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Circadian rhythm disruptions affect response to cortisol


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Disruptions in circadian rhythms adversely affect responsiveness to

cortisol via changes to the glucocorticoid receptor (GR). This might be

related to the methylation issues with the GR in IBD I mentioned





Stress Resilience Returns With Feeling for Rhythm


ScienceDaily (Sep. 23, 2010) ? If your body releases cortisol with fixed

regularity then you can cope with stress better, says NWO-funded

researcher Angela Sarabdjitsingh. She investigated the rhythm of

corticosterone production in rats. This rat hormone is comparable to the

human stress hormone cortisol. Rats deal considerably less well with

stress if the pattern of corticosterone release changes. An irregular

release pattern is a characteristic of chronic stress and stress-related

diseases. It might therefore be possible to treat these by restoring the



The hormone cortisol has to activate other proteins in the body and

brain for a satisfactory response to stress. Yet Sarabdjitsingh

discovered that important genes are activated less as soon as the rat's

body is exposed to flattened corticosterone patterns. In a flattened

pattern individual pulses are no longer recognisable as there are no

more hourly peaks or troughs. That is interesting because conditions

such as depression are characterised by a flattened rhythm in the

cortisol release. Therefore it might be possible to treat such

conditions by using medicines to adjust the rhythm.


Every hour the adrenal glands release the stress hormone cortisol (in

rats corticosterone). However, disease or ageing can cause considerable

disruption to this hourly rhythm with the result that the body responds

less well to stress and pressure. Sarabdjitsingh investigated how the

rhythm influences the stress response and the resilience of the hormonal

and behavioural stress reaction. She also investigated if any changes in

the pattern took place in tissues influenced by the stress hormone.


Crucial protein


Besides discovering that the rhythm of corticosterone release is crucial

for a good hormonal and behavioural stress response, Sarabdjitsingh

found out which protein predominantly suffers under a disrupted rhythm:

the glucocorticoid receptor. This protein could therefore be an ideal

target for the treatment of stress and stress-related diseases.




Angela Sarabdjitsingh obtained these results by being the first to

combine a number of advanced techniques. These methods are now being

used by other research groups as well to explore the subject further.

Sarabdjitsingh carried out her unique research with a grant from the NWO

Mosaic programme. Mosaic is a grant programme that funds the PhD

research of students from ethnic minorities. Ethnic minorities are

underrepresented within science and NWO, as a strong proponent of

diversity, regrets the small number of role models. With Mosaic, NWO

wants to prevent scientific talent from being unnecessarily lost.



Story Source:


The above story is reprinted (with editorial adaptations by ScienceDaily

staff) from materials provided by NWO (Netherlands Organization for

Scientific Research), via AlphaGalileo.

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