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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 - Klusáček; Jan - Hamplová; Dana - Sumová; Alena . Population-representative study reveals cardiovascular and metabolic disease biomarkers associated with misaligned sleep schedules . Sleep. 2023; 46(6)); zsad037 . IF = 5.6 [ASEP] [ doi ]
Liška; Karolína - Dočkal; Tereza - Houdek; Pavel - Sládek; Martin - Lužná; Vendula - Semenovykh; Kateryna - Drapšin; Milica - Sumová; Alena . Lithium affects the circadian clock in the choroid plexus – A new role for an old mechanism . Biomedicine & Pharmacotherapy. 2023; 159(March)); 114292 . IF = 7.5 [ASEP] [ doi ]
Honzlová; Petra - Sumová; Alena . Metabolic regulation of the circadian clock in classically and alternatively activated macrophages . Immunology and Cell Biology. 2023; 101(5); 428-443 . IF = 4.0 [ASEP] [ doi ]
Honzlová; Petra - Semenovykh; Kateryna - Sumová; Alena . The Circadian Clock of Polarized Microglia and Its Interaction with Mouse Brain Oscillators . Cellular and Molecular Neurobiology. 2023; 43(3); 1319-1333 . IF = 4.0 [ASEP] [ doi ]
Vejražková; D. - Vaňková; M. - Včelák; J. - Krejčí; H. - Anderlová; K. - Tura; A. - Pacini; G. - Sumová; Alena - Sládek; Martin - Bendlová; B. The rs10830963 Polymorphism of the MTNR1B Gene: Association With Abnormal Glucose; Insulin and C-peptide Kinetics . Frontiers in Endocrinology. 2022; 13); 868364 . IF = 5.2 [ASEP] [ doi ]
Shi; S.-Q. - Mahoney; C. E. - Houdek; Pavel - Zhao; W. - Anderson; M. P. - Zhuo; X. - Beaudet; A. - Sumová; Alena - Scammell; T. E. - Johnson; C. H. Circadian Rhythms and Sleep Are Dependent Upon Expression Levels of Key Ubiquitin Ligase Ube3a . Frontiers in Behavioral Neuroscience. 2022; 16(Mar 23)); 837523 . IF = 3.0 [ASEP] [ doi ]
Liška; Karolína - Sládek; Martin - Houdek; Pavel - Shrestha; N. - Lužná; Vendula - Ralph; M. R. - Sumová; Alena . High Sensitivity of the Circadian Clock in the Hippocampal Dentate Gyrus to Glucocorticoid- and GSK3-Beta-Dependent Signals . Neuroendocrinology. 2022; 112(4); 384-398 . IF = 4.1 [ASEP] [ doi ]
Honzlová; Petra - Novosadová; Zuzana - Houdek; Pavel - Sládek; Martin - Sumová; Alena . Misaligned feeding schedule elicits divergent circadian reorganizations in endo- and exocrine pancreas clocks . Cellular and Molecular Life Sciences. 2022; 79(6)); 318 . IF = 8.0 [ASEP] [ doi ]
Greiner; Philipp - Houdek; Pavel - Sládek; Martin - Sumová; Alena . Early rhythmicity in the fetal suprachiasmatic nuclei in response to maternal signals detected by omics approach . PLOS Biology. 2022; 20(5)); e3001637 . IF = 9.8 [ASEP] [ doi ]
Abbondanza; Alice - Bas; Irina Ribeiro - Modrák; Martin - Čapek; Martin - Minich; Jessica - Tyshkevich; Alexandra - Naser; Shahed - Rangotis; Revan - Houdek; Pavel - Sumová; Alena - Dumas; S. - Bernard; V. - Janíčková; Helena . Nicotinic Acetylcholine Receptors Expressed by Striatal Interneurons Inhibit Striatal Activity and Control Striatal-Dependent Behaviors . Journal of Neuroscience. 2022; 42(13); 2786-2803 . IF = 5.3 [ASEP] [ doi ]

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Prof. PharmDr. Alena Sumová, DSc.

Head of the Laboratory  ORCID iD icon

Martin Sládek, PhD.

Deputy Head of the Laboratory

prof. Helena Illnerová

professor emeritus

RNDr. Pavel Houdek


Milica Drapšin

grad student

Fyziologický ústav AV ČR - Vývojová kardiologie

Dmytro Semenovykh 

grad student

Kateryna Semenovykh

grad student

Tereza Dočkal

grad student

Eva Tlustá