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Cutting-edge science for health

Laboratory of Biological Rhythms

Laboratory of Biological Rhythms From the left: Central clock in the brain - the suprachiasmatic nucleus (SCN); glial cells in the SCN; lcocomotor activity records of rats; neurons in hippocampus; clock gene expression in the SCN with a phase plot.

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In the center of our interest is the endogenous time-keeping system, circadian clock of mammals, including humans. The system temporally regulates rhythmic processes in our body so that they take place at the proper time of day and are optimally synchronized relative to each other.

A failure of the temporal regulation has a negative impact on human health. Using in vivo and in vitro models, we study the molecular mechanisms underlying the circadian clock as well as the resulting physiological and behavioral rhythms.

We focus on the following questions:

  • What are the mechanisms for entraining (synchronizing) the circadian system and what are the consequences of its failure?
  • How does the circadian system develop and how is it being entrained during ontogeny?
  • How is the circadian system of humans entrained in real life conditions, both in health and in disease?



Fig. PER2 protein in the SCN, 7 days ex vivo recording.


The ontogenesis of the biological clock of laboratory rat

The mammalian biological clock initiates its ontogenesis already during embryonic development in the maternal uterus. Newborn mammals are equipped with clock running in accordance with the maternal clock. We focus on investigating when and how do the newborn clock develop and entrain.  More



Sládek; Martin - Liška; Karolína - Houdek; Pavel - Sumová; Alena . Modulation of single cell circadian response to NMDA by diacylglycerol lipase inhibition reveals a role of endocannabinoids in light entrainment of the suprachiasmatic nucleus . Neuropharmacology. 2021; 185(Mar 1)); 108455 . IF = 5.250 [ASEP] [ doi ]
Ralph; M. R. - Shi; S.-Q. - Johnson; C. H. - Houdek; Pavel - Shrestha; T. C. - Crosby; P. - O´Neill; J. S. - Sládek; Martin - Stinchcombe; A. R. - Sumová; Alena . Targeted modification of the Per2 clock gene alters circadian function in mPer2(luciferase) (mPer2(Luc)) mice . PLoS Computational Biology. 2021; 17(5)); e1008987 . IF = 4.475 [ASEP] [ doi ]
Lužná; Vendula - Liška; Karolína - Sládek; Martin - Sumová; Alena . Hormonal fine-tuning of clock in decidual region of mouse placenta by dopamine; melatonin; insulin; leptin and ghrelin . Placenta. 2021; 108(May); 55-63 . IF = 3.481 [ASEP] [ doi ]
Lužná; Vendula - Houdek; Pavel - Liška; Karolína - Sumová; Alena . Challenging the Integrity of Rhythmic Maternal Signals Revealed Gene-Specific Responses in the Fetal Suprachiasmatic Nuclei . Frontiers in Neuroscience. 2021; 14(Jan 7)); 613531 . IF = 4.677 [ASEP] [ doi ]
Liška; Karolína - Sládek; Martin - Čečmanová; Vendula - Sumová; Alena . Glucocorticoids reset circadian clock in choroid plexus via period genes . Journal of Endocrinology. 2021; 248(2); 155-166 . IF = 4.286 [ASEP] [ doi ]
Sumová; Alena - Čečmanová; Vendula . Mystery of rhythmic signal emergence within the suprachiasmatic nuclei . European Journal of Neuroscience. 2020; 51(1); 300-309 . IF = 3.386 [ASEP] [ doi ]
Sládek; Martin - Röschová; Michaela - Adámková; V. - Hamplová; Dana - Sumová; Alena . Chronotype assessment via a large scale socio-demographic survey favours yearlong Standard time over Daylight Saving Time in central Europe . Scientific Reports. 2020; 10(1)); 1419 . IF = 4.379 [ASEP] [ doi ]
Dodge; A. - Peters; M. M. - Greene; H. E. - Dietrick; C. - Botelho; R. - Chung; D. - Willman; J. - Nenninger; A. W. - Ciarlone; S. - Kamath; S. G. - Houdek; Pavel - Sumová; Alena - Anderson; A. E. - Dindot; S. V. - Berg; E. L. - O´Geeen; H. - Segal; D. J. - Silverman; J. L. - Weeber; E. J. - Nash; K. R. Generation of a Novel Rat Model of Angelman Syndrome with a Complete Ube3a Gene Deletion . Autism Research. 2020; 13(3); 397-409 . IF = 5.216 [ASEP] [ doi ]
Sládek; Martin - Houdek; Pavel - Sumová; Alena . Circadian profiling reveals distinct regulation of endocannabinoid system in the rat plasma; liver and adrenal glands by light-dark and feeding cycles . Biochimica Et Biophysica Acta-Molecular and Cell Biology of Lipids. 2019; 1864(12)); 158533 . IF = 3.367 [ASEP] [ doi ]
Sládek, Martin - Sumová, Alena . Modulation of NMDA-Mediated Clock Resetting in the Suprachiasmatic Nuclei of mPer2(Luc) Mouse by Endocannabinoids . Frontiers in physiology 2019, 10(Mar 29)), 361 . IF = 4.519 [ASEP] [ doi ]

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prof. PharmDr. Alena Sumová, DSc.

Head of the Laboratory

Martin Sládek, PhD.

Deputy Head of the Laboratory

prof. RNDr. Helena Illnerová, DrSc.

professor emeritus

Lenka Polidarová, PhD.

postdoc on maternal leave

RNDr. Pavel Houdek


Petra Honzlová

grad student

Kateryna Semenovykh

grad student

Milica Drapšin

grad student

Philipp Greiner 

grad student

Michaela Kudrnáčová

grad student

Tereza Mičkerová

grad student

Eva Tlustá