Responsible: M. Sc. Türkan Yurtsever
In the frame work of the research focus "Psychobiology of Stress" I am interested in the inter-relationship of the physiological stress system (hypothalamus–pituitary–adrenal (HPA) axis) and the circadian clock system.
The HPA axis physiologically reacts to unexpected stress stimuli through various sensory organs and adjusts the organ activities for survival. The circadian clock system senses the day and night changes and synchronizes the physical activities like behavior, food intake and sleep to a 24-hour period. These systems both depend on the action of trancription factors at the genome level and show mutual interactions. Furthermore, both systems influence the activity and function of the central nervous system and peripheral tissues.
Dysregulation in either of these systems lead to similar pathologic conditions, including metabolic and cardiovascular diseases as well as psychiatric, autoimmune, allergic and sleep disorders. All these problems are provoked by the phase misalignment in the master and/or peripheral clock occurring acutely with jetlag and chronically with night shift work. The understanding of circadian timing and how it affects physiological mechanisms and disease development open new opportunities for drug discovery and developments in the chronopharmacology.
The steroid hormone cortisol as an end-effector of the HPA axis and Period genes (PER1, PER2 and PER3) as circadian clock genes are in the main focus of my studies. I determine the mRNA expression of period genes in peripheral blood mononuclear cells under baseline and after stress in humans. The comparison of the Period gene expression patterns under different conditions as well as their regulation after certain hormonal treatments can give us some clues to understand the molecular interactions of the HPA axis and the circadian clock system, and their interplay in the development of human diseases.