Among the models of mental stress, the most intensive neuroendocrine activation has been observed in tests based on public speech. Frequently, the speech task is done standing in upright position following a period of sitting during which the subject has been preparing his performance. We tested whether simulation of postural changes, which occur during public speech task, activates neuroendocrine systems that could interfere with the effect of psychosocial stress (1). Plasma cortisol, ACTH and adrenaline increased during public speech performed in standing but not in response to postural changes only. The simulation of postural changes was associated with increases in the hear rate, blood pressure, plasma noradrenaline, aldosterone and renin activity, which were similar to those observed during the complete public speech task though the alterations were of much smaller magnitude. Thus, changing the sitting and standing position seems to interfere with neuroendocrine effects of the mental component of public speech tasks. The results of a public speech task study performed under real-life conditions, namely the first oral presentation of young neuroscientists at a scientific meeting also showed a contribution of changes in body posture. Moreover, we observed clear gender differences. In another group of healthy volunteers of both genders, a combination of a 30 min orthostatic stress and a mental stressor (Stroop test) failed to modify salivary cortisol. However, salivary aldosterone showed a significant increase in response to these two stressor, particularly in women in the luteal phase of the menstrual cycle. Our results show that daily stress situations or laboratory models combining mental stressors and changes in body posture have to be interpreted as complex stress stimuli.

(1) Mlynarik M., Makatsori A., Dicko I., Hinghofer-Szalkay H.G., Jezova D.: J Physiol. Pharmacol. 58, 95-103, 2007.

The work was supported by the grants of SAIA and CENDO.