All biological processes recurring daily,
also known as circadian-controlled processes, are governed by the so-called
circadian clock, a self-sustained time-keeping system controlling rhythmic
behavioral, biochemical and physiological processes. In other words, the
circadian clock affects the sleep-wake cycle, body temperature, hormone secretion,
enzyme activity, renal blood flow, heart rate, and various other physiological
activities as well as the regulation of the cell cycle and of apoptosis.
In mammals, the
cogwheels of this clock are the so-called clock genes which control their own
expression via several feedback loops. One of these genes is hPER1,
a clock gene which disposes of a glucocorticoid-responsive element and might
therefore be influenced by glucocorticoids.
In humans, stress
is associated with an increase in the glucocorticoid cortisol and is seen as a
major factor in the etiology of numerous mental health problems. For this
reason, the goal of this paper was to investigate the putative
cortisol-mediated influence of acute and chronic psychosocial stress on the
gene expression of hPER1 as well as hPER2, another
related clock gene from the same family.
The authors applied
laboratory psychosocial stress to thirty-one healthy men and measured cortisol
as well as mRNA levels of hPER1 and hPER2. The
investigation took place on two consecutive days in the laboratories of the
Department of Clinical Psychology and Psychotherapy of the University of
Zurich. mRNA levels of hPER1 as well as hPER2 were assessed in oral mucosa and analyzed in the biochemical
laboratory of the Psychological Institute of the University of Zurich. The quantitative real-time PCR was conducted and cortisol samples
were collected using Salivettes.
The main findings
suggest that acute psychosocial stress influences the expression of hPER1
and hPER2 dependent on the subjective experience of chronic stress.
Therefore, it’s concluded that the reactivity to acute stress on the gene
expression level of these two genes differs significantly between subjects with
high chronic stress compared to subjects with low chronic stress.
Article by Elvira
A. Abbruzzese, et al, from Switzerland.
Full access: http://mrw.so/sbFo2
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