The findings emerging from antibiotic, probiotic, infection and germ-free animal studies strongly suggest that the microbiota residing in the gut play an important role in the development of various aspects of brain functions, in particular activation of the hypothalamus-pituitary-adrenal (HPA) axis and anxiety. These effects might play a role not only in adulthood but perhaps to a greater extent in the early postnatal life, when the initial establishment of the gut microbiota is reached. Accumulating clinical evidence suggests that a disordered balance amongst gut microbiota might be associated with or even be a causal factor for various illnesses as varied as IBD, irritable bowel syndrome (IBS) and psychiatric illnesses. Probiotics can modulate the stress response and improve mood and anxiety symptoms in patients with chronic fatigue and IBS. In light of the mutual relationship that exists between the microbiota and stress response, it seems that early postnatal life is a crucial moment for possible interaction between gut microbiota and HPA axis, because this period of life is critical for HPA axis maturation, programming of the neuroendocrine stress response and is also the period of the initial establishment of the core gut microbiota.

 The aim of this project is

 (1) to compare the response to psychosocial stress in conventional or germ-free mice during early postnatal life and in adulthood.

(2) to determine whether gut microbiota and probiotics are able to modulate the feedback regulation of HPA axis by psychosocial stress

(3) to establish whether the modulation of secondary lymphoid organs by psychosocial stress depends on gut microbiota

This is a new project started in 2015. The project is investigated in cooperation with the Laboratory of Gnotobiology of the Institute of Microbiology of the Czech Academy of Sciences