As the second spotlight for the European Biological Rhythms Society - EBRS - congress, taking place in Luebeck in Northern Germany from the 24th to 28th of August 2025, Prof. Henriette Uhlenhaut (Professor of Metabolic Programming at the Technical University of Munich, TUM, and Director of the Institute for Diabetes and Endocrinology at the Helmholtz Center in Munich) talks about glucocorticoids (such as cortisol), commonly known as the "stress hormones". We discuss how glucocorticoids regulate gene expression at many different sites within our body and how they play different roles in metabolism, immune responses and inflammation. We highlight that glucocorticoids are secreted in a strongly circadian manner and describe which kind of events can acutely increase cortisol levels independent of rhythmic secretion. In contrast to common belief, Henriette explains why high cortisol levels are not always a bad thing, highlighting important links to fasting and caloric restriction. Lastly, Henriette shares her experience attending previous EBRS congresses and why you should consider joining it this year.

Chapters:

(0:00:38) Introducing the EBRS 2025 spotlights

(0:03:39) Henriette Uhlenhaut

(0:06:08) Basics of glucocorticoids

(0:16:26) Circadian rhythm of glucocorticoids

(0:23:21) How to shift the rhythm?

(0:28:49) What events evoke a cortisol response?

(0:36:45) Stress hormones - a fair description?

(0:39:08) Cortisol vs. melatonin

(0:42:16) Link to caloric restriction

(0:50:25) EBRS experience

(0:53:45) EBRS teaser

(0:56:30) Advice for early career researchers

(1:00:28) Funny anecdote

(1:06:35) Outro

Studies that Henriette and I refer to:

Studies on the % of genes that are regulated by glucocorticoids (liver, immune cells etc.): 

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.0010016 

https://pmc.ncbi.nlm.nih.gov/articles/PMC2792167/ 

https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2020.572981/full 

Glucocorticoids universally regulate clock genes such as Per1 inevery cell type: 

https://doi.org/10.1093/emboj/20.24.7128

https://doi.org/10.1210/en.2012-1486

The more fasted you are, the higher your cortisol levels: 

https://doi.org/10.3109/10253890.2015.1121984

Light stimulates ACTH secretion = activation of thehypothalamic-pituitary-adrenal axis: 

https://academic.oup.com/edrv/article/41/3/bnaa002/5736359

Shifting the last meal of the day shifts cortisol secretion: 

https://pmc.ncbi.nlm.nih.gov/articles/PMC5483233/

Shifting sleep time shifts cortisol secretion: 

https://pmc.ncbi.nlm.nih.gov/articles/PMC11899833/

If the feeding time of mice is reversed, there are two peaks incorticosterone secretion: one peak driven by the central clock, and one driven by food availability: 

https://www.embopress.org/doi/full/10.1093/emboj/20.24.7128

Exercise can change cortisol secretion, also locally in tissues: 

https://link.springer.com/article/10.2165/00007256-200535050-00003#Sec4 

https://journals.physiology.org/doi/full/10.1152/japplphysiol.00108.2002

Maternal stress impacts the newborn: 

https://doi.org/10.1016/j.biopsych.2010.05.028

Caloric restriction boosts the cortisol amplitude: 

https://www.cell.com/cell-reports/fulltext/S2211-1247(15)01483-7

Symptoms of rheumatoid arthritis, cough and fever show 24-hourrhythms: 

https://link.springer.com/chapter/10.1007/978-3-642-78734-8_35 

https://www.sciencedirect.com/science/article/pii/S0091674995702121#bib27 

https://www.tandfonline.com/doi/abs/10.3109/07420528809067786

Beyond 12 to 14 hours of fasting, ketone bodies are built based on liver fat and adipose tissue: 

https://link.springer.com/article/10.1007/s10545-014-9704-9 

https://www.cell.com/trends/endocrinology-metabolism/fulltext/S1043-2760(23)00215-1 

Ketogenic diet on rhythmicity in transcriptomes of metabolic organs

https://www.ncbi.nlm.nih.gov/pubmed/28877456

Contact:

Henriette’s research group homepage: https://www.mls.ls.tum.de/metabolism/home/