cortisol Concentration in Mammals and the Level of Global Seismic Activity

A positive correlation was found between the level of global seismic activity and dynamics of cortisol concentration in blood serum of male rabbits (r=0.33, p=0.01) and Campbell's dwarf hamsters (r=0.38, p=0.04). For a small group of healthy volunteers (n=5), we also found a positive correlation between cortisol levels and the number of major earthquakes, excluding aftershocks (r=0.36, p=0.009) and a negative correlation with IL-18 levels (r=-0.28, p=0.04). The body response to earthquakes is not delayed, and the numerous aftershocks do not seem to affect the biological indicators under study. These facts showed that the earthquakes themselves do not affect the cortisol level via the changes of the environmental parameters. In contrast, the underlying biotropic factor is an unknown trigger responsible for an increase in the number of potent earthquakes. Evidently, it is important to take into account the level of global seismicity as a marker of this trigger provoking the rise of glucocorticoid hormones.